Apollo Experience Report the Role of Flight Mission Rules in Mission Preparation and Conduct

8/8/2019 Apollo Experience Report the Role of Flight Mission Rules in Mission Preparation and Conduct

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N A S A T ECHN I CA L N O T E NASA TN 0-7822

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APOLLO EXPERIENCE REPORT -THE ROLE OF FLIGHT MISSION RULESIN MISSION PREPARATION AND CONDUCT

by L d r y W. K y s e rLyndon B. Johnson Space CenterHoustor-2, Texas 77058NAT ION AL AERONAUTICS AND SPACE ADMIN ISTRA TION WASHING TON, D. C. NOVEM BER 1 9 7


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1 . Re r t No. 2. Government Accession No.NrSA TN D-7822 3. Recipient's Catalog No.

National Aeronautics and Space AdministrationWashington, D. C. 20546

1. Title and SubtitleAPOLLO EXPERIENCE REPORTTHE ROLE OF FLIGHT MISSION RULESIN MISSION PREPARATION AND CONDUCT7. Authorb)

Larry W. Keyser9. Performing Organization Name and Address

Lyndon B. Johnson Space CenterHouston, Texas 770582 . Sponsoring Agency Name and Address

14 . Sponsoring Agency CodeI

5. Report DateNovember 19746. Performing Organization Code

8. Performing Organization Report No.JSC S-417

10. Work Unit No.640-89-00-00-7211 . Contract or Grant No .

13. Type of Report and Period CoveredTechnical Note

5. Supplementary Notes

19. Security Classif. (o f this report)Unclassif ied

20 . Security Classif. (o f this page)Unclassified

6. AbstractThis r epo rt de scr ibe s the development of flight mission ru les f rom the mis sion developmentphase through the detailed mission-planning phase and through the testing and training phase.The proce dure for review of the rul es and the coordination requi rement s for mi ssio n-ru ledevelopment a r e prese nted. The application of the rul es to real-tim e decisionmaking isoutlined, and consideration is given to the benefit of training ground cont ro ll er s andflightcrews in the methods of de termining the best respons e to a nonnominal in-flightsituation for which no action has been preplanned. The Flight Mission Rules document isdiscu ssed i n te r ms of the purpose and objective thereof and in ter ms of the definition, thedevelopment, and the us e of mission ru les.

21 . NO. of Pages 22. Price10 $3.00

7. Key Words (Suggested by Aut hor (s) ) 18 . Distribution Statement

'Flight Rules' Mission Operations* Mission Planning

STAR Subject Category : 31


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APOLL O EXPERIENCE REPORTTHE ROLE OF F LI GH T M I S S I O N R ULES

I N M I S S I O N P R EP A R AT IO N AN D C O ND UC TB y L a r r y W . K e y s e rL y n d o n B . J o h n s o n S pa ce C e n t e r

S U M M A R YThe premiss ion preparation of flight mission rules delineates responsibility andauthority for the operational conduct of a mission. Because mission succ ess and crewsafety often a r e dependent on cle ar instructions and pr ec is e actions, the questions ofwho has the authority to act and what the action is to be must be r esoved before themission, whenever possible. The lack of immediate action, when required, because ofundefined responsibilities o r authority, can be just as disastrous as the wrong action.The effect of flight mission rul es w a s to enable prompt and accurate preplanned actionto be taken for 80 percent of the in-flight fa ilu res that occur red during the ApolloProgram.Pr em is si on coordination of mission ru les helps management to observe thedevelopment of the planned execution of the miss ion and to monitor the methods ofoperation f ro m miss ion to miss ion to ens ure continuity of operational philosophybetween missions . The documentation of responses (as many as are practical) toabnormal in-flight s ituations is a good operational practice because it forc es the entiremission-planning tea m to coordinate the various efforts. Premission coordination ofmission ru le s also facilitates the training of ground control lers and flightcrews in themethods of determining the best response to a nonnominal in-flight situation for whichan action ha s not been preplanned.

