On 29 November 2013, an Embraer 190-100IGW (C9-EMC) being operated by Mozambique Airlines (LAM), on a scheduled passenger flight from Maputo, Mozambique to Luanda, Angola as LAM 470 and cruising at FL380 in day VMC in Botswana airspace was suddenly put into a descent without any communication with ATC. This descent continued on the flight plan track until terrain impact in the Bwabwata National Park in the Eastern Kavango district of neighbouring Namibia. No distress calls were made and no signal was transmitted from the ELT after the crash. The wreckage was not located until the following day when it was found that impact and a post crash fire had destroyed the aircraft. None of the 33 occupants survived.
An Investigation was carried out by the Namibia Directorate of Aircraft Accident Investigation (DAAI). A brief Preliminary Report was released on 18 December 2013 and ongoing progress was detailed in an Interim Report released on 1 December 2014.
The two CVFDRs installed in the aircraft were recovered from the accident site on 30 November 2013 and subsequently downloaded successfully at the National Transportation Safety Board (USA) (NTSB). Recorded flight data relevant to the Investigation was obtained from both units and the data recorded by each ‘pair’ of recorder units was found to be identical. Both CVR and FDR units contained data up to impact - 2 hours in the case of the CVRs and approximately 141 hours in the case of the FDRs. ATC recordings of both radar surveillance and voice communication were also available.
It was established that the aircraft had been in normal communication with Gaborone ACC when, at mandatory reporting point EXEDU, Namibian radar recordings showed that the aircraft had "commenced a sudden descent from (its) cruising level of FL380" without advising ATC. Just over 6 minutes later, as the aircraft was descending though 6600 feet amsl, radar and voice contact with the aircraft were lost by air traffic services and 15 seconds after that and one hour 50 minutes since take off, the aircraft impacted terrain at 3390 feet amsl.
Examination of recorded flight data indicated that:
- The aircraft was operating normally and there was no evidence of any mechanical faults.
- Minutes before the crash, the First Officer left the flight deck in order to use the toilet and only the Captain remained there.
- The descent was initiated by changing the FMS mode and manually re-setting the altitude preselect from 38000 feet to 4288 feet, then to 1888 feet and finally to 592 feet - the latter being well below ground elevation.
- One minute after the descent began, the A/T was disconnected manually then re-engaged and the thrust levers automatically retarded to idle in response to the prior selection of FLCH mode and a target altitude requiring significant descent.
- The airspeed was manually changed several times until the end of the FDR recording and remained close to Vmo.
- The speed brake handle parameter indicates that it was commanded to open the spoiler panels and remained in this position until the end of the recording.
- During all these actions, there were audible low and high chimes as well as repeated banging on the flight deck door by the First Officer attempting to re-enter the flight deck.
The AP remained engaged throughout the descent made and the cabin remained pressurised. The data showed that the angle of attack during the descent was not indicative of a stall and that the use of speed brake had ensured that a high rate of descent could be sustained with the AP engaged without exceeding Vmo, which would have resulted in corrective action by the AP to avoid excessive speed. The achieved rate of descent was around 10,000fpm.
EGPWS Alerts began as the aircraft passed 2010 feet agl and a 'SINK RATE PULL UP' Warning was activated 12 seconds before the end of the recording. The CVRs did not record any conversation after the First Officer had left the flight deck.
A simulation of the final 12 minutes of the flight based on FDR data was flown in a Level D Full Flight Simulator. It was noted that "the behaviour of the simulator was very close to the parameters recorded […] on the FDR". It was considered that all the evidence displayed clear intent to set up a high speed collision with terrain which would destroy the aircraft.
Given this conclusion, an attempt was made to investigate his personal circumstances and investigators travelled to Mozambique. Whilst there, they interviewed the family members and friends of both pilots and discovered that the Captain had been through a number of ‘life experiences’ which had included:
- Separation from his first wife on which the divorce process had not been completed after almost 10 years of separation.
- The death of a son who died in a car accident in a suspected suicide in November 2012. The Captain was reported as not having attended his son’s funeral.
- The Captain’s youngest daughter had recently undergone heart surgery in a South African hospital.
It was noted that “although information on the financial and insurance position of the Captain was requested via the Investigation’s Mozambique Accredited Representative”, it proved impossible to obtain this information prior to the completion of the Investigation because of significant “bureaucratic and legal/judicial” hurdles.
The non-receipt of signals from an ELT after the crash was found to be due to a break in the co-axial cable which linked the unit to the external antenna. It was considered that devices containing an integral antenna would be more reliable.
The Investigation determined that the Probable Cause of the crash was "the inputs to the auto flight systems by the crew member believed to be the Captain who remained alone in the cockpit when the person believed to be the Co-pilot requested to go to the lavatory (which) caused the aircraft to depart from cruise flight to a sustained controlled descent and subsequent collision with the terrain".
One Contributing Factor was also identified:
- The non-compliance to company procedures that resulted in a sole crew member occupying the flight compartment.
Upon completion of the Investigation, the following 6 Safety Recommendations were made:
- that the Mozambique Civil Aviation Authority should come up with a mechanism to ensure that the procedure of two people in the flight deck is adhered to at all times as laid out in LAM’s Manual of Flight Operation Chapter 10.1.4, Page 5 of 36, Edition 3 Revision 8, (Absence from Flight Deck). [001/2015 LAM]
- that the ICAO should establish a working group that should look into the operation and the threat management emanating from both sides of the cockpit door. [002/2015 LAM]
- that the ICAO should establish standards that implement recommendations of the working group, formed under safety recommendations number 002/2015 LAM to suitably avert the locking out of the cockpit of authorised crew members. [003/2015 LAM]
- that the ICAO should establish a working group to review the installation of visual recording inside and outside the cockpit that should provide information on who was in the cabin, who exactly was controlling the plane at the time of the accident and even where their hands were in relation to the plane’s controls. [004/2015 LAM]
- that the ICAO should expedite the implementation of international requirements on global tracking of airline flights providing early warning of, and response to, abnormal flight behaviour information to ensure that search and rescue services, recovery and accident investigation activities are conducted timely. [005/2015 LAM]
- that the ICAO Working Group on 'Global Tracking 2014-WP/6' speeds up the research and implementation of aircraft tracking and localization other than ELT system. [006/2015 LAM]
The Final Report of the Investigation was completed on 30 March 2013, approved for release on 5 April and published later the same month.