What could have caused UPS cargo plane crash in Kentucky

At least 11 people were killed and more than a dozen others were injured when a UPS cargo plane crashed while taking off from an airport in Louisville, Kentucky, Tuesday evening.

Aviation experts told BBC Verify that the plane crashed because one engine failed and the other was damaged during take-off.

It is not yet known what caused the plane to crash and explode in a huge fireball after failing to take off from the runway. The images show that the fire engulfed one of the wings of the plane as it was trying to take off, which could have spread to the plane and caused an explosion, or the jet might have caught fire after hitting an object on the ground.

The National Transportation Safety Board (NTSB), which is investigating the crash, said they obtained airport CCTV footage showing the plane’s left engine falling off the wing during takeoff.

The agency also recovered the cockpit flight recorder and the flight data recorder, known as a black box, from the wreckage, NTSB’s Todd Inman said.

It is also clear that the 38,000 gallons (144,000 liters) of fuel in the MD-11 jet required for the flight likely escalated the fire, which quickly spread to several buildings beyond the runway and burned for hours.

BBC Verify is analyzing footage from the night to piece together how the crash happened.

UPS uses Louisville Muhammad Ali International Airport as a distribution center for its global operations, and its Flight 2976 was at the beginning of the 4,300-mile journey to Honolulu, Hawaii, when the cargo plane attempted to take off.

Data from tracking website FlightRadar24 shows that the aircraft began traveling along runway 17R around 17:15 local time (22:15 GMT) and managed to reach a top speed of 214 mph (344 km/h).

However, confirmed images show that when the plane reached this speed, a fire completely engulfed its left wing and the plane tried to move away from the runway before it exploded.

The NTSB said the plane’s engine burned out as it attempted to take off and then separated from the wing. The aircraft managed to climb to an altitude of 175 ft and cleared the fence at the end of the runway before veering into the buildings and businesses surrounding the airport.

Authorities issued shelter-in-place orders for residents and sent hundreds of firefighters to the scene.

Governor Andy Beshear confirmed details in CCTV footage showing the plane flying just a few feet above the ground before a bright flash engulfed the plane. He is then seen crashing into the ground about a minute into his journey as a large fireball explodes around him.

A verified clip taken by a motorist on a nearby highway showed flames rising towards the skyline, while later videos showed smoke rising from the scene.

Aerial footage published by local media showed debris raining down on the runway and landing on the roofs of at least two local businesses.

No meaningful conversation about the crash can be heard as air traffic control communications reviewed by BBC Verify are largely garbled and riddled with interference.

However, analysts speaking to BBC Verify suggested that a serious fault in two engines may have been responsible for the disaster.

The MD-11 transport aircraft uses three engines. Two of them are mounted under the wings, and the third is located in the tail at the base of the vertical stabilizer.

Footage verified by BBC Verify showed a flame engulfing the plane’s left wing, which then tilted to the left as it attempted lift and takeoff.

Two experts independently suggested that the left engine may have separated from the aircraft due to a mechanical or structural failure. The NTSB later confirmed that the left engine separated from the aircraft’s wing during takeoff.

Separate images taken after the crash showed a charred engine lying on the grass next to the runway at Louisville International Airport.

Retired airline pilot and aviation safety expert Terry Tozer told BBC Verify it was “almost unheard of” for an engine to separate during flight.

He referenced the American Airlines Flight 191 disaster in 1979, when 273 people died when the plane’s engine separated while taking off from Chicago’s O’Hare International Airport. Engine parts were damaged while being replaced on the plane, but Mr. Tozer said it was too early to say whether a similar failure caused the engine to separate in the MD-11.

Mr. Tozer said the cargo plane could fly with just two engines, but the damage caused by the fire to the left wing was likely so extensive that it caused the plane’s tail-based engine to lose thrust.

“With such a catastrophic event, we cannot know what other damage may have been caused by the engine drifting,” he said.

Marco Chan, senior lecturer in aviation operations at Buckinghamshire New University, said images showed the third engine was damaged by a smoke explosion. The damage may have occurred when debris from the fire rained down on the vehicle and the engine separated.

“The upper engine, which was emitting some smoke, seemed to slow down immediately afterwards,” Mr Chan said. “This caused only the correct engine to produce thrust, creating a severe power imbalance and causing the aircraft to fail to gain altitude.

“Losing two engines during takeoff leaves the aircraft with only a third of its power and little chance of sustaining flight, especially at maximum takeoff weight,” Mr Chan added.

Images taken after the accident showed a scene of complete chaos, with multiple fires blazing across a large section of the facility and smoke billowing into the sky.

The 34-year-old plane, which was used as a passenger plane until 2006, completed its return trip from Louisville to Baltimore, Maryland, on Tuesday.

It was not confirmed what cargo was on the Hawaii-bound flight, but officials said the plane did not carry anything that would pose a high risk of contamination.

“This was a long-haul cargo flight from Louisville to Honolulu, so the MD-11 was carrying a lot of jet fuel,” Mr. Chan said. “This heavy fuel load not only reduces performance but also explains the large fireball seen after the crash.”

Officials told reporters that the plane was carrying 38,000 gallons (144,000 liters) of fuel for the long journey when it crashed. The fire is likely to grow further on the ground as the plane crashed into a fuel recycling business next to the airport.

Mr Chan said investigators would now focus on how the initial fire started and “whether debris hit the middle engine and whether previous maintenance on the left engine played a role”. He added: “Weather conditions were calm and clear so environmental factors are unlikely.”

The National Transportation Safety Board (NSTB) sent a team to the area and will now conduct an investigation into the causes of the crash, but that investigation could take up to two years to complete.

Additional reporting by Emma Pengelly, Kayleen Devlin and Paul Brown.