I show you how you can duplicate almost every attack aircraft that is available in GTA Online.
Step 1: Player 1 who is in the aircraft you wish to duplicate for your friend (Player 2) lands the aircraft.
Step 2: Player 2 then stands right next to the pilot seat for helicopters or on top of the jet for jets & shoots Player 1, they then hit triangle or Y for Xbox to get into the cockpit.
Step 3: As player 2 is getting into the cockpit, Player 1 sends them a 1v1 deathmatch invite by hitting square or X for Xbox. (Do not spam X or B on Xbox at all to re-spawn quicker, let it do it by default)
Step 4: Player 2 then accepts the 1v1 deathmatch invite once they begin to start their engine.
Now Player 1 should re-spawn in the desired attack aircraft if this has been done correctly. This is currently the only method close to the original one that got patched some months back. Sadly you will still be vulnerable to lock-on’s unlike the previous method, but this is still a great way to give your friends a quick Hydra or Savage, or to help save your friend the time of driving to the military base for a P-996 Lazer.
Also one quick note is I would advise once Player 1 has re-spawned in their aricraft, that Player 2 kill’s themselves before ending the DM in order to re-spawn in a fully 100% vehicle (No damage from shooting your friend at the begging of the glitch)