I NTRODUCTI ONFlight con trol lers accomplished the operational execution of the flight phase ofthe Apollo Prog ram. The most important task of flight control w a s being prepared tomake cor re ct real -time decisions consistent with crew safety, mission-objectivepriorit ies, and mission-operations/ hardware-performance constraints. Sometimesth es e decisions were made in time-critical situations in which th er e wa s no time toreview possible actions- nly time to respond. The action based on these decisionsranged fro m a spacecraft switch reconfiguration or a smal l change in the Flight P lanto an immediate termination of the mission.


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A fundamental approach to the success ful conduct of a mission in any fligh t-tes tprogram is to be prepared f or the lo ss of significant spacecraft functions and to havealternate cour ses of action preplanned where possible. The flight mission rules weredeveloped before a mission to arr iv e at the appropriate c orrec tive actions for potentiallo sse s of functions or capabilities.The primary objective of flight mission rules w a s to provide guidelines for

flight-control and flightcrew personnel to use to expedite the decisionmaking proces s.These guidelines were based on detailed knowledge of and experience with space vehiclesys tems, mission-equipment configuration fo r support of spacecraft syst ems , con-st ra in ts , flightcrew procedures, and mission objectives. All these are as werereviewed in detail and were formulated into a se ri es of basi c ground ru le s to increaseflightcrew safety and to optimize the chances of completing the miss ion objectives;flightcrew safety, however, w a s the overriding factor fo r all decisions. Thesedecisions or ru le s were published and distributed to a ll operational elements.The Flight Mission Rules Document (FMRD) was the controlled publication thatcontained the operational policy necessary for the effective contro l of a mission.Through a review of the FMRD, the Apollo Spacecraf t Pro gr am Office (ASPO) and

other management groups had the opportunity to approve the operational policies fo reach miss ion. Such a controlled document allowed preplanned co ur se s of action to besystematical ly reviewed by the appropriate levels within NASA or to be coordinatedthroughout various intracenter and intercenter organizations and the respectivecontractors .D E F I N I T I O N O F M I S S I O N R ULES

Flight mission ru le s a r e agreemen ts among NASA management, flightcrewpersonnel, flight operations personnel, personnel from the various pr ogram offices,and associated space-vehicle contr acto rs and manufacturers on cour se s of action totake in nonnominal in-flight situations. The NASA Headquarters specified the require-ment for mission rule s in a program directive to all organizations that conducted o rsupported Apollo mission operations. This direct ive contained the general contentsand description of the FMRD and established the responsibilit ies for the prepa ration,coordination, and review of the rul es . The miss ion ru le s included the following.

1. Nominal and nonnominal performance cr it er ia for space vehicle s ys tems andsubsystems2. Trajectory and guidance guidelines3 . Flight-abort criteria4. Cri ter ia for the real-time selection of alternate missions5. Mandatory and highly desirable support requirements of the Mission ControlCenter (MCC), the Spaceflight Tracking and Data Network (STDN), and the Marsha llSpace Flight Center for real-time flight operations and for subsequent analysis andev du at on

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6. Rules about human ,or medical aspec ts of manned flight7. Mission GO/NO-GO riteria based on systems and medical considerations8 . Cr it er ia for extravehicular activity and fo r deployment of the scientificApollo lunar surface experiments package9 . Recovery restrictio ns

10. Launch-window rul es on time of lift-off, launch azimuth, recovery, andspacecraft perf o rmanc e limita tionsBasically, mission rul es were composed of three different types: general rules ,flight operations ru le s, and specific rules. General ru le s were furnished by the Officeof Manned Space Flight (OMSF) to set forth the policy for preparation, coordination,and review of the ru les . Flight opera tions rules, which are guidelines for the creationof the specific rul es , a r e furnished by the Director of Flight Operat ions and by theFlight Director and his staff to provide direction and policy on a detailed, mission-

speci fic level and to ref lec t the position of the Flight Operations Direc torate (FOD) onthe conduct of the mission. The specific rule s, remedial courses of action to be fol-lowed in specific contingency s ituations, a r e compiled by the individual flight control-le r s, afte r coordinating data fr om cognizant personnel according to the generalguidelines s et forth by the OMSF and the FOD, to cover the fa ilures of space-craft and ground systems.Mission rul es also include GO/NO-GO points, which a r e points in the missionwhen the decision is made to commit or not to commit the space vehicle and crew tothe next, usually more critical, mission phase. A GO decision is made after thesta tus of the space vehicle and crew has been ass es se d; it is a statement of confidencein the space vehicle and crew to proceed successfully, to complete, o r to return

