A malfunctioning flight control computer, coupled with delayed action by the pilots due to lack of situational awareness, led to the aircraft carrying Congress president Rahul Gandhi in April this year banking right to an unsafe angle of around 65 degrees and lose altitude of 735 feet within a few seconds, an investigation by the Directorate General of Civil Aviation (DGCA) has found.
The incident occurred on April 26 this year, when Rahul was travelling from the national capital to Hubli in Karnataka to campaign for the state Assembly elections.
After the incident, a Congress leader had filed an FIR against the pilots, alleging “intentional tampering”, and demanded a probe.
According to the complaint, filed by the Congress president’s aide Kaushal Vidyarthee, who was also on board, the flight took off around 9.20 am on April 26, carrying, besides Rahul and Vidyarthee, an SPG officer.
The complaint, addressed to Karnataka Director General and Inspector General of Police Neelmani N Raju, states: “At around 10.45 am, the aircraft suddenly tilted heavily on the left side and the altitude dipped steeply, combined with violent shuddering of the aircraft body. The weather outside was sunny, normal and not windy. A clanking noise was clearly audible from one side of the plane throughout the shuddering of the aircraft body. It was also learnt that the autopilot of the aircraft was not functioning.”
The DGCA report points out that the aircraft banked right, and not left, as mentioned in Vidyarthee’s complaint. The regulator’s findings also show that unlike what is reported in the complaint, the aircraft landed safely in its first attempt. The report also said that the incident was survivable.
Vidyarthee said the aircraft landed in Hubli on the third attempt. “The plane landed at Hubli at around 11.25 am while continuously shaking and making unusual audible sounds. The whole flight experience left the passengers with a lot of anxiety and distress and positively fearing for the lives. The crew was also apparently petrified and admitted that the flight was particularly frightening and uncommon,” he said in his complaint.
The DGCA report, published on Friday, pointed at an intermittently malfunctioning flight control computer (FCC) on the 10-seater Dassault Falcon 2000 that led to an unexpected disengagement of the aircraft’s autopilot system. Once the autopilot was disengaged, the plane started banking towards the right and continued to do so till it attained an angle of 64.95 degrees, it states.
As per aviation safety experts, a civilian aircraft usually does not bank in any direction beyond 30 degrees. If it does, there is a risk of the aircraft losing its flight in the air while causing uneasiness to the passengers. However, the particular plane in question — VT-AVH, operated by charter airline Ligare Aviation — managed to reach the unsafe angle due to lack of situational awareness of the pilots.
The incident occurred when the aircraft was cruising at 41,000 feet. Once the autopilot disengaged, the pilots “got busy in isolating the autopilot” and failed to realise that the aircraft had started going into a right bank. The motion continued for 15 seconds after the autopilot disengaged leading to a dangerous bank angle, which triggered a cockpit warning notifying the pilots. By this time the aircraft had lost 125 feet of altitude. Upon the warning, the pilots took manual control of the aircraft and started correcting the bank angle. By the time they managed to stablise the plane, it had lost another 610 feet.
“This delayed actions caused the aircraft to reach high bank angle value and altitude loss which created panic and scare for the passengers in the cabin,” the report said.
During investigation, the agency covers various aspects that may have led to the incident posing danger to the aircraft. For this, the investigators studied past maintenance records of the plane. It was noted that in the three days preceding that flight, three different defects were found on the plane. However, they were rectified before the flight.
One of these defects, the probe found, pertained to the FCC of the aircraft — different from the one that caused the incident on April 26. The aircraft in question has two FCCs. “FCC#1 was found erroneous on April 23 and was replaced. The incident was caused due to a problem on FCC#2.”
“The yaw damper failure occurred due to intermittent behavior of FCC#2, this caused the auto pilot to disengage and the aircraft went into excessive right bank with altitude loss,” the investigators said, stating the probable cause of the incident, adding that situational awareness of the crew resulting in delayed action was a contributory factor.
To prevent a recurrence, the report has recommended corrective training for the cockpit crew and suggested an audit of the organisation to check the compliance of regulations.