What happened
On June 17, 2015, a Royal Air Maroc Boeing 737-800, registration CN-ROR, landed normally on runway 35L at Mohammed V International Airport (GMMN) following a flight from Agadir El Massira. After touchdown, the crew attempted to vacate the runway via taxiway 'Mike' by executing a 90-degree turn.
The aircraft entered the turn at a ground speed of approximately 35 knots. During the maneuver, the nose gear lost traction, causing the aircraft to skid to the left and exit the paved surface of the taxiway. The crew applied full right rudder and light braking in an attempt to correct the deviation, but the aircraft continued to slide. During the excursion, the nose gear struck a concrete edge, and the left main gear ran over a taxiway light and a curb. The aircraft eventually returned to the pavement of taxiway 'Mike' and came to a stop before the holding point.
There were no fatalities or injuries among the 122 occupants on board. However, the excursion caused significant damage to the aircraft, including burst tires on both nose gear wheels, damage to the nose gear rim, and a torn outer tire on the left main gear. Damage was also sustained to a taxiway edge light.
The investigation
The Moroccan BEAM investigation examined the flight data, maintenance records, and crew testimonies. Investigators found that while the aircraft's mechanical systems, including braking and steering, were fully functional, the speed at which the turn was initiated exceeded manufacturer recommendations.
The board also evaluated the airport infrastructure, noting a concrete elevation change (0.15m high) at the edge of taxiway 'Mike' that contributed to the damage. Furthermore, investigators identified potential safety hazards in the area, such as open drainage ditches and vegetation near the taxiway edges, which could pose risks during future excursions.
Findings
- The primary cause of the excursion was the execution of a high-speed turn at 35 knots, whereas the manufacturer's manual recommends limiting speed to 10 knots for turns exceeding a 30-degree angle.
- The crew was likely under temporal pressure to vacate the runway quickly to accommodate following traffic, as the airport lacks high-speed exit taxiways for runway 35L.
- The loss of adhesion in the nose gear tires during the turn led to the uncontrolled skid.
- The presence of a concrete curb and an unfrangible edge at the taxiway boundary contributed to the structural damage to the landing gear.
- The crew failed to follow standard procedures regarding the preservation of CVR and DFDR data following the incident.