The terrifying reason why LATAM flight could have suddenly dropped

A passenger aboard LATAM flight LA800 has recounted seeing passengers levitating after the aircraft dropped suddenly, injuring 50 passengers.

The mid-air chaos unfolded when the aircraft was about two hours into its flight from Sydney to Auckland, and is now being investigated by Chilean and New Zealand authorities.

"There was one younger boy, in front of me, who was quite traumatised upon seeing his father levitate," passenger Lucas Ellwood said.

The LATAM Airlines Boeing 787 departed Sydney for Auckland at 11.44am local time, but two hours in it experienced what the airline is calling a "technical event" and "sudden movement". It corrected and carried onto Auckland carrying dozens of injured passengers. 

Ellwood told Newshub the terrifying drop happened just after lunch was cleared. 

"People were still finishing their drinks and when the jolt happened, the wine, the unseat-belted people and lots of bags and cell phones all hit the roof," Ellwood said.

Footage was shot from inside the aircraft just after the plane malfunctioned and showed passengers assisting the injured. A photo taken by passenger Brian Jokat showed people hit the roof so hard it caved in. 

"The plane, as I've kind of learnt to understand, dropped something to the effect of 500 feet instantly and then had the effect of it coming like a roller coaster and then started to point down," Jokat said.

Jokat said the pilot told him the instrument panel went blank and he lost control of the plane for a second.

An aviation expert and pilot said a computer malfunction could be one possible explanation for this incident. 

"The most likely one would be possibly a malfunction in the autopilot, when the pilots were least expecting it," Massey University School of Aviation CEO Ashok Poduval said.

In 2008, incorrect data sent to a computer on a Qantas flight caused the autopilot to shut down and the plane suddenly lost altitude. In that incident, 70 people were injured. 

"If you look back at the total number of incidents within the industry, it's extremely rare which is why I refer to it as a black swan," Poduval said.

A black swan incident - one that fortunately wasn't fatal.