[kanawa]

The atmosphere is rarely moist enought throughout its depth to display such a thick and uninterrupted contrail

If it is flight 808 then it is travelling at a constant altitude, 37000'.
The perception of change in altitude is due to the increase in azimuth as it approaches the observer.

I haven't seen the flight plan of UPS902 yet.

[CARTOUCHE]

It isn’t flight 808 and it isn’t UPS902, it’s a missile.