Racetrack approach procedures

[TheKentishFledgling]

I've been looking at various approach plates in the Jepp manual I was given, but still can't work out something about a racetrack procedure (the approach procedure, not as in a hold).

If you compare a tear-drop approach and a racetrack approach, both require you to fly over a locator of some sort, and then fly outbound on a heading for a set distance / time, before turning inbound.

What I can't see is, in the racetrack procedure, you can't simply overfly the beacon, and then turn outbound, as it wouldn't create the "racetrack" shape, and would form the basic shape of a tear drop approach.

I can see how if you were approaching the locator from due east, and then overflew the beacon, and turned outbound onto a heading of 090 it would form nicely, but otherwise, how does it work?

Thanks in advance,
tKF

[FlyingForFun]

tKF, can you give us an example? Airfield/runway?

Cheers,

FFF
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[TheKentishFledgling]

OK, let's look at two approaches. The NDB ILS DME RW28 Manston, and the ILS DME RW27 Norwich.

Firstly, let's assume we're inbound to Manston. We're approaching from the north west, and we're flying on a heading of 140 degrees. We fly direct to our IAF, the MTN NDB. Once we're overhead the locator, we fly outbound on a heading of 114 or 120 degrees.

Now let's assume we're approaching Norwich. Again, we're approaching from the north west, and we're flying on a heading of 140 degrees.
Our IAF is the NH NDB. Once overhead this beacon, we want to position south of the final approach track. If we're been approaching from the east, we'd simply 180 (or near enough) once over the beacon, onto 092 degrees, and this would give us the correct distance to the south to fly the outbound leg of the procedure. It's then simply a case of turning inbound at 7 DME.

So AFAIU, it's easy enough to fly if approaching from the east, but what happens when you're coming from another direction.

This also asks the question, what happens when flying a tear drop approach (as in the Manston example above), and you have to 180 to be on the outbound leg?

Let's say we were approaching Manston from the south, to be on the correct beacon outbound heading, surely we'd need to start the turn earlier than the actual beacon, to be positioned correctly.

Reading back over that, it all seems very confusing, but hopefully you'll see what I'm getting at......!! :\

Cheers,
tKF

[Evo]

Let's say we were approaching Manston from the south, to be on the correct beacon outbound heading, surely we'd need to start the turn earlier than the actual beacon, to be positioned correctly.


In this case don't you position yourself via the appropriate hold entry, and then exit the hold down the outbound track

(Question mark deleted 'cos FFF agrees :) )

[FlyingForFun]

Oh, I see! Ok, here's how I'd do it, but I've only just got my IMC, so interesting to see if others agree.

For anyone trying to follow, the procedures are on-line: Manston (http://www.ais.org.uk/aes/pubs/aip/pdf/aerodromes/32MH0805.PDF) and Norwich (http://www.ais.org.uk/aes/pubs/aip/pdf/aerodromes/32SH0805.PDF).

The answer to the Norwich question is the "alternate procedure". This is shown on the plate with a dotted line, to the right (east) of the IAF. It's also described below (just above Direct Arrivals): "Overhead NDB(L) NH (IAF) at 2000, fly outbound on QDR of LLZ 092deg descending to 1456(1350). At I-NH DME 6 procedure turn right (i.e. turn right 45 deg, then left 225 deg) to intercept LLZ. When established, proceed as for Main Procedure".

At Manston, I would simply join the hold, although if cleared immediately there's no need to actually fly a hold. So from the east, fly to the beacon, then fly an offset entry, and on reaching the beacon again begin the procedure.

Does that help?

FFF
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Edit because Evo got there before me - but we agree on Manston, which is good!

Edit again because I got the hold entry wrong - d'oh!

[wobblyprop]

EDIT : evo and FFF beat me to it.

agree with above additionally you need to be within 30degrees of the procedure track to begin it. So taking up the hold would allow you to be with the 30degrees at the IAF

Hope that helps

[FlyingForFun]

Edit - we have to all stop posting at the same time as each other! I initially posted to disagree with Wobbly, but by the time I'd posted he'd modified his post, so I don't disagree any more!

FFF
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[wobblyprop]

aim to please :p

[TheKentishFledgling]

Thanks FFF and Evo.

wobblyprop - I didn't realise you had to be within 30 degrees of the track to start it - makes things a lot clearer.

One more thing......
Does anyone know if there is an online list of different hold entries I could have read of?

Cheers,
tKF

[Keef]

You need an IFR training manual, or a "holding pattern computer". I had to transplant one into my head for the FAA IR.

There's a nifty little diagram that shows the three hold entries - direct, parallel, and teardrop - and when to use them. Worthy learning to draw that from memory.

Yell if you want me to e-mail it to you. Yell likewise if you want "The Instrument Flight Manual" that I bought for the IR and decided wasn't very good. It has all the basics in it, so is good in that respect, but isn't geared to the IR - which is what I wanted.

[Evo]

tKF - How to... Fly a Hold (http://www.pilotlist.org/zahar/howto.htm) :)

[Keef]

Good grief! That's a complicated way of showing it!

All you need to remember is:

Draw the line 70 degrees to the inbound track
Everything to the right of that line is direct entry.
Below the inbound track is teardrop entry.
Above the inbound track is parallel entry.

