Aviation watchdog DGCA on Friday said the crew of the IndiGo flight from the national capital to Srinagar on Wednesday had sought permission to enter Pakistan airspace to avoid turbulence but the request was rejected.
In a detailed statement about the incident, the Directorate General of Civil Aviation (DGCA) said there was no injury to any passengers who were on the flight and that the aircraft's "nose radome" was damaged.
The incident of the aircraft encountering turbulence is being probed by the DGCA.
On Wednesday, IndiGo's A321 neo aircraft operating flight 6E 2142 encountered hailstorm and severe turbulence near Pathankot.
"As per crew statement, they requested Northern control (IAF) for deviation towards left (International Border) due to weather on the route, however, it was not approved.
"Later, the crew contacted Lahore to enter into their airspace to avoid the weather but the same was refused too," DGCA said.
The DGCA statement confirms PTI report of May 22 that the Lahore ATC had rejected the flight pilot's request to use the Pakistan airspace to avoid turbulence.
According to the regulator, the crew initially attempted to return back but as they were close to the thunderstorm cloud, they decided to penetrate the weather.
"Subsequently, they encountered hailstorm and severe turbulence. Crew chose to continue at the same heading to exit the weather by the shortest route towards Srinagar," the statement said.
While in a thunderstorm cloud, the regulator said warnings of Angle of Attack fault, Alternate Law protection lost, backup Speed scale unreliable were triggered.
"Due to updraft and downdraft encountered by the aircraft the Autopilot tripped and aircraft speed had wide variations. As a result, Maximum Operating Speed/Maximum operating Mach (VMO/MMO) warnings and repeated stall warnings were triggered," the statement said.
During this period, DGCA said the aircraft rate of descent reached 8,500 fpm (feet per minute) and crew flew the aircraft manually till they exited the hailstorm.
"After carrying out all checklist actions (ECAM actions), the crew declared 'PAN PAN' to Srinagar ATC and requested for RADAR vectors and made a safe landing with Auto Thrust operating normally," the statement said.
Generally, 'PAN PAN' refers to an emergency situation.
The regulator said the matter is under investigation and that there was no injury to any of the passengers on-board the flight.
"Post flight walk around revealed damage to the Nose radome," the statement said.
On Thursday, IndiGo, in a statement, said the aircraft was undergoing necessary inspection and maintenance in Srinagar and will resume operations once all clearances have been secured.