How Triton Aviation’s Challenger 604 lost its door mid-flight – NSIB

The door of a private jet operated by Triton Aviation Limited detached mid-flight last month after a cabin crew member approached to inspect it on the captain’s instruction, the Nigerian Safety Investigation Bureau (NSIB) has disclosed.

The incident involved a Bombardier Challenger 604 aircraft, with registration number T7-SEI, operating flight DWC052 from Abuja to Lagos on 15 October.

According to the bureau’s preliminary investigation report, released on Thursday, the incident occurred during the aircraft’s initial climb when the flight crew noticed an unusually rapid increase in cabin altitude, raising concerns about a possible pressurisation problem.

The captain subsequently instructed the cabin crew member to double-check the aircraft’s main door.

The crew member initially inspected the passenger-crew door from her sitting position and reported that it appeared properly closed, with its green indicator band aligned.

However, the captain requested a closer inspection, instructing her to stand up and examine the door.

As she approached it, the door suddenly opened and detached from the aircraft, the report said.

The development prompted the flight crew to declare an emergency and coordinate an immediate return to Abuja.

Crew declares Mayday emergency

The NSIB report said the captain immediately took control of the aircraft following the door separation, while the first officer assumed pilot-monitoring duties.

At 17:19:20, the crew declared an emergency over the radio, repeatedly transmitting the internationally recognised distress call, “Mayday, Mayday, Mayday”.

The crew also informed Abuja Radar Control that the aircraft’s door had opened.

Abuja Radar Control acknowledged the emergency at 17:19:51 and asked whether the aircraft could turn right.

The crew confirmed at 17:20:20 that it could turn and requested a heading and altitude.

Radar Control subsequently approved a northbound heading, which the pilot acknowledged.

At 17:25:35, the pilot contacted Abuja Radar Control to seek clearance to commence an approach.

Two seconds later, the controller reported that the aircraft was nine nautical miles north of the airfield, at POKMO, and cleared it for an Instrument Landing System approach.

The crew was instructed to report when established on the approach.

The aircraft eventually landed safely on Runway 22 at approximately 17:34 local time, with all nine occupants, comprising two pilots, one cabin crew member and six passengers, disembarking without injuries.

The aircraft, however, sustained substantial damage.

The bureau said investigators subsequently recovered the detached door from a cornfield in Gui Village, Abuja Municipal Area Council, approximately five miles southwest of the airport.

PREMIUM TIMES reported at the time that the aircraft made an emergency landing at Nnamdi Azikiwe International Airport, Abuja, after its crew said a door had opened shortly after take-off.

The aircraft had departed Abuja for the Murtala Muhammed International Airport, Lagos, when the crew issued a Mayday call about three nautical miles from the airport.

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The emergency prompted airport fire and rescue personnel and medical teams to be placed on standby ahead of the aircraft’s return.

Following the landing, air traffic controllers observed that the door was missing from the aircraft’s fuselage.

NSIB commenced a preliminary investigation into the incident and recovered the missing door, which was secured at its wreckage hangar.

The preliminary report provides further details about the sequence of events leading to the door’s separation and the flight crew’s response.

However, the bureau cautioned that the report contains factual information established so far and does not include analysis or conclusions on the causes or contributing factors.

The NSIB investigation is ongoing, and a final report containing its findings and any further safety recommendations is expected upon completion.