Are the Eastbound flights also takes less time in MSFS like in real life?

[BandyCypress889]

In real life the Eastbound flights are quicker than the Westbound flights due to Earth rotation and jet streams but I am not sure if it something that is the case in MSFS as well. I didn’t do any (successful) long hauls so don’t know for sure. If anyone has done such a flights can they confirm or deny that MSFS also simulates this effect?

[FlyingBear01]

Wind is modeled, including the jet streams if present (at least provided you use Live Weather), so that aspect is certainly simulated and has a big effect.

Earth rotation has a tiny effect in real life and I strongly doubt it is modeled. Other than as a trivia point in navigation textbooks I have not even heard it discussed as something affecting flight planning, have you?

[gekkoguy35]

I’ve not done any official testing or anything, but in my experience it does make a difference.

[FlyingBear01]

Just expanding on the Earth rotation aspect a little since it is such a fascinating little thing…

The reason it matters at all is of course due to the centrifugal force. The centrifugal acceleration is a = v^2/r. The earth’s average radius is 6,370 km, it rotates at about 15 degrees per hour, so it’s rotational velocity at the surface is about 434 m/s. That gives a centrifugal acceleration of about 0.030 m/s^2, or 0.003G.

Let’s say the aircraft velocity is about 234 m/s. (For those well versed in orbital mechanics this is where we would introduce ECI versus ECEF…). If we fly eastbound the aircraft velocity adds to the earth rotational velocity to give 668 m/s, which gives a centrifugal acceleration of about 0.007G. If we fly westbound the aircraft velocity is subtracted from the earth rotational velocity to give 200 m/s, which gives a centrifugal acceleration of about 0.0006G. The difference between eastbound and westbound is about 0.006G. Note all this was at the equator, at higher latitudes the difference is smaller.

Consider a large airliner with a cruise mass of 250t. At 1G its weight is also 250t (yes technically that should be “ton force”, similar to the non-conversion between lb and lb-f). 0.006G at that weight corresponds to a weight change of 1,500 kg (this is a weight change without a mass change!). Looking at a B777-200ER FPPM, at 250t, long range cruise at optimum altitude, that corresponds to a 0.7% change in fuel flow. I have not calculated what the trip fuel difference is over a flight. The difference in LRC Mach is tiny though, much less than M 0.01, so it does not make a difference in flight time. I cannot imagine the CI Mach schedule changes more than the LRC Mach for that small weight difference (if the FMC even considers it when it computes Mach from CI!).

So the difference exists, but it is so small that I doubt any airline considers it in its fuel planning software (if anyone knows differently, please let me know, that would be interesting to hear about!).