🔗 Share this article

At least nine people have died and 11 others were hurt following a UPS cargo plane crashed during departure from a major air hub in Kentucky's largest city on Tuesday evening.

Aviation experts believe the plane crashed after a single engine malfunctioned and a second seemed compromised while lifting off.

It is unclear what caused the plane to crash, leading to a massive fireball to ignite after it couldn't become airborne from the runway. Video evidence revealed flames were consuming one wing of the plane while it was attempting to take off, potentially spreading through the plane and triggered the blast, or the plane might have ignited upon hitting an object on the ground.

What's clear is that the 144,000 litres of fuel aboard the trijet aircraft required for the journey probably intensified the fire, which rapidly extended to several buildings past the airstrip and burned for hours.

How did it start?

UPS uses the Louisville air hub as a logistics center for its global operations and its Flight 2976 was at the start of a 4,300 mile journey to Hawaii's capital when the freight aircraft initiated departure.

Tracking information from flight monitoring services indicates the plane started moving along the designated runway at around 17:15 local time and managed to reach a top speed of 344km/h.

But verified footage shows that when the plane reached this speed a fire had completely engulfed its port side and the plane couldn't climb before the massive explosion.

Authorities activated a shelter-in-place order to area inhabitants and dispatched numerous fire crews to the scene.

Governor Andy Beshear verified details seen in CCTV footage that shows the plane traveling just metres off the ground before a bright flash consumed the aircraft. It is then seen slamming into the terrain as a huge fireball ignites surrounding it about a minute into its journey.

Authenticated footage taken by motorists on a nearby highway displayed the flames erupting into the skyline while subsequent recordings revealed smoke pouring from the area.

Overhead photographs shown on regional news outlets depicted wreckage scattering across the airstrip and falling onto the tops of at least two local businesses.

Potential causes of the accident

Air traffic control communications reviewed are largely garbled and full of interference so no meaningful conversation can be heard about the incident as it unfolded.

But analysts proposed that a dramatic failure of multiple engines may have been the cause of the disaster.

The MD-11 transport plane uses three engines. Two are installed under the airfoils, and a third is positioned in the tail at the bottom of the tail fin.

Video verified showed a fire consuming the port wing of the aircraft, which then leaned leftward as it tried to achieve altitude and become airborne.

Two experts separately proposed the portside engine may have separated from the plane after suffering from a mechanical or structural failure.

Separate images taken after the crash displayed a burned powerplant resting on the grass adjacent to the airstrip.

An experienced former aviator and aircraft safety specialist said that it was "extremely rare" for an powerplant to separate during operation.

The expert recalled the 1979 American Airlines Flight 191 disaster, in which 273 people were fatally injured when the plane's engine detached as it took off from O'Hare International Airport. Parts of the engine had been damaged when it was installed on the aircraft, but the specialist stated it was too early to say whether a comparable issue caused the engine to detach on the MD-11.

The expert said the freight aircraft would have been able to fly with only two powerplants but the destruction caused by the fire on the left wing was likely so great it caused the plane's third engine to lose thrust.

"With such a catastrophic event we cannot know additional destruction was done when the engine came adrift," the expert commented.

A different aircraft specialist said the footage appeared to show the remaining powerplant had been compromised because it released smoke. The damage could have happened while it was struck by wreckage from the blaze and the engine detaching.

"The tail-mounted powerplant that released smoke seems to shut down almost immediately afterwards," the specialist said. "This left just the right engine generating power, creating a severe power imbalance and leaving the aircraft unable to gain height.

"Failing two powerplants while departing leaves the aircraft with only a third of its power and little chance of staying airborne, especially at maximum take-off weight," the specialist added.

Reasons for extensive destruction

Post-accident videos revealed a situation of total disorder with numerous blazes blazing across a extensive area of the location and smoke rising upward.

The plane, which was 34 years old and had been used as a passenger plane before conversion, had already completed one round trip from the Kentucky hub to Baltimore in Maryland on Tuesday.

Authorities haven't verified which goods was on board the flight bound for Hawaii, though authorities said the aircraft didn't contain anything that would pose an increased danger of environmental hazard.

"This involved extended freight transport from Louisville to Honolulu, so the trijet was carrying a lot of jet fuel," a specialist commented. "The substantial fuel quantity not only diminished capability but also accounts for the massive explosion seen after the crash."

Authorities informed media that the plane was carrying 38,000 gallons of fuel for the long journey when it crashed. The blaze was probably intensified on the surface because the plane crashed into a fuel processing facility next to the airport.

A specialist said authorities will concentrate on the origin of the blaze, and "if wreckage hit the central powerplant, and whether earlier maintenance on the portside powerplant played a role." The expert continued: "Weather conditions were calm and clear, so environmental factors are improbable."

The federal investigation agency has sent a team to the site and will take charge of the investigation into the causes of the crash, though this can take up to two years to complete.