What happened
On 10 January 2018, a Liberty XL-2, registration N518XL, was conducting a private flight near London Biggin Hill Airport. Upon reaching cruise altitude, the pilot noticed an increasing vibration within the cabin. Shortly thereafter, the left-hand door opened abruptly. The force of the slipstream was significant enough to strip the pilot's glasses and headset from their person.
Following the event, the pilot prioritized maintaining control of the aircraft. Although unable to immediately access a spare headset or handheld radio, the pilot successfully donned spare glasses and transitioned the aircraft to an emergency state by selecting the 7700 code on the transponder. The aircraft was subsequently returned to Biggin Hill for landing. No injuries were reported during the incident.
The investigation
Investigators examined the aircraft and determined that a portion of the door had detached following the opening. The recovered fragments of the door were inspected as part of the inquiry. The investigation also reviewed the pilot's pre-flight actions and the cockpit environment. It was noted that while the pilot was operating behind the planned schedule, they did not feel pressured by the timing. However, the pilot could not definitively confirm that the security of the left door had been verified prior to departure and suspected the latch may not have been fully engaged.
Findings
- The primary cause of the incident was that the left door was not fully latched before takeoff.
- The sudden opening of the door led to the loss of cockpit equipment due to slipstream force.
- The pilot's decision to prioritize aircraft control over retrieving secondary equipment prevented further complications.