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28 Jun 2019 - The Indian DGCA have issued their final report into the runway excursion on landing of 737-800, VT-AXT, (36331/2324), at Mumbai on 10 July 2018.

The aircraft landed on Runway 14 at Mumbai in rain with Capt as PF and autobrake MAX.

VABB 100930Z 27010KT 1500 -RA SCT012 SCT018 FEW030CB OVC080 26/25 Q1003 TEMPO 1500 RA=

The flare started at threshold and continued for 14 seconds, the aircraft was slightly high on power and there was a tail wind component of approximately 8 kts. The aircraft touched down approximately 962 meters from the threshold.

The runway was contaminated with water patches due to rain. 3 seconds after touchdown Engine #2 thrust reverser was deployed but the Engine #1 thrust reverser remained in transit and did not deploy.

The F/O immediately called out about failure of thrust reverser and not to use full reverser & use maximum Manual braking. Realizing that there could be controllability issue, PIC put the Engine #2 thrust reverser to IDLE by lowering engine power.

Simultaneously recognizing that the braking action was not sufficient and the aircraft was not decelerating enough as expected, the crew decided to apply manual braking. PIC also asked First Officer to assist him in applying maximum manual brakes. Aircraft crossed the end of Runway 14 in the landing roll by approximately 5 meters before coming to a halt on the paved surface.

The incident was caused due to prolonged flare wherein nearly 40% of the available landing distance was consumed followed by failure of Engine #1 thrust reverser due to defective thrust reverser middle & lower actuator. Dynamic aquaplaning and prevalent weather conditions were contributory factors to the incident.

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SYNOPSIS:

On 10st July 2018, M/s Air India Express Ltd Boeing 737-800 aircraft VT-AXT was involved in runway excursion incident during landing while operating flight IX - 213 (VOBZ-VABB).

Aircraft chocked off at 07:33 hrs from Vijayawada. The flight was uneventful till 50 ft of approach at Mumbai where the aircraft was slightly high on threshold. Runway in use at CSIA, Mumbai was Runway 14. Moderate rain was forecasted in the Meteorological report. Wind was reported as 270 degrees 12 knots and visibility was reported as 2200 meters at Mumbai. Considering the runway length available and the prevailing weather conditions the auto brakes were selected on maximum braking. Landing distance calculations were made well in time. The aircraft profile in approach was normal. The flare started at threshold and continued for 14 seconds as the aircraft was slightly high on power and there was a tail wind component of approximately 08 knots. Aircraft touched down approximately 962 meters from runway 14 threshold at 09:20 hrs. The runway was contaminated with water patches due prevailing moderate rain. After 03 seconds of touchdown, Engine # 2 thrust reversers were deployed but the Engine # 1 thrust reversers remained in transit since touchdown and did not deploy. First Officer immediately called out about failure of thrust reverser and not to use full reverser & use maximum Manual braking. Realizing that there could be controllability issue, PIC put the Engine # 2 thrust reversers to IDLE by lowering engine power. Power of both the engines was immediately reduced. Simultaneously recognizing that the braking action was not sufficient and the aircraft was not decelerating enough as expected, crew decided to apply manual braking. Auto brakes were disconnected and crew applied manual brakes. PIC also asked First Officer to assist him in applying maximum manual brakes to decelerate the aircraft. The rudder was utilized to effectively maintain the directional control of the aircraft. Aircraft crossed the end of Runway 14 in the landing roll by approximately 5 meters before coming to a halt on the paved surface. Later, aircraft vacated Runway via Taxiway E1 on its own power under guidance of Follow Me vehicle and parked on stand V29 at 09:40 hrs (chocks on). No human injury was reported in the incident.

