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downwind
27th Apr 2019, 07:34
Hi All,

Based on the below video and for a unreliable airspeed scenario or something similar to the Air France A330 accident…

https://www.youtube.com/watch?v=jGR-VCy-GhQ

Can you please confirm the below questions I was interested in this area after viewing this video and especially because of the airspeed unreliable scenario at high altitudes.

Questions:

MACH/AIRSPEED INDICATOR RANGE

Airspeed indication presentation range from 45 knots to 450 knots on the B737 classic and NG, please confirm the upper limit for the EADI and PFD airspeed indicator?

Mach number indication is presented on a two-drum digital readout through the range .40 to .99 mach. Below .40 mach the readout is covered by a black mask/blank (NG) on the B737 classic and NG, please confirm the upper limit for the EADI and PFD airspeed indicator?

ALTIMETER RANGE

The range of the altimeter if from -1000 to 50,000 feet with altitudes below sea level displayed by the rotating pointer and a NEG flag covering the counter on the B737 classic and a negative sign appears when altitude below zero feet is displayed for the NG, please confirm the upper and lower limit for the B737 NG altimeter?

STANDBY AIRSPEED/ALTIMETER INDICATOR RANGE

The standby pneumatic airspeed indicator gives indicated airspeed 60 to 450 knots, please confirm for both the B737 classic and NG?

The standby altimeter is a drum-pointer type having a range of -1000 to 50,000 feet, please confirm for both the B737 classic and NG?

ISFD RANGE

What are the speed tape ranges?

What are the altitude tape ranges?

AIR SPEED UNRELIABLE SCENARIO

Stick shaker limits based on the speed tape

Stick shaker ceases below 45 knots indicated, what is the upper speed range limits of the stick shaker on the B737 classic and NG for it to cease?

Overspeed clacker warning upper and lower limit speed range limits when it ceases on the B737 classic and NG?

From a flight warnings perspective for FAR 25 aircraft is this logic the same across the board?

Mad (Flt) Scientist
1st May 2019, 21:52
...

From a flight warnings perspective for FAR 25 aircraft is this logic the same across the board?

Can't answer to the very specific questions on the specified types, but as a general answer to your last question: while the general philosophy for airspeed indication can't be TOO different, since everyone has to meet the same regulations, the regs are not so prescriptive as to restrict everyone to all doing it exactly the same way. So the answer is "At a high level, yes, the logic is generally similar. At the level you are pitching your questions, no, there are differences."