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Amber band Vs Flap maneuver speed

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Member
Registered: Aug 2014
Posts: 35
Hi Hardy,

While reviewing the Boeing's FCTM, I realized that PSX has a behaviour regarding the PFD's lower amber band (Minimum maneuver speed) that differs from what I understand in the aforementionned document. The text states :

"Minimum maneuver speeds (displayed as the top of the lower amber band) should not be confused with flap maneuver speeds. Flap maneuver speeds are based on airplane weight, while the minimum maneuver speed is based on airplane angle of attack and current airspeed."

It would then make sense to me that, from a given situation (let's say level flight, no bank) :
- varying the real aircraft weight would make the amber band move (like the red&black minimum speed band), the Flap maneuver speeds remaining unchanged as long as no weight update is made in the FMC
- varying the FMC declared weight would change the Flaps maneuver speeds, but NOT the amber band (once again like the red&black band, which is also calculated from measured AOA)

However in PSX I think I noticed that the lower amber band varies with FMC weight rather than real weight, the offset between Flap maneuver speeds and top of lower amber band being constant as FMC declared weight varies (at a given altitude of course...).

Is there a misconception from me here ?

Cheers,

Xavier
Moderator
Registered: May 2009
Posts: 5140
Hi Xavier,

we've discussed this already somewhere on the forum.

I can't deliver any new comments on this subject at the moment.


Cheers,

|-|ardy
Member
Registered: Aug 2014
Posts: 35
Moderator
Registered: May 2009
Posts: 5140
Just found it :-)

http://aerowinx.com/forum/topic.php?post=21940#post21940

If you have any news on this subject, please post it here in this thread.


Cheers,

|-|ardy
Member
Registered: Aug 2014
Posts: 35
Thanks !

... and now I feel seriously embarrassed as I realize that I was the one who asked the exact same question 9 months ago, and did not even remember about it :-)

Let's say I'll be definitely curious to know if you ever find some further info about it !

Best regards,

Xavier

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