14 Dec 2015 - VT-AXE 737-800 Heavy landing
The Indian Directorate General of Civil Aviation (DGCA) have released their final report into the heavy landing incident to 737-800, VT-AXE, 29368/1910, operated by Air India Express at Mangalore on Aug 14th 2012.
The Captain, an ex-Indian AF fighter pilot with 7,104 hrs TT, 2,088 hrs on type, was PF for a Flap 40, ILS 24 with a reported met visibility of 800 meters and RVR 1200m.
VOML 140100Z 00000KT 0800 FG SCT003 SCT012 BKN080 24/23 Q1008
The approach was stabilised and normal unitl 245ft AFE when the captain disconnected the autopilot. The pitch was then reduced to 0.5 degrees nose down and the rate of descent increased to 1056 fpm. The aircraft remained at a nose down attitude until flare initiation by the Captain. The GPWS sounded once at 39ft RA.
The aircraft touched down right wheel first at +3.253G impacting the undershoot area at approx 105 feet before the runway threshold. The aircraft bounced to 20ft RA and was airborne for a period of 7 seconds. During the bounce the N1 was slightly increased to 76.3/68.3% from 65.5/65.6% and the pitch attitude was increased to 6.2 deg. and a right bank of 7.4 deg with speed brakes fully deployed. The second touch down had a vertical acceleration of 2.007g, approx.1900 ft from threshold and maximum reverse thrust was commanded followed by maximum manual braking, the subsequent aircraft landing roll was uneventful.
*** Updated 17 Jan 2017 ***
The following excerpts from the report are significant:
The damage to the aircraft was LH horizontal stabilizer lower inboard side leading edge was punctured with hole size approx. 1" X 0.75". Multiple scratches/scribes were found on LH side fuselage aft of LH wing for approx 0.5" to 1" length. #1 main wheel tyre was found damaged with several deep cuts and scratches and some areas were found chipped off. #2 tyre with minor scratches and #3 & #4 main wheel tyres found with multiple cuts on side wall areas around 3" to 4". After carrying out detailed inspection, rectification, structural repair on horizontal stabilizer and all 4 wheels replacement as per Boeing recommendations the aircraft was released for further flight on 16.08.2012.
2.2.6 Procedures: The inadequacy of approach preparation is evident with the work load distribution with respect to monitoring of flight instrument during the visual segment of approach was not adequately covered during approach briefing. Had the Co-Pilot monitored the instruments and called out rate of descent, pitch attitude and glide slope deviation promptly the PIC could have taken a decision of go-around immediately. Due to lack of the above the decision taken by the P1 to continue may be one of the contributory factors to the event. CVR readout does not reveal any advisory comment by the Co-Pilot towards the decision to land by the P1 and it appears that the Co- Pilot was also focused on trying to identify the approach lights.
2.2.7 Sharing of workload in the flight deck : Normally low visibilities due fog compromise the quality and reliability of the visual cues on which the pilot-flying relies for vertical guidance; therefore, only the timely and proper integration of flight instrument data into the flight can detect (or) prevent undesired excursions from the correct flight path. The CVR and FDR analysis shows evidence of both crew carrying out the same task of looking out for the runway approach lights. There was no evidence about the monitoring the instruments of the aircraft during this phase hence no corrective action by P1 or go around call was given by P2. The increased ROD during the last few seconds of the approach is indicative of the flight crew attempting to get a visual reference on the runway and during this period both crew did not realize the aircraft pitch attitude,ROD & glide slope deviation. This may be a situation of not adequately sharing the workload and not adhering to the SOP.
2.2.10 Non reporting to ATC: The flight crew did not report the hard landing incident to the ATC, Mangalore even after switched off the aircraft and seeing the damage to aircraft and its wheels during post flight inspection. The Captain could have reported the hard landing incident on R/T so that ATC could be warned of possible debris on the runway threshold. The arrival AME who carried out late post flight inspection also did not report the damages due hard landing to ATC, Mangalore.
13. Flight Crew failed to monitor the instrument references, after the transition to visual references and thereafter (i.e. during the visual segment of an instrument approach).
14. First officer (PNF) was distracted from his duties to monitor flight instrument due Captain’s instruction to look out for runway lights.
15. The aircraft has been put into a pitched down attitude by the captain in order to gain better visual reference of the runway/runway lights.
16. Captain seems to be concentrating on gaining visual reference at low altitude and in the process loosing focus on high rate of descent, aircraft pitch attitude and flying below glide slope.
17. The FDR/CVR shows that Radio callouts in feet (50, 40, 30, 20) are heard but no actions were observed for landing i.e. flare or thrust reduction.
18. Incorrect landing procedures followed by Commander resulting into an improper landing.
19. The Captain did not receive the appropriate assistance he could expect from First Officer during un-stabilized approach after auto pilot disconnection.
20. The flight crew failed to respond in a proper and timely manner to excessive and deteriorating glide slope deviations and rate of descent by either initiating a go-around or adjusting pitch attitude and thrust to ensure a safe landing procedure.
21. The aircraft first touched down on the right wheel 105 feet short of threshold of the landing runway 24 threshold followed by left wheel touching abruptly on the wet mix macadam part at 49 ft short of runway threshold. While initial touchdown the rate of descent of 1056 ft/min and an N1 of 65.5% with a recorded vertical acceleration of 3.253g(against the limit value of 2.1g) before bouncing and touching down again with 2.007g on runway.
22. The hard landing of the aircraft (3.253g) can be attributed to an abnormal high rate of descent of 1056 feet/min, followed by late initiation of the flare by the Captain at the time of first touchdown.
23. Aircraft wheel touched the undershoot area of runway
24, the loose stones and debris from wet mix macadam part were blown off the ground that appeared to have hit the aircraft’s wheels & surfaces. 24. A bounce of about 20 feet resulted due to heavy touchdown/ROD.
25. The Captain had gained visual reference with the runway after the aircraft bounce and an additional thrust was applied to recover from the bounce. The aircraft touched down again on the right wheel and this time the touchdown was on the runway.
26. In the post flight inspection the flight crew observed damage to aircraft and its wheels but made no attempt to inform the ATC in the interest of safety for other aircraft operated at Airport.
27. The flight crew reported only ‘suspected hard landing’ in aircraft tech log. The aircraft damages were not recorded after post flight inspection.
28. The Flight Crew did not comply with operator SOPs.
3.2 Probable cause of the Serious Incident:
The Committee of Inquiry determines that the probable cause of the incident was due to incorrect control inputs on short finals during transition from IMC to VMC and apparent loss of momentary depth perception by the Captain due prevailing foggy and low altitude cloud conditions.
Contributing to the incident were:
The full report is available for download here