Undamageable planes in Multiplayer

[Monostripezebra]

it seems that under certain conditions players do not take any damage despite beeing hit:

 

notice how player 303_holly has 0 damage

http://72ag-ded.ru/de/sortie/log/12600/?tour=2

 

 

but I did hit him with front and rear guns as well as a collision that occured:

https://www.youtube.com/watch?v=5XuhuL3hVe4

Similar incident, other server (TAW)