If you play with a custom fov (fovLeft, fovTop) when you get into a air craft (only noticed this for helicopters) your fov will revert to the games default values.

My friend managed to find one from tanoa when he was in a humming bird, his FOV values are the same as the above -

before (1.68):
https://image.prntscr.com/image/2c3ef40748834e5d88c7ee2537c80eea.png

after (1.70):
https://image.prntscr.com/image/d376cb6802c84d65af21482aa5171fe9.png

The server we play on doesn't touch anything with fov (if you even can through scripts.)