Accident Boeing 737-8FB (WL) 3C-LLY, Saturday 5 September 2015
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Date:Saturday 5 September 2015
Type:Silhouette image of generic B738 model; specific model in this crash may look slightly different    
Boeing 737-8FB (WL)
Owner/operator:Ceiba International
Registration: 3C-LLY
MSN: 41157/4782
Year of manufacture:2014
Total airframe hrs:1568 hours
Cycles:1761 flights
Engine model:CFMI CFM56-7BE
Fatalities:Fatalities: 0 / Occupants: 112
Other fatalities:0
Aircraft damage: Minor, repaired
Location:ESE of Tambacounda -   Senegal
Phase: En route
Nature:Passenger - Scheduled
Departure airport:Dakar-Léopold Sédar Senghor International Airport (DKR/GOOY)
Destination airport:Cotonou Airport (COO/DBBB)
Investigating agency: BEA Senegal
Confidence Rating: Accident investigation report completed and information captured
A BAe-125 jet, 6V-AIM, operated on a medical transportation flight from Ouagadougou, Burkina Faso, to Dakar, Senegal. On board were a French patient and two crew members as well as a mechanic, a doctor and two nurses. The aircraft departed Ouagadougou at 16:36 hours local time and climbed to the cruising altitude of FL340. The flight contacted the controller at Bamako Center at 17:13, asking if FL380 was available because of the presence of clouds ahead. The controller then cleared the flight to FL380. After negotiating several other options to avoid severe turbulence, the crew decided to remain at FL340. At 18:00 the flight was allowed to deviate 10 NM from the route to avoid an area of bad weather. Last radio contact with the flight was at 18:04. At that time the aircraft was proceeding westward on Airway UA601 at a cleared altitude of FL340.
At the same time Ceiba International flight CEL71 was heading eastward on Airway UA601 at a cleared altitude of FL350.
The Boeing 737-8FB, registration 3C-LLY, had departed Dakar at 17:28 hours and was en route to Cotonou, Benin and Malabo, Ecuatorial Guinea. The aircraft crossed paths with the BAe-125 at 18:12, between points DEMOL and GATIL. At 18:15 CEL71 contacted the controller at Dakar Center, stating they had observed descending traffic from the opposite direction, passing their altitude just behind them. Initially the crew referred to the event as a 'near miss collision'. The Dakar Center controller then attempted to contact the BAe-125, but there was no response.
At 18:16 CEL71 contacted Dakar Center again, stating that the traffic in question likely touched their wing. The crew reported that they did not have any control issues. It was decided not land at Cotonou and continue to the final destination Malabo. After landing it appeared that the top part of the right hand winglet, measuring one metre, had broken off.
Despite several attempts, no contact was made with the BAe-125. At 18:22 the BAe-125 appeared on radar at Dakar, showing an altitude of FL350. The aircraft continued on the planned flight track. It passed Dakar, heading over sea. At 19:07 the aircraft began to descend. At FL330 the aircraft turned right and immediately left, passing FL126 level before it disappeared from radar about 59 NM from Dakar. The aircraft was not found.

The investigation learned that 6V-AIM had a history of level bust incidents in the months leading up to the accident. On three separate flights the aircraft had been flown in RVSM airspace at altitudes for which it had not been cleared. In one case opposite traffic, an Arik Air Boeing 737, had to be given descent instructions in order to avoid a lack of clearance.
Additionally, on the day of the accident, the flight crew received instructions to correct their altitude on two occasions.

PROBABLE CAUSE (transated from French):
The collision is due to 6V-AIM's non-compliance with its flight level. He ended up at FL 350 which was the level assigned to 3C-LLY while at 18H01'11" he had confirmed to CCR2 maintain the 340.
The 3C-LLY captain claimed to have seen it descending towards them.
Only the flight recorders could have helped to determine how such a situation could have occurred; Unfortunately they disappeared with the plane.
The lack of altimetry may have contributed to the collision in flight.

1. Altimetry problems
These problems may have contributed to the collision. The indications of the two primary altimeters were different; The altimeter indications of the pilot in charge of communications and the altitude data transmitted by the transponder were different by about one thousand (1000) feet.
On 23/07/2015, the aircraft was detected at level 310 instead of the 320 assigned by the ATC controller and indicated by the altimeter.
On 31/08/15, 6V-AIM was coordinated by Roberts: SESEL Point at 20H55 and FL 360. Once in radar contact, it was detected at FL 350 without any revision or authorization. After being questioned, he started to climb.
On 05/09/2015, on the outward flight (DKR - OUA), the aircraft had triggered two CLAM alarms:
- Assigned flight level 330 and level acquired by autopilot 311
- Assigned flight level 330 and level acquired by autopilot 333
2. Non-compliance with procedures
* The provisions of the Senegalair operations manual prohibit penetration into RVSM space as soon as there is a 200-foot gap between the two primary altimeters (at flight preparation, the maximum deviation is 75 feet).
They require the captain to provide the aircraft technical report at the end of each flight and that the document be operated immediately by maintenance and operations and archived.
- After the significant incident of 23/07/2015, the technical report was not checked (altimetric problems).
- The aircraft was maintained in operation without technical intervention and without restrictions until 05/09/2015.
- The technician authorized to sign the Approval for Release to Service and to follow up and maintain airworthiness left the company on 15/08/2015. From that date, the aircraft should not have been put back into flight.
* The plane returned from RABAT on 08 August 2015 and remained on the ground until 29 August 2015.
The significant incident report was sent on August 27, 2015.
The rigorous application of the provisions provided for this type of situation would have prevented the aircraft with its altimetry problems from making the series of flights leading to the fateful date of 05 September 2015.
This non-compliance with the procedures has been noted in other sectors of activity cited below:
- in the renewal of the Certificate of Airworthiness (the CofA of 6V-AIM was renewed when there was still a level 1 anomaly);
- the validation of the co-pilot's license (The license was validated when he did not have the physical and mental fitness certificate required by the procedures of the PEL Inspector's Manual. The authentication of the Algerian basic license was not carried out in accordance with RAS 01 and the PEL Inspector's Manual).

Accident investigation:
Investigating agency: BEA Senegal
Report number: Final report
Status: Investigation completed
Duration: 1 year and 11 months
Download report: Final report


"L'avion SENEGAL AIR a croisé un vol de la compagnie CEIBA" (ANACIM)
Rapport Préliminaire, BEA Senegal


Revision history:


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