FINAL INVESTIGATION REPORT ON SERIOUS INCIDENT TO AIRINDIA CHARTERS LTD AIRCRAFT , B737-800NG, VT-AXJ NEAR POSITION PARAR IN VABF 26.05.2010
CONCLUSIONS:
3.1 Findings:
3.1.1 The aircraft had valid Certificate of Airworthiness and was maintained as per the approved maintenance program. The aircraft had all the mandatory modification complied with.
3.1.2 The flight crew had valid licenses and medical.
3.1.3 The correlation with the CVR examination reveal that at approximately 17.52 UTC, the PIC excused himself to go to washroom with speed window open at 0.76 Mach.
3.1.4 At subframe 4764(17:53:22 Z) the nose down command was recorded with control column force sensor sensing approx 20 lbs from the copilot side. This was due to the copilot adjusting his seat forward and inadvertently pressing the Control Column forward. On this input the autopilot went in to CWS PITCH mode, and within another 5 seconds it had gone into CWS ROLL mode. It is indicative of the fact that the copilot also gave input on ailerons and caused the aircraft to bank.
3.1.5 The altitude alert chime sounded as the aircraft had significantly departed the selected altitude of FL 370 at same time approx (17:53:35 Z) and trying to come back to selected FL by autopilot going in ALT Acquire mode. This chime caused panic in copilot and he applied the push force approx 50 lbs as recorded by sensor in control column.
3.1.6 At subframe 4785( 17:53:50Z) at this time the copilot made an attempt to pull the aircraft up however it continued to loss altitude hence he again put the control column forward and aircraft went in further dive.
3.1.7 The PIC had arrived in the cockpit hence the differential input on the control column could be observed. But the PIC applied a approx 125lbs of pull force and got the aircraft in level flight but disconnected the autopilot at subframe 4820(17:54:19Z), after 20 second at 17:54:39 Z engaged Autopilot A and disconnected at 17:54:51 Z, started climbing and turned right on heading 120 to come back on track.
3.1.8 The PIC reached in cockpit when altitude loss was of only 2000 ft and it could be correlated with CVR/DFDR. Subsequently there was application of opposite force by pilot and copilot on control column as the PIC did not takeover as per standard procedure. During this time the aircraft lost 5000 ft and reached FL300.
3.1.9 The PIC did not gradually apply the force to level the aircraft but yanked the control column with approx 125 lb pull force in 2 second and leveled the aircraft in autopilot engaged mode.
3.1.10 The aircraft had reached the maximum operating Mach no of 0.89 at subframe 4831 hence the clacker warning was audible in the CVR. Hence the copilot reduced the thrust to arrest the speed which had gone in red band.
3.1.11 The PIC did not follow the RVSM contingency procedure after the aircraft had dived to the FL 300 in approx 50 seconds and leveled off.
3.1.12 The copilot has not put the seat harness and probably had no clue to tackle this kind of emergency. The jet upset exercise is carried out during simulator check in manual mode and not done with autopilot engaged.
3.1.13 The copilot is not involved in any incident as per the records.
3.1.14 There was complete commotion in the cabin however no passenger got injured as all were seated post dinner service.
3.1.15 The cabin crew had carried all the necessary drill cleaning all the cabin and securing it in case of any emergency evacuation if required.
3.1.16 The Cabin Crew In-Charge permitted R2 flight purser to go in cockpit to brief PIC about the cabin and passengers.
3.1.17 The flight was event free subsequent to incident and aircraft landed safely. All relevant inspection carried out as the aircraft had experienced + 2.1g and – 0.2g respectively.
3.2 Probable cause of the serious incident:
The incident occurred due to inadvertent handling of the control column in fully automated mode by the copilot which got compounded as he was not trained to recover the aircraft in automated mode.
Subsequent recovery actions by the PIC without coordination with copilot was the contributory factor.
4. SAFETY RECOMMENDATIONS:
4.1 The appropriate action shall be taken against the involved crew.
4.2 In view of the incident, AICL should review the training curriculum including the simulator training of the pilots to include such in-flight emergencies.
Final Report By DGCA
Click Here for Full Report of Incident
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