Army Aviation Digest - Mar 1983

8/12/2019 Army Aviation Digest - Mar 1983

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Richardditor


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ircraf taccidents have been striking outyear. Because you have been pitching in, weve been able to break the aviation accident hitof 21 March, 1983, we sustained

24 accidents and 15 fatalities for the sameyear.YOU AND YOU AND YOU can take the creditYoube ACCIDENT FREE IN 83 andin the process, which is a

Our work isn't f inished yet; we have six inningsgo. However, there are some excellentin this igest that will help you be anMr. Charles C Cioffi and Lieutenant ColonelE. S. Merritt have put a lot of needed in-Tail Rotor Control Power:'

the OH-58 tai l rotor. We must be aware of therotor control problems and adoptures which will minimize the possibility ofAnother place constant awareness is requiredcan't think of any place in our business whereisn't ) is Chief Warrant Officer, CW3, Ernest D.

Butnuclear, biological, chemical (NBC) ofstuff I had never made any

twice before, if theMr.with sometruths in this article.An outstanding example of the smartness Ito above has been descri bed by Major

P Jones in Night Vision GogglesIt

significant improvement over theemade remedies' ....-such as taping flash-

lights or other objects to the helmet-that havebeen used in an effort to offset the impossibleto-live-with weight distribution of the AN/PVS-5NVG.So far, the articles I've highlighted have dealtwith positive decisions Army Aviation personnelhave made. The other side of the coin is treatedby Captain Thomas Richard Biang in "Pilot Error,a Decision:' What causes us to make decisionalerrors? Can they be prevented? Captain Biangpresents some fascinating insight on how thehuman mind works in this area.Decisional errors are not a problem for the people who serve in the U.S. Army Aviation Detachment, Japan, at least not those that lead to aircraft accidents. That uni t has been accident-freefor 14 years Chief Warrant Officer, CW2, Roy G.Wise notes that fact as well as others in "NoRelics of the Past:' a report on the Army Aviationmission in Japan.As is readily apparent, there is much goodreading in this issue of your magazine. So don'tmake an error-decide to read all of it.

Major General Carl H. McNair Jr.Commander, U.s. Army Aviation CenterFort Rucker, AL


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I OLWWING Preliminary Report of Aircraft Mishaps(PRAMs) illustrate a well knownbut poorly understood problem withthe tail rotor system on the OH-58family of helicopters. The problemnormally is referred to as loss of tailrotor control authority.PRAM number 1 stated: The ir-craft was observed in a spin approx-imately 50 feet pbove the treesbefore it crashedPRAM number 2 reported: Theaircraft departed a field site fromwhich it had pi ked up passengersand was circling the field site whenit appeared to fallBoth of the above were major accidents, but their common tie lies intheir almost classic portrayal of theloss of tail rotor control authorityphenomenon. How does that track?You can' t tell that from the PRAMsyou say Well, let's look at each ofthese accidents a little closer.

LTC Donald E S MerrittReadiness Project OfficerScout/Observation HelicoptersDirectorate for Systems ManagementUSATSARCOMSt. Louis MO

Mr. Charles C CioffiChief Rotary Wing BranchAircraft Systems Engineering DivisionDirectorate for Systems Engineeringand DevelopmentUSAAVRADCOMSt. Louis MO

MARCH 1983

-PRAM 1The OH-58C was assigned a mission which required flight at lowlevel going from point to point. Theestimated gross weight was 3,000pounds; pressure altitude: plus 1 390feet; free air temperature: plus 30degrees centigrade; wind: estimatedfrom the southeast at 20 knots.Upon approaching the start point,the aircraft was slowed to less than50 knots awaiting clearance to continue. The pilot initiated a righthand turn for entry into holdingwhile still slowing. The holding turnwas continued after completion ofthe first 360-degree turn at whichtime the tail seemed to weathervaneinto the wind and the aircraft madean almost 180-degree spin in the airaround the mast. The pilot pushedin left pedal, added a little forwardcyclic and added a small amount ofpower trying to gain a little forwardairspeed. This seemed to aggravatethe situation and the aircraft begana fast rate of spin to the right. Leftpedal didn't seem to do anything. Bythis time, the aircraft had experienced 8 to 10 360-degree turns and wasabout 75 feet above the trees. Withno place for a forced landing andnot enough control over the aircraftto get to any landing area, the pilotmade the decision to hold the collective pitch in place. The main rotorsystem began to bleed off and cycliccontrol was lost as the aircraftentered the trees.

P R M ~n OH-58A pilot, on a day visualflight rules training mission, wasassigned to participate in a site

survey which required low-levelflight. After takeoff, at about 100feet above ground level, he began aright turn while reducing airspeedbelow effective translational lift.The right turn placed the aircraft ina 16 to 25 knot tailwind condition.Because of the low forward airspeed, the right turn, a high grossweight of 2,961 pounds, and the tailwind, the aircraft began to settle.To check the descent, the pilot increased his demand for power, exceeding the power available. Mainrotor revolutions per minute (rpm)bled off and the aircraft continuedto descend. The tail rotor becameineffective because of the power demand. The aircraft began to spin,completing two turns before hittingthe ground.

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The purpose of this article isto provide OH-58 pilots with information on the phenomenon knownas loss of tail rotor control authority while addressing the limitationsof the tail rotor system.The subject of 'the OH-58 tailrotor and its effectiveness or lackthereof is a frequent discussiontopic of Army OH-58 pilots. Severalarticles have been published ex-plaining the tail rotor problem.Recently, a blue ribbon panel waschartered by U.S. Army Troop Support and Aviation MaterielReadiness Command, St. Louis,M0, to investigate the cause andpossible courses for correction ofthe OH-58/T63 engine droop orpower loss problem.In reviewing power droop incident data and discussing these problems, it became evident that someof these problems may have beendue in part to the OH-58 tail rotor,or more importantly, the degree oftail rotor control power. Further,some of the cases mentioned werenot power loss problems, but morein the area of inadequate tail rotordirectional control for the situationthe OH-58 was in at that point intime.The OH-58 is not a pure militaryhelicopter; it was procured as an

*FlightFax , Volume 6 No. 46 dated 13 September1978, subject: OHS8A Tail Rotor StalLU.S. Army Aviation Digest, September 1977, How toCrash by the Book.U.S Army Aviation Digest, November 1978, OHS8Tail Rotor StalLU.S. Army Aviation Digest, June 1980 Tail RotorBreakaway .U.S. Army Safety Center message, 24192SZ October1978, subject: Inadequate Tail Rotor Thrust inOH58A Aircraft.U.S. Army Aviation Digest, December 1982, OH58Power Droop.Copies of Digest articles are available upon request.Write Editor, U S . Army Aviation Digest, P.O. DrawerP, Ft. Rucker, AL 36362.

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off-the-shelf Federal Aviation Administration certified helicopter andintroduced into the Army's inventory with certain Army militaryequipment and some changes fromits commercial counterpart, but theOH-58A basically was the same asits commercial version.Most military helicopters are procured and tested to Military Specification MILH-850lA, GeneralRequirements for Helicopter Flyingand Ground Handling Qualities.Had the OH-58A been required tomeet a full MILH-850IA, it wouldnot have the tail rotor configurationit has today; in addition, theOH-58C would not only require adifferent tail rotor, but possiblysome form of a stability augmentation control system.The reason for this MilitarySpecification requirement is an attempt to provide the user with aflight envelope which will cover thebasic spectrum where military helicopters will be used; requirementsover and above the basic spectrumare added in the contract specifications for a particular helicopter.

f you refer to the flight manualfor the OH-58A or OH-58C, youwill note a section on hoveringlimitations in chapter 5, entitled,Operating Limits and Restrictions. There are two DirectionalControl Margin charts in themanuals and these define the areaswhere safe operation can be conducted. (NOTE: These charts arenot to be used for out-of-groundeffect flight but only for in-groundeffect hover.) They depict the areawhere safe operation will exist witha 10 percent pedal control margin.This margin is needed in order toprovide a safety factor to accountfor many variables such as amarginal engine, a sudden windchange, slight out-of-rig condition,etc. Whenever operating in the

Yellow area, the safety margin isnot available and problems couldexist with regard to directionalcontrol.As an OH-58 pilot, you should befamiliar with TB55-1520-228-20-29,a technical bulletin which was issuedafter OH-58s were found withsignificant loss of left pedal bladeangle due to improper rigging. Youshould be aware that even with proper rigging, the OH-58 cannot meetthe control requirements of MILH-850IA. Therefore, any misrigging will correspondingly degradethe system and therefore the chartsin chapter 5 of the flight manual willnot reflect your actual OH-58capabilities.The tail rotor of a conventionalhelicopter with a single rotorgenerally consumes 8 to 15 percentof the engine power under hoveringconditions and somewhat less 3 to7 percent) under forward flight conditions. The tail rotor thrust fornormal no-wind hover can beestimated as follows:

tailrotorthrlst - lIai rotor lorq el n l l ~ frOIi center lineof lIain rolor 1 ce lerIi e of lail rolor

Another point which needsclarification is the term tail rotorstal l and how it may be used todescribe certain occurrences in theOH-58. f you refer to a classicalairfoil characteristics chart (figureI), you will note that as the angleof attack is increased, the coefficient of lift also will increase (moretail rotor thrust in this case isachieved by increasing the tail rotorblade angle). This relationship ismaintained until at some point thereis no increase in lift for an increasein angle of attack. Ultimately, the

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urve slopes downward and thusess lift is experienced, and finallyo more lift is produced since theirfoil has experienced (the classicalerm) stall.The given lift produced for aiven blade angle, described above,is with respect to the relative wind.It is presumed that the wind isdirected normal to the airfoil. f hewind s direction changes, then theperceived blade angle of attack alsowill change. Through this mechanism, we would then experienceblade stall at a tail rotor blade angleother than would normally beexpected.

