Air India Express B738 at Mangalore on Aug 14th 2012, touched down short of runway, hard landing

Last Update: December 14, 2015 / 15:37:17 GMT/Zulu time

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Incident Facts

Date of incident
Aug 14, 2012

Classification
Report

Cause
Hard landing

Airline
Air India Express

Flight number
IX-814

Departure
Dubai, United Arab Emirates

Destination
Mangalore, India

Aircraft Registration
VT-AXE

Aircraft Type
Boeing 737-800

ICAO Type Designator
B738

Airport
Mangalore International Airport, Mangalore

Airport ICAO Code
VOML

An Air India Express Boeing 737-800, registration VT-AXE performing flight IX-814 from Dubai (United Arab Emirates) to Mangalore (India) with 166 passengers and 6 crew, was on approach to Mangalore with the captain (57, ATPL, 7,104 hours total, 2,088 hours on type, check pilot) being pilot flying and the first officer (28, CPL, 1,067 hours total, 850 hours on type) being pilot monitoring. While descending towards 2200 feet to intercept the ILS for runway 24 the crew was advised of visibility of 800 meters and 1200 meters RVR on runway 24, which the crew reported to be above their minima, the crew continued the approach, Vref was computed at 141 KIAS with flaps 40, Vapp at 146 KIAS. After intercepting the localizer the flight was cleared to land on runway 24. At 245 feet AGL the captain disconnected the autopilot, the pitch changed to 0.5 degrees nose down and the vertical rate of descent increased from about 720 fpm to 1056 fpm with the engine thrust remaining stable. The aircraft touched down with a right bank angle of 5.6 degrees about 105 feet before the runway threshold, entered a left bank of 8.5 degrees with the left main wheel touching down 49 feet before the runway threshold experiencing a vertical acceleration of +3.253G, the aircraft bounced back to 20 feet AGL, the engine thrust was increased and the nose pulled up to 6.2 degrees nose up, the speed brakes deployed just prior to second touch down, and the aircraft touched down a second time about 1900 feet past the runway threshold at 142 KIAS and a vertical acceleration of +2.007G. Maximum reverse thrust was applied, the aircraft quickly decelerated on the runway and taxied to the apron maintaining routine communication.

India's Directorate General of Civil Aviation (DGCA) released their final report concluding the probable causes of the incident were:

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:

- Not initiating go-around on short finals after autopilot disconnection while flying under marginal weather conditions and inadequate visual reference.

- Inadequate crew co-ordination/CRM during the final approach for the landing under marginal weather conditions.

- Captain’s failure to scan/monitor and control the aircraft attitude on short finals.

- Both Pilots fixated on visual cues (especially after minimums/autopilot disconnection) on looking out lights instead of looking in and out, to guard against visual illusions.

The DGCA reported that after arriving on stand at Mangalore both flight crew performed a post flight inspection and discovered damage to aircraft and wheels. The captain wrote up in the tech log "suspected hard landing".

An aircraft mechanics subsequently arrived to receive a briefing on the hard landing, a more detailed inspection of the aircraft revealed the left hand horizontal stabilizer inboard side had received a puncture at the least edge of about 1 inch by 0.75 inches size. Multiple scratches along the left hand fuselage, the #1 outboard left tyre had received several deep cuts and scratches and some areas were chipped off, the #2 inboard left main tyre sustained minor cuts, the #3 and #4 tyres had mutliple cuts on the side walls.

A runway inspection found stones and loose soil in the area of the runway 24 threshold and subsequently found marks suspected to be aircraft tyre marks prior to the runway threshold.

Following replacement of all four wheels and structural repair of the left hand stabilizer the aircraft returned to service on Aug 16th 2012.

The DGCA analysed that the aircraft and its system did not contribute to the incident.

The DGCA however analysed:

The aircraft was pitched down by the Captain after disconnecting the autopilot at time 00:57:42 UTC. After the pitch down there has been a steady increase in Rate of Descent from 720 ft/min to 1056 ft/min at time 00:57:49 UTC. The auto minimums callout was at time 00:57:38 UTC. ‘Light visible’ call out was at time 00:57:46 UTC. Approach was carried out below Decision Altitude without sufficient visual reference. At approx 130' AFE the runway threshold lights were visible as per CVR recording, the time period between the 100', 50' callout and first touchdown was in the region of 9 seconds, the short time period reflecting the high rate of descent.