Director General of Civil Aviation ordered the investigation of the incident by appointing Inquiry Officer vide order no. DGCA-15018(03)/2/2018-DAS dated 13th July 2018 under Rule 13(1) of The Aircraft (Investigation of Accidents and Incidents) Rules 2017. The incident was caused due to prolonged flare wherein nearly 40% of the available landing distance was consumed followed by failure of Engine # 1 thrust reverser due to defective thrust reverser middle & lower actuator. Dynamic aquaplaning and prevalent weather conditions were contributory factors to the incident.

1. FACTUAL INFORMATION:

1.1 History of Flight:

M/s Air India Express Ltd Boeing 737-800 NG aircraft VT-AXT, was scheduled to operate flight no. IX-213 (sector Vijayawada - Mumbai) on 10th July 2018 at 05:00 hrs with 89 persons on-board including 02 cockpit crew, 04 cabin crew and 01 AME. The aircraft was under the command of PIC (ATPL holder). PIC was the pilot flying and First Officer was pilot monitoring.

Both crew had reported for Flight duty at 02:10 hrs for the first sector of a two sector flight on quick turn around basis. The first sector was IX- 214 (sector Mumbai - Vijayawada). Schedule departure for the first sector flight IX- 214 was at 02:30 hrs however the aircraft departed at 04:26 hrs with MEL 25-10 NEF (Tray table cracked) and MEL 26-02-02 (Engine# 2 loop ‘A’ unserviceable- Engine overheat and fire protection system) active. IX- 214 landed at Vijayawada at 06:51 hrs and choked on at 06:56 hrs. IX- 214 was the first flight of the day for VT-AXT. The flight IX- 214 was uneventful and no defects were reported in this sector. After completion of transit inspection, the aircraft chocked off at 07:33 hrs for the next sector IX- 213 (Vijayawada- Mumbai) without any relevant snag/ MEL and got airborne at 07:47 hrs. The Before Start checklist, Before Taxi checklist, takeoff and climb operations, procedures, checklists and callouts were normal. The cruise phase was also normal. At about 08:30 hrs the PIC read the destination ATIS report: ‘Runway surface – WET, Braking action – medium, 250/10 knots, Visibility – 2200 m, Feeble rain, Clouds SCT- 1000, SCT – 1500, Few CB 3000, OC – 8000, 27/25 degree C, QNH 1003 Hpa, Tempo Visibility 1500 in Moderate rain.’ The NOTAM # A1449/18 was issued for CSIA, Mumbai on 10/07/2018 notifying that ‘Runway 09/27 will not be available for operations from time 14:00 hrs IST up to 15:00 hrs IST of date due Maintenance. However, Runway 14/32 is available for operation.’ However, the crew were not aware about the same as it was not included in their flight folder and hence the briefing and landing distance calculations were worked out for landing on Runway 27 as per latest ATIS information. The Descent checklist was completed and the descent commenced at about 08:39 hrs. At 08:45 hrs during changeover to Mumbai Control, ATC broadcasted that all arrivals earlier cleared for Runway 27 to now expect Runway 14 due runway change which was as per NOTAM. The FMS and navigation were reconfigured for ILS approach Runway 14 and briefing was carried out. The required landing distance with flaps 30 configuration, Auto brakes MAX, medium braking action, approximately 04 knots tail wind (250/10 knots) and reported temperature conditions added with 1000 ft factor of safety was calculated to be 7456 ft, which was within the landing distance available for Runway 14, i.e. 8106 ft.

