[mansonh]

Yah that sounds pretty simple. Yet if you haven't scripted before it would be tough.

In your onplayercommandtext, depends on if you use strcmp, dcmd etc

check players vehicle model is a plane and which airport a player is within range of use IsPlayerInRangeOfPoint looping through all your airport coordinates.
Then send out a message to anyone else within range of the airport by looping through all players and checking if they are in range of the same airport.

To do this you will have to get the locations of the centre of the airports then the radius.

https://sampwiki.blast.hk/wiki/OnPlayerCommandText
https://sampwiki.blast.hk/wiki/GetPlayerVehicleID
https://sampwiki.blast.hk/wiki/GetVehicleModel
https://sampwiki.blast.hk/wiki/IsPlayerInRangeOfPoint
https://sampwiki.blast.hk/wiki/SendClientMessage