Wind correction in the hold

[student-mork]

Hi all,

Im currently getting back up to speed for my IR renewal and cant get to my notes to check this, I've also done the mandatory search with no joy so here goes...

Can anyone remember the table of sin and cos to max drift associated with maintaining a hold?

Thats it, appreciate if you can help me out!

[cavortingcheetah]

Thrice the drift outbound up to a maximum of 30' and once inbound.
It works. Forget the fancy crapulous codes and tables. Draw out the drift roughly on a the back of a cigarette packet, Senior Service for choice, Capstan Full Strength if you're in the Fleet and go and fly like a man, not like an Airbus

[BEagle]

Same as your wristwatch!
15deg off = 1/4 max drift
20 deg off = 1/3
30 deg off = 1/2
45 deg off = 3/4
60 deg off or more = apply max drift.

That's inbound, outbound use 3 x the drift factor as cavorting cheetah ststes.

[student-mork]

Thanks very much guys, thats even better than what I was after!
A good dumbing down and swift solution that'll stay in my head.

[michaelknight]

.....or just stick the hold in the FMS and watch the computer do all the work while you finish your dinner!!

[Piltdown Man]

Guess the drift and be prepared to make a correction. Probably a contentious answer I know. But if you make a "sensible" guess, I recon you'll arrive in a reasonable position to make good your inbound track . Then you are inbound, work out what the real drift actually is. Apply the appropriate correction next time round. Gash I know, but easy on the brain.

[student-mork]

Thanks again, I will try all of these corrections out on RANT and MS flight sim and pick the one that works best

[High Wing Drifter]

Thrice the drift outbound up to a maximum of 30' and once inbound.

And double drift outbound if trippling is more than 30 deg.

[ChocksAwayUK]

And double drift outbound if trippling is more than 30 deg

Or if the wind is within 45degrees of your outbound/inbound axis.

(erm.. i think)

[High Wing Drifter]

Or if the wind is within 45degrees of your outbound/inbound axis.

Use MCT!!!

[AlternativeProcedure]

I learnt the above method of applying tripple drift, but I've heard the American trained guys use a method different method. Can someone please explain that method? I hear with that method, u go into the hold once, keep a note of how long it takes to do the inbound leg and then somehow compensate on the outbound. I dont really get it, so i would appreciate an explanation on that front.

Cheers

[CAT3C AUTOLAND]

Just punch it into the FMC and let the autopilot fly it .

[needajob01]

how many times , did the controller asked you to hold?

for me: never, and I have 1800h flight time including commercial flights.

only instructors ask you to hold (only for more $$$$$)

well, here the US way: guess by experience how much you have to drift and correct by 3-4 degree ,for the timing if you are to short on the inbound(50 sec), extend the outbound to 1m10s.

the best way is to use the FMS.It is an airline requirement , even airlines pilots forget and dont have the time for that.

[High Wing Drifter]

AlternativeProcedure,

That sounds like the "I forgot to work it out on the ground" method

[Tinstaafl]

I've had to hold many times in Oz, UK & now that I'm working here, in the US. Holds *do* happen.

US holding procedures require the pilot to try to make good the hold timing on the **inbound** leg, not the outbound (+/- any HWC/TWC adjustment) as used by ICAO. In effect you need to time both outbound & inbound legs and attempt to adjust the outbound timing so that the inbound time is as close as practicable to the time specified for that holding procedure.

This isn't related to drift correction - just to achieving the specified hold timing on the inbound leg. Drift correction is something else again.

I'm not overly fond of the various X x the estimated drift on the outbound leg methods, although I've used them. Generally I approximate the drift correction by rounding to multiples of 5 or 10 deg deg to adjust my outbound heading. If I suspect the drift will be small then 5 or 10 deg is usually adequate. If medium then 10 or 15 deg, and if strong then maybe 20 deg.

If it's an NDB based hold then I also use the position of the needle for guidance about my position at the end of the outbound leg. For a 1 min hold the needle should be ~30 deg offset from 180 deg (+/- any heading correction). A 2 minute hold gives about 15-20 deg offset. If less than that then I know I've drifted/over adjusted for drift to the 'inside' of the hold & may need to compensate during the inbound intercept. If more than that then I've drifted/over adjusted to the 'outside' of the hold & will probably have to stop the turn at 90 or 45 deg to go. At 90 deg to the intercept the ADF should read ~10 deg ahead of the wing & at 45 deg to the intercept ~5 deg lead. This lets me judge how the intercept is going because I can choose to reduce or even stop the turn if the needle leads by too much or slightly increase the turn rate if it lags with a possible requirement to re-intercept from the other side of the inbound course.

A 2 min hold gives an opportunity for an *approximate* 'double the TE' type heading correction at the 1 min timing point (or half way if the timing is adjusted for HWC/TWC). However many degrees the RBI/RMI is reading above or below the expected 30 deg offset can be doubled to be come a heading correction to hold until the end of the two minutes eg at 1 min the RBI shows 35 deg instead of the expected 30 deg. so make a 10 deg HDG correction towards the holding pattern (towards because the greater reading puts the a/c outside the holding pattern. A 25 deg reading would put the a/c 'inside' the hold so you would then turn away from the hold). No need to be too wound up about it - a hold isn't a precision procedure, especially on the outbound leg.

A VOR can also be used similarly but it takes a bit of OBS twiddling to get the information.