Nigeria's air transport industry appeared to have transformed itself into a small aviation safety success story. But that image is crumbling following two fatal crashes within two days and the grounding of two carriers over safety concerns. Now the search for the root causes begins.

On June 3 a Dana Air MD-83 crashed on final approach to Lagos International Airport following what likely was a dual engine failure. All 153 on board and 10 people on the ground died when the aircraft hit industrial and residential buildings 4-5 nm from the threshold of Runway 18. A day earlier another Nigerian airline, Allied Cargo, lost a Boeing 727-200 on approach to Kotoka International Airport in Accra, Ghana. The aircraft overran Runway 21 after landing in what has been described as a severe thunderstorm. The 727 breached the airport's perimeter fence, crossed a road and hit two cars and a bicyclist. Twelve people on the ground were killed; the crew of five survived with injuries.

And on June 12, the Nigerian Civil Aviation Administration (NCAA) temporarily halted Air Nigeria's domestic operations. This measure was taken to perform a safety audit following a one-week strike by pilots and engineers that had grounded the aircraft. Dana Air has also been grounded since June 4.

NCAA stated the audit was a “routine procedure.” But Air Nigeria, formerly Virgin Nigeria Airways, has been facing allegations about unsafe operations for some time. John Nnorom, the airline's former finance director, claimed in a highly charged public announcement last April that engineers were forced to sign off on aircraft that were unfit to fly. Only one of the company's 11 aircraft was airworthy, he said, but all the rest needed “deep and heavy maintenance.” Nnorom also claimed that the airline could not afford to perform mandatory checks. Air Nigeria denied the allegations.

The latest developments have been a fundamental setback for aviation in one of Africa's largest countries and healthiest economies. The country began to tackle aviation safety in a serious manner in 2005 when Harold Demuren, an internationally respected air transport expert and former head of the International Civil Aviation Organization (ICAO) Council, was appointed to head the NCAA with a mandate to improve safety.

And he did so, believes Gunther Matschnigg, senior vice president-safety, operations and infrastructure at the International Air Transport Association (IATA). “There has been a clear improvement in oversight,” Matschnigg points out. And Demuren also pushed through steps against non-compliant carriers. “A dozen airlines were shut down,” Matschnigg says. Demuren's fight to improve standards was opposed by the affected airlines and by local politicians. Nevertheless, Demuren prevailed. The country had not experienced a fatal accident for the last six years.

Ironically, following the two latest accidents, NCAA and its leader are being accused of not having done enough to improve aviation safety. Stella Oduah, Nigeria's aviation minister, appointed a panel to review “technical and administrative practices.” Demuren is facing calls for his resignation. The country's senate recommends his suspension. But IATA and the Flight Safety Foundation have urged authorities to not let politics interfere with accident investigations and flight safety oversight.

The situation in Nigeria has put African aviation safety back into the spotlight. According to IATA, the rate of hull losses per million sectors flown improved to 6.17 in 2011 from 15.68 in 2010. The figures include Western- and Eastern-built jets as well as turboprops. Matschnigg says the performance this year so far has not changed much. But at a recent IATA regional summit on airline safety, a five-point action plan for Africa was drawn up calling for:

•Government-initiated development of robust safety oversight.

•Focus on runway excursions—the most common accident category in the region.

•Loss-of-control prevention training. •Improved data sharing.

•More widespread use of IATA's Operational Safety Audit (IOSA).

In Nigeria, only two carriers have undergone IOSA—Arik Air and Air Nigeria, the airline that was temporarily grounded last week.

The cause of the Dana Air crash, the worst aviation accident anywhere this year, is still unknown. The crew, comprising a U.S. captain and an Indian first officer, is reported to have declared an emergency around 11 nm out, at an altitude of 5,000 ft. According to NCAA, the crew, along with listing the dual engine failure, also reported that the throttle was not responding. The aircraft touched down at a very nose-high altitude, according to eyewitnesses, which indicates slow airspeed. There have been reports about a possible birdstrike as a causal factor. The flight data and cockpit voice recorders were recovered on June 4.

On that same day, NCAA revoked Dana Air's air operator's certificate for an indefinite period “for safety and precautionary reasons.” The airline had already suspended all operations.

According to Dana Air, the captain had accumulated 18,500 flight hours, 7,100 on MD-83s. The first officer had flown 1,100 hours, 800 of them on MD-83s. The aircraft had logged 60,846 hr. and 35,219 cycles. Its last A check was performed on May 30 and the next C check was set for September. Some staff members have reported that the aircraft had to undergo frequent repairs in the past, but that could not be independently confirmed, and previous flaws might not be linked to the cause of the accident. The aircraft, registered 5N-RAM, was originally delivered to Alaska Airlines in 1990 and sold to Dana Air in 2009.