Ukv Trd 3.1 Holding Patterns

UKV TRD 3.1 (02 Mar 10)

HOLDING PATTERNS

Fly UK Virtual Airways P - 1 -

Document Objectives / Requirements

This document explains the fundamental concepts of the holding pattern and the technicalities related to it.

A basic knowledge of reading charts, a basic understanding of instrumentation (ADF primarily) and use of FMC(payware users) is required.

Practical Training Sessions Available

Please note the Fly UK Training Academy also offer a practical one2one online training sessions on this subject.

Radio Navigation - http://www.flyuk.aero/en/index.php?page=my_training_acad&act=book&id=7 Holding Patterns - http://www.flyuk.aero/en/index.php?page=my_training_acad&act=book&id=12

Contents

This document contains:

Holding Patterns The Hold Holding By Hand

Introduction

At Fly UK we encourage a high standard of flying and we aim to help and support all our members to the best of our ability. If we all follow these guidelines when flying a holding pattern, it will help you to understand how to fly your aircraft to a better standard.

http://www.flyuk.aero/en/index.php?page=my_training_acad&act=book&id=7

http://www.flyuk.aero/en/index.php?page=my_training_acad&act=book&id=12

UKV TRD 3.1 (02 Mar 10)

HOLDING PATTERNS


Holding Patterns

First of all we will look at what a holding pattern is.

A holding pattern is usually a racetrack or oval pattern which is centred around a fixed point, usually a VOR, NDB or Intersection. The fixed point is the start of the first turn, or racetrack pattern. An aircraft will approach the fixed point and once there will then enter the prescribed hold. A standard holding pattern uses right hand turns, however left hand turns are found occasionally. Each hold ‘should’ take 4 minutes in time (each leg being 1 minute in total).

Occasionally you may be asked to deviate from the norm and may be given ‘amended’ instructions. If it is especially busy or there are ATC restrictions then you may be asked to either extend the leg time (for example 2 or 3 minutes). You may also be asked to use a distance rather than a time, so for example you may be asked to make each leg 5nm, albeit this being a rare occurrence.

Most airports in the UK have published holding patterns, which can be found on the appropriate arrival charts. The instructions on the approach plate should be adhered to unless otherwise stated by air traffic.

Holding patterns are mainly used in the vicinity of an airport to delay aircraft that cannot land yet due to congestion, bad weather, blocked runway or other eventualities. Any number of aircraft can use a holding pattern, all of which are separated by 1000ft or more. Some airports have a number of ‘stacks’ or holding patterns. Heathrow for example has 4 stacks.

Finally, a note about flying a holding pattern. All holding patterns should be flown with landing gear and flaps retracted, as this reduces the overall drag and so reduces the fuel burn, all flights should carry the required holding fuel. Typical holding speeds vary from 210kts upto 250kts (this is not tied, some holding speeds are as low as 180kts). Obviously a heavier aircraft will have to hold at a higher speed.

We will now move on and have a look at how we should look-up, enter and fly a holding pattern.

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The Hold

For the following example, we are going to use the standard NDB hold at Bristol.

So what we have here is a diagram of our hold. From the enlarged image we can see that the lowest holding altitude (LHA) is 2500ft AGL. Please note that this hold is part of a procedural approach, which will be continued in another document. For now, all we are interested in is the holding concept. We should also be aware that the maximum speed for this hold is 185kts.

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Following on from this, we now need to look at what our ‘inbound heading’ should be. We can see on the chart that the ‘outbound heading’ from the beacon is 274degrees. We can tell it is the ‘outbound heading’ because the arrow is pointing away from the NDB. With this we can work out the ‘inbound heading’ is going to be 094degrees, because it has to be the reciprocal of the outbound figure ( i.e. the outbound heading minus 180degrees). So we have now got the following information…

Minimum/lowest holding altitude (LHA) is 2500ft.

Maximum speed is 185kts IAS (indicated airspeed)

Inbound course / heading 094degrees, and left hand turns.

This is a parallel entry to the hold. Here we are approach the hold from within a 70 degree angle from the left. So we will overfly the beacon, fly away from the beacon and teardrop round to intercept.

