Determining what caused the engine failure that resulted in the crash of the Dana Air flight 993 on June 3 may be impossible as the Accident Investigation Bureau has revealed that the flight data recorder, a major part of the black box, was destroyed in the explosion.

The AIB on Thursday released a preliminary report on their investigations into the crash of the MD83 aircraft in Lagos that killed 153 passengers aboard the ill-fated flight and more on the ground.

The team was able to salvage 31 minutes from the cockpit voice recorder, which detailed the conversation between the pilots and the control room, in the last moments before the plane crashed into the Iju Ishaga residential area in Lagos.

According to the AIB report, both the recorders, the Cockpit Voice Recorder and the Flight Data Recorder, were analyzed by the National Transportation Safety Board in Washington, DC in the United States.

“The digital tape-based memory in the FDR succumbed to the post-crash fire and melted, consequently no data could be recovered,” the report said. The AIB boss, Capt. Muktar Usman, says investigations will continue, but aviation experts have said that without the Flight Data Recorder, no meaningful information can come of it.

The report revealed that 15 per cent of the plane, its wings and engines, were recovered from the Iju Ishaga crash site and are currently being thoroughly examined.

The detailed investigation also includes examination of the fuel records, which have revealed the fueling of the aircraft was in good condition; other aspects of the the investigation include interviews with relevant personnel, detailed examination of the engines, further testing of fuel samples, continued fact gathering on relevant historical, operational, maintenance and performance information on the MD83 aircraft.

Background checks will also be conducted on the flight crew and the 31 minutes of audio recording from the CVR will be analyzed in detail.

The audio recording included harrowing details of the last minutes, seconds, before the plane plummeted into the residential building in the populated Lagos neighborhood.

The report painted the following timeline:

• 3:41 p.m., Sunday 3 June 2012 – “At 15:41:16 the first officer inquired, ‘Both engines coming up?’ and the captain replied ‘negative.’ The flight crew subsequently discussed and agreed to declare an emergency.”
• 3:42 p.m., Sunday 3 June 2012 – “At 15:42:10, DANA 992 radioed an emergency distress call indicating ‘dual engine failure … negative response from throttle.’”
• 3:42 p.m., Sunday 3 June 2012 – “At 15:42:35, the flight crew lowered the flaps further and continued with the approach and discussed landing alternatively on runway 18L.
• 3:42 p.m., Sunday 3 June 2012 – “At 15:42:45, the Capt reported the runway in sight and instructed the FO to raise the flaps up and four seconds later to raise the landing gear.
• 3:43 p.m., Sunday 3 June 2012 – “At 15:43:27 hours, the Capt informed the FO ‘we just lost everything, we lost an engine. I lost both engines.’
• 3:46 p.m., Sunday 3 June 2012 – Plane crashed at 15:46 hours. “During the next 25 seconds until the end of the CVR recording, the flight crew was attempting to restart the engines.”

“The airplane crashed in a residential area about 5.8 miles north of LOS. The airplane wreckage was on approximately the extended centreline of runway 18R. During the impact sequence, the airplane struck an incomplete building, two trees and three buildings. The wreckage was confined, with the separated tail section and engines located at the beginning of the debris field.”

Usman also added details from the report, saying the air disaster killed a confirmed 163 people – the 153 passengers, including six crew members, and 10 more on the ground. The AIB boss explained that the airplane was on its fourth flight segment of the day, consisting of two round-trips between Abuja and Lagos.

It was minutes away from making a landing on runway 18R at Lagos “when the crew reported total loss of power”.

He went on to add that DAN 992 started its engines at 2:36 p.m., taxied to the runway and went airborne at 2:58 and was estimated to land at 3:45 p.m.

The audio from the CVR, which started at 15:15 hours, noted that Captain Peter Waxtan and the first officer had discussed a “non-normal condition regarding the correlation between the engine throttle setting and an engine power indication”.

“However, they did not voice concerns then that the condition would affect the continuation of the flight. The flight crew continued to monitor the condition and became increasingly concerned as the flight transition through the initial descent from cruise altitude at 15:22 and the subsequent approach phase.

“DAN 992 reported passing through 18,100 feet and 7,700 feet, respectively, at 15:30 and 15.40 hours. After receiving a series of heading and altitude assignments from the controller, DAN 992 was issued the final heading to intercept the final approach course for runway 18R.

“During the period of 15:37 and 15:41, the flight crew engaged in pre-landing tasks, including deployment of the slats, and extension of the flaps and landing gear,” Usman said; however failed engines and an unresponsive throttle resulted in the crash that is considered one of the nation’s worst air disasters to date.