safely fro m the next mission phase. If a NO-GO decision is reached, the next missionphase is not entered and an alternate mission or mission termination result s. TheseGO/NO-GO ecision points a r e defined by the mis sion design and by the initiationof a specific o r unique phase or event. The GO crit eria for the spacecraft syst ems ar esummari zed in cha rts by mission phase. The capabilities listed in these ch art s a r ethe re quireme nts fo r initiation or continuation of a mission phase or event.THE ROLE OF M I S S I O N RULES D U R I N G M I S S I O N P R EP A R AT IO N

Operational preparation f or a mission begins with the spacec raft design and theinitial commitment to the construction of flight vehic les and launch facil ities. Thedevelopment of miss ion operations begins afte r sufficient information on space vehicledesign is available. During the Apollo Program, mission preparatio n was divided intoth re e separ at e phases: the mission development phase, the detailed planning phase,and the testing and training phase. These phases and an example of mission-ruledevelopment a r e discussed in the following paragraph s.

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M i s s i o n D e v e lo p m e n t P h a s eThe mission development phase began approximately 2 ye ar s before the firstlaunch of a new flight program. The conceptual guidelines for conducting operat ionalsupport of the flight were es tablished at the beginning of th is phase. Initial programdirec tion began with the mission definition as outlined in the Mission Requirements

Document. A s the mission became bett er defined, personnel had an opportunity toanalyze the possible effect of various onboard and ground sy st em s fail ure modes on themission and to identify additional sys te ms changes and requi rement s. These analyseslead to the identification of cer tain guidelines and constr aints. These guidelines andconstraints were then used as cr it er ia fo r continuing beyond ce rta in points in themission and subsequently became the GO/ NO- GO cr it er ia for the mission rules. Whena constraint o r guideline could not be satisf ied by a change in the mission design, amission rule was wr itten to e nsure that the constraint o r guideline would not be vio-lated. In some ca ses , the mission profile or spacecraft-system operation had to bechanged when a rul e could not be writte n to satisfy existing const raints .Fo r Apollo, the OMSF rules wer e used during this phase as basic guidelines forthe development of the flight opera tions rules . Flight opera tions ru le s were affectedmost during this phase. As the mission became mor e defined, the various constraintsand guidelines that we re generated often required the addition o r modification of arule. The analyses of these constra ints and guidelines, the mission profile, and themission rule s frequently necessitated recommendations to change either ground-based o r space vehicle hardware and software.

D e ta il ed P l a n n i n g P h a s eThe detailed planning phase for a particular Apollo mission began when thedetailed mission objec tives were assigned (approximately 6 months before the launch).The detailed objectives were assigned prio rit ies and integrated into the mission time

line. This procedure w a s affected by the mission r ul es i f any of the time-line changes,system s constraints, o r operating limits caused a mission rule to be violated. Con-versely, i f certain objectives were to be achieved, other mission ru les had to bewri tten to ensure safe conduct of the mission.The beginning of the detailed planning phase was c ha rac terized by the initialformulation of the specific rules , which were developed to be compatible with otherdocumentation being produced during th is phase. These documents included theSpacecraft Operational Data Book (SODB) and other documents relating to traject ory,time lines, and procedures. The specific ru le s for each specialty a re a were formu-lated by the appropriate flight-operations, launch-vehicle, experiment, scien tific,medical, recovery, and space-radiation personnel. These rul es we re based on exist-

ing capabilities, requirements , limitations, mission objectives and mission applica-bility wherein flight crew safety was the overriding fac to r. The data used for writ-ing the specific ru les were derived fro m flight-test experience, ground-test experi-ence, engineering simulations, training experi ence, space vehicle and crew-equipmentdesign specifications, and the flight operations rules.

