Harridon Suffian of Universiti Kuala Lumpur said this was one aspect that should be looked into, based on footage he had seen of the incident.

“When the control system of the helicopter suddenly freezes, the pilot would not be able to get the right or optimum trajectory, which might have led to the collision,” he told FMT, adding that the maintenance log would provide a clearer picture.

The head of the aviation search and rescue department of the university’s Institute of Aviation Technology also said a communication breakdown between the pilots of the two helicopters was also a possibility.

He said pilots involved in parallel or formation flying would need to communicate with each other “so that they know when to bank to the left or right”.

Harridon said based on the footage circulated on social media, the navy’s air team was rehearsing a basic formation. Such aerial stunts would take hours of briefing and practice on and off the ground, he said.

Practice was needed for precision flying whether in tandem or parallel to one another, he said.

“The timing has to be precise, and that includes the area of communication, angle of attack, rotation and trajectory. All of these have to be precise to avoid colliding with each other.”

Earlier today, two helicopters collided and crashed during a rehearsal for a Royal Malaysian Navy event, which has since been called off.

All 10 aboard the two helicopters were killed in the incident.

A 21-second video that has gone viral on social media shows one helicopter crashing into the tail of another mid-air, and both crashing to the ground after that.