Subsequently, upon getting clearance for the ILS approach, the aircraft was established on ILS and reported at 7.3 miles ILS DME at 09:17 hrs. It was raining on the Approach and Mumbai Tower reported the Surface wind as 270 degree, at 12 knots, Runway surface WET. At 09:18 hrs Flaps 30 was selected and the Landing checklist was completed. At 1000 ft Radio altitude the Stabilized callout was made with Approach lights in Sight. Subsequently, Runway edge lights & Runway was also visible. At 453 ft RA the auto pilot was disconnected. The aircraft was stabilized on ILS up to 50 ft RA. The aircraft was at around 50ft RA at threshold. The flare started at threshold by increasing the pitch of the aircraft. The aircraft was slightly high on power with varying winds having tail wind component. After 14 seconds of flare, aircraft made firm touchdown at 09:20:30 hrs with a vertical acceleration of 1.15 g in tail wind of around 8 knots. The aircraft touch down at approximately 962 meters from runway 14 threshold at 09:20 hrs. Auto brakes MAX being active, Speed brake lever was immediately deployed on touchdown. The runway was contaminated with water patches due prevailing moderate rain. After 03 seconds of touchdown, Engine # 2 thrust reversers were deployed but the Engine # 1 thrust reversers remained in transit since touchdown and did not deploy. There was an Amber Reverser indication in upper display unit. First Officer immediately called out about failure of thrust reverser and not to use full reverser & to use maximum Manual braking. PIC put the Engine # 2 thrust reversers to IDLE by lowering engine power upon being realized that there could be controllability issue. Power of both the engines was immediately reduced. Simultaneously recognizing that the braking action was not sufficient and the aircraft was not decelerating enough as expected, crew decided to apply manual braking. Auto brakes were disconnected and crew applied manual brakes. PIC asked assistance of First Officer for applying maximum manual brakes to decelerate the aircraft. Aircraft crossed the last available exit taxiway E1 of Runway 14 and overrun Runway 14 end by approximately 5 meters. The aircraft halted at 12.55 meters right of the center line on the paved surface at 09:21 hrs. The rudder was utilized to effectively maintain the directional control of the aircraft. Succeeding arrival flight was instructed to carry out missed approach by tower. After the aircraft came to halt, the First Officer informed Mumbai Tower that the aircraft was on hard surface slightly ahead of the Threshold, due Technical. As crew expressed their inability to turn and exit the Runway, the controller instructed crew to hold position until a Follow Me vehicle was sent. Later, at 09:23 hrs Follow Me vehicle and Fire Tenders # 1, 4, 5 & 6 were reported at aircraft. The aircraft followed instructions from Tower and Follow Me vehicle and taxied via taxi way E1 on its own power. Approximately at short of taxiway N1 the Follow Me was discontinued. The aircraft arrived and parked at Stand V-29 at 09:40 hrs. The Shut down and Secure procedures and checklists were completed.

Aircraft’s take-off weight was 61,421 Kg and landing weight was approximately 57,600 Kg, which was within limits.

1.11 Flight Recorders:

The report on CVR readout is as follows: The CVR readout commenced at 07:37 hrs with the VGA ATIS broadcast. The Before Start checklist was carried out and the takeoff data card was prepared for VGA Runway 26. Both engines were started normally, ground equipment disconnected and the aircraft taxied out for departure after performing the Before Taxi checklist. The takeoff and climb operations, procedures, checklists and callouts were normal. The cruise phase was also normal. At about 08:30 hrs the PIC read the destination ATIS report: ‘Runway surface – WET, Braking action – medium, 250/10 knots, Visibility – 2200 m, Feeble rain, Clouds SCT- 1000, SCT – 1500, Few CB 3000, OC – 8000, 27/25 degree C, QNH 1003 Hpa, Tempo Visibility 1500 in Moderate rain.’ Thereafter, the Landing distance was worked out preparing for a Flaps 30 landing. The Descent preparation and Approach briefing was adequately covered through the ILS 27 chart details, Approach profile & Minimas. Descent checklist was completed and the descent commenced at about 08:39 hrs. At 08:45 hrs during changeover to Mumbai Control, ATC broadcast to all arrivals earlier cleared for Runway 27 to now expect Runway 14 due runway change. The subject flight was cleared to descend to flight level 170. The FMS and navigation was reconfigured for ILS approach Runway 14. Briefing was carried out from ILS 14 chart. Subsequently, the flight was cleared to intercept the localizer on a heading of 180 degrees and cleared for the ILS approach. The aircraft was established on ILS and reported 7.3 miles ILS DME and contacted Mumbai Tower at 09:17 hrs. Mumbai Tower reported the Surface wind as 270 degree, at 12 knots, Runway surface WET. The landing configuration with Flaps 30 was selected and the Landing checklist was completed after the Landing clearance was obtained. At 1000 ft Radio altitude the Stabilized callout was made with Approach lights in Sight. The presence of rain was assessed by 500 RA callout. The Autopilot was disengaged and the aircraft landed with a firm touchdown, going by the sound profile, and the Speed brake lever deployed on touchdown.

