Instrument Rating Drift Allowances???
Join Date: Jun 2003
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Why the holds? Maybe they assume that cat A & B ACFT have no real speed control!
My flights take me in and out of controlled and/or radar airspace. A few times it has been because of unplanned SSR failures (once TXP, other times the SSR heads), once its been because of an ATC coordination problem on entry to CTA and other times I just do as I'm told.
You're welcome to the weather and traffic in the UK. Haven't had to hold much for weather or stacked ACFT in my part of the world.
Why the holds? Maybe they assume that cat A & B ACFT have no real speed control!
My flights take me in and out of controlled and/or radar airspace. A few times it has been because of unplanned SSR failures (once TXP, other times the SSR heads), once its been because of an ATC coordination problem on entry to CTA and other times I just do as I'm told.
You're welcome to the weather and traffic in the UK. Haven't had to hold much for weather or stacked ACFT in my part of the world.
Join Date: Sep 2003
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Found the following interesting tidbit in "Whitts Flying", which may be of interest:
It might be of interest to know that the shape of the holding pattern used today was created because earlier gyroscopic instruments needed the straight sides to prevent precession.
Join Date: Jul 2003
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Hi there Novicef,
A rule of thumb I used to teach cadets was to examine the drift/wind direction and velocity observed on your way inbound to the IAF then roughly calculate the x-wind component on the holding pattern and if its 20 kts x-wind ( using 3 times the drift for a 1 min pattern ) allow 20deg drift which equates to x-wind/3 @ 150kts = 7 x 3 = 21deg.
Then at 45seconds outbound check to see that the ADF needle is 30 deg off yr inbound track. If its 20 degrees off the inbound yr too close so widen out by 10deg for the last 15 sec's and turn at rate one. If the needle is, say, 40 deg off then yr being blown out so turn in by 10 degrees for the last 15 sec's.
You can't go far wrong and you don't even really need to know the drift if you check the needle displacement relative to the inbound track ( while outbound ) and then use that drift information once inbound.
Happy to talk about it in detail if your stuck.
Damo
A rule of thumb I used to teach cadets was to examine the drift/wind direction and velocity observed on your way inbound to the IAF then roughly calculate the x-wind component on the holding pattern and if its 20 kts x-wind ( using 3 times the drift for a 1 min pattern ) allow 20deg drift which equates to x-wind/3 @ 150kts = 7 x 3 = 21deg.
Then at 45seconds outbound check to see that the ADF needle is 30 deg off yr inbound track. If its 20 degrees off the inbound yr too close so widen out by 10deg for the last 15 sec's and turn at rate one. If the needle is, say, 40 deg off then yr being blown out so turn in by 10 degrees for the last 15 sec's.
You can't go far wrong and you don't even really need to know the drift if you check the needle displacement relative to the inbound track ( while outbound ) and then use that drift information once inbound.
Happy to talk about it in detail if your stuck.
Damo
Join Date: Dec 1999
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I'm still not sure where is a direct reference stating that the outbound track of a holding pattern must be parrallel to the inbound track? I cant find it in the AIPS unless your referring to the diagrams which are a nil wind situation. As a note if you ever saw the protected airspace diagrams as outlined in the PANS-OPS requirements I can assure you the worst thing to do is overshoot the turn onto the inbound track as this is the least protected area and much less margin for error than on the holding side. The Holding side has a much larger area of protection and by the shape of it you can see it allows for non-parrallel flying of the outbound track, it sort of bulges out at each end. Anyway just my 2 cents worth!