This is a direct entry to the hold. As you can see, we are approaching the beacon almost dead on. In this case we can enter the hold from the second we reach the beacon.

This is a teardrop or offset entry to the hold. This is quite a simple one. We approach the beacon from within a 70 degree angle from the right. We overfly the beacon and teardrop round onto the inbound heading.

What we need to work out now is how we are going to enter the hold. This actually all depends on which direction we approach the beacon from. There are 3 types of entry to the hold, all of which will be demonstrated for you in this document. We have the direct entry, which as the name suggests is straight into the hold. We have the offset (or teardrop) entry, and then we have a parallel entry. These are displayed in diagrammatical form below:

UKV TRD 3.1 (02 Mar 10)

HOLDING PATTERNS


Please note. The above descriptions are valid for right handed holds. For left handed holds (like the one I am about to display) The parallel entry will be applicable when approaching from the right and from the left with the offset approach, so it is reversed. The reason I am doing this is to show you from both perspectives.

Ok, so we have a very brief description about how we are to enter the hold, don’t worry at this stage if you don’t understand, hopefully things will become clearer in the demonstrations to follow. What we will now look at is a step by step guide at how to intercept and enter a hold using each of the entries above. As stated, we will be using the Bristol NDB and for the purpose of these demonstrations I will be using the FMC and systems from the PMDG 737-800.

Okey, so we now imagine we are inbound to hold at the Bristol NDB. The first thing we need to do is put the details into the FMC ‘Hold Page.’ When you have put in the correct details, it should look something a little like this (this is assuming you are flying the PMDG 737 series).

So going down the FMC we can see the following. Starting on the left hand side at the top, we can see ‘BRI’ which is the fix we are using for the hold.

Below that we have 094degrees and‘/L TURN’ this is our ‘inbound heading’ and direction of turn for the hold.

Again going down, we can see we have a leg time of ‘1.0 MIN’ this is obviously the length of our legs, so we should have a total hold time of 4 minutes.

Going across to the top right, we see our target speed and target altitude. We have put in ‘185 / 2500’ and again; quite simply, we can deduce that this shows 185kts IAS and an altitude of 2500ft AGL for the hold.

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The next thing we need to do is verify that the data is being portrayed correctly on our Navigation Display (ND).

The holding pattern has now been embedded onto the fix. We are currently flying a heading of 210degrees. This puts us on an intercept heading to join the hold. Looking at the diagrams above, we can see that this should be a parallel entry (taking into account this is a left handed hold). So moving on, we will continue on this heading until we reach the beacon.

Once we overfly the beacon, we will then turn to fly the reciprocal of the ‘inbound heading’ this will now take us away from the NDB and will put us in a position to fly our base turn to intercept the hold. When we reach the point parallel to where we would turn in the hold, we then turn back in towards the hold and start the base turn.

Parallel Entry…

UKV TRD 3.1 (02 Mar 10)

HOLDING PATTERNS


Once we start the base turn we carry on with the turn until we end up facing the NDB once again. This has now just basically turned into a normal direct entry. You can happily enter the hold from this heading, and continue to fly the racetrack until you need to exit. You can either engage ‘LNAV’ to fly the hold (provided it has been input into the FMC) or you can fly it manually.

When you arrive over the beacon, you will then start the left hand turns to take up the normal hold, remembering to keep the speed at 185kts or less!

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What we will look at next, is the direct entry into the hold. This is the basis of all the entries as both the parallel and offset entries eventually place you in a direct entry position.

So again, we will presume you are inbound the BRI NDB, but this time on a more direct heading.

From the images we can see that this time, we are approaching the hold from an almost head on direction, this is the easiest way to enter the hold as it does not require any kind of procedure turn. As you get closer to the beacon you should start turning so that you arrive over it on the inbound heading, or as close to it as possible. This way it will make entering the hold as accurate as possible. If the FMC is flying the hold for you, it should do this automatically and put you in a good position to start the orbits.

