In article ,
"Alan Burke" wrote:

Thanks guys for the response. What I suppose I am asking if how do you work
out the times (pre-planning) of the hold. I.e if you know the wind direction
and speed for the hold, I've worked out the single drift and in my notes it
says to work out the timings use 75% of the head / tail wind factor.

This is where I get stuck. How do you work that out??

Don't try to "work it out". Your primary job is to fly the airplane, not
work out complex geometry problems.

As you're approaching the hold, take a WAG (Wild Assed Guess) at wind
strength. In most common trainers, you'll be holding at about 90 kts. A
really big headwind component on your outbound leg would be 30 kts, making
your outbound groundspeed 60, and your inbound groundspeed 120 (double your
outbound).

So, that's pretty much an upper limit, and gives you your first WAG: with a
really honking headwind outbound, fly the outbound leg for 2 minutes.
Estimate down from the with a moderate headwind outbound, try 1.5
minutes. With little or no wind, try 1 minute. With a moderate tailwind
outbound, try 50 seconds, and with a really honking tailwind outbound, try
40 seconds. If you're trying to get things any more accurate than that,
you're doing way too much work.

It's better to fly your first outbound leg a little bit long rather than a
little bit short. If you under-estimate how long to fly outbound, by the
time you complete your inbound turn, you can be almost on top of the NDB
and not have enough time to re-intercept the inbound bearing before you
reach station passage. When that happens, you tend to just keep getting
more and more confused and lost.

But, the real way to do NBD holds is to tear that piece of crap ADF out of
the panel and train in a GPS-equipped airplane. If your school doesn't
have GPS in their trainers, find another school.