What happened
On June 19, 1999, an Aigle Azur Boeing 737-2K5, registration F-GMJD, was performing a scheduled passenger flight from Paris Orly to Malta. During the takeoff roll on runway 08, the crew experienced a violent impact affecting the nose gear and the fuselage at approximately 150 knots. Following the impact, several cockpit alarms, including "DOORS" and "FWD ENTRY," were triggered.
After the takeoff, the crew notified air traffic control, who informed them that a concrete block had been found on the runway. The crew decided to return to Orly to land. To ensure safety, they flew over the airport for a visual inspection by ground controllers, who found no visible anomalies. Due to the closure of runway 08, the aircraft diverted to Paris Charles de Gaulle, where it landed without further incident. There were no fatalities or injuries among the 127 passengers and 5 crew members, though the aircraft sustained significant damage.
The investigation
The investigation focused on the integrity of recent runway maintenance performed on the taxiway lighting locations. Investigators discovered that the concrete used to fill cavities left by removed light fixtures had failed to adhere to the runway surface.
Technical analysis of the repair material revealed that the contractor had used a fast-setting mortar that was chemically incompatible with the ambient temperature. While the product's technical sheet specified that fast-setting versions should only be used between -25°C and +5°C, the repairs were conducted in temperatures near 20°C. Furthermore, the material was found to be non-homogeneous, suggesting improper mixing of the components.
Evidence also showed that the preparation of the repair site was inadequate, as the cavities were shaped in a way that promoted the dislodging of the material under stress. Notably, an Air France A320 that had departed just two minutes prior to the F-GMTJD had already reported a strike on a lighting element, which had damaged its nose gear tire.
Findings
- The primary cause of the accident was the use of inappropriate repair materials and the failure to follow the manufacturer's technical instructions during runway maintenance.
- The contractor selected a fast-setting mortar that was unsuitable for the 20°C ambient temperature at the time of application.
- Improper mixing of the concrete components led to a lack of structural homogeneity.
- The repair site preparation was insufficient, preventing proper adhesion between the new material and the existing runway surface.
- Operational pressures to maintain runway availability contributed to the selection of unsuitable, rapid-curing materials.