Direct Entry…

UKV TRD 3.1 (02 Mar 10)

HOLDING PATTERNS


And finally, we will have a look at the offset (or teardrop) entry to the hold. This is again quite an easy way to get into the hold. The diagrams below will explain better.

We are approaching the hold from the left this time. However taking into account that it is a left hand hold, this will be an offset (teardrop) entry.

Once we pass overhead the beacon as shown, we continue on a heading away from the beacon towards the far side of the hold. It is down to pilot judgement when to turn, but it must be before you pass through the outbound leg, i.e. you must turn before you hit the far magenta line.

Offset Entry…

UKV TRD 3.1 (02 Mar 10)

HOLDING PATTERNS


Upon reaching our turning point, we will make a normal turn (usually about 3degrees per second) until we end up tracking the inbound heading towards the beacon. Once we are established on the ‘inbound heading’ we should then be able to take up the hold with little or no difficulty at all.

Just as a recap, from the second image we can very easily see the way the hold takes shape. Take note that once we arrive over BRI we will then turn to the left as per the chart.

UKV TRD 3.1 (02 Mar 10)

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So there we have the three ways to enter the hold. They may seem daunting to look at, but all it takes is a little bit of practise and maybe a session or two with the training academy to become proficient at them!

Finally we will have a look at the way the hold itself, and the 4 sectors or legs of it. Once we have entered the hold using one of the three prescribed methods, we then need to fly the hold itself. This is the easiest part, as most aircraft with an FMC will do it for you. If you don’t have an FMC, then programs like vasFMC or FSNavigator can fly a reasonable hold. If you have neither of these, then a trusty stopwatch and your Direction Indicator will have to do!

So let’s look at a typical hold (remembering that this is a left hand hold)…

Leg 1. Leg 2.

Leg 3. Leg 4.

UKV TRD 3.1 (02 Mar 10)

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Going through leg by leg then:

Leg 1. When we arrive over the beacon after our entry we will then start our turn towards the outbound leg. This is the first leg, it should take a total of 1 minute to complete and should be flown using a standard rate 1 (3 degrees per second)turn.

Leg 2. Once we have completed our first turn, this puts us onto our ‘outbound heading’ which we should fly for a total duration of 1 minute, at which point we will reach our base turn point.

Leg 3. This is our base turn, which will put us back onto our ‘inbound heading.’ Like the other turn, this should take a total of 1 minute and should be flown at a standard rate 1 turn.

Leg 4. This is our inbound heading and will take us back to the beacon where we can either exit the hold, or start the hold all over again, as per usual this leg should take 1 minute.

The last thing we will look at is exiting the hold. This is very simple and can be done a number of ways. Firstly, if you are flying the hold on ‘LNAV’ mode, then all you simply need to do is either change to ‘HDG HOLD’ mode, or press the ‘EXIT HOLD’ button on the FMC (see left). If you are flying the hold on ‘HDG HOLD’ mode then, if you engage ‘LNAV’ it should carry on your flightplan as per the FMC, provided that the hold is not set as the active waypoint in the ‘LEGS’ list.

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Holding By Hand

Now we know what a holding pattern is and what it looks like, we will now have a brief look at how to fly one by hand, or by using the instruments we have on board (No use of the FMC).

What we have here is a section of theprocedural NDB/ILS/DME approach for runway 28 at Blackpool. So what can we learn by looking at the chart?

Well, we can tell that it is a right hand hold, with 1 minute legs, and a LHA (lowest holding altitude) of 2000ft.The inbound leg is 095degrees and the outbound is 275degrees.

Now we understand the basic concept of the this hold, we will now look at how to fly it; using nothing but a Stopwatch, a HSI and an ADF needle.

When using basic radio nav equipment, it is important to first of all work out if we are indeed using the correct beacon. To do this we must ‘Identify’ the beacon. This is very simple and requires the press of a few buttons and a careful listen.

The first we need to do is put in the NDB frequency into the appropriate section of our ‘Radio Navigation’ stack. Please bear in mind that on the chart it says that the frequency is ‘318KHz’. In Flight Simulator 2004 the frequency you need to put in is, ‘420KHz’. The problem with FS2004 is that a lot of the frequencies are out of date now and are different from their real world counterparts.

