IMC Question
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I suspect some of the 2x v. 3x confusion may come from different ways the hold is taught.
Let's say you have a hold on which the inbound leg is 270, and the outbound leg is (obviously) 090 (to keep the picture simple).
If there was no wind I would fly the inbound at 270. Then I would turn onto a heading of 090 (not, as is often taught, fly a rate-1 turn for 1 minute) and, if there was any wind apparent on the previous (inbound) leg, apply the opposite wind correction.
Let's say the wind is from the south, 20kt. This will manifest itself through me having to fly a heading of about 260 to track the inbound (270) leg. The easy rule being "max drift is half the wind" tells me the wind is probably 20kt but I don't need to know this! All I need to know is the 20deg offset, so when I turn onto the outbound leg, instead of turning onto 090 I turn onto 100. Easy.
Done this way, one applies one wind correction on the inbound, and one wind correction on the outbound.
You can call it unconventional but it works extremely well. It also prevents you totally fu*ki*g up the whole thing if something goes wrong with the stopwatch... (which never happens
)
Critics will say I fly holds on headings rather than the stopwatch because I cheat and watch my actual position on the GPS. In fact I did all the stuff in the IR training and checkride this way and nobody said a thing. The only time I was timing turns was on partial panel, when the only instruments not covered up were the TC, the liquid compass, and the altimeter.
I don't really know why holds are taught to fly the curved legs by timing them for 1 minute. It yields inaccurate headings, unless your rate-1 is held precisely which is impossible to do in any turbulence. It also requires a 3x wind adjustment which is excessive at spamcan speeds - because the whole business of adding-up wind corrections relies on trigonometry of small angles, and 30+ degrees isn't a "small angle".
Let's say you have a hold on which the inbound leg is 270, and the outbound leg is (obviously) 090 (to keep the picture simple).
If there was no wind I would fly the inbound at 270. Then I would turn onto a heading of 090 (not, as is often taught, fly a rate-1 turn for 1 minute) and, if there was any wind apparent on the previous (inbound) leg, apply the opposite wind correction.
Let's say the wind is from the south, 20kt. This will manifest itself through me having to fly a heading of about 260 to track the inbound (270) leg. The easy rule being "max drift is half the wind" tells me the wind is probably 20kt but I don't need to know this! All I need to know is the 20deg offset, so when I turn onto the outbound leg, instead of turning onto 090 I turn onto 100. Easy.
Done this way, one applies one wind correction on the inbound, and one wind correction on the outbound.
You can call it unconventional but it works extremely well. It also prevents you totally fu*ki*g up the whole thing if something goes wrong with the stopwatch... (which never happens
)Critics will say I fly holds on headings rather than the stopwatch because I cheat and watch my actual position on the GPS. In fact I did all the stuff in the IR training and checkride this way and nobody said a thing. The only time I was timing turns was on partial panel, when the only instruments not covered up were the TC, the liquid compass, and the altimeter.
I don't really know why holds are taught to fly the curved legs by timing them for 1 minute. It yields inaccurate headings, unless your rate-1 is held precisely which is impossible to do in any turbulence. It also requires a 3x wind adjustment which is excessive at spamcan speeds - because the whole business of adding-up wind corrections relies on trigonometry of small angles, and 30+ degrees isn't a "small angle".
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I don't really know why holds are taught to fly the curved legs by timing them for 1 minute
The question should be moved to the instructors forum for some replies from people who actually teach this stuff.
Ask your instructor for clarification. That is all that is required. To fly a hold to the standards required for the IR takes several hours, time which does not exist during an IMC course, so things tend to get simplified. This is not to reduce the quality, it is just that the required outcome for the IR (inbound track +/- 5 degrees for 15 seconds) is not something anyone cares about in the real world.
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The following method for flying the hold is simple and will get you a pass on the CAA initial IR flight test. It is relatively easy and works in the real world as well
Basics;
1. You have to remain within the holding area and you have to establish on and track the inbound track for a "reasonable" amount of time during each hold.
2. While keeping it within the holding area it is good to be both slightly wide and slightly long at the end of the outbound leg.
