Leaving the hold..

[HEATHROW DIRECTOR]

When ATC issues instructions to leave a holding pattern in the form of, for example, "continue the right turn heading 130" why do some pilots head back to the holding facility before taking up the heading? It seems to be a procedure which many crews have adopted in the last few years and I wonder if that's what they're trained to do? If so, why? If I want you to set course from the facility I would use the phrase "return to XXX and leave heading 130", etc. Sometimes we want you to turn directly on to a heading to save time and by returning to the facility you could delay your place in the sequence.

[PPRuNe Pop]

Interesting question HD. Bin a while since I did this but didn't the instruction include "take-up" or "turn onto" once upon a time? Phrased like you describe could it not be mis-understood? "Continue the turn onto 130" is less ambiguous as would "continue the turn and take-up a heading of 130" be. Just a thought. Like I said, it's been a while.

I will watch with interest.

[spekesoftly]

PP Pop.... Suggest a) "C/S fly heading 130"

......................or b) "C/S stop turn heading 130"

But IMHO, HD still has a valid question.

[ 07 February 2002: Message edited by: spekesoftly ]</p>

[Young Paul]

There are variations on the precise wording.. ."Next time over BNN, make your heading 130.". ."Continue the turn back to BNN and leave heading 130.". ."Continue the right turn onto a heading of 130."

So partly different behaviour follows different instructions.

Also, partly, it is laze. There is a button on the CDU/MCDU of most modern airliners labelled "Exit Hold." You press this, and the aircraft turns back to the holding facility and points downroute. You can then select the heading and change mode, without having to wind the heading bug round and round and living with the worry that, in the event of a power glitch it might suddenly start turning in the other direction if you rotate it more than 180 degrees from your current heading.

Oh, the anxieties of the airliner driver!

Interestingly, the Boeing FMC seems to do lazy turns in LNAV but 30 degree banked ones in HDG SEL, whereas the Airbus does 30 degree ones in NAV but 25 degree ones in HDG.

You can do the aviation equivalent of "cutting up" an aircraft underneath you if you are both cleared outbound at the same time and you get back there first. But not very often .....

[Manual Reversion]

It could be that many FMC's take you back to the entry hold point, which is then used as the exit hold point.. .Depending on where the aircraft is in the hold will determine if it does a full hold or turns straight towards the holding reference.. .Just a thought, but saying something along the lines of 'heading now xxx' should do the job. On Mr Boeings finest, this should prompt the driver to do it with 'Hdg select', bypassing the FMC's desire to exit via the reference point.. ........ .ooops crossed with groggs who posted a far more eloquent explanation

[ 07 February 2002: Message edited by: Manual Reversion ]</p>

[fireflybob]

Heathrow Director - as a pilot I quite agree with you - I cannot imagine why anyone would do other than select HDG and then fly the requested HDG!!

What the FMC etc is programmed to do is surely irrelevant, subject to flight safety this is a clear ATC instruction which should be complied with!

[HEATHROW DIRECTOR]

fireflybob and others. Many thanks for the comments. I appreciate that in this case different controllers have different ways of issuing an instruction but it's probably born from experience - ie issuing the one they think will work. Orbits, circles, 360s and other "leaving hold" type instructions aren't fully covered by our bible! Given a "continue right onto..." instruction I think most of my colleagues would expect a pilot to do just that, rather than turn towards the VOR. It's particularly noticeable at BNN in a northerly wind.. as they turn outbound we say "continue right to 130" and at least 50% will then turn north until they are north of BNN and then go through strange gyrations to get back over the VOR before heading 130. Meanwhile we've snatched three other a/c to fill the slot.

[Aluminium Importer]

How about "present position heading 130"?

However non-standard, it seems to work for me!

AI

[Max Angle]

I agree with the poster above, if I am in hold at LHR (as I seem to be twice a day sometimes) I would take up an assigned heading as soon as it was given. If the intruction was return to BNN and leave heading xxx then thats what I would do. Some controllers seems to use the phrase "heading now. 130" which would seem to clear up any confusion.

By the way, I assume that all the app. controllers for London TMA are now at Swanwick with everyone else, how is going there?. Seems to be OK from our point of view.

[HEATHROW DIRECTOR]

Max.. no we're still incarcerated at West Drayton along with those for Gatwick, Stansted and Luton and the TMA controllers. Terminal Control is not expected to move down to the seaside for some years yet...

