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Climb Mach Offset ~M0.03


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I've noticed on several flights that the aircraft will pitch to climb M0.02-M0.03 below the target value (both prior to the latest patch and today after the hotfix).  I set the speed bug to 290 kts above 10,000 feet and the speed is rock solid!  At 29,000-30,000 ft, 290 kts = M0.74, so I press the IAS/MACH button and the aircraft pitches up to increase the climb rate, letting the speed decay down to about M0.72.

 

I've found I have to set the speed bug to ~M0.76 in order to climb between M0.73 and M0.74.

 

Am I doing something wrong?

 

 

Screenshot 2021-05-29 090006.png

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  • CRJ Forum Moderator

I have seen this same effect when manually switching to Mach mode at around 29,000 feet.,It has been added to our bug tracker.

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  • 1 month later...

Seconded this issue, although 

On 5/30/2021 at 8:23 AM, JRBarrett said:

I have seen this same effect when manually switching to Mach mode (...)

 

I have seen this issue even when the switching from IAS to MACH is done automatically at 31.5k, not just when manually switching

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Also … even if set to 0.74 at FL290 manually and the climb continues … often at FL 315 the system again switches to mach speed settings … and therefore populating that current offset speed of 0.72.

 

result is that the pfd  suddenly shows 0.72 “selected” despite i never did select  that myself.

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6 hours ago, DGH said:

Also … even if set to 0.74 at FL290 manually and the climb continues … often at FL 315 the system again switches to mach speed settings … and therefore populating that current offset speed of 0.72.

 

result is that the pfd  suddenly shows 0.72 “selected” despite i never did select  that myself.

I think someone mentioned here before that there is an Auto Switch over to Mach Speed around that point....

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On 7/25/2021 at 11:01 AM, LesOReilly said:

I think someone mentioned here before that there is an Auto Switch over to Mach Speed around that point....

 

It appears that the target mach is reset to the current mach at 31,600 ft (switch over point).  I will typically manually switch from IAS to MACH at M 0.74, and reset the target to M 0.77 (to account for this offset behavior).  The aircraft will continue to climb at M 0.73-M 0.74, which will cause the target mach to change to M 0.73 or M 0.74 at 31,600 ft (resulting in a climb around M 0.72 if I don't remember to reset it).

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