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Onboard and ground-control procedures w ere developed during this phase i nparallel with the mission rule s. To aid the development of onboard procedures, theflightcrew was kept appris ed of mission ru les ; to keep the mission rules current, theflight controllers were advised of the latest crew procedures. The ru le s and proce-dur es had to be compatible to ensure the proper us e of spacecraft systems. Ground-control procedures for flight controllers were developed similarly , in parallel with themission ru les . Constant coordination between the flightcrew and the flight con tro lle rswas requir ed to keep each group appr ised of the c ur re nt thinking on the various rul esand procedures.T e s t i n g a n d T r a i n i n g . P ha s e

An Apollo miss ion testing-and-training phase began approximately 90 days beforelift-off; at this time, operational testing of the ru le s was performed in a simulatedenvironment. The flight-control and flightcrew personnel exerc ised the rules duringintegrated simulations; the rules were changed when, as a result of simulations, itwas determined that a rule was wrong o r that a new rule was required. Frequently,simulations resu lted i n the discovery that a ru le could not be implemented because ofa lack of t ime or because of inadequate data. In such cas es, the rul es were modifiedto compensate for the delays in data processing o r the lack of data. The flightcrewand flight-control procedures were also refined during this phase as the rules wereexercised.A s the rul es changed, the procedures w ere changed to make them compatiblewith the rul es ; in instances when rul es were not changed, the procedures were alte redto prevent violation of any rul es, guidelines, o r constra ints.The ru le s were reviewed throughout the NASA Lyndon B. Johnson Space Center(JSC) (formerly the Manned Spacecraft Center (MSC)) by personnel in each specialtyarea and were later reviewed i n a NASA-wide review to ensure compatibility amongoperational elements. These reviews were conducted by the Flight Director in con-junction with the ASPO, the flightcrew, the contr act ors (as required), the safetyoffice, other mission- support personnel, and the flight controllers f rom the system sspecialty ar eas .The rules we re influenced at the se reviews by any new developments or fai lures -effec ts analyses, test-vehicle repor ts, simulation evaluations, manufacturer repo rt s,and pad-test resul ts. The SODB and other documentation were updated as the ruleswere changed as a consequence of these reviews. The simulation-review-rewrite-simulation i ter ative cyc le during thi s phase continued until lift-off and provided theru le s thei r finest critique.

Example of M i s s i o n - R u l e D e v e l o p m e n tA good example of the development of a mission rule involves communicationswith the lunar module (LM) during descent to, and ascent fr om , the lunar surface duringthe Apollo 11 mission. After ASPO had outlined the attitude guidelines fo r the first

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lunar-landing mission, the mission planners constructed an attitude time line. Thistime line revealed that during lunar descent and ascent, for landing si te s outsiderf: 20" longitude, the STDN would lose telemetry and tracking coverage of the LMbetween an altitude of 50 000 and 20 000 feet.

The LM contractors proposed several hardware, software, and proceduralchanges to the ASPO. One proposed change wa s to maneuver the spacecraft attitudebetween 50 000 and 20 000 fe et altitude to provide good communications through betterantenna pointing. The ASPO decided not to change the LM hardware or software designbecause of weight, schedule, and cost fac to rs . The flightcrew concurred with theASPO on no spacecraft changes but also went on record as not favoring an attitudeconstraint, at least not that long before mission simulations could validate the con-straint. The flightcrew believed that "voice only'' communications between 50 000 and20 000 feet altitude were satisfactory for crew safety.

Flight controllers examined the effect that the los s of this telemetry and trackingdata would have on crew safety and on mission success; they concluded that it wasmandatory to keep all communications. The flight con trol ler s agreed with the flight-crew and wi th the ASPO on no spacecraft modifications but believed that an attitudeconstraint was best and should be planned because it might be required.

The flight controllers then submitted their operational constraints to the missionplanners; these constraints stated that constant telemetry and tracking coverage wererequired for the enti re descent and ascent phases. The mission planners thenexamined different attitude profiles for these phases and determined the proper attitudefo r good, continuous communications at different landing sites.When the flight contro llers wrote the preliminary mission r ul es fo r thesephases, telemetry and tracking were requ ired t o begin and to continue through descent.After the ramifications of various LM fai lures without communications were di scussedwith everyone involved, the crewmembers agreed to perform an attitude maneuver to

keep continuous communications during ascent or descent, if necessary. The simula-tions provided a rea lis tic impression of the ascent and descent phases of the mission,and a decision w a s made that constant telemetry and tracking were not absolutelyrequired; however, ground-based personnel did require adequate data to make eachGO/ NO-GO decision to continue powered descent. The mission ru le concerning lo ssof LM telemetry for the Apollo 11mission is given i n figure 1.