Keef's freehand drawing is here:Simple Hold (http://www.jillings.dsl.pipex.com/hold.jpg)

It's worth memorising that - it ain't hard!

That a right-hand hold. For left hand, hold the paper up in the air and look from the other side (or draw it that way round).

[reynoldsno1]

A racetrack and a holding procedure, whilst similar, are not quite the same thing.
A racetrack is a reversal procedure like a base turn(teardrop) or procedure turn, and normally forms part of the initial approach. Reversal procedure design is limited, amongst other factors, by the maximum rate of descent allowed on both the outbound and inbound legs. The nice thing about racetracks is that you can go round them more than once, and in some cases they are the only way to lose height if the procedure commencement altitude is very high.

[Spitoon]

Speaking as a controller, the main practical difference is that alternate procedures that use an extension of a holding pattern is that it's easier (and quicker) for an aircraft already established in the hold. It can also offer flexibility because I can extend the outbound leg a bit further for sequencing purposes if I want to. (subject to lots of other considerations, of course!).

[Evo]

Keef - is your parallel entry correct? Seems sensible to me, but it's different to how i've seen it drawn in books. Thom's book 5 says to fly to the fix, turn onto an outbound heading parallel to the inbound track, hold the heading for a minute (+/- wind correction), turn in the direction of the holding side through more than 180 degrees and return to the fix. Then enter the hold.

Just to confuse things (or myself) further, I think of two types of direct entry - if you turn through 180 degrees or more to take up the outbound track, then begin the turn as soon as you reach the fix. If you need to turn through less than 180 degrees, then you hold your inbound heading past the fix - the turn to the outbound leg should take 1 minute, so if you only need to turn 90 degrees (which takes 30 seconds in a rate 1 turn) then you hold past the fix for a further 30 seconds. Turn through 135 degrees then hold heading for 15 seconds and turn for 45, etc.

I know you've got an IR while i'm just an aspirant IMC, so tell me if i'm overcomplicating things. I'm trying to get all this stuff to stick in my head, because if i cannot think it through while sat in front of a computer with a cup of coffee then i'm never going to be able to do it while flying an aeroplane :)

Now, can anybody give me an easy way of working out wind corrections in the hold... :confused:

[Keef]

Evo

Don't get hung up on it!

All I was trying to do was to simplify the "how to join the hold or racetrack" cos I found those long series of pictures too much to fit into my tiny brain. That simple one worked for me, and satisfied the FAA IRE.

But anyway...

PARALLEL ENTRY

There are many representations of it, with varying levels of complication. The most artistic one has you pass the fix for a calculated distance, then fly one minute in the "wrong" direction and parallel to the inbound heading, then do a pirouette - something like 225 degrees left, then 45 degrees right - to get onto the inbound track.

I tried that a few times, but never ended up on the correct inbound heading. For the precision flyers, who can do all the wind calcs in their heads, it's great. Me, being a coarse pilot, my parallel entry looks more like a teardrop-shape but at least I end up roughly on the right inbound track.

DIRECT ENTRY

Yes, correct. Adjust your turn (and when it starts) to suit. Easy! The key reference point is abeam the holding fix on the outbound leg.

WIND CORRECTIONS

There's lots of theories. Again, I can't remember the mathematical tables, so I do the "three times inbound drift" thing on the outbound, and plus/minus one second per two knots of inbound tail/headwind component for the outbound time. Then see how that works and adjust next time around the hold.

I'm sure there are better formulae. But if the wind is 40 knots and gusting, it's all rather academic in a PA28.


In 18 years of IFR flying, I've never yet flown a hold "in anger", although I've done hundreds in practice and renewal tests. Radar vectors to ILS, now, those I have done for real aplenty.
I'm just spoiled by helpful ATC folks.

[Tinstaafl]

Just curious Keef, but have you always flown in the UK or other country that disallows instrument approaches OCTA?

My experience has been that arriving at a busy-ish OCTA aerodrome in bad Wx then stacking ourselves in the hold to wait in turn for an approach is one of the best ways to ensure we don't all try to use the same bit of air at the same time. I've also been given holds by ATC often enough. Less so with radar CTA than procedural CTA.

[Keef]

It's probably the sheltered life I lead. Most of my IFR arrivals are at Southend, where not a lot flies if it's IMC: the fine chaps in the tower will happily offer radar vectors to ILS.

I have done some bimbling in the USA, and had radar vectors there too. Again, mostly into less-busy places.

I don't fly into major airfields very often: I'm sure I would get to do plenty of holds if I used LHR or LGW.

I wonder how many PPLs (with IMC or IR) actually get to fly holds for real (as opposed to practice or revalidation).

[FlyingForFun]

What's the name of that hold that's marked on the 1/2-million chart near Biggin? It's not an area that I fly in very often, but the last time I was round there, my planned track took me right through the middle of the hold.

"No problem," I thought. "I'll just listen out on Thames radar and check no one is in the hold, and keep a good lookout." So that's what I did. Quite surprised to hear one aircraft after another after another being put into the hold, on a good VMC day. :eek: Decided to fly around it :ok:

FFF
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[bluskis]

I think you are referring to Alkin, and note 15 on the chart. I believe a communication, AIS or some such, has been issued advising avoiding this area.