Attempted solution..
I'll give it a shot...
The sun moves at an apparent 15 degrees per hour...111 km (59.9 nm) times the cosine of the latitude, should give you the apparent distance per hour and thus apparent speed, right? I guess for altitude effects you would need to account for the increased dimension of the radius between Earth's axis and the A/C.
This reminds me of something interesting. I either read or was told in a lecture given by a former SR-71 pilot (can't recall which at the moment), that said pilots were the only aircrew to see the sun "rise" in the west. I never put any math to it but it sounds believable.