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Wind correction angle advice

Has anybody got any tips for working out wind correction angles when flying holds in IMC?
I realise that these things are best thought abovut at the flight plan stage, but if the wind changes or you go to an unplanned airfield, what method ad hoc do people use?

Goodwood

when you arrive at your destination airport you should already have an idea about the wind aloft – so when you enter
the one minute or DME holding pattern use 3x WCA on the outbound leg. When you have a GPS fly the appropriate track for the outbound leg
and use 2x WCA (wind correction for the curved parts of the holding). When ATC is kind enough to let you fly a longer hold you experience
the result when turning inbound and establishing on the correct radial or QDM inbound …

Last Edited by nobbi at 19 Nov 19:50
EDxx, Germany

Are we talking the way to pass your test or the way to fly a hold in practice?

If in practice I do the following.

  1. approaching the holding fix make sure it is active waypoint, fly a heading
  2. Set the GPS OBS to the inbound course.
  3. Overhead the fix turn to a 30 degree intercept of the reciprocal until xtrk error is 2nm.
  4. Fly outbound until 4nm from holding fix then establish 30 degree intercept of inbound track.
  5. Repeat.

This is clearly even easier with an autopilot that can capture the inbound track in NAV mode.

Last Edited by JasonC at 19 Nov 20:11
EGTK Oxford

If you are doing it for real, you use the GPS and the moving map display

Make a DCT to the holding fix, set the GPS to OBS mode and set the OBS value to the inbound leg bearing. With the autopilot in HGD mode, fly the appropriate hold entry method, and use the NAV mode to intercept and track the leg leading to the holding fix, then switch to HDG mode, fly the turn, fly the outbound leg track with the heading equal to the track but adjusted by “half the wind” (if the crosswind component is say 20kt then do a 10deg offset), then (after the 1 minute, plus a bit for any headwind but rarely for less than 1 minute because it makes the next hit harder) turn towards the inbound leg and switch to NAV mode to intercept that again. This is basically the same thing as Jason wrote above except that he is flying the hold by distance (more accurate and needs no messing with the outbound leg timing) rather than by timing (the “approved” method everywhere)…

Or you can fly the whole thing with the heading bug, if you have a decent moving map. A lot less effort, perfection is not required, and the protected area will be big enough for a 747…

If you are doing it in an IR test, try to find out what the examiner will be expecting

The FTOs have taught various methods over the years, with some of them teaching some pretty complicated methods with “gates” and such. There is an RNAV training manual written by one prominent private pilot here which I believe covers this stuff in minute detail.

When I was doing my FAA to JAA IR conversion, the instructor said he doesn’t teach the gates, so I was just doing it the “obvious” way which was tracking the inbound leg (to the holding fix) using the CDI (if VOR) or the RMI (if NDB), and using something like 3x the wind. However for strong values of wind, 3x is often too much.

The best thing you can do is have the test on a calm day. It will not only reduce turbulence (and massively reduce the pilot workload because you have to hand fly most of it) but also makes stuff like holds a lot easier.

Last Edited by Peter at 19 Nov 20:19
Administrator
Shoreham EGKA, United Kingdom

Also for those with GPS and autopilot that can fly a missed approach hold. Often the hold at the start of a procedure is the same as the missed approach hold. If you activate the missed approach fix you can have the autopilot fly the hold until you are told to start the approach. You do that by activating the fix at the start of the procedure.

EGTK Oxford

Very very system dependent, that one

Administrator
Shoreham EGKA, United Kingdom

Yes but works on 430w/DFC90 and G1000/GFC700. You prob need roll steering.

EGTK Oxford

On my system (Aspen PFD with the ADF displayed), NDB holds using raw data are pretty easy:

  1. Tracking to the fix to join the hold, line up the ground track diamond with the ADF pointer
  2. Set up the heading bug to the desired outbound track from the beacon,
  3. As you pass the beacon just line the diamond up with the heading bug. The tail of the ADF pointer will catch up after a few seconds and is ALWAYS in exactly the right place.
  4. Turning inbound, set the heading bug to the desired inbound track and start turning. Ignore the pointer until you’re established on the desired ground track. If you estimated the outbound track correctly (2X wind correction angle for track seems to work) then you’ll be within a few degrees and just need to correct a little.
  5. Over the fix, turn outbound, setting the desired track on the heading bug
  6. Rinse, repeat

This is kind of cheating, but it is good enough for the test. And of course this is also very system dependent…

Garmin say they will be adding functionality to the GTNs for arbitrary holds at any point. Having seen a hold flown off a GTN using GPSS steering, there is no doubt that this is the future.

Tangentially, what is the “official” method for flying an RNAV hold if one were to come up in an exam? Follow the magenta line, or treat it like a traditional hold with a course to a point in space?

EGEO

Tangentially, what is the “official” method for flying an RNAV hold if one were to come up in an exam? Follow the magenta line, or treat it like a traditional hold with a course to a point in space?

I asked an FTO IR instructor/examiner:

The very essence of RNAV is to able to use all the information generated from properly fitted and certified GPS equipment, having checked its coverage and RAIM.

Therefore my feeling is that one should be able to fly a hold using the full RNAV display available, which would mean following the magenta line.

Administrator
Shoreham EGKA, United Kingdom

If it’s completely ad hoc and in a very basic aircraft with no GPS etc, I enter the hold in the appropriate way and fly inbound. I work out the WCA on the inbound leg and then apply 2x correction to the outbound. I don’t fly holds all that often but whenever I have, this has given a more that satisfactory result.

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