B777-300ER Turbulence Speed Schedule
Join Date: Jul 2007
Location: Sandy Surroundings!
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The way that I remember it - below FL350, I open the speed window and set 280 IAS, above FL350 open the speed window and set M0.82!
Once the coffee has settled down, and only below FL350, I ensure that the speed is 15Kts above the amber band!
Have to keep it simple - after 8 hours staring into the darkness things must be easy!
Once the coffee has settled down, and only below FL350, I ensure that the speed is 15Kts above the amber band!
Have to keep it simple - after 8 hours staring into the darkness things must be easy!
Join Date: Jun 2004
Location: Australia
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Pedantic Mode ON
The Crossover Pressure Height for 280/0.82 is 34928 ft.
Why is Turbulence Penetration Speed 270 CAS at 25000 feet, but 280 CAS at 34928 ft? ..... Because EAS is within 1 knot of 263 EAS (Ve) which is what we need. (Aircraft need EAS, not CAS).
Why, at whatever level we must ensure no lesser speed than Vls+15? ..... Because Vls provides 1.3G protection, insufficient for Moderate turbulence. Buffet protection increases at the rate of 0.1G per 7 Kt above Vls, so to provide for 1.5G (moderate turbulence) we should fly at no less than Vls+14 (Nicely rounded up to +15).
Pedantic Mode OFF
Regards,
Old Smokey
The Crossover Pressure Height for 280/0.82 is 34928 ft.
Why is Turbulence Penetration Speed 270 CAS at 25000 feet, but 280 CAS at 34928 ft? ..... Because EAS is within 1 knot of 263 EAS (Ve) which is what we need. (Aircraft need EAS, not CAS).
Why, at whatever level we must ensure no lesser speed than Vls+15? ..... Because Vls provides 1.3G protection, insufficient for Moderate turbulence. Buffet protection increases at the rate of 0.1G per 7 Kt above Vls, so to provide for 1.5G (moderate turbulence) we should fly at no less than Vls+14 (Nicely rounded up to +15).
Pedantic Mode OFF
Regards,
Old Smokey