At 00:57:51 UTC aircraft altitude was 87 ft AFE, Speed 148 Kts, CDI Glide Slope bar indicated two dots fly up indication(-0.17 DDM). The winds were light and variable. Aircraft touchdown with high rate of descent of -744 ft/min and a right bank of 4.6 deg. Due to over correction by left bank (-5.8 deg) and momentum of the landing aircraft, the left wheel also touched the ground heavily. FDR shows delay in flare maneuver and during touchdown the N1 was 65.5% and high vertical g of 3.253 was recorded. The aircraft had bounced. After the bounce the second touchdown was on the right wheel with high vertical g of 2.007. The aircraft bounce is due to no thrust change, delay in flare and high rate of descent at touchdown.

The speed brake was partially deployed on first touchdown but not fully extended. This could have produced some extra drag during second touchdown, after which the spoilers were fully deployed. CVR analysis revealed that in the critical phase of the landing both crew were occupied in trying to locate the runway lights and not adhering to the airlines SOP. Also from the CVR analysis it revealed that they made no attempt to execute goaround which led to undershoot the runway. It was observed that after the first touchdown aircraft had a long bounce of 7 seconds and attained 20' radio altitude, during this period aircraft was unstable Captain tried to land the aircraft instead of executing a safe go-around as per SOP.

With respect to weather the DGCA analysed:
Due to fog at airport, the tower controller did not have visual contact of the landing aircraft which was cleared for an ILS approach RWY-24. Aircraft was advised to report runway lights in sight. The visibility for the period then was reported to be 800 meters while none of the tower officials were able to sight the aircraft’s landing profile and its exit from Runway 24 after landing presumably due to low visibility. This underscores the fact that visibility at the time of incident may not have been same that was reported at 00:30 UTC MET REPORT and manual RVR reported by the Met official at 00:37 UTC. Sudden changes in RVR can occur due to the natural variability in the density of fog.

The aircraft landed at 00:58 UTC. The visibility and RVR reported at 01:00 UTC was 800 meters and at 01:30 UTC was 100 meters. This shows a decreasing trend in the visibility. The sudden reduction in visibility around the time of incident which could not be clearly seen through the tinted glass at new ATC tower placed a constraint upon the Met officer in informing the revised weather information to the pilot who, with the updated visibility, could have possibly gone around without carrying out the approach, thereby avoiding the whole incident.

The weather information provided to the crew was as given by the approach plate (RVR 1200 meters). This information was given with a manual assessment of the visibility. The weather minima prescribed by Airlines(AICL) for ILS approach to Runway 24 at Mangalore Airport, for their B373-800NG aircraft was RVR:1200 meters and Decision Altitude(Height): 520'(212'). It was observed from the weather report that the visibility was in a deteriorating trend. It is likely that the crew was subject to visibility lower than what was expected or reported by the ATC/Met. The visibility information was very critical in the preparation and decision to be made by the crew with respect to the landing. It is also evident from the CVR that the approaching minimum call out was given by P2 at 282 ft AFE at approx.0.8 DME. Subsequently, ‘lights in sight’ call out was given at 174 ft AFE. At this time aircraft was below the glide slope with increasing ROD and Pilot could not control the aircraft prior to touch down.

The DGCA further analysed: "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."

The DGCA analysed: "The WMM mixture provided for smooth flushing purpose prior to beginning of Runway 24 threshold has got stones that are embedded upon the mixture. Due to natural factors, this surface is very vulnerable for easy wear and tear leading to loosening of stones which has the potential to turn into a FOD (Foreign Object Damage) when the surface is hit upon, even accidently by any aircraft. ... The initial touchdown of the aircraft in the undershoot area led to dislodging of the stones from the WMM mixture laid on the area before the beginning of the RWY.24. The cause of aircraft’s wheel damages, puncture in LH stabilizer and scratches found in fuselage and wing skins are the result of flying loose stones from WMM mixture."

Metars:
VOML 140200Z 12003KT 1000 BR SCT003 SCT012 BKN080 24/23 Q1009=
VOML 140130Z 10003KT 0100 FG SCT003 SCT012 BKN080 24/23 Q1009=
VOML 140100Z 00000KT 0800 FG SCT003 SCT012 BKN080 24/23 Q1008=
RVR (RUNWAY 24) 1200M REPORTED AT 0037 UTC
VOML 140030Z 11003KT 0800 FG SCT003 SCT012 BKN080 24/23 Q1008=
VOML 140000Z 09003KT 0200 FG SCT003 SCT012 24/23 Q1008=