An Israel Aircraft Industries 1125 Westwind Astra was being readied for an executive charter flight from Baltimore (Maryland, USA) to Chicago (Illinois, USA) on this day in 2015.
Onboard of the aircraft, a crew of 2 and 5 passengers for the ~1000 kilometer (~625 miles) flight.
The aircraft after landing and coming to a stop with the main entry door open. (Source; Aviation-safety.net © FAA)
After the passengers had boarded the pilot monitoring (PM) closed the main entry door. A visual check was (reportedly) performed to ascertain the door was closed and locked, The CABIN DOOR warning and CABIN DOOR SEAL caution lights were confirmed off. After receiving the necessary clearances the engines were started, and the aircraft headed toward the runway. The weather was good;
Wind - Calm
Clouds - Few at 6000 feet / scattered at 25.000 feet
Visibility - 10 miles
Temperature - 23 º
Dewpoint - 13 º
Altimeter - 29.95 inHg
Once take-off clearance was received the aircraft accelerated down the runway and lifted off. Immediately after lift-off the crew observed the CABIN DOOR warning and CABIN DOOR SEAL caution lights were illuminated. ATC was contacted to inform them about the situation and request a return to the field. ATC granted the request to return to the field and the PIC started a turn to return to the field. At that time the main entry door opened fully. The crew contacted ATC to declare an emergency, but the reply from ATC could not be heard by the crew because of the noise resulting from the open main entry door. LIght signals were used by ATC to issue the landing clearance. When the aircraft touched down and the nose was brought down on the runway the main entry door contacted the runway, however, it remained attached to the door frame.
Close up of the damaged main entry door. (Source; Aviation-safety.net © FAA)
A subsequent inspection of the aircraft revealed that both the main entry door and the airframe structure surrounding it were substantialy damaged during the accident sequence. As part of the Australian Transportation Safety Board (ATSB) the aircraft door was removed from the aircraft and shipped to the manufacturer, although several issues were found when the door (locking mechanism) was inspected, the conclusion was that there were no anomalies with the door securing mechanism that would have precluded normal operation prior to the accident.
In its final report, the ATSB (available by clicking here) concluded that the probable cause for the accident was the flight crew's failure to visually ensure that the cabin door locking pin was in place before takeoff.