UKV TRD 3.1 (02 Mar 10)

HOLDING PATTERNS


Once we have put the correct frequency into the ‘ADF’ box, we need to ‘Identify’ it. We do this by selecting the ‘ADF’ audio function on our radio.

After we have pressed the ‘ADF’ button (as shown lit up green on the above panel) we should hear an Ident in Morse code. You don’t need to be an expert on Morse code to understand the Ident. The series of ‘dots and dashes’ you want to hear are displayed on the chart. So by looking back at the chart we can see this:

BPL 318KHz. (420KHz on FS9)

_ . . . . _ _ . . _ . .

In layman’s terms we are listening out for something which sounds something similar to the layout of ‘dots and dashes’ above. The lines in the code represent the longer beeps. The dots represent short beeps. When you listen for yourself you should be able to tell the difference.

Once we have identified the beacon, we can safely and accurately use it. If you do not get an Ident, then you must assume that the beacon is offline or not working properly and you must not use it.

Once we put ‘420KHz’ into the ‘ADF’ section of our radio stack we should see that the ‘ADF’ needle point to somewhere relatively close to the beacon. Provided we have done these checks and we can verify that the needle is working, we can take off and perform the procedure.

‘ADF’ Needle

UKV TRD 3.1 (02 Mar 10)

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We will now look at the hold itself. For the purpose of this, we are going to use a direct entry to the hold.

Okey, so by looking at the two images, we can quite easily see that we are on track for the BPL, and also our ADF needle on the cockpit is pointing directly ahead. The arrow points relative to the beacon, so if the beacon was behind you, the arrow-head would be pointing backwards towards it, you will understand more as we progress with the document.

Okey, so by looking at the two images, we can quite easily see that we are on track for the BPL, and also our ‘ADF’ needle on the cockpit is pointing directly ahead. The arrow points relative to the beacon, so if the beacon was behind you, the arrow-head would be pointing backwards towards it, you will understand more as we progress with the document.

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Once we arrive over the beacon, this is where our hold actually starts. Before we reach the beacon, we want to put ourselves in a suitable position that will make our first turn as easy as possible, I would suggest that you use no more than a 30degree closing angle when approaching the beacon. When you are over the beacon, the next thing to do is continue on that heading for approximately 5 seconds.

When you are overhead the beacon; the needle will drop (usually to the right). You can see above the way the needle has dropped. It will go to the 1 o’clock position, followed by the 4 o’clock position, then slowly it will pass the 5 o’clock position and will eventually point backwards towards the beacon (please remember that the beacon is where the arrow-head is pointing, and not the tail-end).

To check our progress, I have included a number of instrument and FSNavigator shots. I have used FSNavigator for the sole purpose of trying to show to you how the hold works. After we have flown a constant heading for 5 seconds, we will now begin our rate 1 (3 degree per second) turn.

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The key here is to keep a rate 1 turn going all the way round to the outbound heading of 275degrees. A rate 1 turn is what we call the standard turn for all holding manoeuvres. It consists of a turn with a bank angle of about 15degrees, certainly no more than that. It generally works out that you pass 3degrees per second whilst turning. With this knowledge you can work out that a 180degree turn will take 1 minute, fairly simple really.

As we keep the turn going, we should notice the ‘ADF’ needle slowly slip round the ‘RBI’ (Relative Bearing Indicator) towards the 9 o’clock position, when we reach the 9 o’clock position on the ‘RBI’ this means we are at the ‘abeam’ position and we can start our 1 minute timer for the outbound leg. (See diagrams below for a step by step demonstration of the first turn).

Once we pass the beacon, travelling away from it, we can see that the arrow-head is now pointing towards the beacon, this is indicator that we are now travelling directly away from it. We need to maintain this heading for about 5 seconds, and then being the turn.

