Image copyright Jonathan Druion Image caption The Boeing 737 Max-8 aircraft that crashed soon after take-off

Details have begun to emerge of the final moments of an Ethiopian Airlines flight which crashed three weeks ago.

An anti-stalling system on the plane, a Boeing 737 Max, has been blamed for the disaster which killed all 157 people on board.

Soon after take-off - and just 450ft (137m) above the ground - the aircraft's nose began to pitch down.

One pilot, according to the Wall Street Journal, said to the other "pitch up, pitch up!" before their radio died.

The plane crashed only six minutes into its flight.

'Catastrophic failure'

The Wall Street Journal - which says it has spoken to people close to the ongoing investigation - says the information it has "paints a picture of a catastrophic failure that quickly overwhelmed the flight crew".

Leaks this week from the crash investigation in Ethiopia and in the US suggest an automatic anti-stall system was activated at the time of the disaster.

The Manoeuvring Characteristics Augmentation System (MCAS) flight-control feature was also implicated in a fatal crash involving a Lion Air flight in Indonesia last October.

The Boeing 737 Max went down shortly after take-off from Jakarta, killing all 189 people on board.

Image copyright Getty Images Image caption All 157 passengers and crew on board were killed during the crash earlier this month

An investigation of the Lion Air flight suggested the anti-stall system malfunctioned, and forced the plane's nose down more than 20 times before it crashed into the sea.

The Ethiopian authorities have already said there are "clear similarities" between the Lion Air incident and the Ethiopian Airlines crash.

The airline and authorities have refused to comment on leaks from the investigation.

Concerns about the Boeing 737 Max have led to a worldwide grounding of the plane.

System update

Boeing has redesigned the software so that it will disable MCAS if it receives conflicting data from its sensors.

As part of the upgrade, Boeing will install an extra warning system on all 737 Max aircraft, which was previously an optional safety feature.

Neither of the two planes that were involved in the fatal crashes carried the alert systems, which are designed to warn pilots when sensors produce contradictory readings.

The aircraft update is designed to ensure the MCAS will no longer repeatedly make corrections when a pilot tries to regain control.

Boeing is also revising pilot training to provide "enhanced understanding of the 737 MAX" flight system and crew procedures.

Image copyright Getty Images Image caption Investigators have not yet determined the cause of the accident, which took place just minutes after the plane took off from Bole Aiport in Ethiopia

Earlier this week, Boeing said that the upgrades were not an admission that the system had caused the crashes.

Investigators have not yet determined the cause of the accidents, but a preliminary report from Ethiopian authorities is expected within days.

Boeing has tried to restore its battered reputation, while continuing to insist the 737 Max is safe.