Airspeed in turbulence
Thread Starter
Joined: Apr 2008
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From: nowhere
Airspeed in turbulence
Concerning the incident on the last page of this report....
http://www.bea.aero/ita/pdf/ita.005.en.pdf
Why is it better to select an airspeed than a mach number.
Conduct of flight in turbulent atmosphere
The pilot selected a Mach number, and not
a speed, in accordance with the instructions
in moderate turbulence, which led to speeds
above the recommended speed (308 kt
maximum) without, however, approaching
VMO(15). These actions were not sufficient in
face of the strength of the turbulence that was
in fact encountered.
http://www.bea.aero/ita/pdf/ita.005.en.pdf
Why is it better to select an airspeed than a mach number.
Conduct of flight in turbulent atmosphere
The pilot selected a Mach number, and not
a speed, in accordance with the instructions
in moderate turbulence, which led to speeds
above the recommended speed (308 kt
maximum) without, however, approaching
VMO(15). These actions were not sufficient in
face of the strength of the turbulence that was
in fact encountered.
Bottums Up
Joined: Feb 2000
Posts: 3,440
Likes: 3
From: dunnunda
At a guess I'd say IAS/Mach crossover (haven't read the report). On the Douglas/Boeing 717, turbulence penetration speed (above 10,000') is 275 kias/ M0.75 whichever is the less.
It's quite common to see folk preselect M0.75, which can be significantly faster than 275 kias, depending on the altitude.
It's quite common to see folk preselect M0.75, which can be significantly faster than 275 kias, depending on the altitude.
Last edited by Capt Claret; 10th August 2012 at 21:04. Reason: "select" changed to preselect
Joined: Jan 1999
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From: On the dark side of the moon
Capt claret! You are spot on with your reply!
On a 777 the turb speed is m.82 or 280 whichever is less, if you are heavy it is
To be 15 kts above the yellow band, this causes sometimes confusion !??! ???
The crossover usually is between FL 340 and 350 then 280 becomes M.82
Amazingly during climb pilots observe this speeds quite strict,during descent
They tend to fly faster and do not care to much about turbulence, - strange, but
That's how it is!
On a 777 the turb speed is m.82 or 280 whichever is less, if you are heavy it is
To be 15 kts above the yellow band, this causes sometimes confusion !??! ???
The crossover usually is between FL 340 and 350 then 280 becomes M.82
Amazingly during climb pilots observe this speeds quite strict,during descent
They tend to fly faster and do not care to much about turbulence, - strange, but
That's how it is!
Last edited by mach 84; 10th August 2012 at 14:55.
Joined: Apr 2010
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From: Home soon
The aircraft gust envelope is plotted against EAS, that's why.
Would you be kind to explain or provide me an explanatory document?
Thanks a lot.