In order for a helicopter to hover,the main rotor thrust (lift) mustequal the weight of the helicopter;if the thrust is greater than theweight you will climb, if thrust is lessthan the weight you will descend.The thrust of a rotor blade in simple terms is:

. rotor bladet ~ r s t X air X dis X u t l a r- (oeffid dllsity area Yllodty

From the above formula, it can beseen that for a given situation at aspecific point in time, the only wayto increase thrust would be tochange the thrust coefficient or theblade speed, since all other factorswould be constant.Since the OH-58 (or any turbinehelicopter) generally operates at afixed blade speed, you must lookfurther to determine how to increasethrust. Thrust coefficient is a termwith dimensions; this term variesdirectly with the blade angle of attack. Therefore, to increase thrust(where blade speed is essentiallyconstant), you increase blade angleof attack. However, for a givensituation, if you only increase bladeangle of attack, you must also increase power to the rotor if youwant additional lift. f you couldmanually increase only the OH-58blade angle and hold all other factors constant, the rotor would slowdown. Thus, if you want to get anincrease in lift you increase bladeangle while increasing engine

FIGURE : Classical simple airfoil curve

maximumcoefficientof li t point

stallpoi nt

angle of attack

power. Conversely, if you only increase blade angle and hold enginepower constant-the rotor speeddecreases. f rotor speed thusdroops-obviously, lift decreasesand the aircraft descends.

In the OH-58 as you increaseblade collective pitch (blade angle),the engine power is increasedautomatically through the flightcontrols systems. Let s assume yourT63 engine is peaked-out at maximum power, then if you increaseblade angle, the blade speed slowsdown and the aircraft eventuallydescends if all other factors are heldconstant. Since a helicopter-orrotary wing vehicle- hangs by itsmain rotor as opposed to a fixedwing, which indirectly uses power tomove the wings through the air tocreate the lift required to sustainflight, the helicopter s flightcharacteristics by their very naturebecome much more directly relatedto the powerplant and thepowerplant operating characteristics.The thrust of the tail rotor variesdirectly with the tail rotor speed (seeTail Rotor Breakaway, page 40,

June 1980 Aviation Digest . Thenormal OH-58A operating range is101 to 103 percent; the maximumdesign thrust for the tail rotor isproduced at 103 percent enginespeed.Whenever the OH-58A is in anincreased engine power demandcondition, the main rotor speed maydecrease below 330 rpm before theengine governor acts to increase themain rotor speed .

The main rotor is driven by theengine through the main transmission from a driveshaft at the frontof the engine, the tail rotor is alsodriven by a power takeoff point onthe engine through the tail rotorshaft and tail rotor gearbox. Therefore, if the main rotor speed droops,

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then the tail rotor speed must alsobe drooping (speed decreasing).The available thrust of theOH-58A tail rotor (and/or its ability to counteract the main rotor torque effect) is at its maximum whenthe main rotor is at 103 percent (seefigure 2). Note as the main rotorspeed is decreased, the maximum

thrust which the OH-58A tail rotorcould produce is also decreased (ifall other factors are held fixed).Recalling the rotor thrust formula, note with a decreasing speed(blade angular velocity) and a fixedthrust coefficient, you obtain lessrotor thrust at decreasing speeds.

The purpose of figure 2 is toshow, for example, if for somereason you let the main rotor speeddroop 3 percent or to approximately 100 percent NR the tail rotor'sability to counteract the mainrotor's torque has decreased by 9percent (actually a fraction over 9percent). What this tells you is thatwhen you let the main rotor droop3 percent, you need 9 percent moretail rotor torque to maintain thesame fixed conditionIn order to provide the pilot withan indication of a low main rotorrpm condition, an audio and visualwarning is given whenever the OH-

FIGURE 2: OH58A rotor sP 8ed effect ontall rotor capability

tail rotor capability to counteractmain rotor torque _' co


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ping, see AMC Pamphlet AMCP706-201, para 6-3.) To explain whatthis means, let's suppose you werein a condition in which you neededto input more tail rotor control.First, you perceive this condition, soyou add tail rotor pedal to correctit. Because the OH-58 has negligible damping, a rotational rate buildup results.Since it is not dampened, the normal point when you perceive theneed to neutralize is actually whileyou are in fact accelerating-andwhat results is not neutralizing butadding an opposite input todecrease the acceleration. Thus, youget into the high pilot workloadregime which is common to theOH-58.The directional control responserate thus will increase steadily withtime because the OH-58 has a lackof yaw rate damping. What shouldhappen, if the helicopter fully metMIL-H-8501A standards, is that theyaw rate should reach a maximumvalue quickly, dependent only uponthe magnitude of control displacement and not upon duration of theinput. Actually, if the control inputis continued, the rate builds up andthus it would e easy to overcontrol.In view of this, what should bedone during hover is to input a control movement and then neutralizeit efore you normally perceive itshould be neutralized, since the rateis building up

The above condition in theOH-58 occurs mainly during hover.The rates and accelerations willdecrease significantly as densityaltituqe is increased. During hoverwith the OH-58, there should be noproblem with the pitch and rollaxes, but yaw may be a problem.Because of the above factor, it ismore difficult to maintain a preciseheading. The control inputs required to compensate for heading

MARCH 983

disturbances could result in moderate pilot induced oscillations.To compound this problem, theOH-58 has a relatively high pedalforce (10 to 15 pounds) which is outof proportion to the force in thelateral and longitudinal controlsystem (0.5 pounds). This does notmean that the OH-58 is uncontrollable, but what does result is it is difficult for low-time pilots to maintain a precise heading during hover.This also could lead to overcontrolling and thus cause pilot induced

oscillations.The helicopter stability and control requirements specified by MILH-8501A and its correspondingdamping requirements are difficultto achieve by the damping inherently available from the rotor. f fullMIL-H-8501A compliance is required, then the OH-58 will needsome form of a stability augmentation system.The OH-58 operator must beconsistently aware of the enginepower margin as it relates to aircrafthover performance. The OH-58Cwith the T63-A-720 engine doeshave a greater degree of hot day hover performance than the OH-58Ahas with the T63-A-700 engine.One of the findings of the blueribbon panel was that the OH-58has no throttle openstop. Once thethrottle twist grip is moved (rotated)to full open there is no mechanicalstop (or detent) to hold it there. Thethrottle twist grip is held in anygiven position by its built-in systemfriction. The throttle twist grip is 2inches in diameter. A movement atthe circumference of the grip of 0.6inches is required to move theengine throttle from flight idle tomaximum. This is about 34 degreesof rotation. Throttle rotation isabout linear with engine N 1changes, thus very small movementsaway from the full open position

could result in large power reductions especially if the OH-58 is at apoint demanding maximum poweroutput. A movement of 1/32 of aninch from the full open point couldreduce maximum Nl by 2 percent.At sea level standard day conditions, this could result in a potential power loss of 30 horsepowerAn engine performance checkwas recently distributed to OH-58users as Safety of Flight Maintenance Mandatory Message No.OH-58-82-01, Maintenance Procedures and Engine PerformanceCheck for OH-58 Aircraft." Themessage gives a method for checking the proper T63 engine performance in the OH-58.It is important to make sure yourengine has the correct power outputespecially since you now are awareof the figure 2 graph.A training videotape (TVT46-2)was prepared by the NationalGuard Bureau entitled, How Notto Crash by the Book. t has beenmade into a training film for viewing by Army aviators. This tape canbe obtained through the audiovisualoffice that services your area. AllOH-58 operators and maintenancepersonnel should view it.The tape covers the performanceplanning card (PPC) which is DAForm 4887-R 1 July 80). Properuse and understanding of the purpose and the intent of the PPC cannever be overemphasized. Thiswould be especially true in the caseof the OH-58A or any otherhelicopter which is engine-powerlimited, at increasing OAT values.Review of this article will make youaware of the tail rotor limitationsand other factors which could leadto a safer flight. When performingnap-of-the-earth operations, use ofthe PPC and proper compliancewith the flight manuals could giveyou that extra margin of safety.


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The following is a hypothetical situation in an OH58A; it does not represent any actualincident. It lists some flight situations which you may experience, describes the causesand shows what action should have been taken:

The pilot starts a right pedalturn and does not use counterpressure on the left pedal tocontrol the rate of turn.

The OH58 has negligible directional damping; recall thepreceding narrative description and remember you will have a ratebuild-up. When cont rol pressure is applied, if it is not neutralized,the input will result in accelerationRecall also the "Tail Rotor Stall and the "Tail Rotor Breakaway"articles (see bibliography at end of article) as well as the directionalcontrol margin limits in the flight manual. Your OH-58 must beoperated in an envelope only where you have safe limits; anytimeyou are in the 10 percent control margin you are asking forproblems.

After a rate turn hasdeveloped, he or she applies leftpedal which causes a power demand resulting in a momentarydecrease in N2 and subsequentdecrease in main rotor lift andtail rotor effectiveness. Thiscauses a slight descent of theOH58.

