The Way this Louisville UPS Aircraft Accident Developed and Potential Might Have Led to It

No fewer than nine people lost their lives and 11 left injured after a freight aircraft went down during departure from a major air hub in Kentucky's largest city on Tuesday evening.

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

The exact cause remains unknown why the aircraft failed, prompting a huge explosion to erupt after it couldn't become airborne from the airstrip. Video evidence revealed flames were consuming a single wing of the plane during its takeoff attempt, which may have spread across the aircraft and caused the explosion, or the jet could have caught fire after colliding with an object on the ground.

What's clear is that the 38,000 gallons of fuel aboard the trijet aircraft needed for the flight probably intensified the fire, which quickly spread to several buildings past the airstrip and continued burning for hours.

How did it start?

The shipping giant operates from Louisville Muhammad Ali International Airport as a logistics center for its global operations and its designated flight was beginning of a 4,300 mile trip to Hawaii's capital when the freight aircraft attempted to take off.

Data from flight monitoring services indicates the plane began to taxi along the designated runway at around 17:15 local time and attained a top speed of 214mph.

But verified footage demonstrate 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.

Officials issued a shelter-in-place order to local residents and dispatched numerous fire crews to the location.

The state's governor 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 erupts around it about a minute into its journey.

Authenticated footage taken by drivers on adjacent roads displayed the fire rising into the air while later videos revealed smoke pouring from the area.

Overhead photographs broadcast by regional news outlets showed debris showering the runway and falling onto the roofs of multiple nearby establishments.

Potential causes of the accident

ATC transmissions examined are largely garbled and full of interference so no clear dialogue can be heard about the incident as it unfolded.

However, experts suggested that a catastrophic malfunction of two of the engines may have been responsible for the tragedy.

The trijet cargo aircraft employs three engines. Two are mounted under the wings, and a third is positioned in the tail at the base of the vertical stabilizer.

Video verified revealed a blaze engulfing the left wing of the plane, which then tilted to the left as it attempted to gain lift and take-off.

Two experts independently suggested the portside engine may have separated from the plane after suffering from a technical or physical breakdown.

Separate images taken after the crash showed a charred engine sitting on the grass adjacent to the airstrip.

An experienced former aviator and aviation safety expert said that it was "extremely rare" for an engine to detach in flight.

The expert recalled the 1979 aviation disaster tragedy, in which 273 people were killed when the aircraft's powerplant separated as it departed from O'Hare International Airport. Parts of the engine had been compromised when it was installed on the aircraft, but the specialist stated it was premature to determine whether a similar fault caused the powerplant separation on the MD-11.

The specialist explained the freight aircraft would have been capable of flight with only two powerplants but the destruction caused by the fire on the left wing was probably extensive enough it resulted in the aircraft's remaining engine to lose thrust.

"Given the severe nature of the incident we cannot determine additional destruction was caused when the engine came adrift," the expert commented.

A different aircraft specialist observed the footage seemed to indicate the remaining powerplant had been compromised because it expelled a burst of smoke. The damage could have happened while it was pelted with debris from the blaze and the engine detaching.

"The tail-mounted powerplant that released smoke appears to wind down right after," the specialist said. "This left just the right engine generating power, creating a significant thrust asymmetry and making the plane incapable to gain height.

"Failing two powerplants during take-off leaves the aircraft with only a fraction of its thrust and little chance of maintaining flight, especially at full departure mass," the expert added.

Why did the crash cause such damage?

Footage from the aftermath showed a situation of total disorder with multiple fires burning across a large swathe of the location and smoke billowing into the sky.

The plane, which was three decades old and had been used as a passenger plane until 2006, had previously made one round trip from Louisville to the East Coast on the same day.

Authorities haven't verified which goods was aboard the flight bound for Hawaii, though authorities said the plane was not carrying anything that would create a heightened risk of environmental hazard.

"This was a long-haul cargo flight from Louisville to Honolulu, so the MD-11 was carrying a lot of jet fuel," a specialist said. "The substantial fuel quantity not only diminished capability but also accounts for the large fireball seen after the crash."

Authorities told reporters that the aircraft was transporting 144,000 litres of jet fuel for the long journey when it crashed. The blaze was likely amplified on the surface because the aircraft slammed into a fuel processing facility next to the airport.

The expert indicated authorities will concentrate on the origin of the blaze, and "whether debris struck the central powerplant, and whether earlier maintenance on the left engine were a factor." He added: "Atmospheric conditions were favorable, so weather-related causes are unlikely."

The National Transportation Safety Board has sent a team to the site and will take charge of the probe into the causes of the crash, though such inquiries may require years to complete.