Instrument Rating Drift Allowances???

[novicef]

I am studying for my IREX and I was just wondering if there were any rules not laid down in the books that would allow for wind in the holding pattern.

I asked some of the new IR graduates and they didn’t seem to know of any, however one of the older instructors mentioned 3 times the drift for a 1 min pattern and he thought it was 2 times the drift for a 2 min pattern. He also said there was a rule for the 80degree procedure turn whereby you held that heading for so many seconds but he could not recall how long.

Are there any from the old school who know of these rules?

[Gear in transit]

There's lots. But whatever you do just make sure you have at least ONE technique! There's nothing worse than watching a poor old candidate who has no idea on wind allowance and makes a botch of it.... :ugh:

I personally use 2 times the drift outbound in the holding pattern, and 1sec per knot per minute for approach in a headwind, 1/2 second for tailwinds. Works reasonably well.

Make sure you pic something that you UNDERSTAND and even more importantly can APPLY it!

[Capt Claret]

novicef

He also said there was a rule for the 80degree procedure turn whereby you held that heading for so many seconds but he could not recall how long.

From Jeppesen/Terminal/AU-20/3.9.2

a. Procedure Turn (45°/180°) Consisting of a specified track & timing from the facility or fix, a 45° turn away from the outbound track for 1 minute from the start of the turn for categories A and B aircraft (1 minute 15 seconds for categories C, D and E aircraft), ....

As for drift in a holding pattern, I can count on the fingers of one hand the number of times I've had to hold for real. Finding that I rarely knew the actual wind to apply a rule of thumb I'd apply what seemed reasonable, and when turning inbound assess how the outbound drift went.

Whilst inbound, given one is tracking a bearing or preferably a radial, the drift is easy to determine, and then apply on subsequent patterns.

I found that this frees brain space for other considerations. :\

[Macrohard]

Novicef,

As a general rule, yes you are correct. If you can understand the theory behind it, it makes it simpler to understand.

If you are in a 1 minute holding pattern, holding ten degrees of drift on the inbound leg, after your turn outbound you will require 30 degrees of drift. Basically, the pattern can be dived into four separate parts - the inbound leg, the 1st tun outbound, the outbound leg, and the inbound turn. In a G/A type of aircraft, the inbound leg takes 1 min, oubound turn 1 min, outbound leg 1 min, and inbound turn 1min. Total time of 4 minutes for a 1minute holding pattern. If you are only able to make an adjustment for wind during the inbound and the outbound legs, compensation must be made for the wind effect during the turns. Thus, if you are established inbound and can estimate your drift as being say 10 degrees, you have worked out how much drift is required for 1/4 of the pattern. Now we realise that we must compensate for the outbound leg as well as the turns - equal in time. To find the allowance for the outbound, we now multiply the drift on the inbound leg by 3, as the adjustment is now for the remaining 3 minutes of the pattern. 30 degrees allownace outbound.

Jees this would be easier with a whiteboard!

2 minute pattern, 4 different parts. Inbound 2mins, turn 1min, outbound 2mins, turn 1 min. Total time 6 minutes. 10 degrees drift inbound, 1/3rd of total pattern. Therefore 2/3rd's remaining, multiply by 2 - 20 degrees outbound.

[MOR]

You will get many differing ideas on this, and generally airline folk will give you a different answer to GA folk (mainly due to the different speeds involved).

For lots of fun stuff that might help you with this, have a look at http://www.flightinfo.com/rulesofthumb.asp

Excellent site.

[planemad_bk]

If i were you i'd make sure you know alternates and alternate requirements inside out before you get into any of the holding pattern stuff for your IREX.

[AerocatS2A]

Yeah, I don't recall any questions about drift allowances in a holding pattern. That's the kind of thing you learn, and are tested on, when doing the flight training.

[novicef]

Macrohard,

Thanks for that, just one more question. Regarding the 80 degree procedure turn. For instance if the inbound track is 360 and there is an 80 degree procedure turn to the right, wind in 090/15, I am told that there is a rule of thumb where by you hold that heading say 080degrees for so many seconds, on the other hand if the wind was 270/15 you do not turn onto a Hdg080 but some lesser Hdg so that you don’t get blown to far down wind. Can you remember such a rule??

