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Old 26th Apr 2012, 19:39
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wiggy
 
Join Date: Feb 2001
Location: The Winchester
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Is it different for large aircraft?
Sort of.

One problem is that the "heavies" typically hold clean at perhaps 210 - 230 knots IAS or even more, dependant on type. If you use the rule of thumb that the AOB required for a rate one turn = ((TAS/10)+7) you'll see that at normal holding altitudes in the Terminal Area of say 7 - 12000 feet, you need at least 30 degrees of bank to generate a rate one turn. Trouble is most authorities stipulate a 30 degree AOB limit, so with the bank limited the rate of turn reduces below rate one.

In addition the Flight Management Computer, which feeds the Flight Director/Autopilot, will attempt to achieve a fixed in-bound leg time, rather than a overall four minute timing; as a result it's certainly not unusual so see 4 1/2 to 5 minute holds.

Last edited by wiggy; 27th Apr 2012 at 08:35.
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