Holding questions - protected area and terrain clearance
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Holding questions - protected area and terrain clearance
Capt asked me yesterday 2 questions that embarrasingly I didn't know the answer to. I don't have any resources at the mo to look them up so I'll ask here :
1) What minimium terrain clearance does a holding procedure guaruntee ? ( I assumed this was 1000ft)
2) What are the dimensions of the protected area around a hold ?
Thanks in advance for the answers.
Buzz
1) What minimium terrain clearance does a holding procedure guaruntee ? ( I assumed this was 1000ft)
2) What are the dimensions of the protected area around a hold ?
Thanks in advance for the answers.
Buzz
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See PANS-OPS, Part I, Section 6, Chapter 2 (page 134 of the PDF).
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Don't be too embarassed. The data for establishing a hold is substantial and complex, and varies somewhat with the organization which has established the hold. The criteria for a hold may be different in different parts of the world depending on what authority applies to the creation and oversight of that hold. The "protection" is not uniform.
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I like to try and keep it simple if I can. So I keep the basics in mind.
Hold at or above the min published holding altitude, go for the 4 min hold and fly below the ICAO max speed. If you fly min clean to best holding speed for your a/c you will be OK but have the RA monitored, especially, when at min holding alt.
Don't got to "sleep" or get too fast.
I stand to be corrected on the above and shoot me down, if I should be!
Hold at or above the min published holding altitude, go for the 4 min hold and fly below the ICAO max speed. If you fly min clean to best holding speed for your a/c you will be OK but have the RA monitored, especially, when at min holding alt.
Don't got to "sleep" or get too fast.
I stand to be corrected on the above and shoot me down, if I should be!
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In the normal course of events, there's no problem in holding at the maximum PANS OPS or TERPs speed at the published minimum altitude. The fact is that the holding area is substantial and caters for a lot of eventualities that will, in all likelihood never happen - that's the underlying principle for everything other than the winds and temperature extremes associated with cyclones and similar types of unusual weather phenomena. All bets are off in those situations!
However, there's nothing wrong with erring on the side of safety, as espoused by justlooking_tks. The only thing I'd say is that, short of encountering really extreme weather, don't sacrifice any of the flexibility that MIGHT be provided by the lowest holding altitude.
To answer part of the original question, the minimum obstacle clearance that is guaranteed by a PANS OPS holding pattern is 300 metres, or 984 feet. As has already been said, the area isn't uniform in size and varies fairly massively to cater for sector entries and a certain amount of inaccuracy in tracking around the hold. There are limits to this but, if you have any sort of a decent standard of instrument flying, even on raw data, you shouldn't run into anything solid.
However, there's nothing wrong with erring on the side of safety, as espoused by justlooking_tks. The only thing I'd say is that, short of encountering really extreme weather, don't sacrifice any of the flexibility that MIGHT be provided by the lowest holding altitude.
To answer part of the original question, the minimum obstacle clearance that is guaranteed by a PANS OPS holding pattern is 300 metres, or 984 feet. As has already been said, the area isn't uniform in size and varies fairly massively to cater for sector entries and a certain amount of inaccuracy in tracking around the hold. There are limits to this but, if you have any sort of a decent standard of instrument flying, even on raw data, you shouldn't run into anything solid.