[411A]

The Heathrow Director has raised an interesting point...I wonder if "newer" guys/gals are so ingrossed in the FMS that they do not actually "listen up"? I have watched on many occasions where a new pilot watches the aeroplane do something unexpected only to find that the FMS was programed incorrectly...or malfunctioned.

[tired]

I agree with fireflybob - if the instruction was issued as quoted by HD in his first post, then the obvious thing to do is go to HDG and select 130. Can't see any problems there!!

I suspect 411A may have a point - I wonder if it isn't the newer boys 'n gals who are reluctant to take command of the FMS? It's not their fault tho' - the training system these days seems to suggest that the FMS is God.

[Hand Solo]

As a reasonably recent graduate of the flying school sausage factories, my understanding of the rules is that when instructed to 'leave the hold heading xxx' one should continue the hold then leave on that heading next time over the holding fix. If instructed 'fly heading xxx' then that should be carried out immediately. Suppose its down to how the instructions issued.

[innuendo]

What would be wrong with "XXX, hold cancelled, (OWTTE) right turn to 130"?

[HEATHROW DIRECTOR]

Innuendo.. dunno what OWTTE means but have tried that phraseology and the same percentage simply head back to the VOR before taking up the heading.

[offshoreigor]

What about that old favourite everywhere else in the world:

"For Vectors to Final or Vectors for Spacing...Turn Right Heading 130."

Seems simple to me.

Cheers <img src="eek.gif" border="0"> OffshoreIgor <img src="eek.gif" border="0">

[HEATHROW DIRECTOR]

I don't think that phraseology is UK approved! However, there is no reason to believe that it would have any effect. I mean, how much more precise do you need to get than "turn right heading 130".... and why do some crews not do just that thing? It's always "vectors to final" at Heathrow so that should be understood.

[innuendo]

DIRECTOR, OWTTE = or words to that effect, sorry.. .If someone returns to the hold fix after acknowledging, f'rinstance, "Hold cancelled, turn right/left to 130" then they could not have understood the instruction. Why I can't imagine. I do not know how much clearer it should have to be.

[HEATHROW DIRECTOR]

Thanks everyone.. doesn't seem to be a simple answer does there? I'll continue with the phrase one I've had some success with: "Continue right heading 130, no need to go back to Bovingdon"!!

[innuendo]

Hello again Director, I hope I am not sounding argumentative, but, you suggested the use of:. ."Continue right heading 130, no need to go back to Bovingdon"!! . .I wonder if the addition of "no need to go back to Bovingdon" just adds to the opportunity for confusion. Particularly if one the recipients is busy at the time (advising company of delay, advising F/A's, pax and so on).. .All they have to do is garble the "no need" part and now Bovingdon is in the transmission muddying the thoughts. I can hear it now, "Whadesay? Back to Bovingdon?" and so on. . .I still like "Hold cancelled, right turn to 130"

[NorthernSky]

With respect,

It would be a big help if you all used standard phraseology. At least one post above offers three alternatives, none of which are correct.

And yes, HDG SEL Is the only way to go, and go now...

[innuendo]

Well don't keep us in suspense, set us all straight then.

[HEATHROW DIRECTOR]

NorthernSky... With respect, the whole point of my original posting was that standard phraseology doesn't always work! It seems to be a problem which has started in recent times and, judging from earlier comments, possibly attributable to various flight management systems. If pilots responded to standard phraseology in the situation referred to this thread wouldn't exist.

[NorthernSky]

Well, the bloke in exile wrote:

"Next time over BNN, make your heading 130.". ."Continue the turn back to BNN and leave heading 130.". ."Continue the right turn onto a heading of 130."

None of which (if memory serves) feature in the Part 1.

He continues:

Also, partly, it is laze. There is a button on the CDU/MCDU of most modern airliners labelled "Exit Hold." You press this, and the aircraft turns back to the holding facility and points downroute. You can then select the heading and change mode, without having to wind the heading bug round and round and living with the worry that, in the event of a power glitch it might suddenly start turning in the other direction if you rotate it more than 180 degrees from your current heading.

He's part of the way to being right, but the wrong-way turn has nothing t do with power glitches, just the type/variant being flown, and the EXIT HOLD prompt does different things on some types (some will complete that 'lap' of the hold, others will turn immediately to the fix and leave), and in any case using EXIT HOLD in rersponse to an instruction to leave the hold on a heading would be poor technique.

