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correcting drift in a hold

Posted: Mon Aug 20, 2007 9:31 am
by SQ
hello
do you have a quick way to calculate drift for wind in a hold instead of bracketing , or is bracketing the only way to have the better correction after having done the first pattern ?

thanks
SQ

Posted: Mon Aug 20, 2007 10:11 am
by Hedley
Never, ever do an instrument training flight without getting the winds aloft first - 3000 and 6000 will generally do.

Suggestion: use the speed of the wind aloft in knots for your outbound heading correction. It's simple, easy to remember, and the important thing is to not get blown downwind, which is what your instructor/examiner will try to arrange.

Posted: Mon Aug 20, 2007 1:21 pm
by WRX
There are more complex way to calaulate the drift angle but,

Unless it's direct crosswind or direct head/tailwind, I start with half of the upper wind speed for the outbound timing and heading.

20kts wind
20/2 = 10 degrees heading correction into the wind on outbound.
20/2 = 10 seconds added/subtracted from outbound timing, depending on headwind or tailwind on outbound leg.

Pretty good point to start for me anyways.

Posted: Tue Aug 21, 2007 8:51 pm
by Spokes
When tracking the navaid inbound, note the drift. Then for the outbound double it. Works great for me. Shown to my by the good folks over at PROIFR.

Posted: Tue Aug 21, 2007 8:56 pm
by Cat Driver
Just follow the hold racetrack on your Anywheremap moving map.

Posted: Tue Aug 21, 2007 10:15 pm
by good_idea
Spokes wrote:When tracking the navaid inbound, note the drift. Then for the outbound double it. Works great for me. Shown to my by the good folks over at PROIFR.
Love it!

for the timing in and outbound. take the error assciated with timing in bound vs. one minute and take 2/3 of it and apply it to out bound for 1 min inbound.

ie...
1:18 inbound... longer means headwind.

18 sec longer so take 2/3s of it and subract it from 1 min outbound

2/3 of 18=12

outbound for 1 min minus 12 .... 48 seconds

good_idea

Posted: Tue Aug 21, 2007 10:18 pm
by good_idea
Cat Driver wrote:Just follow the hold racetrack on your Anywheremap moving map.
good call... just buy an airplane equiped with a G1000 and you'll never have to think again....

the G1000 is amazing have you tried it out?

Posted: Wed Aug 22, 2007 7:50 am
by Cat Driver
the G1000 is amazing have you tried it out?
No, I have not flown small airplanes for many years (Except the Pitts and a few aerobatic types.)

But the Airbus and Boeings have glass and it makes life easy.

I use the Anywheremap for ferrying airplanes internationally and it is just like a mini EFIS.

Posted: Wed Aug 22, 2007 12:35 pm
by good_idea
[/quote]

I use the Anywheremap for ferrying airplanes internationally and it is just like a mini EFIS.[/quote]

is the Anywheremap like a hand held GPS?

Posted: Wed Aug 22, 2007 2:50 pm
by Cat Driver
is the Anywheremap like a hand held GPS?
It is generally run on a PDA, I run mine on a n Ipac 2100.

Posted: Thu Aug 23, 2007 9:35 am
by SQ
thanks for those tips

I'd like to use this anywhere map but I doubt the examiner would appreciate it :wink:

Posted: Thu Aug 23, 2007 10:49 am
by Hedley
Some people do this weird thing with their thumb on the HI to figure out the entry, but ...

Draw the hold on your kneepad. Draw your track to it. Draw the wind.

Given the picture above, you should be able to able to figure out your hold entry and initial fudges for track and time on the outbound leg.

After a while, you don't need to draw the picture. This visualization skill is probably the most important skill of the IFR pilot. Being a biological auto-pilot is nice, and so is chasing needles, but you can see why GPS moving maps are so popular - they do the visualization for you.

There is one more skill that an IFR pilot needs to stay alive, and that's developing a healthy respect for the weather (CB's, icing, dewpoint).

Posted: Fri Aug 24, 2007 9:27 am
by SQ
just obtained IFR / IATRA this week :smt033
still the flight test and all will be set.
thanks a lot for your tips, I'll try them in real flight.