THE ROLE OF MISSION RULES I N F L I G H TThe in-flight application of the mission r ule s to nonnominal s ituat ions actually

began before lift-off. Some of the ru le s applied to fa il ur es during the prelaunch count-down of space vehicle instrumentation that might be required for mahing GO/NO-GOdecisions la te r in the mission. Other ru le s applied to the MCC capability to supportthe mission. Consumables-loading redlines were als o exerc ised during the prelaunchperiod. Failures of flight instrumentation o r ground-support equipment during thecountdown could have caused a hold or a s crub of the launch. A l l the failures o ranomalies that could have possibly caused a hold or a sc ru b should have been docu-mented in the FMRD.


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TEM-' 0 - 5 5

N A S A - M a n n e d S p a c e c r a f t . C e n t e rMISSION RULES

S E C ' I O N 20 - C C M M U \ I CA T I O N S AV D I X S T D U M E N T A I I O N

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Figure 1.- Mission rules 20-55 and 20-56 or the Apollo 11 mission.

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Any decision involving these f ai lures or anomalies was preplanned and automatic; i fthese failures or anomalies had not been documented, a decision, based on the philos-ophy used to develop the rul es that were documented, w a s made at that time. Afterlift-off, the instrumentation and ground-support rul es no longer applied.Throughout the Apollo Pr og ra m, approximately 80 percent of all problemsencountered in flight, both lar ge and small , had been analyzed previously and a courseof action documented before the flight. This analysis allowed the choice of a bestco ur se of action subsequent to most fa ilu res to be essent ially automatic. The remain-ing 20 percent of the problems we re solved readily i n flight by using the s am e deci-sionmaking logic used to develop mission ru le s before the mission; this p rocedure ,however, is not as desirable as having mission rules available, because little o r notime exists for a review-simulation-rewrite cycle to validate the r ul e and the proce-du re s involved.The implementation of a mission rul e begins with the recognition of an abnormalcondition by the flightcrew or by the flight-control team. Once identif ied, i f thefailure is time cri tica l and catastrophic, an immediate flight abor t is required; if timeallows and i f the failure is not catastrophic, a search is made to isol ate the problemsource. This is accomplished by flightcrew observations during the execution ofsy st em s malfunction procedures, by flight-control re al- tim e observations of the mal-function procedures, by analyses of taped re co rd s of te lemetry and voice playbacks,by trend analyses, by analyses of p remission testing and data, and by a comparison ofprevious-mission data. If the identification of the problem source reve als an impend-ing catastrophic failure, an attempt is made to circumvent the problem by proceduralchanges i n the use of the systems . An immediate terminat ion of the flight may berequired if the failure is still imminent. If the failure is not imminent, continuationof the remainder of the flight depends on the number of mission objectives remainingto be accomplished. The mission ru le s, the nominal Flight Plan, and any preplannedalte rnate mission plans must be examined to determine an acceptable cou rse of actionfor the accomplishment of the mission objectives, with crew safety kept as the para-mount issue . In some ca se s, after this examination, the scheduled nominal mission ispermitted to continue; in other c as es, an alternate mission is chosen.

C O N C L U D I N G REMARKSThe flight miss ion r ul es proved to be a ve ry effective tool i n planning andexecuting Apollo miss ions in a safe manner. The ru le s enabled prompt and accura tepreplanned action to be taken for approximately 80 percent of the in-flight f ai lu re sthat occurred. The experience gained in developing these ru le s enabled the ground andflight personnel to determine rapidly and effectively corr ect ive actions for the remain-der of the failures.

Lyndon B. Johnson Space CenterNational Aeronautics and Space Adminis trationHouston, Texas, July 17, 1974640- 9-00-00-72

8 NASA-Langley , 1914 S- 17


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Apollo Experience Report the Role of Flight Mission Rules in Mission Preparation and Conduct

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