Batik Malaysia B739 at Kathmandu on Apr 19th 2018, rejected takeoff due to takeoff config warning results in overrun

Last Update: May 3, 2020 / 21:25:19 GMT/Zulu time

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Incident Facts

Date of incident
Apr 19, 2018

Classification
Incident

Cause
Rejected takeoff

Airline
Batik Air

Flight number
OD-181

Departure
Kathmandu, Nepal

Destination
Kuala Lumpur, Malaysia

Aircraft Registration
9M-LNJ

Aircraft Type
Boeing 737-900

ICAO Type Designator
B739

Airport
Tribhuvan International Airport, Kathmandu

Airport ICAO Code
VNKT

A Batik Air Malaysia (former Malindo Air) Boeing 737-900 still in Malindo colours, registration 9M-LNJ performing flight OD-181 from Kathmandu (Nepal) to Kuala Lumpur (Malaysia) with 132 passengers and 7 crew, had backtracked runway 20, was cleared for takeoff and commenced takeoff, when the crew rejected takeoff at high speed (about 165 knots over ground). The aircraft came to a stop about 75 meters/250 feet past the end of runway 20 with all gear on soft ground, the crew advised they were off the runway and had rejected takeoff due to a takeoff configuration warning detailing upon further query, they believed a system malfunction had caused the takeoff configuration warning. There were no injuries, the damage to the aircraft is being assessed but believed to be minor.

The runway was closed for more than 12 hours until the aircraft could be moved to the apron.

Malaysia's Air Accident Investigation Bureau (AAIB) released their final report concluding the probable causes of the serious incident were:

The probable cause of the runway excursion was due to the PIC attempted to reject the take-off at high speed, following take-off Configuration Warning. The rejected TO was initiated at the speed of 154kts, which is above V1. In addition, the maximum braking was not applied throughout the stopping.

The AAIB reported the aircraft was accelerating for takeoff from runway 20 when at about V1 the takeoff configuration warning activated. The captain decided to reject takeoff considering the high terrain and bad weather all around Kathmandu. The aircraft however could not stop before the end of the runway and came to a stop about 50 meters past the end of the runway. The crew consulted with Kathmandu Tower, the passengers disembarked via door 2R and the slide there. There were no injuries. Two main tyres deflated, the aircraft did not sustain any other damage.

The captain (42, ATPL, 14,349 hours total, 6,473 hours on type) was pilot flying, the first officer (30, ATPL, 3,022 hours total, 2,822 hours on type) was pilot monitoring.

The AAIB analysed:

According to the flight data the RTO was initiated 4 seconds after V1, at a CAS 154kts. There is no evidence of TO Warning during the take-off roll recorded. The RTO was performed initially with autobrake, and it was disconnected immediately after by applying pressure on the brake pedals by the CPT. Flight data shows a progressive movement of the braking pedals from 30% to close to 90% in 10 seconds. After that point, constant maximum pressure was applied until aircraft came to stop. Runway excursion occurred at Groundspeed 30kts, and the aircraft was stop close to 50m after the RWY02 threshold.

...

Full test performed found nil current faults. Take-off warning reports indicate that speed brake lever was not in down position. Troubleshooting carried out found that speed brake lever switch was out of range and giving an intermittent signal. Adjustment carried out on the switch found satisfactory. Aircraft take-off warning test carried out found satisfactory. EGR carried out found all parameter reads normal.

...

On 7th August 2015 Boeing issued the Technical Bulletin number 737-04-1 R1. This bulletin was issued to address several reports received at Boeing of take-off configuration warnings because the speed brake handle was not in the DOWN detent (not stowed). According to this bulletin, the Boeing 737 Pre-flight procedure and checklist include the step to check the Speed Brake in the “DOWN DETENT”. Speed brake cable friction and/or speed brake lever spring back force may prevent the handle from dropping completely into the detent by causing the handle to catch securely in the detent. In this bulletin Boeing recommends the technique to ensure the speed brake is properly stowed by pushing down firmly on top of the speed brake handle. Additionally it is mentioned that this technique will not prevent a false warning if the speed brake warning switch is not adjusted correctly, but it should prevent a warning due to the handle not being fully stowed.

According to the information gathered during the interviews, the FO check firmly the Speed brake handle at the down detent, and the CPT check it again once the take-off configuration warning sounded, however both actions were not enough to prevent this warning.

Additionally, the bulletin emphasises the fact that if the take-off configuration warning occurs during the take-off roll before 80kts, the flight crew should accomplish the Rejected Take Off non-normal manoeuvre as described in the Manoeuvres chapter of the QRH.

Metars:
VNKT 191820Z 16003KT 6000 -TSRA FEW015 FEW025CB SCT030 BKN100 17/15 Q1014 NOSIG CB TO S SE AND NE=
VNKT 191750Z 19004KT 6000 -TSRA FEW015 FEW025CB SCT030 BKN100 17/15 Q1014 NOSIG CB TO S SE AND NE=
VNKT 191720Z 00000KT 7000 FEW015 SCT100 18/15 Q1013 NOSIG=
VNKT 191650Z 00000KT 7000 FEW015 SCT100 19/13 Q1014 NOSIG=
VNKT 191620Z 15004KT 7000 FEW015 SCT100 18/14 Q1014 NOSIG=
VNKT 191550Z 00000KT 7000 FEW015 SCT030 18/16 Q1013 NOSIG=
VNKT 191520Z 12004KT 7000 FEW015 FEW025CB SCT030 BKN100 19/14 Q1013 NOSIG CB TO NW AND N=
VNKT 191450Z 19011KT 6000 -TSRA FEW015 FEW025CB SCT030 BKN100 18/13 Q1013 NOSIG CB TO SW W NW AND NE=
VNKT 191420Z 24005KT 6000 TSRA FEW015 FEW025CB SCT030 BKN100 20/17 Q1013 NOSIG CB TO SW W NW AND NE=
VNKT 191350Z 23006KT 6000 TSRA FEW015 FEW025CB SCT030 BKN100 21/17 Q1012 NOSIG CB TO SW W NW AND NE=
VNKT 191320Z 23008KT 6000 TS FEW020 FEW025CB SCT030 BKN100 22/16 Q1012 NOSIG CB TO SW W NW AND N=