Application of tail rotor pedal means increasing its blade anglewhich would produce more thrust. However, to produce morethrust requires more horsepower; this is sensed by the engine. Ifthe engine is at or near maximum output, what is perceived is amomentary decrease in N2 since if more horsepower is demanded instantaneously it subsequently causes a loss in main rotortorque/rpm. If N2 does not immediately increase and dependingon the existing power loading, the OH58 may descend slightly.One other point to consider is if too much tail rotor pedal wereadded, the required reaction would be opposi te pedal to neutralizethe effect . These pedal reversals obviously take power and depending on the magnitude can also result in a corresponding N2 droop.The larger the pedal reversal, the larger the power required andthe larger the droopIn design considerations for helicopters, pedal reversal conditions, especially full pedal reversals, are considered an importantdesign point since power required and loads will be substantial

The pilot increases pitch tostop the descent which causesfurther increase in left pedal.This causes a power demandwhich results in a momentarydecrease in N2 and subsequentdecrease in main rotor lift andtail rotor effectiveness.

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The natural reaction to correct the descent is to call for morecollective pitch which should stop the descent. Raising the collective results in the main rotor blades having an increased bladeangle which should have the resulting effect of more lift. However,more lift can be only produced if more horsepower is provided;recall the earlier discussed lift formula. You should also be awarethat the collective is mechanically linked in the flight controlsthrough the linear actuator to the N2 governor; thus raising thecollective should cause the governor to have a setting whichshould result in more power output.As you are no doubt aware by now the engine power does notincrease immediately as power is called for; there is a built -in timelag. Thus as you beep-in a demand for power or raise the collective the resultant power output is not instantaneous.For information, the T63 engine response characteristics aresuch that once the power droops there is a delay of about 3 to 5

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seconds before it recovers to full power output. Obviously thelower you go on the power curve, the longer it takes to get thepower back up. Also, as you are aware, there reaches a point onrotor rpm where the OH-58 will not sustain fl ight; thus the low rotorrpm warning system was furnished to make you react in time totake appropriate corrective action.One other consideration must be taken into account and thatis your power margin. Obviously if all other given factors remainthe same, the OH-58C has a greater engine power available marginthan the OH-58A. In considering the T63 power recovery responseyou must also consider where you are in relation to the power re-quired versus power available curve. If you are at the upper limitsof this curve, it is obvious that the engine will not be able to re-spond as indicated in the preceeding paragraph-pulling collective to ask for more power at or close to the upper end of the curvewill not result in any additional power outputThe "beep" switch on the collective will cause a change in thelength of the linear actuator and thus is used to make minor poweradjustments. Thus, if you were already "beeped" to maximum youhave no place to go with the beep switch.Also, remember the twist grip, it also controls engine power;remember too that a small amount of twist grip backoff can greatly affect power output

~Depending upon how fast theengine power increases, therecould be another slight descentof the OH58 or rate of turn. Ifthe pilot overreacts and pulls inmore pitch, step 3 may berepeated.

Once the engine power increases, more torque is available forthe required amount of tail rotor control, but you must recall twofactors now. The first factor is that you can' t "split" the power be-tween the main rotor and the tail rotor. Although you are askingfor more main rotor thrust to stop the descent-and tail rotor powerto counteract the helicopter rotation-the added main rotor thrustnow requires an even greater amount of tail rotor thrust tocounteract the increased main rotor torque.Recall the graph shown in figure 2 It shows that the maximumtail rotor thrust for the OH-58A is at the prime main rotor speedof 354 rpm or 103 percent engine speed. As the main rotor speeddecreases, then total tail rotor thrust decreases; thus, for theOH-58A you can't get your full tail rotor thrust capability below 103percent engine speed or 354 rpm main rotor speed.Since you are now descending it indicates your power isdecreasing as is, most likely, your main rotor speed-thus it is alsomost probable you will NOT have full tail rotor thrust capability

~By this time the pilot mayhave run out of left pedal, and hewill be at a high power setting.

MARCH 1983

You have run out of pedal, caused by one or more of thefollowing:a Less than full tail rotor thrust capabil ity on the OH-58A at lessthan 103 percent rpm.b You may have entered the initial flight condition with lessthan a 10 percent margin.c The additional main rotor torque requires additional tail rotorthrust to offset the condition-over and above what was requiredinitially

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The higher power setting willthus generate a higher mainrotor mast torque and lowerrpm.Because of the flywheel effect the main rotor rpm cannot instantaneously increase; it must overcome many factors includingthe mass inertia of the system.

~ The rate of turn begins to increase and the pilo t now may tryto overcontrol the OHSS withthe cyclic stick.The higher mast torque correspondingly requires an additionalamount of tail rotor thrust; see also paragraph 5 above for otherfactors. In addition you can also have tail rotor stall.

The spin cannot be controlledanymore.

In summary, some of thepoints you should be aware of are: Make sure your engine has adequate power available (refer toMessage OH-58-82-01). Be aware of the tail rotorcapabilities as a function of mainrotor speed (figure 2). Stall can occur in the tail rotorblade airfoil; know what it is andwhy it will occur. Make sure you will have the 10percent control margin available.Don't get into a position where yourmargin is less. Be aware of the OH-58's directional control hover damping characteristics and how the OH-58reacts. When the main rotor speedcomes down from its normal flightrating, be aware of what your directional control capabilities are. Assure your tail rotor has beenproperly rigged. Be thoroughly familiar with theflight manual, especially the hover

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Refer to the flight manual to see how to recover; obviously thebest approach would be to lower the power to decrease the mainrotor torque and to straighten the OH-58 out and get into a forwardflight mode. However if flying in a confined area this may not bepracticable.

charts and directional controlcharts. When operating at maximum conditions be aware of whatis happening to your power reservemargins. Be sensitive to wind conditionsand wind direction and how they affect tail rotor performance. Whenever you are flying theOH-58 and you are getting close tothe tail rotor pedal travel limitstay alert.In closing, we ll cite a hypothetical example and you draw yourown conclusions: First, let's say yourpeople didn't comply with TB55-1520-228-20-19, thus you probably don't have full tail rotor control power available.Second, presume it's a hot dayand you are nearly grossed-out,the place where you intend to landis not sea level-it will have somenice density altitude to it.Then suppose your engine wasclose to time between overhaul andyou never had an engine perfor-

mance check o r at least one hadnot been done recently (MessageOH-58-82-01). Let's also supposeyou didn't notice it, but by leavingyour hand on the twist grip yourolled back the throttle only slighttly-say 1132 of an inch. Let's sayyou did mission preplanning, butnow as you come into the hovermode you suddenly encounterheavy winds.

All of a sudden as you startyour descent preparatory to gettingin the pattern, you hit tail winds: theOH-58 starts to settle, so you callfor more power; then the aircraftstarts to spin to the right; you honkin full left pedal, still grabbing thecollective for more power; the rotorspeed drops off; the aircraft stillspins; then the horn sounds.What do you write on the PRAMas the cause? .. faulty fuel con-trol. ...excessive power droop .. .lossof tail rotor control authority .... tailrotor improperly rigged ... . or all ofthe above?



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OER AppealsAn officer who has unsuccessfully appealed an OERshould request a copy of his or her microfiche to seeif the appellate correspondence appears on the Performance" fiche. Recent selection boards have recommended that the individual officer should request thathis appeal be removed from the" P fiche and placedon the "Restricted" fiche. Unsuccessful appeals onlyclutter the officer's fiche and may present an overallnegative connotation. To obtain a copy of your official file write to DA, MILPERCEN, ATIN: DAPCMSR-S, 200 Stovall St., Alexandria, VA 22332. Your

military personnel office (MILPO) can help you withthe necessary details.

Use Your Local MILPOIn order to provide you better service, you must beable to reach us on the phone. Our phones are tiedup while we answer routine questions that could behandled through your local MILPO.MILPOs were designed, and are equipped, to handle the "nitty-gritty" of all personnel actions normallyfound at the installation level. Give them the opportunity to work for you.Let's go one step further-talk to your commander,as he can answer most of your questions. We are alsoready to answer all questions you might have for yourupcoming officer calls. Use of your MILPO and unitofficer calls are great ways to reduce individual callsto Branch.

Officer Record BriefThe Officer Record Brief (ORB) offers a greatsnapshot of an officer's file. Together with your

MARCH 983

official photo and microfiche, it gives a selection boardthe essential elements for selection or nonselection.You are responsible for keeping your ORB current,keeping it free from cluttering duty titles and makingsure all other entries are accurate and current. This isno small task, as anyone who has ever tried to makechanges will tell you. Stay on top of your ORB Wewill help you any way we can, ut it remains yourresponsibility. Talk to your MILPO Allow 30 to 60days for the changes to "take:'

Congratulations New Test PilotsCPT (P) Edward J. Tavares, CPT Eric L. Mitchelland CPT Alan D. Sodergren graduated 10 Decemberfrom the United States Naval Test Pilot School atPatuxent River, MD.CPT Tavares is a student at Air Force Staff College while CPTs Mitchell and Sodergren have begunutilization tours at U.S. Army Engineering Flight Activity at Edwards AFB, CA, and U.S. Army AviationDevelopmental Test Activity at Ft. Rucker, AL.

