Analysis of the flight recorders of the crashed Ethiopian Airlines plane has begun, the airline said, amid reports that the pilot requested permission “in a panicky voice” to return to the airport shortly after take-off.

The New York Times cited “a person who reviewed air traffic communications” from Sunday’s flight saying controllers noticed the plane was moving sharply up and down by hundreds of feet and appeared to gain speed.

An airline spokesman has said the pilot was given permission to return, but the plane crashed minutes later outside Addis Ababa, killing all 157 on board.

French authorities have the plane’s flight data and voice recorders for analysis, but have said it is unclear whether data could be retrieved. The data recorder appeared to be damaged.

Ethiopian Airlines said a delegation led by its chief accident investigator had arrived in Paris.

In Ethiopia, officials started taking DNA samples from victims’ family members to assist in identifying remains. The dead came from 35 countries.

Mourners at the scene
Mourners at the scene (Mulugeta Ayene/AP)

Nations including the US have grounded the Boeing 737 Max 8 as the American company faces the challenge of proving the jets are safe to fly amid suspicions that faulty software might have contributed to two crashes that killed 346 people in less than six months.

The decision to send the flight recorders to France was seen as a rebuke to the US, which held out longer than most other countries in grounding the jets. The US National Transportation Safety Board sent three investigators to help French authorities.

The US Federal Aviation Administration said regulators had new data from satellite-based tracking that showed the movements of Ethiopian Airlines Flight 302 were similar to those of Lion Air Flight 610. That flight crashed into the Java Sea off Indonesia in October, killing 189 people.

An engine recovered from the crashed Lion Air jet
An engine recovered from the crashed Lion Air jet (Achmad Ibrahim/AP)

The data shows both planes flew with erratic altitude changes that could indicate the pilots struggled to control the aircraft. Both crews tried to return to the airport.

Boeing said it supports the grounding of its planes as a precautionary step, while reiterating its “full confidence” in the safety of the 737 Max.

Engineers are making changes to the system designed to prevent an aerodynamic stall if sensors detect that the jet’s nose is pointed too high and its speed is too slow.

Boeing also announced it had paused delivery of the Max, although the company planned to continue building the jets.

Boeing 737 Max jets are grounded at Sky Harbour International Airport in Phoenix
Boeing 737 Max jets are grounded at Sky Harbour International Airport in Phoenix (Matt York/AP)

Investigators looking into the Indonesian crash are examining whether software automatically pushed the plane’s nose down repeatedly, and whether the Lion Air pilots knew how to solve that problem.

Ethiopian Airlines says its pilots received special training on the software.

At the crash site in Hejere, about 30 miles from Addis Ababa, searchers continued to pick through the debris. Blue plastic sheeting covered the wreckage of the plane.

Anxious family members began giving DNA samples and waited for news on the identification of remains. Members of Israel’s Zaka emergency response team were granted access to the site for forensic work.