What is Reddit's opinion of Flight Map?

From 3.5 billion Reddit comments

you'll be going considerably slower than the official softban speed, which is set around about 1000km/h in a direct line of travel.

If you try to launch the game while airborne, You might be able to get GPS sync, but phone GPS needs a window seat, as the aluminium in the plane hull, blocks most radio and microwave radiation (the more you know). it also bounces around radio inside the plane, since it's a faraday cage at that point.

There are apps, like https://play.google.com/store/apps/details?id=marko.android.flightmap that can plot your position on a map, but you need an offline map, and PoGo needs an internet connection. it might work, but it won't display the map area.

Niantic has supported international travel and plane flight for years, i've gone to HK, JP and NYC with Ingress, and it's fine.

Your account will be ready to go once you land and GPS resyncs for your area.

I'd probably take your simcard out unless you enjoy roaming fees, but you might be able to use airport wifi to play until you get a local simcard.