The pilot of the Dana Air flight Sunday radioed "mayday" shortly before crashing in Lagos, Nigeria. The pilot also reported "two engines had failed," according to Harold Demuren, the director of Nigeria's civil aviation authority.
The 22-year-old McDonnell Douglas 83 has only two Pratt & Whitney engines. That means that, as the aircraft was approaching Lagos after a one-hour flight from Abuja, Nigeria's capital, it was effectively without power.
What would cause both engines to fail?
While the investigation into what caused this jet to crash – killing all 153 people on board and an as yet unknown number of people on the ground – won't produce a report for months, pilot and aviation safety forums have already begun speculating.
Jet engines, even old ones, rarely fail. And it's even more unusual for both engines to stop.
The speculation centers on two possible causes: bird strike or lack of fuel.
In fact, this same Dana Air jet lost an engine when several birds were ingested as it took off from Lagos airport (which is near the Atlantic Ocean) in 2010, according to the Aviation Safety Network. The aircraft made an emergency landing on April 19, 2010. No one was injured.
The other leading theory is that the aircraft ran out of fuel. Running out of fuel is less common than a bird strike, but it does happen.
In 2001, Air Transat flight 236 from Toronto to Portugal ran out of fuel over the Atlantic Ocean. The Airbus 330 instruments indicated that there was a fuel imbalance – meaning one tank had more fuel than the other. Following standard procedure, the pilots transferred fuel from one tank to another. Unknown to the pilots, the twin-engine aircraft had developed a fuel leak in a fuel line to its right engine. First, one engine died due to fuel starvation. Still running on one engine, the pilots decided to divert to a nearer airport. Thirteen minutes later, the second engine died. The aircraft, with 306 people on board, was still 65 miles from the airport.
The pilots were able glide the plane to a rough landing at Lajes Air Base in the Azores. Everyone survived. An investigation by Portuguese aviation authorities found that the fuel leak in the No. 2 engine was caused by the use of the wrong part, installed by the maintenance crew, which didn't fit correctly.
"My very early *speculation* would be that the [Nigeria] plane ran out of fuel, in which case both engines would be lost," says Aerospace engineering professor Ella Atkins at the University of Michigan, in an e-mail. "If this happened on approach with insufficient altitude to glide to the runway, the plane would be forced to land somewhere on the approach path, and in a densely-populated region there may not be many choices."
Professor Atkins adds: "The MD-83 that crashed had a three-person cockpit crew including a human flight engineer responsible for managing fuel. If it turns out to be the case that poor fuel management was a factor, this is important to share with the public, particularly given fear of automation these days. Newer two-crew aircraft with advanced flight management systems continuously predict fuel use and expected reserves on landing based on real-time fuel flow data and the flight plan, making it far less likely the more automated aircraft will run out before reaching its destination."
While the Monitor was among those reporting that the age of the aircraft may have been a factor, pilot blogs suggest that aircraft maintenance is a more likely culprit. "The MD-83 was maybe not the youngest aircraft but I agree with you totally: 1990 is not old," wrote IberiaMD-87, a regular contributor to JetPhotos.net aviation discussion forums.
Dana Air told reporters that an investigation into the cause of the crash was already underway. "We extend our deepest sympathies to the families and friends of the deceased, and we are doing everything we can to assist them in this extremely difficult time," a statement signed by Dana Air CEO Jacky Hathiramani read.