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B738, Mangalore India, 2012

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Summary
On 14 August 2012, a Boeing 737-800 crew continued a previously stable ILS Cat 1 approach below the prescribed MDA without having acquired the prescribed visual reference. The aircraft was then damaged by a high rate of descent at the initial touchdown in the undershoot in fog. The occurrence was not reported by either the crew or the attending licensed engineer who discovered consequent damage to the aircraft. Dense fog had prevented ATC visual awareness. The Investigation attributed the undershoot to violation of minima and to both pilots looking out for visual reference leaving the flight instruments unmonitored.
Event Details
When August 2012
Actual or Potential
Event Type
Controlled Flight Into Terrain (CFIT), Human Factors, Weather
Day/Night Day
Flight Conditions On Ground - Low Visibility
Flight Details
Aircraft BOEING 737-800
Operator Air India Express
Domicile India
Type of Flight Public Transport (Passenger)
Origin Dubai International Airport
Intended Destination Mangalore International Airport
Take off Commenced Yes
Flight Airborne Yes
Flight Completed Yes
Flight Phase Landing
LDG
Location - Airport
Airport Mangalore International Airport
General
Tag(s) Event reporting non compliant
CFIT
Tag(s) Undershoot on Landing
HF
Tag(s) Inappropriate crew response - skills deficiency,
Ineffective Monitoring,
Manual Handling,
Plan Continuation Bias,
Procedural non compliance,
Spatial Disorientation,
Ineffective Monitoring - PIC as PF
RE
Tag(s) Continued Landing Roll
WX
Tag(s) Fog
Outcome
Damage or injury Yes
Aircraft damage Minor
Causal Factor Group(s)
Group(s) Aircraft Operation,
Airport Operation
Safety Recommendation(s)
Group(s) Aircraft Operation
Investigation Type
Type Independent

Description

On 14 August 2012, a Boeing 737-800 (VT-AXE) being operated by Air India Charters on a scheduled international passenger flight from Dubai to Mangalore as IX814 touched down in daylight after an ILS approach ended short of the intended landing runway 24 at the destination in low visibility due to fog. The aircraft sustained impact-related damage as a result but completion of the landing on the runway and taxi in were without further event. None of the 172 occupants were injured.

Investigation

An Investigation was carried out in accordance with ICAO Annex 13 procedures by a Committee of Inquiry constituted by the Ministry of Civil Aviation. Data from the DFDR and CVR were successfully downloaded and used to support the Investigation.

It was noted that the 57 year-old Captain was one of the Operator's 12 Check Pilots and had 7104 hours total flying experience, the majority of which had been obtained during a 32 year career as a pilot in the Indian Air Force. He had joined Air India Charters immediately on retiring from the Air Force and had qualified to operate the 737-800 as Co-Pilot in 2008, before being promoted to Captain a year later and to Check Pilot six months prior to the accident. He had 2088 hours on the incident aircraft type, of which 1467 were in command. The 28 year-old First Officer had joined the Operator after pilot training and had qualified to operate on the 737-800 almost 20 months earlier. He had 850 hours experience on the incident aircraft type. Both pilots were familiar with operations at Mangalore.

It was established that, with the aircraft commander as PF and after confirmation from ATC that the prevailing visibility, which had been below limits, was now 800 metres and the RVR was 1200 metres (the latter being the minimum permitted), an ILS Cat 1 approach to runway 24 at Mangalore was approved and commenced. Adequate fuel for diversion to two alternates, Kochi (Cochin) and Kozhikode (Calicut), was available. Landing clearance was given at 6nm with the surface wind reported as calm and no advice that the previously-communicated visibility or RVR had changed. Soon afterwards, the Captain asked the First Officer to "look out for lights" - which was considered to have distracted him from his duty as PM to continue to monitor the flight instruments and call deviations until the PF announced the acquisition of the required visual reference at or prior to DA. DFDR data confirmed that the approach had been flown normally (Vref 141 KIAS) and remained stabilised with the AP engaged until the prescribed Decision Altitude (DA) of 520 feet QNH (212 feet ARTE) was reached.

Three seconds prior to the auto callout of 'Minimums' the First Officer had called "approaching minimums". However, after DA the aircraft continued below DA without visual reference. Four seconds after the minimums auto call, the AP had been disconnected and the aircraft began to go below the ILS GS as the rate of descent increased. Immediately prior to the 100 feet agl auto callout, the CVR recorded the First Officer calling "lights in sight". Finally, soon after the 10 feet agl auto callout, "an unusual scraping sound was heard followed by a bounce to a second touchdown after which the thrust reversers were activated". The initial touchdown occurred right wing first without any prior reduction of thrust from the earlier approach setting with a rate of descent of about 950 fpm - a vertical acceleration of 3.253g was recorded. A bounce to 20 feet agl lasting 7 seconds followed before a second touchdown which registered 2.007g. The auto brake was activated at the first touchdown and the speed brakes were partially deployed. Auto brake application and full speed brake deployment followed at the second touchdown. Tyre marks in the undershoot area were found to begin 32 metres (right main gear) and 15 metres (left main gear) prior to the runway threshold.

Damage to the aircraft was found to include a hole in the underside of the left hand horizontal stabiliser and extensive superficial damage to the left side of the fuselage, both caused by debris impact, as well as damage to the main landing gear wheels and their tyres to the extent that all four wheels required replacement as part of the return to service process.