[MrGaspo]

Regarding drift allowance in the holding pattern, was lucky enough to attend a lecture about twelve years ago by a guy ( whose name escapes me ) who was one of two blokes in the " Department " at the time whose job it was to design new approaches. He was quite positive about his views on drift correction in the holding pattern and that was that " triple the drift " for a 2 min pattern and " double the drift " for a 3 min pattern were not approved procedures.
In correcting for a wind that blows you into the pattern what you are actually doing on the outbound leg is purposely flying the aircraft wide and in doing so you could leave the protection of the surveyed area with regards to obstacle clearance.

ENR 1.5 3.4.1 states;

" When flying the standard holding pattern , an aircraft MUST;

a. follow the prescribed track inbound to the holding point;

b. execute a 180 turn in the direction specified , SO AS TO FLY
OUT-BOUND A TRACK PARALLEL TO THE INBOUND TRACK;

c. continue outbound to the earlier of the time, or the DME limit
specified ; and

d. execute a 180 turn to realign the aircraft on the inbound track."

Paragraph "b" is quite explicit , you MUST fly the outbound leg so as to parallel the the inbound track , no mention of "triple" or "double" the drift. It was made clear to all at the lecture that all you are permitted to do on the outbound leg is apply the known drift in order to keep the leg parallell

Perhaps someone involved at this level of approach design today could be found to comment.

Regards Mr Gaspo

[Arm out the window]

Lots of people advocate the double or triple drift idea, but if you do that you're not correcting for known or forecast wind to maintain the planned track, you're aiming to fly a track different to the one on the plate - ie. a holding pattern with non-parallel straight legs, which to me isn't right, so I use single drift and adjust the bank to get the turns right.
It's a bit of a catch-22 though, because if you do apply drift to fly the 'right' track as per the plate you're stuck with varying the turns at each end away from rate 1, going against what the AIP says.

[Icarus2001]

Mr Gaspo you beat me to it. Thank you.

The Jepps and AIP are VERY specific, you MUST plan to fly the OUTBOUND LEG parallel to the inbound leg, no correspondence will be entered in to!

It doesn't matter if that is what you were taught.
It doesn't matter if that is what you have always done.
It doesn't matter if a bloke in the bar knew someone at Qantas who did it that way.

End of story.

[MOR]

The problem with that being that if you do fly a parallel track outbound in strong crosswind conditions, you have precisely no hope of regaining the inbound track without exceeding your max bank angle. Using the information described above in a crosswind situation,the only decision you have to make is which parameter you want to exceed, outbound trackkeeping, inbound trackkeeping, or bank angle.

My view is that the rule is written for still-air, and the obstacle clearance plane is in any case well outside the point where you would turn inbound, using a rate one turn, to regain the inbound track in any conceivable crosswind. Hold tolerances are simply not that tight, and where obstacle clearance is limiting, the outbound limit is defined by a DME distance or cross-bearing (or both).

[MBA747]

Some of you guys should enlighten yourselves a bit more than just reading the Oz publications. Read the Jeppesen ATC booklet under the United States Page 1. for holding patterns. It says drift time 3.It also explains why.

[AerocatS2A]

That'd be very relevant if we were all flying in the USA, but we're not, so we must comply with the Australian requirements, regardless of whether they are the best way of operating or not. Ideally, if they're not the best, then we need to get the publications changed to match what the safe and practical practice is.

We also don't all have access to the US Jepps.

[MOR]

You guys don't seriously believe that a holding pattern is supposed to be symmetrical, do you? Seriously?

Have you ever flown one...?

:ugh: :ugh: :ugh:

[Icarus2001]

Which part of parallel do you have difficulty understanding?

MBA747, as Aerocat says, we fly to our AIP/Jepp requirements. Should we also not use supplemental oxygen until (is it) FL140, as per US rules. Obviously our air here is thinner, but it does seem to help our comprehension skills.:)

[MOR]

OK smartarse, please explain how, using exactly parallel inbound and outbound tracks, using no more than 25 degrees AoB with a 50kt crosswind, you have any chance at all of regaining the inbound track. You CAN'T. Simple trigonometry.

More to the point, Australian procedures are based on PANS OPS II, which does NOT require parallel inbound and outbound tracks.

2.2 Controls
2.2.1 The controls that apply to procedure design and DAP administration are listed in the
following references:
l ICAO PANS-OPS (Doc 8168), Volume II
l ICAO Template Manual for Holding, Reversal and Racetrack Procedures (Doc
9371)
l ICAO Manual on the Use of the Collision Risk Model (CRM) for ILS Operations
(Doc 9274)
l ICAO Instrument Flight Procedures Construction Manual (Doc 9368)
l CASA Manual of Operational Standards (MOS)
l CASA Aviation Safety Surveillance Program (ASSP)
l Airservices Australia Flight Survey Manual.
n

(My bolding)

There is no "difference" listed for Oz procedures.