Congratulations 0-6 Command DesigneesMore congratulations to 0-6 command designeesMILPERCEN released the 0-6 command list inJanuary. The following aviators have been selected forcommand:COL Robert S. FrixCOL Everett O. GreenwoodCOL Charles P. HarmonCOL Edward K. LawsonLTC (P) Barry J. SottakLTC (P) Jack L. Turecek


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CW Ernest D KingsleyHeadquarters and Headquarters Troop3/4 CavalryFort Lewis WA

I T WAS A HECTIC morning late in the spring whenthe last alert was called. twas especially inconvenient too, being held at 0230 and all, without aninkling of forewarning. The firstthought was to grumble that the OldMan had thought it necessary thatwe do this one more time, but thatsoon turned into a prayer. This wasthe real thing, and the frenzy of activity in the company was proofenough that these troops were aboutto become engaged in a struggle fortheir very lives. t was a crisp, clearmorning, rare for Germany, andeveryone raced to their tasks carrying mountains of alert gear to theappropriate location, addressing thelast-minute crises which alwaysseem to appear and giving that little extra to make it all go.The first stop was to pick upweapons and protective masks.They were letting us take whateverwe could carry in the way of personal ammunition and C-rations,which I thought was just dandy. Butthe nuclear, biological, chemical(NBC) officer (for crying out loud)was issuing stuff I had never madeany plans for (and had only worn

twice before, if the truth were everknown). Masks, OK. But now camenew NBC uniforms, hoods (some ofwhich had a big blue X on them,and I was afraid to think what thatmight mean), boots and gloves. Ihad to leave some of my personalgoodies behind just to carry theNBC equipment, though I wasn tsure just how smart that W1.S. Iknew I would miss those extra rations at the next meal.There were a great manyunanswered questions adding to thetension of the moment. Was thisreally a war-footing alert? Wouldthe families make it out with theNEO (Noncombatants EvacuationOrder) program? Would the forward arming and refueling point(F ARP) be able to keep up with us?How about the supply of ammunition? Would the commander be successful in coordinating a viable andrealistic mission in which we couldbe effectively employed, or wouldwe be thrown into the breach andwasted in an unfavorable conflict?There was not enough informationto make even a good wager overthese questions.Our platoon leader s pre-missionbrief was short and to the point. Wewere headed to the assembly areawe all knew so well, and we were tofly there in full mission orientedprotection posture (MOPP) 4 NBCgear. Was he kidding? t had been3 months since anyone had worn

that dang mask in flight, and onlya few of us had done that with anyreal intentional learning spirit.Heck, it was still dark outside. We dhave lots of time at the assemblyarea.No matter, said the NBC officer, feigning conviction. Wemust wear the mask after crank.Almost as an afterthought he added, Put your hood on the maskbefore you don it, unless you haveone of those n w hoods.So, what s a n w hood? Ithought. I was thinking that an ol

hoo was some kind of Fonzy witha beard, and NBC defense wassomething practiced only by the opposition, or by our ground troops,but not me I am an aviator.First platoon was in and out ofthe FARP in record time, with fiveCobras. The platoon leader, Captain T, looked sort of silly flying hisOH-58 Kiowa around in fullMOPP ; he was the subject ofseveral intraplatoon comments, butI informed my back seat that I wasgoing to play the game and wear mygear. He wasn t impressed.Oh no, not another one. We llhave time to put it on in the assembly area, if we have to. Only a foolwould fly with that stuff on unlesshe had to.I didn t say much, but several ofthe other guys must have felt thesame way, because I began to seemasks in each aircraft. Anyway, the


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T E USE differential power is addressed inseveral fixed wing operator's manuals. Although itsuse is recommended for normal and crosswind takeoffs and crosswind landings, it is not further definedor explained. Aircrew training manuals make no mention of it, nor does Field Manual 1-50, Fixed WingFlight. What is meant by differential power ?When and how does the aviator use it?Simply stated, differential power is the unbalanceduse or application of power in relation to the longitudinal axis of multiengine airplanes.Apart from the obvious use of differential powerWhen encountering certain emergency procedures, itmay be used to augment directional control duringtakeoffs, crosswind landings and taxiing.TakeoffsWhen performing a normal takeoff, use of differntial power at the beginning of the takeoff roll can assistin directional control. The aviator must be aware,however, that the use of unbalanced power or the application of less than takeoff power during the takeoffroll will result in extension of the normal takeoffdistances.When performing a crosswind takeoff, after applying controls to counter the effects of the crosswind,leading with upwind power at the beginning of thetakeoff roll will assist in maintaining directional control. As stated in the preceding paragraph, thistechnique will result in the extension of the takeoffdistance. Under light wind conditions, the inherent

4

directional stability of .the tricyle gear configurationtends to keep the airplane straight on its roll while thenosewheel is on the ground and the tendency toweathercock is minimal. However, in strong, gustywind conditions, or known bumpy runways, it is advisable to build up to the proper flying speed beforeliftoff. Otherwise, the airplan'e may settle back to therunway as it starts to drift, resulting in heavy side loadson the landing gear.After the airplane is positively airborne, establisha crab with rudder to continue down the centerline.t is advisable when establishing the crab angle not todrop a wing because this reduces the lift. Once the crabis established, continue as in a normal takeoff.The retraction of the landing gear and flaps aftertakeoff must not be initiated until the airplane ispositively airborne and climbing.andingsNormal landings with no crosswind should be con

sistently good landings. They are the result of a combination of good judgment, good technique and goodtiming. Because there are a number of things to do onlanding, use of the checklist and cockpit proceduresshould be so regulated that the aviator is free to concentrate on flying the airplane.Crosswind landings present a greater challenge tothe aviator. The combination of good judgment, goodtechnique and good timing is required to an evengreater degree. The object is to bring the airplane onto the runway with zero drift. Drift can place a heavy



17/44

side load on the gear and can result in damage to tiresand in an extreme case to possible gear failure.The usual method of countering the effects of acrosswind during landing is to use a combination ofslip and crab. This is accomplished by crabbing anddropping the upwind wing to fly a track with the runway centerline. (Because of the possibility of sideloads, it is imperative that proper runway alignmentbe achieved at the instant of touchdown.) This methodis appropriate for most crosswind conditions.Another method is to crab into the wind when firstestablished on final approach. This gives the aviatora feel for the strength of the crosswind and with experience he will learn to anticipate the amount of slipand crab that will be required for alignment on shortfinal, roundout and touchdown.In all crosswind landings, especially when strong orgusty wind conditions are encountered, differentialpower can assist in maintaining runway alignment andprovide a greater margin of safety. This technique requires the aviator to establish a slip by lowering theupwind wing and applying opposite rudder for runway alignment. Power is applied to the upwind enginewhich causes the nose to yaw toward the high wing,thus relieving some of the opposite rudder pressure.The result is that the rudder is given greater authori tyif needed to counter gusty conditions on short final,roundout or touchdown. s power is reduced in thelanding sequence, the reduction is equal on all engines.In this way, the power differential remains constantthroughout the landing process.

There are instances where the techniques discussedwill be inappropriate, such as aircraft configured withspecial electronic equipment and antennas. A simplecrab may be the only option available to the aviatorin countering a crosswind. In no instance will any ofthe discussion be interpreted as authority to disregardcrosswind limitations as stated in aircraft operatorsmanuals.TaxiingThe use of differential power can also assist in directional control when the situation calls for prolongedtaxiing in crosswind conditions. Under ordinary crosswind conditions, use of nosewheel steering if availableand the intermittent application of upwind power willbe sufficient to keep the airplane lined up with the taxiway while using a minimum of brakes. In a severecrosswind it will probably be necessary to carry constant power on the upwind side to counteract the crosswind. This tends to increase taxiing speed and will probably require more frequent use of brakes. f so, apply the brakes intermittently to prevent overheating.It is not the intent of this article to present the useof differential power as the panacea for all the prob-

MARCH 1983

lems aviators might encounter during crosswind operations. Rather, it is offered as one of the many techniques that professonal aviators will have at theirdisposal under certain operating conditions.

The following Hotli ne numbers can be called on officialbusiness after duty hours. They will be updated andreprinted here periodically for your convenience. If youragency has a Hotline it would like included, please send itto Aviation Digest PO .Drawer P, Ft. Rucker, AL 36362.

UTOVON ComrylercialAviationFt. Rucker, AL 5586487 2052556487EngineerFt. Belvoir, VA 3543646 7036643646Field Artillery

Ft. Sill, OK ARTEP 6392064 4053515004Redleg 6394020 4053514020InfantryFt. Benning, GA ARTEP 8354759 4045454759IntelligenceFt. Huachuca, AZ Tralnlng 8793609 6025383609Maintenance and SupplyTobyhanna Army Depot, P 7957900 7178947900Missiles and MunitionsRedstone Arsenal, AL 7466627 2058766627Ordnance Help Line)Aberdeen Proving Gnd, MD 2834357 3012784357QuartermasterFt. Lee, VA 6873767 8047343767SignalFt. Gordon, GA 7807777 4047917777TransportationFt. Eustis, VA 9273571 8048783571Turbine EnginesCorpus Christl Army Depot, 8612651 5219392651TX

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18/44

Broken Win s notbroken bodies

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Te C-12A WITH 5passengers aboard was 30minutes into its flight fromRamstein Air Base to Northolt,England. The aircraft was at16,000 feet and climbing whenthe left engine exploded andcaught fire. The aircraft yawed,pressurization was being lost,warning lights were flashing,flight instrument off flags wereactuated, and engine instrumentswere fluctuating. The pilots successfully extinguished the fire,but when an attempt was madeto contact Frankfurt radar, theyfound the number one VHFradio, UH radio, andtransponder, along with all otherinstruments and equipmentassociated with the number oneavionics bus, were inoperable.rankfurt radar had lost contact

16

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with the aircraft when thetransponder failed. The pilotknew he would have to descendinto the overcast where icingwould be likely. He acceleratedto recommended minimumairspeed which would provide theleast ice accumulation, but hecould not maintain altitude.Although number two VHFradio was weak, Frankfurt radarresponded and cleared descent to6,000 feet. The aircraft was turned over to Ramstein ground control approach which had difficulty maintaining positive identification without the transponder butgave further clearance to 2,600feet. Accumulating i e could beshed from the wings, but theheat for the pilot s windshieldhad been lost when the left isolation current limiter failed.

