During all the turmoil and chaos in 1999 during the Kargil operation, a Pakistani naval aircraft was shot down by MIG-21s after it entered Indian airspace.
After, the radar detected the plane inside Indian airspace, the Migs were immediately summoned to intercept the intruder.
Upon requesting the Pakistani plane to land immediately or return back, it turned away in a dangerous manner. The plane was carrying torpedoes and was unresponsive.
The MIGs immediately retaliated back and the plane was shot down with an Air-to-Air missile.
This incident occurred immediately after the 1999 conflict and hence was even blown out of proportions. It is famously called as the ‘Atlantique Incident’.
International protocols follow these steps:
- Communicate with the intruder ASAP.
- In case, there is no response, send interceptors immediately.
- If communication is down, the intruder pilot will be asked to rock his wings or flash light to ascertain emergency. It also depends whether it is a commercial, transport or a fighter aircraft.
- If emergency is critical, the plane will be allowed to land.
Now, the questions states that it has accidentally flown into enemy territory. You can accidentally fly into enemy territory and remain in the vicinity of the international border, i.e 2–3 kilometers.
If it is beyond that distance, then it certainly in no way is accidental. It will be shot down. You cannot expect a plane to be flying over Amritsar or Jaisalmer and claim it to be accidental.