Now why not try using a little common sense rather than a slavish obedience to the wording of a single reference? Ever heard of context? :ugh: :ugh: :ugh:

Update: The Oz AIP says this:

"3.2.1.e - Wind Allowance. Allowance should be made in heading and timing to compensate for the effects of wind to ensure the inbound track is regained before passing the holding fix inbound. Full use should be made of indications available from the aid and estimated or known winds."

The point being that the priority is to regain the inbound track. You can't do that with a symmetrical holding pattern in a strong crosswind because of the limiting AoB (25 degrees).

I can't believe I was reduced to reading the AIP in my spare time... ;)

[MrGaspo]

MOR ,
You raised some interesting points and if I may I'd like to comment on some of them.
After spending a few minutes on my WIZZ-WHEEL to nut out your 50 Kt crosswind problem in the holding pattern in say something like a warrior with lets say a tas of 100 Kt's , I come up with a correction angle of 90 degrees for a one minute pattern!!!!!
On your point concerning the holding pattern not being symmetrical , after having viewed all of the post's up to your one , and after reviewing the AIP re-holding patterns , I may have missed something but can't find any mention of "symmetrical" other than in your post. No one has said (AIP included) that the holding pattern must be symmetrical , only that the out-bound leg should parallel the inbound leg.
You seem to be of the opinion that it is a requirement to regain the inbound leg at the beginning of that leg , it isn't. This is explained in your reference to ENR 1.5 3.2.1
"allowance should be made in heading and timing to compensate for the effects of wind to ensure the inbound track is regained BEFORE passing the holding fix inbound"
This actually precludes a symmetrical pattern in all but nil wind conditions. There is a completely separate method of correcting for wind in the holding pattern that I have been using for over twenty years of teaching them and yes, it's based on trigonometry. But I dont want to give that away just yet, I'm curious as to whether any other PPruners' have any suggestions.

[MBA747]

The point I was trying to make, it was the only place I have seen where this is recommended ie. 3 times drift. A holding pattern is the same in any part of the world. It sometimes pays to read other publications,it makes one a lot more informative. Apart from CPDLC and ADS we are in the backwaters when it comes to aviation.

The other points about symmetrical holding patterns, yes they can be flown quite easily provided you are in an aircraft which has an FMC and where the ADIRU position is not only updated by navaids but also GPS. Modern aircraft now have an RNP1 with an ANP0.3 the holding patterns are nearly perfectly symmetrical. Aircraft flown in LNAV.

[MOR]

MrGaspo

I was using "symmetrical" to describe two parallel lines/tracks, but, sure, it isn't precisely the right word.

You seem to be of the opinion that it is a requirement to regain the inbound leg at the beginning of that leg , it isn't. This is explained in your reference to ENR 1.5 3.2.1

No, I'm not of that opinion, quite the reverse. My point is that if you attempt to fly a parallel outbound leg and then fly through the inbound track because you have a large crosswind component and a limiting bank angle, you no longer have two parallel tracks as the track to regain the inbound course will no longer parallel the outbound leg you just flew. It should be obvious that the inbound tracking is more important than the outbound, particularly if you end up never regaining the inbound track before you get to the fix or beacon. Common simulator scenario.

I was looking at the problem more from the point of view of jet speeds and bank angles, as the altitudes we fly at are more likely to produce the crosswinds I was describing, and also produce a more limiting bank angle. However, the principle is the same for light aircraft.

[AerocatS2A]

Rather than flying a non-parallel outbound, you could just use a shallow bank angle turning outbound so that your parallel track is further away and allows for an easier intercept of the inbound.

[Centaurus]

b. execute a 180 turn in the direction specified , SO AS TO FLY
OUT-BOUND A TRACK PARALLEL TO THE INBOUND TRACK

And that is all you need to do. You can go stir crazy trying to remember formulas and your pure instrument flying accuracy will be degraded. If you overshoot the inbound leg that's OK - just ensure you are back on track to the aid before reaching overhead. I also knew the bloke in DCA who confirmed multiple drift angle corrections was not on because of the danger of straying outside the protected area - he worked in the office next door to mine 36 years ago.
Aerocat S2A. Just watch the "shallow" bank angle theory. With some gyro systems running the weather radar and also ADI, any prolonged angle of bank less than six degrees can give rise to marked errors in the vertical gyro system. This shows as false ADI wings level and/or pitch attitude and in turn the weather radar stabilisation system will go ape and paint echoes only on one side or the other. Stick to minimim rate one turns and the gyros are happy.