With power from only oneengine and moderate accumulation of ice, the pilot had difficulty maintaining altitude and sufficient airspeed to prevent a stall.Clearance to descend to theminimum vectoring altitude of2,400 feet enabled him to maintain airspeed and altitude. Theemergency, however, wasn tover. Ice on the pilot s windshield severely restricted his vi-sion as the copilot strained tofind the runway approach lightsthrough fog. The copilot was inexperienced in landing oroperating the aircraft s controlsfrom the right seat and wasunable to take over and completethe landing. The pilot, using onlyvisual cues from his side windowand the partly obstructedcopilot s window, landed the

U S ARMY AVIATION DIGEST


19/44

aircraft without further incident.Result: eight lives and a valuableaircraft saved. The pilot receivedthe Broken Wing Aviation SafetyAward.In June of 1967, the Commandant s Broken Wing AviationSafety Award was established atthe Army Aviation School atFort Rucker to recognize aviatorswho demonstrate exceptional,professional knowledge, judgment and skill in recovering fromin-flight emergencies. Nominations were submitted to a safetya ward committee chaired by theA viation Center Safety Director.The committee included thedirectors of the Department ofRotary Wing Training and Advanced Fixed Wing Training, andthe Chief, Maintenance Division,Office of the Deputy Chief ofStaff for Logistics.The first five awards werepresented by the Commandant ofthe Aviation School, MajorGeneral Delk M. Oden, inFebruary of 1968. Two additional awards were sent to Vietnam and Korea for presentationin the field. As a result ofpublicity about the award, questions were received on how itcould be used in othergeographic areas. The U.S. ArmyBoard for Aviation AccidentResearch USABAAR), now theU.S. Army Safety Center, wastasked by the Director of ArmyAviation, Office of the DeputyChief of Staff for Operations,Headquarters, Department of theArmy, to study implementation,and the award was made Armywide in September of 968 whenit was included in AR 385-10.Army Regulation 672-74 currently governs the Army AccidentPrevention Awards Program, including the Broken Wing Aviation Safety Award. The purposeof the award is described in Sec-tion IV, which also gives the circumstances for which it is given.The regulation specifies informa-

MARCH 983

tion which must be included innominations. U.S. Army militaryaircrews officer and enlisted),Department of the Army civiliansand contract personnel are eligible to receive the Broken Wing,which consists of a gold lapel pinand a certificate. A change to theregulation, currently being processed, will provide for inclusionof a Certificate of Achievementin the personnel records of theindividual concerned.) The aircraft involved must be Armyowned, or leased by the Army,at the time of the mishap.

The Broken Wing AviationSafety Award Program ismonitored by the Deputy Chiefof Staff for Personnel, Headquarters, Department of the Army. Nominations are sent to theCommander, U.S. Army SafetyCenter USASC), who chairs acommittee of at least five aviatorrepresentatives from USASC, theU.S. Army Aviation Center, andother aviation agencies located atFort Rucker. The committeemeets monthly to review nominations and select persons who willreceive the award.

Normally only one person isawarded the Broken Wing for asingle in-flight emergency, but ifmore than one crewmember contributes materially to therecovery, both may receiveawards.In 1982, for the first time, theBroken Wing was awarded to anonaviator crewmember. ACH-47B helicopter was engagedin external load operations. During approach, the student pilotdetected and identified a normalengine beep trim system failurehigh side) on one of the engines.When he increased thrust, in anattempt to slow the rate of descent, decay of rotor rpm resultedand further increased the sinkrate. The instructor pilot was attempting to control rotor rpmwith emergency engine trim and

was unable to reach the cargorelease switch on the cyclic control. The flight engineer, a staffsergeant, made a quick assessment of the emergency andreleased the load, preventing theaircraft from going down in treesat the end of the confined area.Since September of 1968, whenthe program was implementedArmy-wide, 1,380 nominationsfor the Broken Wing have beenprocessed and more than 700crewmembers have received theaward. Countless dollars inequipment, cargo, and trainingfunds have been saved, but theseare insignificant when comparedto the lives which could have

been lost. While the awardrecognizes flying skill during anemergency, the pilot must first ofall have the necessary knowledgewhich is gained from good training and experience, and then beable to make sound judgments.The aviator must be able toweigh possible damage to the aircraft against possible injury tocrew and passengers. For example, should the pilot attempt tostretch an autorotative glide overan obstacle to a clear area wherelittle or no damage to the aircraft would result, or attempt tocontinue on to an area where thelikelihood of damage to the aircraft is greater but risk to the occupants is less? Once this decision has been made, the skill ofthe aviator in flying techniquescan make the difference inrecovering from the emergency.

Unfortunately, not all deserving crewmembers are nominatedfor a Broken Wing. Any personwho is aware of performance byan aviator, or crewmember,which they believe warrants thisaward may submit a nominationto the Commander, U.S. ArmySafety Center, ATTN: Chairperson, Broken Wing Safety AwardProgram, Fort Rucker, Alabama36362. ,

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PILOT ERRORDECISIONCaptain Thomas Richard BiangCaptain Biang was student management officer HancheyDivision Department of light Training U S Army AviationCenter Fort Rucker AL when he wrote this article

A H-J MAINTENANCE test pilot is progressing normally, completing the in-flight checks required during an end-of-phase test flight. Up to thispoint the flight is uneventful. The wind is calm, nota cloud in the sky. The aircraft is responding normally, weight and power requirements apparently wellwithin limits. As the pilot attempts to make an outof-ground effect power check, the aircraft begins toturn. The pilot responds with the correct control input, but the aircraft continues to rotate. Hastily thepilot interprets the situation as an in-flight tail rotorfailure and decides to retard the throttle and autorotatefrom a hover height of 35 to 40 feet. A hard landingresults and major damage is incurred.

Had the pilot recognized what was happening hecould have recovered by reducing collective pitch until he was safely on the ground or until he had descended to a safe, autorotational altitude. The ensuing investigation concluded that the pilot misinterpretedan in-flight failure (interpreted insufficient tail rotorthrust as tail rotor failure) because of INADEQUATEWRITTEN PROCEDURES FOR OPERATION INNORMAL MAN-MACHINE-ENVIRONMENTALCONDITIONS.

8

Is that it? Is the absence of a written procedure thecause for the pilot to decide to retard the throttle, oris there more?Pilot error is involved as a factor in about 6 percent of air carrier, 88 percent of general aviation and80 percent of Army Aviation fatal or nonfatal accidents. The cause, pilot error, was analyzed by theOffice of Aviation Medicine, Federal Aviation Administration, and divided into three behavioralcategories: procedure, perceptual-motor and decisionalerrors. The analysis showed that more than 5 percentof the fatal pilot-error related accidents were directlyattributed to decisional errors.The study of human error as a natural condition oflife is the job of Dr. Donald Norman, a theoreticalpsychologist at the University of California at SanDiego. Writing for sychology Today (April 1980),Dr. Norman views the human mind as an exceedinglycomplex computer with an information-processingsystem and it produces human errors as slips. Themind can slip when stray information throws off thehuman information processing system.

Of the different types of slips described by Dr. Norman, the one that fits aviation best is description.Given a choice of solutions, sometimes we describe thewrong situation to ourselves (this may explain the action of the UH-1 Huey maintenance test pilot).For example, we tend to use previous experiencesas much as possible in finding a solution, processingonly enough new information to figure out where itfits in the mind's banks of previous experience.That is done partly by forming a description of thesituation, a description that characterizes things at ahigh level of abstraction.

u s ARMY VI TION DIGEST


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Tail rotor failure and loss of tail rotor thrust sharea common high-level description: The loss ofantitorque control sets us up to expect failure so wedon't process the word thrust ; the meaning is in themind but the information is too abstract to describethe situation.

Most psychologists believe that the success ofabstract information processing depends largely onhow familiar we are with a specific action. The morefamiliar we are, the more subconsciously we relate toprevious experiences; conversely, the less habitual weare, the more conscious intervention is required tocomplete a task. Consider the following near-accident,extracted from Analysis ofFY 79 rmy Aircraft Ac-cidents (April 1980): An OH-58A instructor pilot ona training flight to transition a ra ted pilot into a newcategory aircraft improperly monitored student performance. During practice of a standard autorotation,the IP allowed the pilot to apply cushioning pitch toohigh and obtain an excessive nose-high attitude. Theaircraft landed hard on the heels of the skids, forcefully rocked fore and aft, and sustained spike knock.

That instructor had completed the IP course at Ft.Rucker, AL, 4 months before and had accumulatedonly 2 hours of IP time. Without the repertoire ofexperience neatly sequenced in the subconscious, theconscious mind was obviously absorbed in the information processing mechanisms and not free to dealbeyond the abstract picture.

