Without Warning

Equestrian Airlines flight 690 is a schedule Inter-dimensional flight from Canterlot, Equestria to Bali, Indonesia, and Palomino Air Charter flight 6X7 is a charter flight from Long Island, Manehattan, Equestria to Crystal Empire, Equestria. The flight is cruising above the seaside, north of Manehattan, then on 3:08 P.M the aircraft disappears from the radar, and the plane caught at the mid-air crash in the eye of the employee from the cargo ships. All 221 passengers and crew are confirmed dead from both plane

Aircraft
the aircraft is a 7th years old Boeing 777 that already flown around 119,000 flight hour (Equestrian Airlines flight 690) and the 20 years old Dornier 238 that already flown around 12,000 flight hour (Palomino Air Charter flight 6X7)

Equestrian Airlines flight 690
Equestrian Airlines flight 690 are taxiing to the runway with 178 Passenger and 10 Flight crew onboard. After 25 Minutes the Air Traffic Controller (ATC) see something weird, For whatever reason, flight 690 descending too fast. The ATC contact flight 690, but it went unanswered until minutes later the flight is missing on the radar. Flight 690 is crash on the sea, north of Manehattan. the cabin and the cockpit are detached mid-flight. A cargo ship saw the accident helping to search the survivor but, There is no point, all 188 passengers and crew are dead

Palomino Air Charter 6X7
Palomino Air Charter flight 6X7 is inbound to Mi Amore Cadenza International Airport. The aircraft was breakup mid-flight. The wreckage is 200 meters from the Equestrian Airlines flight 690 wreckage. all 33 passengers and crew are dead

Cause
Equestria Transportation Safety had three theory the caused of the crash

The Radio Dead Zone
The Palomino Air Charter flight 6X7 is not equipped with the long-range radar. After the Palomino Air Charter flight 6X7 takeoff, they cleared to climb and maintain 36,000 ft. After that, the Dornier crew had to use a Visual Flight Rules called "Seen and Been Seen". The Radio Dead Zone is disabling a critical system on the other plane including TCAS (Traffic Collision Avoidance System). And that's the first probable cause

ATC Failed To Warn West Equestria Central ATC About The Incoming Flight
The ATC on Long Island Airfield didn't tell the Central Air Traffic Control for incoming Palomino Air Charter 6X7 on 36,000 ft. That leading it to the crash

Visibility
Both Aircraft crash inside the cloud where the visibility is 2 km, it is determined that the PAC 6X7 crews aren't noticed until it was hitting Equestrian Airlines flight 690 fuselage

Aftermath
After the accident, the Dornier 328's fleet is now equipped with long-range radar and the ATC on Long Island Airfield is sentenced to jail for 1 year