[Near Miss]

Talk about ask a simple question….. :}
If you are just doing your IR in a Be76, a :mad: PA30 (god help you), or even a PA28, just use these: If you’re holding 10 degrees of drift to maintain inbound track, then hold 3 times (ie 30 degrees) outbound (1 min pattern) or 2 times (ie 20 degrees) outbound (2 min pattern). At the speeds you’ll be doing you won’t “stray” too far. ;)
As for your 80/260 problem try this one: If your outbound is 360, right turn 80/260, wind from the right, hold the heading of 080 for 1 second longer for each knot of x-wind. If the wind is from the left, start the turn back to the left 1 degree earlier for each knot of x-wind. You won’t be far out.
As for adding or subtracting seconds to the outbound try this: For each 10 knots of wind add or subtract 10 sec (head or tail). You’ll find the distance travelled is pretty close to what it would have been in nil wind. We are talking 100 to 120 knots here. If you want to get :8 add/subtract 10% for each 10 knots of wind. So a 1 min hold becomes 66 seconds. Works really well for a aircraft doing around 120kts and works regardless of the holding time. But really, who cares??? Just make some allowance, especially if you are pushing into a big headwind outbound, as you won’t be back on track when you cross the aid again. Which is a problem if you want to actually commence the approach and not just continue holding.
Another useful rule of thumb is: Half the x-wind to work out your drift. Say taking off and you want to maintain runway centreline (QDM 360), 10 knots from the right, turn onto a heading of 005, and you will be pretty close.
Like it has been said before, unless you want to go beyond Rate One (or 25o AOB), then correct for the drift. Unless the Checkie has a data-logger like we used to have on the ag machines (you got to love SatLoc), he isn’t going to be able to say you are not paralleling the inbound.
Now if the big jets do it so “right”, then tell me why does the FMS on my aircraft adjust the timing to give me 1.5 min inbound, and not outbound like the regs say? :confused: Must admit leaving it in LNAV, and letting it do the work, is pretty cool. :ok:

[MOR]

AerocatS2A

And exactly how do you work out what that bank angle should be?

Centaurus

If you overshoot the inbound leg that's OK - just ensure you are back on track to the aid before reaching overhead. I also knew the bloke in DCA who confirmed multiple drift angle corrections was not on because of the danger of straying outside the protected area

Actually it isn't OK. Leaving aside for a minute the fact that the wording assumes still air, the rule for holds - in the rest of the world, anyway - is that you should regain the inbound track as soon as is practicable after turning inbound. As for straying outside the protected area, there is absolutely no chance of that happening if you fly a drift-corrected outbound leg which subsequently allows a rate one turn to place you back on the inbound track. If your guy believes that is not the case, he needs to have a look at the construction of a PANS OPS II hold. The clearance surfaces are well outside any possible deviation that is purely to correct drift. The holds (and the protected area around them) are designed with exactly this purpose in mind.

That, anyway, is true for PANS OPS II holds, which your government says it abides by for these purposes.

Having said that, it would be just like Australia to try and do it differently to the rest of the world...

[Icarus2001]

the rule for holds - in the rest of the world, anyway - is that you should regain the inbound track as soon as is practicable after turning inbound. Do you have a reference for that or is that just the way that you have always done it?

Aerocat and Centaurus are both on the right track (no pun intended) there is no mention that I can find of how wide a holding pattern should be. It is sensible to ensure that the outbound leg is far enough away from the inbound leg to give you a fighting chance of getting back on to the inbound track prior to the aid. Although as mentioned, this is not required as often once overhead the aid another different outbound track must be intercepted. Sure it makes you feel warm and fuzzy to be on track inbound to the aid prior to station passage and then turning to intercept the outbound but it is not required. Following a change to the wording in the mid 1990's the descent can be commenced once on an intercept heading rather than the previous requirement to be within five degrees.

