Two equipment, Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) were found by a team from the Accident Investigation Bureau (AIB) on Monday from the wreckage of the MD 83 aircraft.
They were handed to AIB's Director of Engineering, Emmanuel Diala, at the site of the crash.
Our reporter quoted a civil aviation chief as saying that the engines of the aircraft failed before it went down.
"They declared mayday," Nigerian Civil Aviation chief, Harold Demuren, told AFP. "The reason was that the two engines failed."
The clues emerged as rescuers recovered burnt human remains after the plane slammed into the neighbourhood on the northern outskirts of one of Africa's largest cities, making it one of the country's worst air disasters.
There were concerns that the inability to find the two black boxes could make investigation very cumbersome but not impossible. Stakeholders based their concern on the tumultuous crowd that swarmed around the wreckage on Sunday as security operatives had a difficult time in dispersing them.
Like in the case of Bellview crash in Lisa, Ogun State, the CVR and FDR were never found, thereby making probe into the crash difficult as some persons had contaminated the scene.
Flight Data Recorder (FDR) (also ADR, for Accident Data Recorder) is an electronic device employed to record any instructions sent to any electronic systems on an aircraft.
It is a device used to record specific aircraft performance parameters. Another kind of flight recorder is the Cockpit Voice Recorder (CVR), which records conversation in the cockpit, radio communications between the cockpit crew and others (including conversation with air traffic control personnel), as well as ambient sounds. Both functions have been combined into a single unit. The current applicable FAA TSO is C124b titled Flight Data Recorder Systems.
Popularly referred to as a "black box," the data recorded by the FDR is used for accident investigation, as well as for analysing air safety issues, material degradation and engine performance.
Due to their importance in investigating accidents, these ICAO-regulated devices are carefully engineered and stoutly constructed to withstand the force of a high-speed impact and the heat of an intense fire.
Contrary to the "black box" reference, the exterior of the FDR is coated with heat-resistant bright orange paint for high visibility in wreckage, and the unit is usually mounted in the aircraft's empennage (tail section), where it is more likely to survive a severe crash. Following an accident, the recovery of the FDR is usually a high priority for the investigative body, as analysis of the recorded parameters can often detect and identify causes or contributing factors.
A Cockpit Voice Recorder (CVR), often referred to as a "black box," is a flight recorder used to record the audio environment in the flight deck of an aircraft for the purpose of investigation of accidents and incidents.
This is typically achieved by recording the signals of the microphones and earphones of the pilots' headsets and of an area microphone in the roof of the cockpit. The current applicable FAA TSO is C123b titled Cockpit Voice Recorder Equipment.
Where an aircraft is required to carry a CVR and utilises digital communications, the CVR is required to record such communications with air traffic control unless this is recorded elsewhere.
As of 2005, it is America's Federal Aviation Administration (FAA) requirement that the recording duration is a minimum of 30 minutes, but the NTSB has long recommended that it should be at least two hours.