FrankGehry 28 Posted September 12, 2021 Share Posted September 12, 2021 In the CRJ7, as I'm climbing to cruise altitude, say FL340, my aircraft always climbs considerably slower as it approaches FL30. Around FL310, the speed will switch from Knots to Mach on the PFD. I also notice that I'll be going a lot faster than Mach .74 as is prescribed in the VNAV setup in the MCDU. What is the correct way to handle this? If I'm climbing at 290 knots, should I start to turn back the speed as I approach the switch from Knots to Mach so I end up around Mach .74 when the switch happens? If I leave it at 290 knots, the aircraft tends to hit a ceiling around FL310 unless I dial the speed back. Link to comment Share on other sites More sharing options...
Aplato 133 Posted September 12, 2021 Share Posted September 12, 2021 My understanding is that you climb at 290 IAS until your MACH reaches 0.74. At this point you switch to MACH mode (click the inner button on the speed knob) and climb at 0.74 instead and you'll start climbing at a faster rate. This usually happens around FL260. Link to comment Share on other sites More sharing options...
CRJay 429 Posted September 13, 2021 Share Posted September 13, 2021 Climb in 290 until current mach speed reaches M.74, manually switch to Mach mode. It's usually a bit later than Aplato mentions in my experience, generally around FL280-290. And from FL360 on, switch to M.77 for climb to cover your behind (at certain weights and altitudes, minimum drag speed can reach M.74 and it can be easy to get on the wrong side of the drag curve, so climbing at M.77 gives you some leeway). At the moment, the transition is a bit bugged though, at FL316 it will reset the speed bug to whatever your current speed is. It should not do that, so you might have to reset your desired speed. Link to comment Share on other sites More sharing options...
FrankGehry 28 Posted September 13, 2021 Author Share Posted September 13, 2021 14 hours ago, CRJay said: Climb in 290 until current mach speed reaches M.74, manually switch to Mach mode. It's usually a bit later than Aplato mentions in my experience, generally around FL280-290. And from FL360 on, switch to M.77 for climb to cover your behind (at certain weights and altitudes, minimum drag speed can reach M.74 and it can be easy to get on the wrong side of the drag curve, so climbing at M.77 gives you some leeway). At the moment, the transition is a bit bugged though, at FL316 it will reset the speed bug to whatever your current speed is. It should not do that, so you might have to reset your desired speed. So above FL360, set the climb speed to Mach .77? I've also noticed that when the speed tape is set to Mach, the magenta number that my climb speed is set to will differ from the speed in white text at the top of the tape. Is that normal? For instance, I'll have it set to climb at Mach .74, but the white text speed at the top will read out a higher speed. Link to comment Share on other sites More sharing options...
Deputy Sheriffs Herman 1591 Posted September 15, 2021 Deputy Sheriffs Share Posted September 15, 2021 On 9/13/2021 at 7:38 AM, FrankGehry said: I've also noticed that when the speed tape is set to Mach, the magenta number that my climb speed is set to will differ from the speed in white text at the top of the tape. Is that normal? For instance, I'll have it set to climb at Mach .74, but the white text speed at the top will read out a higher speed. Is this the same issue? Link to comment Share on other sites More sharing options...
FrankGehry 28 Posted September 15, 2021 Author Share Posted September 15, 2021 15 hours ago, Herman said: Is this the same issue? Yep, that's it. Thank you. I'll patiently wait for the update to come through. Link to comment Share on other sites More sharing options...
Deputy Sheriffs Herman 1591 Posted September 16, 2021 Deputy Sheriffs Share Posted September 16, 2021 With your OK, I'll close this with an invitation for anyone else noting this to post over in the other thread. Keeps the focus and information in one place instead of several. Link to comment Share on other sites More sharing options...
FrankGehry 28 Posted September 16, 2021 Author Share Posted September 16, 2021 9 hours ago, Herman said: With your OK, I'll close this with an invitation for anyone else noting this to post over in the other thread. Keeps the focus and information in one place instead of several. OK Link to comment Share on other sites More sharing options...
Aerosoft Jonas S. 466 Posted September 16, 2021 Aerosoft Share Posted September 16, 2021 Because we believe this topic has been answered we have closed it. If you have any more questions feel free to open a new topic. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.