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B738, vicinity Denpasar Bali Indonesia, 2013 (CFIT HF)

Category: Accidents and Incidents

Summary

On 13 April 2013, a Lion Air Boeing 737-800 flew a day non precision approach to runway 09 at Bali (Denpasar) and after encountering deteriorating visibility conditions continued below MDA before impacting the sea short of the intended landing runway after a go around had been called following the EGPWS ‘Twenty’ call. The aircraft broke up on impact but there was no fire and all 108 occupants survived with only 4 sustaining serious injury. An investigation is continuing.

Event Details
When	April 2013
Event Type	CFIT, HF
Day/Night	Day
Flight Conditions	IMC

Flight Details
Aircraft	BOEING 737-800
Operator	Lion Air
Domicile	Indonesia
Type of Flight	Public Transport (Passenger)
Origin
Intended Destination	Bali
Flight Phase	Descent
	ENR / APR

Location - Airport
Airport vicinity	Bali

General
Tag(s)	Non Precision Approach

CFIT
Tag(s)	Into water No Visual Reference Vertical navigation error IFR flight plan

HF
Tag(s)	Manual Handling Plan Continuation Bias Violation

Safety Net Mitigations
Malfunction of Relevant Safety Net	No
TAWS	Available but ineffective

Outcome
Damage or injury	No
Aircraft damage	Hull loss
Injuries	Few occupants

Causal Factor Group(s)
Group(s)	Aircraft Operation

Safety Recommendation(s)
Group(s)	Aircraft Operation

Investigation Type
Type	Independent

Description

On 13 April 2013, a Boeing 737-800 being operated by Indonesian carrier Lion Air on a scheduled domestic passenger flight from Bandung to Denpasar, Bali impacted the sea and was destroyed short of the intended landing runway 09 at Bali after making a non precision approach. The aircraft broke up on impact in shallow water near the shoreline but there was no fire and all 108 occupants survived with only 4 sustaining serious injury.

Evacuation from the aircraft after the accident (Reproduced from the Official Report)

Investigation

An Investigation was begun by the Indonesian NTSC and has gathered factual information and documented initial findings. The aircraft was estimated to have come to rest facing north about 20 metres from the shore in a position approximately 300 metres southwest of the threshold of runway 09. It was concluded that all damage to the aircraft was“consistent with post accident impact with the sea floor, coral reef and sea wall”.

The CVR and FDR were recovered from the wreckage and successfully downloaded. It was demonstrated from this data (see diagram below) that the aircraft final approach had not penetrated any EGPWS Alert criteria and that the standard radio height call outs from the same equipment had functioned normally throughout. In all significant respects, the aircraft was found to have been airworthy. The VOR and DME navigation aids being used by the accident aircraft for the approach were also confirmed as serviceable as was the PAPI and runway lighting.

The aircraft commander, an Indonesian national, was found to have substantial aircraft type flying experience and to have been twice the age of the foreign national Co Pilot, who had been designated PF for the accident flight and for whom experience gained on the accident aircraft type with Lion Air in the two years since joining the airline constituted most of his flying experience.

It was established that although the surface wind had remained light, there had been a transient deterioration in the visibility during the last few miles of the final approach due to rain and low cloud. The TWR controller reported having had visual contact with the approaching aircraft when issuing landing clearance as it passed approximately 1600 feet but the aircraft did not subsequently remain visible. A report from the pilot of an aircraft that made an approach 5 NM behind the accident aircraft stated that they could not see the runway at the published minima and decided to go around. One of two aircraft waiting to take off from the same runway reported that, at the time of the accident approach, it was raining and the surface visibility was between 1000 metres and 2000 metres with the accident aircraft evident on the TCAS display at a range of 3nm but not visible. A recording from airport CCTV nearby confirmed a significant deterioration in visibility on the four minutes prior to the impact.

CVR and FDR data showed that at approximately 900 feet, the PF no longer had the runway in sight. When the EGPWS call ‘Minimum’ was annunciated at approximately 550 feet shortly afterwards, the PF had disconnected the APand A/T (Autothrottle) and continued the descent. Twenty seconds later, at 150 feet agl, the aircraft commander took control and the Co Pilot, having again stated that he could not see the runway, reverted to the role of PM. Eight seconds after that, the EGPWS call ‘Twenty’ was annunciated and the aircraft commander called a go around one second before impact occurred. FDR data showed that the descent angle had increased below 500 feet.

The Investigation is continuing. On the basis of the work so far three Safety Recommendations were made as a result of the Investigation as follows:

• that PT. Lion Mentari Airlines emphasises to pilots the importance of complying with the descent minima of the published instrument approach procedure when the visual reference cannot be obtained at the minimum altitude.
• that PT. Lion Mentari Airlines reviews the policy and procedures regarding the risk associated with changeover of control at critical altitudes or critical time.
• that PT. Lion Mentari Airlines ensures the pilots are properly trained during the initial and recurrent training program with regard to changeover of control at critical altitudes and or critical time.

A Preliminary Report of the Investigation: KNKT.13.04.09.04 was published on 13 May 2013. It notes that at the time of publication, the NTSC had not been informed of any Safety Actions following the accident.

Further Reading

• Controlled Flight Into Terrain
• Approach and Landing Risks
• CFIT Precursors and Defences
• Situational Awareness
• Crew Resource Management
• Cross-checking Process
• Terrain Avoidance and Warning System (TAWS)