I can’t remember if this has already been addressed, but I was wondering if there’s a reason that (with just the 777 family) the IF autopilot Mach number and the number on the PFD are consistently one number off.
Also now that I think about it, there’s also a thing with all live cockpit aircraft where the PFD will show certain degrees of bank, but the HUD is consistently 5 degrees off.
is it still mach 0.84 on HUD, if so, i think its just set to 85 but the plane is just flying at 84, like if you set it to 220 IAS and it was flying 217 IAS
I forgot to check the HUD mach number but the thing is that it’s consistently inconsistent. I think it’d be great if they made everything uniform. It would be weird and possibly catastrophic if a real plane’s HUD, autopilot setting, and cockpit displays were different.
Actually I’d recommend leaving the Autopilot on M0.84, as the 777 cruises at M0.839 with this setting, I wouldn’t be surprised if this is also the case IRL, you’d rather fly a wee bit slower than faster (for fuel consumption).
I remember seeing a video from the cockpit in an AirFrance 777 and the pilots set M0.84 on the auto-pilot but the plane was actually cruising at M0.839.
(Same thing happens on the 787 which likes to cruise at M0.86 with tailwinds when the A/P is set to M0.85).
For the bank angle, I think there are several indicators. One is the bearing and the other is the heading. You will find the heading on the HUD, and both on the PFD. I’d like someone to crosscheck that if possible.
As for the Mach speed, I have some data.
Context:
KJFK-HECA
A/P speed : M0.84
Real speed : M0.8421
Indicated speed HUD : M0.84
Indicated speed PFD : M0.84 Winds : 127 kts direct tailwind.
Normal altitude, normal weight and balance.
So as you can see, the tailwind is allowing me to cruise at a solid M0.84.
Tomorrow once I land I will try the same scenario with no wind, and with headwind, I’ll let you know of the results.
As for bank, this may be the same issue, discussed previously:
As for Mach number and winds:
Winds should not affect Mach number because the mach number is a true airspeed - it’s your speed measured relative to the moving air mass. So, how fast the air mass moves will not make a difference.
Only when the wind changes and the aircraft must “catch up” with the new wind would one expect some temporary difference.
Why does it changes then? With the wind being the only factor I changed. There must be something going on between the wind pushing the aircraft and the power not being able to readjust precisely to M0.85 therefore the aircraft would be flying a bit faster than usual.
I think the Mach number difference is maybe something like roundoff error (Is it true the difference is never more than .01?).
You can see the effect with wind if you go into solo mode and take a 777 up to cruise altitude, get stable with a fixed Mach setting for speed and at level altitude with no wind.
Then abruptly change the wind speed slider. This causes a sudden change in the Mach number and other speeds (as long as it’s not a 90 degree crosswind). And the auto throttle goes to work changing the excess or deficiency in speed until you end up with the same Mach number you had before.
The only thing different after the transition is the GS now reflects the added wind. But as your Mach number is TAS as a fraction of the speed of sound, Mach stays the same after the auto throttle adjusts for the temporary speed surge (whether up or down).
I like to think about a hot air balloon drifting in a nightmare wind blowing at the speed of sound. It’s moving over the ground at the speed of sound, but it’s Mach number is zero (passengers in the balloon feel no wind as its TAS is zero).
Even in this “tested” environment, abruptly changing the winds is something that wouldn’t happen in game under normal circumstances. No wonder the aircraft has to work to keep the Mach under control, an extreme change like an abrupt change in winds with the slider would make things chaotic.
I actually have a clear memory of it occurring. It was a rather abrupt change in wind direction from takeoff to the mid altitudes while ascending. The amount of wind was fairly strong and the wind direction arrow turned about 180 degrees due to ascending, and quickly enough to cause the auto throttle to abruptly change.