The First Officer called out the failure of the Thrust Reverser 3 seconds after the touchdown and called out for no full reverser & maximum manual braking. PIC asked FO for assistance in manual braking. After the aircraft came to halt, the First Officer informed Mumbai Tower that the aircraft was on paved surface slightly ahead of the Threshold, due Technical. When initially the crew advised Mumbai Ground that they were unable to turn and exit the Runway, the controller instructed crew to hold position until a Follow Me vehicle was sent. Eventually, when the Follow Me vehicle arrived the aircraft following instructions from Tower and Follow Me vehicle was turned to the left and taxied via taxi way E1. On changeover to Mumbai Ground 121.75 taxi instructions were followed to initially Hold Short N1 where the Follow Me was discontinued. The aircraft arrived and parked at Stand V29 at 09:40 hrs. The Shut down and Secure procedures and checklists were completed and the CVR Circuit Breaker was pulled at 09:42 hrs.

FDR Data

The graph of Pitch variation Vs Power Vs RA Vs DME Vs Time (see below) depicts that the aircraft was at around 50ft RA at threshold which was considered slightly higher than normal. As per FCTM, in normal approach the aircraft is about 30ft RA on threshold. The flare started at threshold by increasing the pitch of the aircraft. The maximum pitch recorded during flare was 4.04º, which was normal. The power from Engine # 1 & 2 was observed to be 58.2% N1 and 59.5% N1 respectively at threshold which was lowered down to IDLE,32% N1 and 32.75% N1 respectively, at 09:20:25 hrs. Subsequent to lowering the power, aircraft made firm touchdown at 09:20:30 hrs. The power was considered to be slightly higher during flare. Aircraft touched down after 14 seconds of flare at 962.6 m/ 3158 ft from the threshold. The power of Engine # 1 & 2 was immediately reduced after deployment of right thrust reverser.

Graph of Pitch variation Vs Power Vs RA Vs DME Vs Time

The graph of Auto brakes Vs 1 & 2 TR Vs DME Vs speed brakes Vs Rudder input Vs Time depicts that Auto brakes were active & speed brakes were deployed immediately after the touchdown. Right (#2) thrust reverser was deployed after three seconds of touchdown and Left (#1) thrust reverser did not deploy. Auto brakes were active for six seconds after touchdown and disconnected at 09:20:37 hrs. The rudder was utilized to effectively maintain directional control of the aircraft.

2.2 Operational aspects:

Both the crew members were medically fit, had valid license, had adequate rest and found to be within FDTL limits before they operated flight on 10/07/2018. Medical fitness & FDTL of the crew was not a factor to this incident. IX-213 was scheduled to depart at 05:00 hrs but departed at 07:33 hrs after quick turn around. Delay of 02:33 hrs was not a factor to this incident as the delay was due to delay in arrival from the originating sector. The Before Start checklist, Before Taxi checklist, takeoff and climb operations, procedures, checklists and callouts were normal. The cruise phase was normal. Top of descent checklist was also followed and landing distance calculations were worked out considering Runway 27 active. Later after getting information on runway change, it was again worked out for Runway 14. The non-availability of NOTAM for runway change was not considered as a factor as revised landing distance requirement was well within the Runway 14 LDA limits and; crew reconfigured FMS & navigation and carried out briefing for the same well in time. The revised landing distance calculations were found to be correct considering the active Runway 14 and available aircraft configuration and weather conditions. Landing checklist was completed for flaps 30 landing and 1000 ft RA stabilized call out was made. Approach lights, runway lights and runway were sighted by crew. Crew was aware about the wet runway conditions, prevailing rains and winds. Autopilot was disengaged thereafter. The aircraft was stabilized up to 50 ft RA on ILS. From the FDR data it is observed that winds below 50 ft RA were varying in terms of direction and speed both.