[Arm out the window]

I think the 'how wide' question is pretty straightforward - as wide as a rate 1 turn at the maximum speed for holding.
Naturally the designers will have allowed for any reasonable crosswind component when considering the protected area.
If the wind's blowing toward the inbound track then you'll overshoot it a bit on the inbound turn, but they will have allowed for that - so, fly rate 1 turns and allow only for know or forecast wind and you'll be complying with the regs, I reckon.

[MOR]

Do you have a reference for that or is that just the way that you have always done it?

The specific reference is contained in the PANS OPS II document. I don't have one to hand, and they cost a fortune, so I'm not going to go and buy one for the sake of this discussion. However, in a previous life I used that document when route-proving new routes, so I know what it says.

An interesting point comes from the UK AIP, which is based on the same PANS OPS criteria:

3.5 These procedures have been established in accordance with the ICAO PANS-OPS, except for those UK differences shown
at GEN 1.7. While certain specified allowances for wind effect have been made in determining the areas which will contain the various
procedures, it is emphasized that these Holding and Approach to Land procedures are based on still air conditions and in practice due
allowances must be made for wind.

http://www.ais.org.uk/aes/pubs/aip/pdf/enr/20105.PDF

It doesn't say HOW allowance should be made.

there is no mention that I can find of how wide a holding pattern should be. It is sensible to ensure that the outbound leg is far enough away from the inbound leg to give you a fighting chance of getting back on to the inbound track prior to the aid.

The maximum width of a hold is calculated using the holding speed appropriate to the class of aircraft (A-D), and a pre-computed crosswind component. It isn't a fixed size, other than for planning purposes where still air is assumed.

Can anyone please explain how a holding pattern with two (widely spaced) parallel tracks consumes less airspace than one with two divergent tracks? It DOESN'T. The only issue here is the point that you end up at, from where you commence your turn inbound. That point will be exactly the same whether you choose to use a divergent outbound track, or a lower rate turn when turning downwind. The difference is that you have a much greater chance of achieving the correct turn-in point by using a drift correction, that you do by trying to guesstimate a bank angle. More to the point, you will drift a lot further whilst carrying out a shallow turn downwind that you will if you just make a rate one turn and apply a drift correction.

Sure it makes you feel warm and fuzzy to be on track inbound to the aid prior to station passage and then turning to intercept the outbound but it is not required.

It may not be required (in Oz), but it is definitely good airmanship to be established on track at the earliest possible time when inbound to the fix or beacon. If you are not, you run the risk of missing the beacon or fix altogether, and then the job of intercepting the outbound procedure track becomes more difficult.

I am amazed that any pilot with any experience at all, could advocate not only being off-track, but not making an immediate attempt to regain it.

As the parallel-but-widely-spaced hold profile actually uses more airspace than the divergent method, I fail to see how it could possibly be safer - even if lateral protection was an issue, which it isn't at any promulgated holding speed or conceivable crosswind.

As I said before, the only important point (and the point that takes all the skill that a instrument pilot develops), is the point at which you commence your inbound turn. If you have done it properly, you will end up on your inbound track. If you haven't, you are now playing catch-up. That may be OK in Oz, but nobody else thinks like that. In fact, in two or three airlines I have worked for, that sort of thinking would get you a nice big "fail" against the holding item on the LPC check form.

[wdn]

why do people assume 25 degrees is the maximum bank angle allowed?

AIP ENR 1.5 p3.2.1 page 21


All turns in nil wind should be at a bank angle of 25 degrees or Rate One.....


we are obviously not talking about a nil wind situation.

whether or not anyone thinks the AIP is wrong the fact is it says you must fly the outbound leg parallel to the inbound track. people who violate written procedures or regulations because they think their method is better are asking for trouble IMHO....

there are methods to help vary the AoB to be on TR when you roll out.

with 90 degrees to run, the RB should lead the TR by 10 degrees. with 45 to run, the RB should lead the TR by 5. you can check again at 30, 20 and 10, where the RB should be pretty close to the TR.

shouldn't people be using a similar method to ensure they roll out on track during the base turn of an NPA? if you don't, then you're not really very appreciative of the wind effect there either.

as to the wider holding patterns for faster aircraft, in cases where it matters wouldn't they have a higher minimum altitude for the hold for faster speeds, check the holding pattern at CCK on the Canberra plate.

to say that
the only important point (and the point that takes all the skill that a instrument pilot develops), is the point at which you commence your inbound turn
is ridiculous in my opinion. the important point is to comply with the written procedures that you are required to comply with. in the absence of particular directions in your ops manual, it would have to be the AIP in this case wouldn't it?