More...

Interestingly, the Boeing FMC seems to do lazy turns in LNAV but 30 degree banked ones in HDG SEL, whereas the Airbus does 30 degree ones in NAV but 25 degree ones in HDG.

Here, he's plain wrong. Both aircraft, in NAV or LNAV, will use various rates of turn at various times. How they choose to do this is real rocket science. In HDG SEL, both types will use a pre-selected angle of bank, selected on the MCP/FMP.

No offence to Exile, but a little knowledge is a dangerous thing.

[NorthernSky]

Director,

We both posted simultaneously. My gripe is not so much with sparing use of non-standard phraseology, but failure to use standard phraseology and 'best practise'.

I don't mind 'ABC001 Fly heading 130 degrees, turn right onto that heading now' (standard phraseology backed up with a little nudge for common sense), but I loathe 'ABC002 right now one three zero'. Another good example is 'XYZ003 contact London 118.82, that's eighteen eighty-two' used when an aircraft has missed the frequency first time.

[Young Paul]

Yes, what I wrote was a drastic oversimplification. But I was talking particularly in the context of holds. In a B737, if you take HDG SEL and 30 degrees of bank, you will do a 30 degree banked turn onto a heading. If you stay in LNAV, then it will fly round its nice tidy racetrack, with (in some winds) as little as 5 degrees of bank to keep it sweet. In an A320, you may be turning back to the hold with a 30 degree turn in NAV (which a B737 will rarely use, as it works out its nice tidy racetracks). If you pull HDG, it will slope it off to 25 degrees. And if there's a way to override this 25 degree turn in HDG at that level, with no other modes engaged, then I don't know what it is. Yes, a little knowledge is a dangerous thing. Perhaps you might like to explain how that can be achieved then?

The point I was making is that pulling HDG in an A320 will not necessarily improve your turn. In a B737, selecting HDG SEL and a 30 degree AOB will give you the best turn. This has a bearing if you are told to "tighten up the turn" - a subject which is related.

I would have written a full behavioural explanation of the autoflight systems of the B737 and the A320, but I thought it might cause people's optic nerves to leap down their throats and strangle them before they died a horrible death of boredom.

The radio calls are not standard. They are all used, and are all precise instructions. I don't know to what extent HD or others were aware of the variations used by other people. I guess the LATCC crowd are pretty aware. Others might not know all the details of this argument but might be interested.

[HEATHROW DIRECTOR]

Exile.. points noted. As I mentioned earlier, the "non-standard" R/T instructions are a result of controllers finding out from experience which ones produce the required result - ie which ones the crews immediately understand. As for the technical explanation - much appreciated but even that doesn't explain the following typical scenario: Bovingdon hold - roughly southeasterly inbound track with a right turn outbound... As an aircraft starts it's right turn I say "xxx turn right heading 130 degrees" (perfectly standard and non-ambiguous phraseology). The aircraft now turns on to a northerly heading to take it north of BNN... then turns right to the VOR to pick up a heading of 130.. (Happened to me the other afternoon). In miy mind the crew believed that my instructions intended them to start the heading from the VOR.

When started this thread I was expecting someone to say "yes, we're trained always to fly to the beacon before taking up the heading"... but nobody has. Incidentally, in my experience it is only British pilots who do this. Americans, Europeans, South Africans, etc, all simply turn on to the heading. Maybe my colleagues will comment otherwise...?

[covec]

Heathrow Director

As a "baby" IR (qualified last June!) I would continue with the right turn, rolling wings level to take up a heading 130.

I will now shutup as I am "uncomfortable" with the level of experience here as compared to mine!

All the best to you all - hope things get better.

Out.

[ornithopter]

As an even younger IR, I was told (in America) that the American way was to fly from wherever you are, and the British way is the go back to the fix and fly from there. So I was certainly taught to go back to the fix, although with your terminology I would probably have done what you wanted. However, I am still wet behind the ears.

[Diesel8]

How about: "xyz, fly heading 130" or if you want xyz to execute the turn after the fix:"xyz, reaching zyx, fly heading 130". .". .Should there be doubt as to the direction of the turn, ie the long way around, one could say: "xyz, turn left heading 130"

But given a heading,with no other instructions, I would certainly hdg-sel and turn promptly.