At 09:20:16 hrs around 50ft RA the aircraft was at threshold which was slightly higher than normal. The flare started at threshold by increasing the pitch of the aircraft with power of 58.2% N1 and 59.5% N1 available from Engine # 1 & 2 respectively. The application of power was higher than required. The pitch of the aircraft varied between 0.87º at starting of flare to its maximum value 4.04º during flare which was normal. Power of Engine # 1 & 2 was lowered down to IDLE, 32% N1 and 32.75% N1 respectively, at 09:20:25 hrs at 09 ft RA. Subsequent to lowering the power, aircraft made firm touchdown at 09:20:30 hrs. The vertical speed of the aircraft was observed to be normal. Aircraft took 09 seconds from threshold (around 50 ft RA) to reach 09 ft RA and further 05 seconds from 09 ft RA to touchdown. Higher power application during flare combined with varying winds having tail wind component lead to flaring the aircraft for 14 seconds. As a result, aircraft touched down at 962.6 m/ 3158 ft from threshold, with vertical acceleration of 1.15g. 962.6 m of runway was covered during flare which is considered as a prime contributory factor to the incident. Lateral deviation of the aircraft was within limits throughout the approach.

Crew action of putting Engine # 2 thrust reverser to IDLE by reducing both the engine powers post identification of Engine # 1 thrust reverser failure upon touchdown was correct in order to maintain the directional control of the aircraft.

Further, crew realized after touchdown that the runway was contaminated with water patches due to rain. Crew felt that the deceleration rate of aircraft was not as desired and took decision of using maximum manual brakes. The decision to use maximum manual brakes was correct in order to get the desired deceleration considering the contaminated runway surface, prevailing tail wind and absence of thrust reverser.

Both PIC and FO applied manual brakes and simultaneously the rudder input was also given to effectively maintain the directional control of the aircraft. With application of maximum manual brakes, the aircraft could be stopped on the paved surface after crossing the Runway 14 end by 5.2 meters and at 12.55 meters right of the center line.

The handing of the aircraft post touchdown with one thrust reverser failed, contaminated runway surface and prevailing tail wind conditions was satisfactory and hence it was not considered as a factor to the incident. Crew showed good CRM throughout the flight.

Total distance travelled from threshold was 2476.2m/ 8123.8 ft and aircraft crossed end of Runway 14 by around 5.2 m/ 17ft.

Surface Friction Test of Runway 14 was conducted on 29/06/2018 and friction coefficient values were found to be within the limits. Two arrivals and two departures operated on Runway14 before arrival of IX- 213 and none of the aircraft reported adverse braking action. Hence, runway surface friction was not considered as a factor to the incident.

2.3 Dynamic Aquaplaning:

Horne's formula (V = 9 x √P) is used for calculating the minimum ground speed for initiation of dynamic aquaplaning on a sufficiently wet Runway based upon tyre pressure where V = ground speed in knots and P = tyre inflation pressure in psi. In the incident case, the surface of Runway was wet due to moderate rain showers at the time of landing. The aircraft touched down with ground speed of 142 knots at 09:20:30 hrs and the tyre pressure of all tyres was measured to be 205 psi post incident. Therefore, minimum ground speed for initiation of dynamic aquaplaning is V = 9 x √P = 9 x √205= 128.86 knots. Hence, it is ascertained that there would have been dynamic aquaplaning occurred on the incident flight till the time the aircraft ground speed was above 128.86 knots. The ground speed was recorded to be 123 knots after 05 seconds of touchdown, i.e. at 09:20:35 hrs. Therefore, it is assumed that the aircraft had encountered dynamic aquaplaning for around 05 seconds between 09:20:30 hrs to 09:20:35 hrs and probably during this time crew felt that the braking action was poor & deceleration rate of aircraft was not as desired. Subsequently at 09:20:37 hrs Auto brakes were disconnected and manual brakes were applied. Dynamic aquaplaning was considered as a contributory factor to the incident.