[MOR]

why do people assume 25 degrees is the maximum bank angle allowed?

AIP ENR 1.22.1

http://www.airservicesaustralia.com/publications/current/aip/enr/15739.pdf

it says you must fly the outbound leg parallel to the inbound track.

In still air, yes.

important point is to comply with the written procedures that you are required to comply with.

Which includes:

17.4.2 The pilot in command must, at all times, take positive action to regain
track as soon as a deviation from the correct track is recognised.

... which also applies to holding patterns, when half way round, after a parallel outbound leg in a crosswind, you suddenly realise you about to overshoot the inbound track by quite a lot...

but no, you just carry on with your slavish obedience to a misinterpretation of a single phrase... :ugh: :ugh: :ugh:

[Oktas8]

This from the NZ AIP, which follows PANS-OPS quite closely these days.

Turns
3.3.6 All turns are to be made at a bank angle of 25°, or at a rate of 3° per second, whichever requires the lesser bank.

Wind Allowance
3.3.7 All procedures depict tracks and pilots should attempt to maintain track by making allowance for known wind by applying corrections both to heading and timing during entry and while flying in the holding pattern.

It seems clear to me that, in wind, you can either comply with 3.3.6 or 3.3.7, but not both. Some pilots prefer to obey the one and ignore the other, other pilots vice versa.

Isn't there a minimum five nm buffer between the nominal pattern and the nearest critical terrain? This would be enough to take account of single, double, triple drift variations would it not?

You must have quite a headache by now MOR, what with all that head-banging. Try this one instead :p - it's easier. :}

[MOR]

Yeah, really! I give up. The Ozmates can fly holds however they like, if they want to be different to the rest of the world, I suppose we shouldn't be surprised.

They'll look a pack of prize charlies trying it in non-Oz airspace though... you know, in countries where track-keeping and accuracy are important...!

[novicef]

Its given me lots to think about.

[AerocatS2A]

Nocivef, you won't get a question about drift in a holding pattern in your IREX. But you will most likely get taught a method such as holding 2 or 3 times the drift on the outbound leg in you flight training. If that is what you are taught, and that is what your testing officer expects, then that is what you do, regardless of the strict interpretation of the AIP.

[Freek Flyer]

Here's a handout I gave to students back in the day...

Hope it helps

http://members.ozemail.com.au/~steveth6/DRIFT%20RATES.jpg

[NOtimTAMs]

MOR:
"Quote: why do people assume 25 degrees is the maximum bank angle allowed?
AIP ENR 1.22.1"
This refers to IAL procedures. IAL means Instrument Approach to Land, not Holding.
As the radius of turn for Class C & D aircraft is so much larger than the Class A & B aircraft most do their ratings in, then the rules of thumb outlined above will not not exceed the protected area. In holds above the area LSALT there is little practical problem anyway.
I've received few actual holds - and the majority of these have been requested by ATC based on GPSRNAV capability - unpublished random holds or unpublished holds based on a GPS Waypoint at altitudes and locations where "protected area" doesn't apply.
A great way to see how you go with holds is to borrow a portable GPS (e.g. GPSIII Pilot) which keeps a track log and fly a few entries/holds and NDB approaches and look at the shape of what you've done - very instructive!

[MOR]

This refers to IAL procedures.

OK then use 3.2.1.e, which describes holding procedure limitations. A hold is a hold, whether enroute or as part of an IAL procedure.

I have had to hold virtually every day (at LHR, CDG, MAN and BHX usually).

Another point that nobody seems to get, is that if you fly a parallel outbound and accept that you will fly through the inbound as a result of a crosswind and the AoB limitation quoted above, two things happen. Firstly, you cannot possibly fly a parallel inbound leg, as you have to re-intercept it; and secondly, the amount (ie distance from the still-air track) you would have flown upwind to end up back on the inbound, is the same distance that you will end up displaced out the other side of the hold if you attempt to fly a parallel outbound leg. Think about it.

Crayon drawings available for those who still don't get it...

[AerocatS2A]

Firstly, you cannot possibly fly a parallel inbound leg, as you have to re-intercept it; and secondly, the amount (ie distance from the still-air track) you would have flown upwind to end up back on the inbound, is the same distance that you will end up displaced out the other side of the hold if you attempt to fly a parallel outbound leg. Think about it.
Crayon drawings available for those who still don't get it...

