Thanks for this feedback, you and @DEAN01973 are correct that speed was the culprit. Explains completely why it occurred most often during cruise.
With that out the way I’ll say thanks again to the DC Designs team, I have had a string of perfect flights today and have decided Barbados to London is my favorite flight plan.
I actually watched that last night, LOL.
So far, all is good on my fuel transfer, especially for AFT. When I descend, in a few hours, I can do fuel transfer forward correctly (last night it would not bring fuel to #9 from #11, but I’m sure it was something I did wrong.)
@CodenameJack447 - you are a genius. After I reached out 58,000 ft, I engaged auto-throttle 1 & 2 (I had to arm both for some reason, otherwise it wasn’t working) and THEN I armed MAX CRUISE, like you said, and voila:
We’re at a steady 2.04!
Everyone, I am doing a test and it is to automate that when you transition from max climb to max cruise, if mach hold is not engaged when AT is on, it automatically engages. Sounds good?
Sounds great!!!
PS, if I have auto-throttle and max cruise armed (as I do now), why are the afterburners going? Is that normal (I ensure the piano keys are not armed)
I am on SU 8 (not 9 Beta). Should this be happening?
because you are full throttle i think, just retract a bit to disable them and throttle again to full.
So I got it working, I armed auto throttle on the overheard panel, hit MACH hold and then max cruise and it it decelerated back and is currently holding M2.04 for me nicely. Should you always arm auto throttle using the overheard panel instead of using the auto throttle piano key first?
Edit: I turned off the autothrottle and then turned it on again using the piano key, hit MACH hold and max cruise, thought it was holding it but I looked 5 mins later and I’m at M2.23, armed the auto throttle again using the overheard and it decelerated back and is currently holding M2.04 again
Let’s say the overhead switches in the real plane connect and disconnect each engine to the AT system, but in MSFS it’s all or nothing (there are no AT channels per engine). If the piano keys are up, the ones OVHD are activated as well. If you deactivate the OVHD ones you disarm the piano keys too. The AT by itself does not work if IAS HOLD, MACH HOLD or IAS ACQ is not active. That’s why you must have one of them active before going to Max Cruise.
Well…well…well…almost 1200 pages of in depth “study level” discussion tons of info on the fuel system alone. Seems this plane just may be complex and in depth enough to generally called…“study level”??? Isn’t this the goal of “study level” planes not just in depth sim technicalities but also enough immersion and intricate procedures to bear a fruitful almost 1200 page technical forum discussion of trial and error user cooperation and exchange of technical information?
This thread alone is a beautiful thing and I’d take this sort of mass exchange of interests and technical discussion any day over the ancient ten commandment perceptions of what’s “study level” in 2022🍻
As mentioned yesterday, it can be very difficult to read the miles and ground speed numbers on the HSI if the sun is at the wrong angle
I still think there are some issues with the Concorde and ILS. Today I flew KJFK to TBPB. Most of the flight was fine except of course for the 09 ILS. In fact I reloaded several times to try different things to see what would work. There are problems with both localizer capture and glideslope capture in my opinion. Sometimes I was able to capture and sometimes I was not.
I think the developers do not see this because they unconsciously always fly the plane with the same basic assumptions that the rest of us do not share. It’s possible the plane is even coded in a way with these assumptions built-in. I have seen this on other aircraft in other simulators. Everything works perfectly for the developer because they coded the plane to fly the way they fly. When other people have slightly different assumptions, or push buttons in a different order, things don’t work properly.
For example, I still have more testing to verify this but I think that glideslope will not capture if ALT HOLD is engaged. I think localizer will not capture unless both NAV1 and NAV2 are tuned to the ILS frequency.
I think that there are a bunch of if then statements in the software which assume a certain path towards ILS capture.
But basically, however you arrive there, if the rad/GPS switch is in RAD mode, the VOR LOC button is pushed, and the correct ILS frequency is set in Nav1, the localizer should capture no matter what else is pushed. No localizer course needs to be set since Localizers do not need it.
If VORLOC is pushed, all other guidance modes should disable automatically. This includes heading hold, TRK HDG and INS.
I can easily make a video to show that this does not happen.
Sorry for such a long post but I’m sure the developers want to improve the systems of this wonderful aircraft as much as I do. Once I have more testing results I will post them here. If the developers want me to assist with more beta testing, I’m happy to help also.
Just finished my first around the world jaunt in the Concorde, and really enjoyed it. Yes, this aircraft has a few niggly issue that detract from the perfect experience, but overall it lets me relive the memories I have of flying the SSTSIM Concorde in FS9 but this time in VR and with much better graphics. Thanks again DCD for your efforts in bringing this beautiful aircraft to the MSFS skies! 
BTW, the legs I flew if anyone is interested are as follows: YSSY → NSTU → PHNL → KLAX → MMMX → KJFK → EGLL → OBBI → WSSS → YSSY
Reading all these amazing posts makes it even sadder that I can’t get this bird airborne at all 
What seems to be the problem?
I’ve mentioned it earlier, when I load on the runway after selecting a flight plan in the world map…click ‘fly now’ and all is normal but as soon I throttle up to take off the engines die and I’m just sat there on the runway going nowhere…it’s the only plane that does this as I fly Deans jets quite regularly so I have no idea what’s going on
And you’re not in beta su9?
AT on or off?
What external hardware are you using?
SU8
No AT
X56 Hotas which works superbly with every other aircraft in the sim