2.4 Weather:

The weather below 50 ft RA at CSIA, Mumbai contained varying winds in terms of direction & speed and reflected tail wind component. Runway surface was wet and moderate rains were prevalent during landing. The flaring was initiated at 50 ft RA, i.e. at threshold, and the presence of varying winds having tail wind component adversely contributed in the duration of flaring. Further, the presence of moderate rains lead the runway to become contaminated with water patches felt to be having more than 3mm depth. During such conditions, if the ground speed of aircraft is higher than the minimum ground speed for initiation of dynamic aquaplaning, then the dynamic aquaplaning occurs. As the ground speed of the aircraft at the time of landing, i.e. 142 knots, was greater than the minimum ground speed for initiation of dynamic aquaplaning, i.e. 128.86 knots, it is assumed that the aircraft had encountered dynamic aquaplaning at touchdown. The aircraft ground speed was more than minimum ground speed for initiation of dynamic aquaplaning for around 05 seconds from touchdown. Hence, it is assumed that the dynamic aquaplaning was present from time of touchdown and lasted for around 05 seconds. Probably due to dynamic aquaplaning crew felt poor deceleration rate immediately after touchdown. The prevalent weather affected the duration of flare and developed a condition wherein dynamic aquaplaning was encountered. Hence, weather was considered as a contributory factor to the incident.

2.5 Circumstances Leading to the Incident:

Flight IX-213 was departed from Vijayawada in airworthy condition with PIC as pilot flying and FO as pilot monitoring. Appropriate procedures and checklists were followed up to the descent phase. The landing distance was worked out for Runway 27 as per the latest ATIS information. On the course of descent, the notification of runway change was received by the crew from ATC due NOTAM. Accordingly, the landing briefing, FMS & navigation configurations and calculations were again worked out for Runway 14. Landing checklist was completed and aircraft was configured for flaps 30 landing with MAX Auto brakes and speed brakes armed. On getting the clearance, ILS was also captured and approach commenced. After 1000 ft RA stabilized call out approach lights, runway edge lights and runway became visible. The auto pilot was disconnected. Aircraft was stabilized in the ILS approach up to 50 ft RA and crew were aware about the wet runway condition due moderate rain, wind direction & speed reflecting tail wind component. At 50 ft RA the aircraft was slightly high on approach at threshold where the flare normally begins. The flare started at threshold with increase in pitch attitude of aircraft but with the power application higher than required. There was a presence of varying winds below 50 ft RA with tail wind component. The flare continued for the 09 seconds with the power application higher than required. After 09 seconds of flare the power was reduced to IDLE. After 05 seconds of reducing the power aircraft touched down firmly on the runway surface with vertical acceleration of 1.15g. The pitch attitude and rate of descent were observed to be satisfactory during flaring. Total 14 seconds were spent in flaring the aircraft from threshold to touchdown point due to higher power application and presence of varying winds having tail wind component. During these 14 seconds 962.6 m/ 3158 ft of the runway was passed. Immediately after touching down the auto brakes and speed brakes were applied. Left thrust reverser did not deploy due to failure of middle and lower thrust reverser actuators and right thrust reverser was deployed after 03 seconds from touchdown. FO called about failure of thrust reverser immediately and right thrust reverser was brought back to IDLE by reducing the power of both the engines in order to maintain directional control. Meantime, the aircraft was assumed to have encountered dynamic aquaplaning for first 05 seconds from touchdown when MAX auto brakes were being applied. Probably during these 05 seconds crew felt that the braking action was poor and they immediately disengaged the auto brakes and decided to apply maximum manual brakes. The directional control of the aircraft was being maintained by the rudder inputs. Application of maximum manual brakes by both PIC & FO could stop the aircraft on paved surface at a distance of 1513.6 m/ 4965.8 ft from the touchdown point, which was 5.2m/ 17 ft beyond the Runway 14 end and towards 12.55m right of the center line. The aircraft then taxied to bay V-29 under the guidance of Follow Me vehicle on its own power.