Agreed on the second point. Disagree with the first point. It's a matter of semantics really, but if you fly through the inbound leg, then you initially fly a heading to intercept the parallel inbound leg. The inbound is still parallel, but you spend some time intercepting it. Obviously the hold is not nice and symmetrical, and the 3 x drift method is still a much nicer way of tackling the crosswind regardless of what the Aus AIP says.

[NOtimTAMs]

MOR

Now we (nearly) agree: the correct reference for bank angle: 3.2.1.d.

novicef

For the purposes of your question, in an initial IFR issue or renewal in Australia in a cat A or B ACFT you shouldn't run into any significant problem using freek flyers pretty pic. For the purposes of flying a cat A or B ACFT generally you will not exceed the protected area using the methods described, either. For the faster stuff I bow to higher authorities on the forum.

[MOR]

NOtimTAMs

OK I'll give you that one... :}

BTW why do they give you enroute holds, and not just a bit of speed control?

AerocatS2A

Yes it is semantics. However, if you have to spend time intercepting the inbound, and you only have a minute to do it, your actual track is not going to be parallel to the outbound, apart from the last bit!

[Freek Flyer]

This debate has been going on for many years... I once remember having it out with a Deputy CFI once (nicely of course)... I don't have an AIP with me to reference at the moment, from memory doesn't it state something along the lines of "Adjust outbound heading so that you can intercept the inbound track" my interpretation is that you don't necesarilly fly a parrallel outbound track, but thats just it, its all about interpretation of the rules... For instance I now fly cat D aircraft, holds are flown using a FMC. The FMC will reduce angle of bank on the outbound turn, thence fly a parrallel track followed by a 25 degree AOB turn to intercept the incound track, this is effecectively the same as 3x drift as it trakes you wider than the nil wind parrallel track...

And just to note, remember that you are in fact adjusting track INTO WIND, this coupled with the required hold speeds should always keep you inside the protected area...edit spelling

[NOtimTAMs]

MOR
Why the holds? Maybe they assume that cat A & B ACFT have no real speed control! :rolleyes:
My flights take me in and out of controlled and/or radar airspace. A few times it has been because of unplanned SSR failures (once TXP, other times the SSR heads), once its been because of an ATC coordination problem on entry to CTA and other times I just do as I'm told. ;)

You're welcome to the weather and traffic in the UK. Haven't had to hold much for weather or stacked ACFT in my part of the world.:D

[QSK?]

Found the following interesting tidbit in "Whitts Flying", which may be of interest:It might be of interest to know that the shape of the holding pattern used today was created because earlier gyroscopic instruments needed the straight sides to prevent precession.

[MOR]

As opposed to circles? That would make a lot of sense. Funny how this stuff gets forgotten!

[Damien Toohey 64]

Hi there Novicef,
A rule of thumb I used to teach cadets was to examine the drift/wind direction and velocity observed on your way inbound to the IAF then roughly calculate the x-wind component on the holding pattern and if its 20 kts x-wind ( using 3 times the drift for a 1 min pattern ) allow 20deg drift which equates to x-wind/3 @ 150kts = 7 x 3 = 21deg.
Then at 45seconds outbound check to see that the ADF needle is 30 deg off yr inbound track. If its 20 degrees off the inbound yr too close so widen out by 10deg for the last 15 sec's and turn at rate one. If the needle is, say, 40 deg off then yr being blown out so turn in by 10 degrees for the last 15 sec's.
You can't go far wrong and you don't even really need to know the drift if you check the needle displacement relative to the inbound track ( while outbound ) and then use that drift information once inbound.
Happy to talk about it in detail if your stuck.
Damo

[Ratshit]

Get a moving map and just eyeball it !

In 20 years I have only ever flown a holding pattern in training.

[MOR]

Probably not qualified to comment then! :rolleyes:

[Angle of Attack]

I'm still not sure where is a direct reference stating that the outbound track of a holding pattern must be parrallel to the inbound track? I cant find it in the AIPS unless your referring to the diagrams which are a nil wind situation. As a note if you ever saw the protected airspace diagrams as outlined in the PANS-OPS requirements I can assure you the worst thing to do is overshoot the turn onto the inbound track as this is the least protected area and much less margin for error than on the holding side. The Holding side has a much larger area of protection and by the shape of it you can see it allows for non-parrallel flying of the outbound track, it sort of bulges out at each end. Anyway just my 2 cents worth! :rolleyes: