Ramon Lopez/WASHINGTON DC David Learmount/LONDON
THE TRANSATLANTIC bilateral aircraft-certification process has been thrown into turmoil following accusations by the US National Transportation Safety Board (NTSB) that the French aviation authority and the ATR consortium were to blame for an ATR 72 crash in the USA in 1994 which killed 68 people. The US Federal Aviation Administration also contributed to the accident, it says.
In a report on the accident of the Simmons/American Eagle ATR 72 at Roselawn, Indiana, on 31 October, 1994, the NTSB accuses the French Directorate General for Civil Aviation (DGAC), the aircraft's lead certificating authority of "-failure to ensure the continued airworthiness" of the ATR series, and of "-failure to provide the FAA with timely airworthiness information developed from previous ATR incidents" as required under International Civil Aviation Organisation rules.
The report absolves the pilots, saying that ATR (now expanded into Aero International (Regional) with British Aerospace) did not tell operators that the aircraft was susceptible to violent rolls in certain extreme icing conditions.
Contributory factors, says the report, were the FAA's poor oversight of operational requirements for flight into icing conditions, and of the aircraft's history in service.
NTSB chairman Jim Hall says that the 22-month investigation points to "a larger problem" in the flow of safety information between the world's aviation authorities. Overall, the report has revealed a cavernous divide between the US and French interpretations of the accident causes and of events which the NTSB says presaged the crash.
The French Government and the aircraft manufacturer say that the report is flawed, and the FAA has been quick to defend the bilateral aircraft-certification process.
The NTSB concludes that the probable cause of the accident was loss of control caused by a sudden aileron hinge-moment reversal which occurred after a ridge of ice accreted aft of the wing leading-edge de-icing boots. It alleges that ATR "-failed to completely disclose" to operators, and to incorporate in ATR 72 operating manuals, "adequate information concerning previously known effects of freezing precipitation" on the aircraft.
After the Roselawn accident, US operators of ATR 42s and 72s were required to install larger wing de-icing boots to counter icing conditions the severity of which was not, at the time of the accident, covered by any certification requirement.
Hall insists, however, that the flightdeck crew did not have information "-that other individuals in the system had in regard to possible aircraft performance problems- This raises issues of how aircraft airworthiness is monitored after initial certification. There were deficiencies regarding the ATR 72." He says that the final report addresses "-the larger problem regarding expedited flow of safety information between where an aircraft is operated and the country of manufacture."
John O'Brian, of the Air Line Pilots Association, agrees, saying that "-this investigation shows the need to collect and analyse data and make sure it is disseminated properly". He adds: "It is clear that ATR and the certification authorities had information on problems in certain icing conditions, but shared it to only a certain degree".
The Bureau Enquetes-Accidents (BEA), the French accident investigating authority, says that the final report "-is incomplete, inaccurate and unbalanced", insisting that even the report's probable-cause finding is "erroneous". It says that the accident was caused by the crew, who were "...so oblivious to the icing conditions they encountered that they ignored the multiple warnings, instructions and regulations they already had received regarding proper operations in such conditions".
The BEA disagrees with the NTSB point-by-point, citing Simmons Airlines' own ATR 72 operating manuals as evidence that the NTSB is wrong in its contention that crews were not provided with information about the kind of aircraft behaviour they could expect in extreme icing conditions.
The most penetrating BEA accusation, however, is that the NTSB did not study the Roselawn accident closely, relying for its conclusions upon three former icing incidents in the USA and two overseas. The BEA puts a different technical interpretation upon each of these cases, and observes that the NTSB, although fully involved in the investigation of one of the US cases (at Mosinee, Wisconsin), had no recommendations to make at the time.
Criticising the bilateral process, the NTSB report observes: "The FAA's ability to monitor the continued airworthiness of the ATR aircraft was hampered by inadequately defined lines of communication. Such excessive reliance on a foreign airworthiness authority may result in the certification of a foreign-manufactured aircraft without sufficient oversight and is not in the best interests of safety."
Source: Flight International