3. The inbound turn from a slightly wide position should allow you to stop the turn with heading of about 60deg to go to the inbound track and lock the wings level so that :-
a) You remove the dip error; and
b) You can nicely judge the turn to exactly establish on the inbound track.
4. Have the gate and abeam point drawn on your chart for ease of reference.
To allow for wind - use 3* the inbound drift for the outbound unless that heading is within 30deg of the wind when you use 2*drift.
At the beacon start the stopwatch and turn onto the outbound heading that you have judged.
If you steady on the heading before passing abeam, check the time it takes you to reach the abeam point (you have a headwind outbound to allow for in the timing).
At the abeam point restart the stopwatch.
If you steady on the heading after the abeam, restart the stopwatch and remember you have a tailwind outbound to allow for in the timing.
If you reach the gate +/- the drift angle before time time is up then track the gate away from the beacon until the time is up.
If you are sightly wide and a few seconds long at the end of the outbound leg, you are guaranteed to make the hold.
Turn onto a heading 60 degrees from the inbound track (90 deg may be required if turning into a very strong wind across the hold). Level the wings and concentrate on keeping the wings level.
Now with no ADF dip to worry about, wait for the pointer to indicate about 10deg from the final track (depending on wind) and start the turn to establish inbound.
You are going to end up inbound +/- 5 degrees with some time to run to the beacon.
Repeat the process while refining the hold as you go!
-------
IO540,
Your system does not allow for the difference in radius of turn at each end in a crosswind i.e. turn into wind is small radius leaving you close to the inbound track, then the turn out of wind is large radius taking you screaming through the inbound track.
I love your comments when the only instruments not covered up were the TC, the liquid compass, and the altimeter.
Where was that then?.........A school that thought the ASI and VSI also failed when the gyro's failed?
Regards,
DFC
Basics;
1. You have to remain within the holding area and you have to establish on and track the inbound track for a "reasonable" amount of time during each hold.
2. While keeping it within the holding area it is good to be both slightly wide and slightly long at the end of the outbound leg.
3. The inbound turn from a slightly wide position should allow you to stop the turn with heading of about 60deg to go to the inbound track and lock the wings level so that :-
a) You remove the dip error; and
b) You can nicely judge the turn to exactly establish on the inbound track.
4. Have the gate and abeam point drawn on your chart for ease of reference.
To allow for wind - use 3* the inbound drift for the outbound unless that heading is within 30deg of the wind when you use 2*drift.
At the beacon start the stopwatch and turn onto the outbound heading that you have judged.
If you steady on the heading before passing abeam, check the time it takes you to reach the abeam point (you have a headwind outbound to allow for in the timing).
At the abeam point restart the stopwatch.
If you steady on the heading after the abeam, restart the stopwatch and remember you have a tailwind outbound to allow for in the timing.
If you reach the gate +/- the drift angle before time time is up then track the gate away from the beacon until the time is up.
If you are sightly wide and a few seconds long at the end of the outbound leg, you are guaranteed to make the hold.
Turn onto a heading 60 degrees from the inbound track (90 deg may be required if turning into a very strong wind across the hold). Level the wings and concentrate on keeping the wings level.
Now with no ADF dip to worry about, wait for the pointer to indicate about 10deg from the final track (depending on wind) and start the turn to establish inbound.
You are going to end up inbound +/- 5 degrees with some time to run to the beacon.
Repeat the process while refining the hold as you go!
-------
IO540,
Your system does not allow for the difference in radius of turn at each end in a crosswind i.e. turn into wind is small radius leaving you close to the inbound track, then the turn out of wind is large radius taking you screaming through the inbound track.
I love your comments when the only instruments not covered up were the TC, the liquid compass, and the altimeter.
Where was that then?.........A school that thought the ASI and VSI also failed when the gyro's failed?
Regards,
DFC
Fixed+Rotary (aircraft, not washing lines)
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As someone going through IMC training at the moment it is threads like this one and the one on 'Descending through cloud..." that really demonstrate the value of PPRuNe. Thanks to everyone for their input.