3. CONCLUSION:

3.1 Findings:

  • Airworthiness Review Certificate of the aircraft was valid up to 03/09/2018.
  • Aircraft was departed with valid Certificate of Release to Service on 10/07/2018. The aircraft was considered airworthy and serviceable before the incident flight.
  • The defect reported on 09/07/2018 and its rectification was not a contributory factor to the incident.
  • Delay of 02:33 hrs in departure of incident flight was not a factor to this incident as delay was attributed to the delay in operating originating sector.
  • Both crew members had valid licenses while operating incident flight.
  • Medical fitness & FDTL was not a factor to this incident.
  • Crew followed standard procedures and checklists in all phases of flight.
  • NOTAM for change in runway was not available with crew however the same was not a factor to this incident.
  • Configuration of aircraft for landing was correct as per briefing and landing calculations.
  • The aircraft was stabilized up to 50 ft RA on ILS.
  • Lateral deviation of the aircraft was within limits throughout the approach.
  • Aircraft was at 50ft RA on threshold, slightly higher than normal.
  • Winds below 50 ft RA were varying in terms of direction and speed both.
  • The flare started at threshold and lasted for 14 seconds due to higher power application and presence of varying winds having tail wind component.
  • The pitch attitude and rate of descent were observed to be satisfactory during flaring.
  • Aircraft touched down firmly at 962.6 m/ 3158 ft from threshold. 962.6 m of runway was covered during flare which was a prime contributory factor to the incident.
  • Vertical acceleration of the aircraft at touchdown was 1.15g.
  • Engine # 1 reverser did not deploy on touchdown because of the defective thrust reverser middle actuator & thrust reverser lower actuator. The failure of deployment of Engine # 1 thrust reverser resulted in increase in landing distance required and hence contributed to the incident.
  • Crew action of putting Engine # 2 thrust reverser to IDLE post identification of Engine # 1 thrust reverser failure upon touchdown was correct.
  • The aircraft was assumed to have encountered dynamic aquaplaning for first 05 seconds after touchdown and probably due to same crew experienced poor braking action after touchdown. Dynamic aquaplaning has contributed to the incident.
  • The decision to use maximum manual brakes was correct.
  • Both PIC and FO applied manual brakes to decelerate aircraft.
  • Serviceability of the brakes was not a factor to the incident.
  • Rudder input was used to effectively maintain the directional control of the aircraft post touchdown.
  • Aircraft overrun Runway 14 end by 5.2 meters and halted at 12.55 meters right of the center line on the paved surface. Total distance travelled by the aircraft from threshold was 2476.2m.
  • The handing of the aircraft post touchdown was satisfactory and was not a factor to the incident.
  • Runway surface friction was not a factor to the incident.
  • Prevalent weather at the time of landing was a contributory factor to the incident.
  • Crew shown good CRM throughout the flight.
  • The aircraft taxied to bay V-29 under the guidance of Follow Me vehicle on its own power.

3.2 Causes:

  • The incident was caused due to prolonged flare wherein nearly 40% of the available landing distance was consumed followed by failure of Engine # 1 thrust reverser due to defective thrust reverser middle & lower actuator.
  • Dynamic aquaplaning and prevalent weather conditions were contributory factors to the incident.

The full report is available here

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