IBC Airways Flight 405

The aircraft took off at 19:36 local time from Santo Domingo, Dominican Republic, to San Juan, Puerto Rico. The last radio contact with the flight occurred around 20:08, as the aircraft was descending from 11,000 feet to 7,000 feet. At that time, air traffic control instructed the crew to maintain an altitude of 3,000 feet until reaching the"TNNER" waypoint and to prepare for an ILS approach. The crew acknowledged the instruction. This was the last communication between air traffic control and the aircraft.^[3]

By 20:10:08, the aircraft had descended to 8,300 feet and began a 20-degree left turn. By 20:10:13, it had descended further to 7,300 feet and then initiated a 45-degree right turn. At 20:10:18, the aircraft had descended to 5,500 feet. Calculations later showed that the aircraft had descended at a rate of 12,000 feet per minute between 20:10:08 and 20:10:13, and at a rate of 21,000 feet per minute during the following five seconds.^[3]

The accident was investigated by the National Transportation Safety Board (NTSB), which lasted 2 years and 7 months. Investigators concluded that it was caused by the flight crew's excessively abrupt use of the elevator controls during a rapid descent at night. This led to structural overload and the subsequent in-flight breakup of the aircraft. A contributing factor was an initial loss of control, the cause of which could not be determined, as the investigation revealed no mechanical anomalies.^[5]