Resident Evil 6 [Medal] - Destroyed 3 helicopters with the VTOL's barrel gun

This is one of the medals which I could not obtain in my Piers walkthrough because this medal is exclusively for Chris. This medal is straightforward: All you have to do is to destroy the three helicopters (which are marked with red arrows on the HUD)as Chris before Piers destroys all anti-aircraft artilleries which triggers the next phase in this area. It should be doable without much effort, just make sure that you don't crash into a helicopter or the carrier. If you need more time, you can prevent Piers from reaching the anti-aircraft guns on one side by staying on the other until you are finished destoying the choppers. (Difficulty 2/5) --- Resident Evil 6 Medal , Resident Evil 6 Achievement , Resident Evil 6 VTOL , Resident Evil 6 Aircraft , Resident Evil 6 Plane , Resident Evil 6 Chris chapter 4 , Resident Evil 6 Piers chapter 4