However, the human mind has the amazing abilityto prevent the vast majority of simple human errorsthrough a conscious monitoring system. Errors arecaught in two ways: in the various ways we monitorour behavior, consciously comparing our actions to

MARCH 983

the intended outcome, or when errors cause somethingto happen that immediately attracts our attention. Inaviation, the most dangerous errors committed bypilots are those which do not result in some obviousreminder and are, therefore, the ones most oftenoverlooked.Pilot errors resulting from in-flight emergencies areaffected primarily by stress. Psychologists learned longago that some stress will actually improve the level ofperformance while high anxiety or an intense emotional response can impair performance. Conditionsof stress are affected by the individual s physiologicaland emotional response, but equally important is theperson's attitude. The successful outcome of a highstress situation hinges on a positive attitude towardsuch conditions. Pilots who show signs of timidity orapprehension in critical situations which requirestraightforward, quick decision thinking often cannotdeal successfully with such situations. Conditions ofstress (physiological and emotional) and attitude,together with the habit patterns already developed(through previous experience and knowledge), are theingredients that make up the big picture and willdetermine the pilot s performonce.Training for the purpose of strengthening habit patterns does not seem to be the answer for dealing withpilot error. It would be a mistake to rely on habitmemorization to comply with emergency procedures,at the expense of common sense. Simply, Army Aviation personnel must place emphasis on consciousmonitoring of habit patterns and must constantly strivefor excellence through application of sincerity and professionalism. Such efforts can only lead to a declineof pi/at error a decision.

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Directorate of Evaluation StandardizationR PORT TO THE FIELD VI TIONST ND RDIZ TIONTraining Voids

GROUND COMMANDERS are becoming moreaware of the firepower, mobility and depth that aviation can provide when fully integrated into the groundtactical plan. Whether employed as part of a companyteam, or at division level as part of an economy offorce element, aviation assets give ground commandersa significant increase in their ability to put steel downrange.The September-October issue of nfantry magazinehad several articles concerning the integration of aviation in the combined aims. Major General Robert L.Wetzel, commandant of the United States Army Infantry School, ends his opening remarks in that issueby saying, "Practice Combined Arms " This adviceto practice combined arms is essential if aviators aregoing to be able to find, fix and destroy the enemyas far forward as possible. Army aircraft can't act assingle elements alone on the battlefield, like lone eagleshunting their prey. They must be employed as an effective fighting force operating within the overallscheme of maneuver."Practice" is synonymous with training. A verysignificant portion of an aviator's training comesthrough the evaluation process, or what most aviatorscall "checkrides." The checkride process traditionally has determined the aviator's ability to fly theairplane and not necessarily how to 'employ it. Becauseaviators must t rain the same way they are expected tofight, they must understand their role in the combinedarms element. With this understanding, aviators canprovide knowledgeable advice to ground commanders

22

GLOSSARYACP air control point

ARTEP Army Train ing and Evaluation ProgramAASPR Army Aviation Systems Program Review

DES Directorate of Evaluation and StandardizationFARES forward area refueling equipment system

LZ landing zoneOPFOR opposi ng force

PZ pickup zoneRP release pointSP start point

on employment of their limited aviation assets.Preparing aviators to assume full roles in the combined arms team takes a lot of training, substantiallymore training time than their nonaviator counterparts.Currently, most aviators' training time is spent on aircraft specific duties. In the aviators' development process, the tactical employment of aviation units, andtheir interface with other units, is not taught withenough depth. This has created training voids whichexist in both aviators' and ground commanders' formal training programs. Recently the various branchschools have adopted 9 shared tasks common to aviation. These will be taught as part of their branch officer advanced courses. This is a step in the right direction and will be of tremendous value in advancingground commanders' knowledge of the employmentof aviation.The 982 Army Aviation Systems Program Reviewidentified several areas that aviators need to stress tocontinue filling these voids. Specifically, areas impacting on the doctrinal employment of aviation assets asmembers of the combined arms must be emphasized.However, it was observed during AASPR-82 that thisarea is not sufficiently covered in the basic and advanced officer courses provided by the carrier branchschools, or during flight school. This helps exlain whymost aviators can fly it but not fight ie'The solution to this problem is made more difficultby the differences in the training aviators receive beforeand after attending flight school. While combinedarms tactics are taught in the carrier branch schools,the same emphasis is not placed on certain subjectareas by all of these schools. One officer advancedcourse may stress land navigation while another onlyrequires the successful completion of a land navigation pre-test. Greater emphasis will be placed in varying degrees on the different weapons systems employedby the individual branch advanced schools. Aviatorsnow are being drawn from all the carrier branches andtherefore have different backgrounds. It is not unusualto have officers from Armor, Infant ry and the Combat Engineers all assigned to the same attack helicoptercompany. Each officer has received a different training in the concept and employment of combined armsbased on the carrier branch school's emphasis in training. Couple this training difference with the trainingvoid which is created when only aircraft peculiar tasks



25/44

are taught at Ft. Rucker, AL, and aviators are (inmany cases) ill prepared to fight as full-fledgedmembers of the combined arms team.In an effort to determine the depth and impact ofthe training voids problem, several changes are beingstudied.One such effort is a change in the philosophy andmanner in which aviators are being evaluated.Previously, emphasis has been on aircraft maneuvers-how w ll can aviators fly a traffic pattern or perform an auto rotation. Without a doubt these are important elements of aviators' overall requirements. Butspecific aircraft duties are only part of the needed bodyof knowledge aviators must possess to accomplish theirmissions.The change in philosophy for evaluation will includemission tasks not normally associated with flightmaneuvers. The Directorate of Evaluation and Standardization is identifying tasks that individuals mustperform as members of a collective effort so that theoverall mission can be accomplished. Evaluations forcommissioned aviators will include tactical tasks andspecific aircraft tasks needed to complete a mission.This is in contrast to the conventional contactcheckride normally associated with a DES evaluation.The manner of evaluation for aviators being studiedis to provide a scenario (from an appropriate ARTEP)

DES welcomes your inquiries and requests to focus attentionon an area of major importance. Write to us at: CommanderU.S. Army Aviation Center ATTN: ATZQ-ES Ft Rucker AL

c

at the beginning of the evaluation, then follow the individual aviator through the mission sequence to mission accomplishment.Examples of some of the tasks being considered are:Select flight routes, provide for ease of navigation,avoid known or suspected OPFOR positions. Select,in concert with the ground commander's tactical plan,PZs and LZs. Designate SPs, RPs and ACPs as partof an air movement plan. Select command post, trains,FARES and aircraft laagers (protected areas). Selectmovement routes, holding areas, attack and fire positions (attack/aeroscout). Coordinate fire support. Planfor unit displacement (offense).The purpose of expanding the evaluations to includethese mission tasks is to add realism to the evaluationprocess. We must evaluate our ability to employ ourforces.Aviation's acceptance as a full-fledged member ofthe combined arms team places a heavy burden on allof us. We must train, equip and organize to take maximum advantage of the impact aviation has on thebattlefield.Initiatives in training, reorganization under Division 86 and a change in the thrust for evaluationsand joint training exercises will add to the ability ofaviation to not only be Above the Best but also,Among the Best. :vc .

36362; or call us at AUTO VON 558-3504 or commercial 205-255-3504.Afterdutyhourscal/ Ft. Rucker HotLineAUTOVON558-6487 or 205-255-6487 and leave a message

NI\ I I I ( ) ( P i l I p / r / llnlng AnalysIs and ASSistance Team

DA Form 4S07 RISSUE: Maneuvers listed on the back of the DAForm 4507-R, Standardization Flight Evaluaton/ltaining Gradeslip, should be changed to reflect the task

lists in the aircrew training manual (ATM).COMMENT: DA Form 4507-1-R is being reviewed to make it as accurate as possible for all Armyaircraft.

MARCH 983

Some of the listed tasks on the 4507-1-R will notcorrespond directly with the A TM for any particularaircraft.Unless w want to burden ourselves with a gradeslipfor each aircraft, the present format with minorchanges should be satisfactory.Adequate blank lines are available for tasks notlisted. DA Form 4507-2-R (comment slip) can be usedfor any overflow or additonal tasks.

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26/44

PEARI SPersonal Equipment And Rescue/survival

Debbie Bacle photo by Tom Greene

Cuffs And Waist Bands-CWU-36/P And CWU-45 P Flight JacketsDear PEARL, can you provide us with the NSNsfor CWU-36IP and CWU-45IP flight jacket cuf fs andwaistbands?The cuffs and waistbands fit all sizes of these jacketsand NSNs are: Cuffs: NSN 8315-01-028-3627;Waistbands: NSN 8315-0l-028-4896. However, the flightjacket has not been adopted for Army use at this time.We hope this information proves to be of value, andwe thank you for writing PEARL. I f further information is required, our point of contact is Mr. TommyVaughn, AUTOVON 693-3307/2492.Flight Clothing RepairDear PEARL, I recently had something happen tome that shocked me. I was given a Hhand-me-downflight suit CWU-27IP. What shocked me was the condition of he suit. The patch that was sewn on the suitcertainly was not in accordance with any sewing procedures, and the appearance was terrible. Aren t wesupposed to present a neat military appearance? Whyshould I have to wear a hand-me-down when I am newto the Army? Why shouldn't I be issued a new flightsuit, or at least a serviceable one?In answer to your questions, the procedures forgeneral repair to clothing and textiles are covered inFM 10-267, and also in Technical Manual (TM)10-8400-201-23, General Repair Procedures forClothing and Individual Equipment. I have review-