UKV TRD 3.1 (02 Mar 10)

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UKV TRD 3.1 (02 Mar 10)

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From the last set of images; we can see that we have arrived at the ‘abeam’ position. The definition of the ‘abeam’ position is very simple and can be described as the point where you are in line with the beacon on the outbound track. In this case, our outbound track is 275degrees (as depicted on the chart) so when we are flying steady on a heading of 275degrees we can call ourselves established on the outbound track.

Carrying on with the hold then. As we travel along the outbound leg, we will eventually reach a point called the ‘gate position’. Now this is slight tricky and can sometimes be misleading, however I will explain it for you!

Once we have completed our 1 minute outbound leg, we should have arrived at the point depicted above. This is where we at a 30degree angle away from the beacon. We can look at this two ways. We can imagine a line running through the aircraft longitudinally and then another line running from the beacon to the middle of the aircraft. The angle that the lines would intersect at would be 30degrees.

Alternatively, we can work on a QDM and QDR basis. QDM is a ‘Q-Code’ for the magnetic bearing to the beacon, and QDR is a ‘Q-Code’ for the magnetic bearing from the beacon. This is much more complex and requires you to mentally transfer the image on the ‘ADF’ needle across to that on your HSI (Horizontal Situation Indicator) or DI (Direction Indicator).

RBI (‘ADF’) HSI

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The way we need to think about this is that the RBI (Relative Bearing Indicator) is called an RBI because it only provides a ‘relative’ bearing. You may notice that on the RBI, it is shown that we are flying ‘North’. This is not the case, you can rotate the compass card on the RBI if you wish to make things easier, however I just prefer to transfer the picture across in my head.

So by now looking at the HSI we can tell that our heading is roughly 275degrees, which is the outbound track.By transferring the ‘ADF’ needle across in your head onto the HSI, we can see that the arrow-head would be pointing approximately towards 060degrees. The ‘gate position’ is roughly the inbound QDM minus 30degrees. So in this case, the inbound QDM minus 30degrees would be 060degrees. So when our ‘ADF’ needle on the RBI is pointing towards 060degrees, we will then begin our ‘base turn.’ This sounds very confusing, but in essence is very simple, you just simply have to picture in your head, the relative position of the beacon and your position in relation to it.

So let’s now carry on with hold. We have reached the ‘gate position’ so it is now time to make our ‘base turn’ The base turn is the turn that will bring us back onto the inbound track. Again this is a 1 minute turn, and will take us from the ‘gate position’ to the start of our inbound track.

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From the series of images above we can see how the ‘base turn’ develops. From the initial start point, we would start our stop watch and time for 1 minute. We would maintain a rate 1 turn all the way round until we established on our inbound track. Once were are established on the inbound track, we will maintain it until we pass over the beacon again. Once we have passed over the beacon, we can elect to make another hold and it would be at this point where we would start the turn, or we can continue to follow a procedure approach (more on this in another document).

A couple of things we need to quickly discuss are the effects of wind on the hold. I won’t go too deeply into it as it is generally common sense. When in the hold, we need to work out where the wind is coming from and what effect it will have on each of the legs, primarily on the outbound track. If you have a tailwind on the outbound leg, you would probably reduce the leg time to 50 seconds, and you would then make the inbound leg a little bit longer than 1 minute, for example 1 minute and 10 seconds. Vice versa occurs if you have a headwind on the outbound leg, you will probably fly a leg time of about 1 minute and 10 seconds. Also take note that a wind will affect you in the turn, so just be prepared for this, the turns should all still be rate 1 and last for 1 minute, do not alter the time of the turns, any corrections to be made should be done on the straight sections.

So in a nutshell we need to remember a couple of things:

Select the appropriate frequency in the box,

Identify it using the audio selector,

Display on the ADF needle (automatic but just check the reading).

This can be remembered using the acronym SID.

Finally, remember the different positions of the hold, the ‘abeam’ and ‘gate’ positions are the most important, and don’t forget to keep a constant glance at all of the instruments in order to maintain accurate and sensible flight.

This concludes this document on holding, if you have any questions or have found anything in this document difficult to understand, then there are training sessions available from the training academy!

End of Document

Ukv Trd 3.1 Holding Patterns

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