What happened
On 16 April 2021, an ATR 72-211, registration G-CLNK, was performing a commercial cargo flight from Guernsey Airport to Jersey. Following the unloading of several containers from a previous leg, the remaining three Unit Load Devices (ULDs) were repositioned within the cargo hold. During the takeoff roll, the flight crew heard a minor thud, which they initially dismissed as the movement of items within the cabin.
Upon landing and subsequent braking, a second, much louder impact was felt throughout the airframe. An inspection of the cargo area revealed that one ULD had shifted significantly from its original position in bay C3 to bay C2. This movement caused damage to the cargo rails, rollers, and locks.
The investigation
The investigation established that while the aircraft's weight and balance remained within safe limits during the flight, the cargo securing mechanism had failed. Examination of the aircraft revealed that the locks and rails between bays C2 and C3 had been dislodged and pulled from their tracks.
An inquiry by the ground handling company determined that the locks at the rear of the ULD in bay C3 had been left in the down position. While the forward locks had been raised to secure the container, the lack of rear restraint allowed the ULD to slide backward into an empty bay during takeoff. During the landing deceleration, the container then slid forward with enough force to break through the forward locks and damage the floor fittings.
Findings
- The primary cause of the incident was that the rear locks for the ULD in bay C3 were not raised during the loading process.
- The ground handling process lacked an independent verification step to confirm all locks were correctly engaged.
- The ULD was able to be positioned such that forward locks could be engaged even though the rear locks remained down, likely due to friction and visual cues from the bay markers.
Safety action
Following the incident, the ground handling organization implemented a new procedure requiring an independent check to verify the position of all locks during loading. Additionally, the aircraft operator has introduced 'void bay awareness' training into their Operator Proficiency Checks to educate crews on the risks associated with operating with empty cargo bays.