24

ed these two documents and they are very specific onhow clothing can be repaired. Chapter 7, TM 10-8400201-23 covers maintenance of the Army Aviationcrewmember's uniform. You should have been givenan initial issue of clothing in accordance with CTA50-900 when you entered the Army, and specializedclothing when you entered the flying program or aircraft maintenance program. In any case, I will quoteparagraph 7 7 of referenced TM which coversworkmanship. All work shall be accomplished bypersonnel skilled in the trade applicable to their dutiesin the repair of subject item. Darning shall be neatlyaccomplished and patches shall be of proper size andfirmly stitched to the garments.Stitching and reseaming shall be secure and looseends shall be turned and removed. Buttons, bucklesand belt loops shall be securely and properly attachedto function as they were intended. The finished itemsshall be complete and well repaired, thoroughly cleaned and rinsed and free from all defects which may affect serviceability or general appearance. By the way,I happened to see the flight suit you were talkingabout. t was at the recent SAFE (Survival and FlightEquipment) Conference in early December 1982.Members of other services also saw it and said underno circumstances would they have issued such a garment to be used. Your quality assurance people shouldbe notified of this problem.Why Wear Nomex?(reprinted from PEARL's September 1969From a flight surgeon's statement in an accidentreport: All three occupants were seen to exit the aircraft with clothing afire, but under their own power,by the pilot of the second ship. After remaining in theair for several minutes making emergency calls, thepilot of the second ship landed. He stated that at thetime none of the downed crew had their flight helmetson. However, he noted that none of them had burnsin the areas covered by the helmet. The pilot of thedowned aircraft remarked to the pilot of the secondship, I f only I had worn my Nomex.'Both the pilot and crewchief succumbed as a resultof severe burns. The severity of the burns sustainedwas directly attributable to the failure of all threecrewmembers to wear Nomex protective clothing. Hadthe suits been worn, these needless deaths could havebeen avoided.

u s RMY VI TION DIGEST


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Firewater and Flying from June 1969 USARV Avia-tion Pamphlet by Major Anthony A. Bezreh, MePete climbed out of the sack slowly, very slowly.When his upper torso reached the vertical position, hegrabbed his head with both hands to make sure thatit wouldn't fall off. There was a sort of dried out feel-ing in his innards; his eyeballs looked like a Rand-McNally road map; and his mouth felt like the bot-tom of a birdcage. Pete mustered up enough deter-mination to make it to his feet and carefully navigatedhis way out of the hooch. Guess I really hung meone on, he muttered to himself. No matter how Ilook at it, this is going to be one miserable day.

Poor Pete What a condition to fly in. Of course,he's flown in this condition before and, so far, he isstill alive to make the same mistake again. And, if hegets away with it this time, he'll probably get away withit the next time ... probably, that is.Pete is the willing victim of a delightful beveragecalled ETHYL ALCOHOL, which comes in a varietyof forms to please every taste. Obviously, Pete is suf-fering from the aftermath of his overindulgence theevening before, affectionately known as the HANG-OVER. Unfortunately, Pete thinks that his hangoveris just a sort of reprisal for all the good spirits he sharedlast night, a necessary evil, but nothing serious, youknow. That is, it couldn't affect his performance inthe cockpit. ..or could it? Maybe it would be worth-while to look at some of the facts. You know, no mat-ter what subject it is you want to talk about, there'salways some joker who will look at it scientifically;and until we find some way to eliminate these people,we probably will have to listen to them.f you drink 2 ounces of WHISKEY or two bottlesof beer, you will get a blood alcohol level of 0.05 per-cent and you are legally not under the influence. f youdrink 6 to 7 ounces of WHISKEY or six to seven bot-tles of BEER, you will have a blood alcohol of 0.15percent or above, which is considered as primafacieevidence (whatever that means) that you are legallyDRUNK, that is that your behavior is significantly in-fluenced by alcohol. Blood alcohol levels from 0.05to 0.15 percent are considered as relevant to prosecu-tion, especially if you ACT LOOPED. f you have ablood alcohol level increasing from 0.15 to 0.50 per-cent, you will pass through stages characterized asDIZZY and DELIRIOUS, DAZED and DEJECTED,DEAD DRUNK and finally just plain DEAD.Now, if you take an average Army aviator like Peteand give him a normal highball to drink every halfhour for 4 hours, at the end of his 4 hours and eightdrinks he will have a blood alcohol level of about 0.22

percent. That puts him in the dizzy and deliriouscategory. Then let's suppose Pete has finally hadenough and decides to hit the sack and sleep it off.f he sleeps for 8 hours (and who does these days), he

will wake up with a blood alcohol of 0.15 percent, and,if he jumps into an aircraft within the next 2 hours,he is now boring holes through the blue with theglorious blood alcohol level of only 0.13 percent, a full0.08 percent above the level at which he is legally safeand sane. Pete has more than just a hangover. Goodold Pete is still drunk In fact, it won't be until about24 hours after the start of his last night's spree thatPete will be down to the 0.05 percent level and by thattime he is starting the same thing all over again. Pret-ty discouraging, isn't it?

Add to this the fact that it really doesn' t take muchbooze to cause a significant amount of motor, sensoryand mental impairment. For example, let's look atmotor impairment. A moderate drinker suffers a 20percent impairment of his steadiness in standing at ablood alcohol level of 0.02 percent, 60 percent impair-ment at 0.05 percent and 120 percent impairment atonly 0.10 percent.As for mental impairment, memory, judgment andreasoning are affected. For example, an experimentwas done on telegraph operators receiving codedmessages. Those who drank only two bottles of beerwere 22 percent less efficient than before; their effi-ciency dropped to 72 percent after two bottles more.With respect to sensory impairment, alcohol causesa constriction of the visual fields and, for example,would impair a pilot in watching for planes in theperiphery of his field of view. Night vision and visionat low levels of illumination are impaired by alcohol,and even the sense of touch is decreased.Of course, when Pete is flying his chopper, hopeful-ly at least, he is using all three-motor, sensory andmental functions. Pete can figure that three or fourbeers will knock his overall performance by abut 5percent, when his blood alcohol level reaches its peakof 0.05 percent.As a rule of thumb, you can count on your bodygetting rid of about 1 ounce of whiskey per hour. Butremember that the metabolism of alcohol is handledby the body at a fixed rate and there is very little youcan do to speed it up. All of the ice cold showers, walksaround the block and black coffee in the world won'thelp your body get rid of that alcohol any faster.

Do you have a PEARL S photo to nominate or publicationin the Aviation Digest? Send it to Editor, U S Army AviationDigest P.O. Drawer P Ft. Rucker, AL 36362

If you have a question about personal equipment or rescue/survival gear write PEARL DARCOM ATTN: DRCPO-ALSE4300 Goodfellow Blvd. St. Louis MO 63120 or call AUTOVON 693 3307 or Commercial 314-263-3307

MARCH 983 5


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NIHTVISIONGOGGLSCOUNTERBLNCESYSTEM


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NVGCOUNTERBALANCE6443, requisitioned by the yard. Themeasurements of the bag are 3.5 by3.5 by 1 inches. The closing flap issecured by Velcro and is 1.5 by 3.5inches. Velcro fastener tape, looppile, 2 by 3 inches, NSN 8315-00-450-9837, is sewn on the rear of theweight bag for attachment of thebag to the SPH-4 helmet.b. Velcro fastener tape, nylonpile, 2 by 5 inches, NSN 8315-00-926-4930, two strips glued vertically at the center rear of SPH-4helmet. This tape is longer than required to accommodate a futuremodification to the AN/PVS-5. Adual battery pack will be attachedin this location.)c. Surgical tubing, NSN 4720-00-141-9080, 24 inches per helmet. Tubing is secured to curved end of Dring.d. Clamp, two each, NSN 5340-00-533-3513, attached using existingscrews on side of SPH-4. Helmetshave both screws or socket snaps atthis location; the clamp can be us-

FIGURE 2: Styrofoam Liner

ed with either.e. Nylon strap ties, NSN 5975-00-074-2072, four each, for securing overlapped surgical tubing to Dring.f. D-ring, NSN 5365-00-260-1412,two each, for connecting surgicaltubing to snap release.g. Socket snap, NSN 5325-00-276-4946, two each, used with cap,NSN 5325-00-276-9724 two each.h. Leather strap and metal snaprelease, two each, are componentsfrom strap assembly, NSN 5855-00-125-0762. These components are used with socket snap and cap (gabove) to form snap attachment insert, figure 1).i. Weights, :INSN l2530-00-272-7518 or 2530-00-241-7190, .5 ounce,for a maximum of 22 ounces peraviator.The proper mounting of thecounterbalance system is shown inthe photograph on page 26. t maybe necessary, on some helmets, toremove a small portion of the

h I. t.11 11 J h ~ shr fr of=r ttyrofoo .eeo 04.f.

fh

28

styrofoam liner in order for theNVG to fit properly under thehelmet shell. A minimum of 3/8inch distance from the edge of thehelmet shell to the styrofoam lineris required. The maximum distancerequired to accommodate the NVGis 5/8 inch see figure 2). This doesnot mean removal of 3/8 to 5/8inches of styrofoam. Rather itmeans that an area free ofstyrofoam is created, measuredfrom the edge of the helmet to thestyrofoam. The crash attenuationproperties of the SPH-4 helmetcould be degraded if this measurement is made incorrectly.The importance of night NOEflight is well established. Providingthe aviation community with thebest tools to do the job at night isbeing aggressively pursued. The introduction of the counterbalancesystem is another effort to safelyand economically improve our aviation capabilities.

