What happened
On February 16, 2002, a Bell 412EP helicopter, registration EC-HFD, was performing a commercial passenger flight from Ceuta to Málaga. The aircraft was carrying a crew of two and eight passengers. During the cruise phase of the flight, while traveling over the Mediterranean Sea approximately 25 nautical miles from Málaga Airport, the flight crew noticed a loud noise in the passenger cabin.
Upon inspection, the crew discovered that one of the rear emergency windows had detached from the airframe. The two passengers seated directly in front of the opening pointed toward the vacancy. The crew immediately checked all aircraft parameters, reassured the passengers, and reduced the cruise speed to approximately 80 KIAS to mitigate the effects of the opening. The aircraft landed safely at Málaga Airport at approximately 09:15 local time. No injuries were reported, and no damage to the helicopter was found during a subsequent ground inspection.
The investigation
The investigation focused on how the acrylic window, weighing approximately 1.3 kg, became detached. The design of the window requires simultaneous pressure on both lower corners to release it from the frame, a mechanism intended to prevent inadvertent opening.
Investigators examined the behavior of the passengers seated near the opening. Evidence suggested that the two passengers in question exhibited signs of euphoria or unusual excitement during boarding. One passenger claimed to have woken up due to the noise of the wind, while the other stated that their leg had accidentally struck the window, causing it to partially open and subsequently detach due to aerodynamic forces. Furthermore, reports indicated that both passengers appeared to be under the influence of narcotics, though no formal toxicology tests were performed.
Findings
- The most probable cause of the window detachment was intentional action by one or more passengers who may have been under the influence of controlled substances.
- The window detached while the aircraft was flying at approximately 120 kt.
- While the window did not strike the helicopter, the investigation noted the potential risk that a detached object of that mass could impact the tail rotor.
- The crew followed correct emergency procedures to manage the flight following the incident.