Nigeria Airways Flight 2120 was a chartered passenger flight from Jeddah, Saudi Arabia, to Sokoto, Nigeria on 11 July 1991, which caught fire shortly after takeoff from King Abdulaziz International Airport and crashed while attempting to return for an emergency landing, killing all 247 passengers and 14 crew members on board. The aircraft was a Douglas DC-8 operated by Nationair for Nigeria Airways. Flight 2120 is the deadliest accident involving a DC-8 and remains the deadliest aviation disaster involving a Canadian airline.

The aircraft departed King Abdulaziz International Airport bound for Sadiq Abubakar III International Airport in Sokoto, but problems were reported shortly after takeoff. Unknown to the crew, the aircraft had caught fire during departure, and though the fire itself was not obvious since it started in an area without fire warning systems, the effects were numerous. Pressurization failed quickly, and the crew was deluged with nonsensical warnings caused by fire-related circuit failures. In response to the pressurization failure, Allan decided to remain at 610 metres (2,000 ft), but the flight was cleared to 910 metres (2,990 ft) as a result of the controller mistaking Flight 2120 for a Saudia flight that was also reporting pressurization problems due to Captain Allan mistakenly identifying as "Nationair 2120" rather than "Nigerian 2120", a mix-up that lasted for three minutes but was ultimately found not to have had any effect on the outcome. Amidst this, First Officer Davidge, who had been flying C-GMXQ out, reported that he was losing hydraulics. The crew only became aware of the fire when a flight attendant rushed into the cockpit reporting "smoke in the back ... real bad". Shortly afterwards, Davidge reported that he had lost ailerons, forcing Allan to take control; as Allan took over, the cockpit voice recorder failed. At this moment, the air traffic controller realized that Flight 2120 was not the Saudia flight and was in trouble, and directed them towards the runway. Allan subsequently contacted air traffic control multiple times, among his pre-mortem communications being a request for emergency vehicles.

When the aircraft was about 18 kilometres (11 mi; 9.7 nmi) from the airport and at an altitude of 671 metres (2,201 ft), a point where the landing gear could conceivably have been lowered, it began to experience an inflight breakup and a number of bodies fell from it, indicating that the fire by that time had consumed, at least partially, the cabin floor. Just 2,875 metres (9,432 ft) short of the runway, the melting aircraft finally became uncontrollable and crashed, killing whatever portion of the 261 occupants on board—including 247 passengers—had not already suffocated or fallen out of the aircraft. Nine of the fourteen crew were identified, but "no attempt was made to identify the passengers".