[HugMonster]

As a middle-aged (Brit) IR, I cannot for the life of me understand why pilots would not take up that heading immediately.

Were the phrasing to be "Leave the hold heading 130 degress" or "Next time over the beacon head 130 degrees", then perhaps...

[Capt Pit Bull]

Well, if its the British Way then its news to me!

Heathrow Director,

As a matter of interest, how often are you talking about? 10% of the time? 1%? Or what?

Are there any operators that do it more often?

There are certain types of finger trouble that can catch any of us out, if the rate of occurance is very low I would suggest that error is a more likely cause than deliberate policy.

CPB

[HEATHROW DIRECTOR]

Capt Pit Bull. I would guess that BA is the winner with a few BM types too. With foreign ops it's virtually nil, which prompted me to wonder if it's something which is taught in the UK. I'm not trying to get at anyone; I'm simply curious, as are some of my colleagues. Maybe it's our fault? So often we say "return to XXX and leave heading xxx" that when we ask them simply to continue a turn onto a heading they interpret as meaning return to the VOR.

[Metro man]

I'm a night freight pilot and never have to hold anywhere ,almost always get direct routings.Only holding I ever do is on instrument renewal tests. <img src="smile.gif" border="0"> <img src="smile.gif" border="0"> <img src="smile.gif" border="0">

[moleslayer]

I'm a regular at BNN(20+ years),the most often heard clearance is 'next time over BNN leave on a hdg of xxx'.Followed by 'next time over BNN,one orbit right,then xxx'.Occasionally 'no need to complete the hold,just turn on to hdg xxx'.

All this seems quite unambiguous.

However,a couple of nights back,when all aircraft were being given headings to take up directly,I heard a classic,the like of which I'd never heard before.'Midland xxx can you see that Swissair 320 below going down your left hand side'...Affirm,'good then turn left and follow him'.. .Absolutely brilliant :) That wouldn't be you would it HD :) :) . .A very slick operation it was too.

. . <img src="wink.gif" border="0">

[ 18 February 2002: Message edited by: moleslayer ]</p>

[Young Paul]

Well, I guess in summary: as somebody who frequents BNN, if I was told to take a heading of 130, that is what I would do. If there was any doubt, I'd clarify it - "Would you like us to route via BNN?" But as HD points out, and as the other example clearances suggest, such ambiguity is rare. LATCC doesn't have the slack to allow it.

[NigelOnDraft]

HD...

The many ways of "leaving the hold" expressed by ATC, and the rumours of what "they really mean" occupy our brains, and the Route Checkers even more...

Maybe if you think you have said something clearly, and we do not "obey", a little jibe or question might help all... As a QPQ, if we are unsure, maybe we could ask.

IMHO, blaming the FMS is weak - we are supposed to know what the FMS will do (I don't half the time!), but can always override it if we don't like it (so I have to...!)

BRegrds. .NoD

[HEATHROW DIRECTOR]

Moleslayer... it wasn't me if it was very recently because I am on days off. However, it is a procedure which I do use to great effect in VMC conditions! Maybe it was somebody who has benefitted from my vast experience over the years. (But don't tell him. Tee Hee!!)

[Max Angle]

Having watched the a/c track carefully the other day whilst leaving the hold the other thing that occurs to me is that no matter what you do the a/c ends up pretty well over the beacon when you leave the hold. Most of the heading assignments are almost aligned with the hold anyway so if you are given a heading to steer from most parts of the holding pattern you are going to pass over or very close to the beacon.

[HEATHROW DIRECTOR]

Max Angle. Have you heard Fred's corollary to Sod's Law? It goes like this: Given two identical aircraft at an identical position in the hold and both instructed to "continue right turn heading 130", the one above always ends up exactly 2 miles in front!

[Capt Pit Bull]

Max Angle,

Not always so. If the field has a holding fix not in the overhead or centreline, depending on its orientation you'll get radically different results.

e.g. LGW Willo hold, Rwy 26L in use. If you are turned downwind as you are approaching the end of the outbound leg you'll be tracking say 3 or so NM south of Willo. Continue to Willo before turning, and you'll be perhaps 2 or 3 NM north of Willo. All depends on speed of course, but we are still talking several miles difference in cross track position.

CPB

[Max Angle]

You are both correct of course, my statement really only holds (excuse the pun) true for the two stacks to the North of LHR which seems to the only place we end up on the Airbus nowadays.