Tanzanian authorities said Thursday that the pilots who flew a Precision Air plane which crashed into Lake Victoria last November failed to heed warnings from an automatic "pull up" alarm system.
Nineteen people died when the plane plunged into Africa's largest lake on November 6 last year, with police blaming bad weather for Tanzania's worst aviation accident in decades.
President Samia Suluhu Hassan promised a formal investigation into the disaster as anger erupted over the government's handling of the rescue effort.
In the second preliminary report to be published since the accident, the transport ministry said Thursday that an enhanced ground proximity warning system (EGPWS) issued three alerts "about the excessively high descent rate".
"The warning was not followed by corrective action of the flight crew," the ministry's aircraft accident and incident investigation branch said.
"Instead, the flight crew pushed the control column into a nose down position."
The EGPWS alerts the cockpit if a plane is in danger of flying into the ground or hitting something.
The report said the pilots were flying in bad weather and in conditions marked by poor visibility, which "may have contributed to the failure to react to terrain warnings during the final approach."
"This type of weather is common around the Bukoba airport and is well known to pilots," it said, adding that the aircraft circled for about 20 minutes before its descent.
An earlier report published by the ministry soon after the accident said the rescue effort was too slow, and that more passengers would likely have survived had emergency workers been better prepared and equipped to carry out their duties.
Fishermen, who were the first to arrive on the scene, used canoes to pluck people to safety after a crew member unlocked a rear door, allowing survivors to get out.
But most of the victims were in the submerged front of the plane, while the two pilots were unable to escape the cockpit.
Investigators said the cause of the crash was still being probed.
Precision Air, which is partly owned by Kenya Airways, said 39 passengers and four crew members were on board flight PW 494 from financial capital Dar es Salaam to the northwestern city of Bukoba.