It was noted that the Aerodrome Meteorological Service at Mangalore did not issue TREND forecasts and that RVR measurement were carried out manually on request from ATC. It was noted that ATC reported having been unable to see the landed aircraft for two minutes on or exiting from the runway and that the shortest distance between the TWR cabin and the edge of runway 24 was 182 metres. It was also noted that half an hour after the investigated event, visibility was being reported at 200 metres, with this and other evidence all pointing to a deteriorating visibility trend as the aircraft neared its intended touchdown. It was concluded that "the crew was subject to visibility lower than what was expected or reported by the ATC/Met" and noted that "the visibility information was very critical in the preparation and decision to be made by the crew with respect to the landing". By the time the runway was acquired visually, it was considered that it was too late for the pilot to properly control the aircraft.

It was additionally surmised that the aircraft had (not necessarily intentionally) been "put into a pitched down attitude by the Captain in order to gain better visual reference of the runway/runway lights" and that "in concentrating on gaining visual reference at low altitude" he had, in the process, lost focus on the increasing rate of descent, the aircraft pitch attitude and descent below the glide slope. The hard landing was considered to be a direct consequence of the (unappreciated) high rate of descent, late acquisition of visual reference and lack of prior thrust reduction as the auto callouts of height reduced in 10 foot increments below 50 feet agl. There was no reported explanation of the Captain for the violation of DA but on the CVR after the incident, the Captain was recorded as saying that "less than 50 feet when they were about to flare out, there was a right cross wind and […] they lost the depth perception" and that "after the bounce they had the runway in sight and they were coming back on the runway they decided to continue….".

It was noted that although the Captain entered "suspected hard landing" in the Aircraft Technical Log after completing the flight he had not reported the occurrence to ATC over the radio or after observing aircraft damage on a post-flight external inspection. The engineer who was supposed to meet the arriving aircraft – but only arrived later – also did not inform ATC after discovering the damage and being aware of the 'hard landing' defect entry. The result was that debris on the runway threshold was not discovered until approximately two hours later during a routine inspection, upon which it was simply removed which the Investigation considered demonstrated that "the runway inspection team members are not adequately aware about investigating deviations observed from normal situations as in this case the value of material evidence like aircraft tyre marking in the undershoot area and loose stones in such incidents". It was, however, noted that no other aircraft had landed between the undershoot and the first subsequent routine inspection which discovered the debris.

It was formally determined that the Probable Cause of the investigated Serious Incident was "incorrect control inputs on short final during transition from IMC to VMC and apparent momentary loss of depth perception by the Captain due (to) prevailing foggy and low altitude cloud conditions".

Four Contributory Factors were also identified as follows:

  1. The failure to initiate a go-around on short final after autopilot disconnection while flying under marginal weather conditions and inadequate visual reference.
  2. Inadequate crew co-ordination/CRM during the final approach for the landing under marginal weather conditions.
  3. The Captain’s failure to scan/monitor and control the aircraft attitude on short finals.
  4. The fixation of both pilots on visual cues (especially after minimums/autopilot disconnection) and looking out for lights, instead of looking in and out to guard against visual illusions.

Seven Safety Recommendations were made as a result of the Investigation as follows:

  1. that Air India Charters should immediately enhance the awareness of its crew in respect of the hazards of transitioning to visual reference from Instrument Meteorological Conditions (IMC) when the visibility is deteriorating and there is a crosswind component, and reviews its crew training on landing under marginal weather and low visibility conditions.
  2. that Air India Charters should provide appropriate corrective training as deemed fit for the Captain and First Officer involved. The emphasis should be given to operations in marginal weather conditions. Practice in approaches with transition from IMC to VMC conditions in cross wind with and without the use of automated approaches should be included.
  3. that Air India Charters shall in future ensure prompt reporting of any abnormality noticed by flight crew/AME during or after a flight to all concerned authorities/ATC in the interest of safety. In the event of any possibility that any debris or FOD may have resulted from the flight or take off/landing profile of any aircraft, the flight crew must inform ATC by the fastest means so that (any risk) of damage to other aircraft operated at the airport may be prevented by a Runway Inspection by the Airport Operator under such circumstances.
  4. that Mangalore Airport re-assess the effectiveness of reporting procedures for visibility at Mangalore given the peculiar weather phenomena at Mangalore in which the topography leads to localised low cloud / low visibility.
  5. that the Competent Authority should consider whether meteorological services at Mangalore need to be revamped/rationalised. In particular, the provision of a transmissometer (as part of) the Automatic Weather Observation System (AWOS) should be considered, so that instantaneous RVR values are available when visibility drops, and the Class 3 status of the Meteorological Office at Mangalore should be upgraded so that TREND forecasts are issued around the clock.
  6. that the Airports Authority of India (AAI) should consider the installation of runway centreline lights at Mangalore in view of the table top operation, surrounding topography and frequently changing weather phenomena.
  7. that Mangalore Airport should take action to make the Airport Runway Safety Team more active and effective.

The Final Report of the Investigation was completed on 5 December 2013 but not subsequently published until 14 December 2015. Note that the copy published does not include either the Glossary or the 'Annexures' listed in the Index to the Report.

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