The modi fied face plate Is beingevaluated by the Materiel Development and Readiness Command andthe Training and Doctrine Command for worldwide use to Improvethe operational capabilities of theAN/PVS5 night vision goggles Thisproposed modification Is compatlble with the counterbalance system



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AWARDSFt. Campbell, KY -CW3 Max B. Kelley hasreceived a citation for flying 10,000 hours inrotary wing aircraft without an accident orincident.Ft. Hood, TX-The 16th Air Traffic Control Bat

talion's aviation section has completed 2 yearsof accident-free flying, logging more than 1,500hours in rotary and fixed wing aircraft.Receiving special recognition for their contributions to the unit's record were CW4 DavidE. Nees, section leader and standardization instructor pilot, and SSG Sammy Vega, the sectionNCOIC.Ft. Bragg, NC-An Aviation Mishap PreventionAward of Honor for 2 years of accident-free flying has been presented to the 517th Transportation Company (AVIM), 1st Corps Support Command. It was accepted by CW4 Dennis Fry, theunit's aviation safety officer for that period. Unitcommander is MAJ P) Julian Sullivan.The 517th's primary mission is to provide intermediate level maintenance for aircraft, armament avionics and peculiar aircraft items ofground support equipment as well as aircraftparts.Ft. Rucker, AL-U.S. Army Aviation CenterCertificates of Achievement recognizing a totalof 3,000 accident-free flight hours were awardedrecently to aviators from Cairns Division, Department of Flight Training.Recipients were CPT Rollie J. Edwards andCW3 Larry K. Rutland, 1,000 hours each, and CPTFreddie J. Mills and CW3 Richard E. Martine, 500hours each.

3

10,000 Safe Hours. Major General Charles W. Bagnal, left,commanding general, 101st Airborne Division (AirAssault) and Ft. Campbell, KY, presents Chief WarrantOfficer, CW3, Max B. Kelley, B Troop, 2d Squadron, 17thCavalry, with an award for flying 10,000 hours Incidentand accident free. CW3 Kelley is a UH60 Black Hawk instructor pilot

UNIT REPORTSFt. Hood, X The 2 68th Air Traffic ControlCompany (Forward), supported by the 1 68th ATCCompany (FWD) of the 16th ATC Battalion(Corps), 7th Signal Command, used two fieldsites for a recent 5-day FTX-Strip 12 for thetower team and Anderson Mountain for the f lightcoordination center.That center was tasked to flight follow aircraftup to 1,400 feet in the Ft. Hood military restrictedarea. The controllers also provided en route instrument flight rules air traffic control, advisories, and weather and air warning information

to pilots in that area.Action was taken to resolve a potential conflict between Air Force C-130s operating at Strip12 and Army helicopters under the control of theflight coordination center (FCC).Operating the FCC in the restricted area wasextremely vital. When any firing point went hot,pilots were notified immediately. The facility alsoimplemented hand-offs with Hood Flight Following located at Hood Army Airfield.HQ, 5th Signal Command, APO NY -Uniquetraining problems call for unique solutions, andthe 59th Air Traffic Control Battalion's new tactical certification program is just such a solution.

We have ways to measure some areas oftraining, explained CPT James Hassinger, leader of the 1st Platoon, 240th ATC Company. Wehave the SaT for soldier skills and fixed basecontroller ratings, but we had no way to measuretactical readiness. Now we can measure all threeareas and determine when we have a competentsoldier, fixed base specialist and tacticalspecialist. It is an excellent management tool toquantify readiness.Regardless of MOS, certain requirements forcertification must be met by all 59th members.The battalion commander prescribes specifictraining tasks from soldiers' job books that mustbe performed each month, and 50 percent ofmodule I of the job book must be completedbefore the tactical certification can be earned.

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Hangar Talk is a quiz containing questions based onpublications applicable toAnny Aviation. The answers are atthe bottom of the page. f you did not do well, perhaps youshould get out the publication and look i t over.

M 1 51Rotary Wing FlightCW2 P) Gary R. Weiland

Directorate of Training DevelopmentsU.S. Army Aviation CenterFort Rucker, AL

1. Moist air is heavier than dry air.a . True b. False

2. The tail rotor of a single main-rotor helicopteris more aerodynamically efficient at a hoverthan in forward flight.a. True b. False

3. Attitude change about an aircraft'sxis is called pitch.a. Lateral c. Longitudinalb. Vertical d . Cyclic

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M RCH 1983

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4. When conducting multihelicopter operations ina high threat environment, and contact ispossible, the method of move-ment should be employed.a. Traveling overwatchb. Bounding overwatchc. Traveling

5. What is the safest way to cross a wireobstacle?a. Overfly at the midpoint between the supporting polesb. Underfly at the midpoint between the supporting polesc. Overfly at or near a supporting poled. Underfly at or near a supporting pole

6. Dark-adaption for optimum night visual acuityapproaches its maximum level in aboutminutes under minimal lightingconditions.a. 10 to 15b. 20 to 30c. 30 to 45

7. The optimum time for conducting night flightduring a full moon is:a . Just after sunsetb. Prior to midnightc. Shortly after midnightd. Just before sunrise

8. The best tactical lighting configuration for approaches initiated from terrain flight altitudes isthe tactical T.a. True b. False

9. The thinner air of higher altitudes causes theairspeed indicator to read low.a. True b. False

10. Mast bumping is likely to result when low-Gmaneuvers are performed in helicopters withsemirigid rotor systems .a. True b. False

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Major Raymond R. BensonCentralized Aviation Readiness TeamFort George G. Meade, MD

Soviet high performance aircraft which pose a threat to ourhelicopters can generally be divided into two categories by mission: 1}ground attack and 2} armed reconnaissance. Current Soviet doctrine dic-tates that primary targets for ground attack aircraft are enemy nuclearweapons, command and control centers, and reserve forces. These targetsare preplanned with only a limited number of resources allocated for im-mediate air attack missions. Aircraft on armed reconnaissance missionshave primary targets of nuclear weapons delivery systems and counter-attack forces.Tactically, ground attack aircraft will generally approach their target areaat an altitude of 50 to 100 meters m) above ground level AGL). The pilotsare not allowed to deviate from their predetermined flight plan withoutground control approval. While this positive control allows for safe cor-ridors, it does not give the aircrew much flexibility. Therefore, they are oflittle threat to friendly helicopters unless they are in the designated targetarea.

Of more concern then, are the ground attack aircraft on armed recon-naissance missions. These aircraft may operate alone or in small forma-tions and may have authority to attack without first gaining ground controlapproval. Since they are searching for targets, their altitude is higher, be-tween 275 m and 1,500 m. However, when a target is spotted they des-cend, approaching the target at about 60 m AGL. They then climb to analtitude of several hundred meters to attack. This type of aerial recon-naissance is considered an integral part of Soviet operations and is con-sidered especially important in a fluid situation such as a meeting engage-ment where the enemy disposition is not precisely known.Although not primary targets, it is likely that helicopters would be at-tacked by Soviet high performance aircraft on ground attack missions ifthey are in the designated target area, and as targets of opportunity bySoviet aircraft on armed reconnaissance missions.

Threat SectionDirectorate of Combat DevelopmentsU.S. Army Aviation CenterFort Rucker, AL

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PERFORMANCE THREATIMAGINE, IF YOU will, that you are 30 minutesinto a combat aerial resupply mission when suddenlyyou hear your crewchief's voice on the intercom: Sir,there are two enemy fighters rolling in on us from 8o'clock high. As the aircraft commander of yourhelicopter, what actions would you take?

f you are not sure, you may have never experiencedsuch an encounter. Although helicopters are not normally a prime target for enemy fighters, helicoptersare indeed vulnerable to attack by enemy high performance aircraft. Cognizant of this fact, Company C,28th Aviation Battalion of the Virginia Army NationalGuard, recently participated in jo int tactical trainingin which A-7s from the 192d Tactical Fighter Groupserved as aggressor aircraft. Helicopter crews fromCompany C were systematically exposed to an actualA-7 threat in a controlled setting which provided aunique opportunity to practice and refine evasivetechniques.High performance threat concerning helicopters isaddressed in Field Manual 1 101. Generally, the tacticsand doctrine outlined in these manuals proved to bevalid, although several factors not addressed were alsofound to be significant during the conduct of the threattraining. This article will examine high performancethreat as it applies to helicopters and will focus on thefollowing.

Factors affecting the ability of high performanceaircraft to acquire helicopters. Tactics which can be employed by helicopters toreduce the risk of detection. Evasive tactics which helicopters can employ oncethe threat aircraft has committed itself to an attack. Tactics used by fighter aircraft to attack

helicopters.

Factors ffecting the bility of Fighter ircraftto Visually cquire Helicopters

Because of their inherent design, most fighter aircraft have severe cockpit visual limitations. The restrictions to forward visibility are especially acute (figureI). The speed of the fighter and its altitude also impact on the acquisition process. The greater the

MARCH 1983

airspeed, the less probability that the fighter aircraftwill be able to visually acquire operational helicopters.The optimum acquisition altitude for the threat aircraft is variable and depends on a variety of factorsRE OF MOST

PROBABLE ACQUISITION

The cockpit configuration.. generally limit the aviator '.scanning vl.w to about 40 to10 forward and from 30 to46 on .ach .Id.. Rgur. 4-4repre.ent. the Thraviator'. flald of vl.w .

FIGURE : Threat high performance aircraft visibility

which include fighter speed, terrain, weather and therelative position of the helicopter. The altitude of thehelicopter is extremely important, with helicopters inthe nap-of-the-earth (NOE) mode being the most difficult to v

Army Aviation Digest - Mar 1983

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Transcript of Army Aviation Digest - Mar 1983