‘All is not well,’ safety board member John Goglia declares
Airline flying is becoming less safe and maintenance errors are playing an increasing role in the reduced operational level of safety, according to a new study of the role maintenance mistakes play in aircraft accidents and incidents.
The examination marks an unprecedented effort to take a comprehensive look at the impact of maintenance error on operational safety, said professor Gary Eiff, who directed the study at Purdue University‘s Department of Aviation Technology in Lafayette, Ind.
The findings – that maintenance errors were a contributory factor in far more incidents and accidents than previously thought – come at a time when financially-strapped airlines are contracting out more maintenance to save money, and in a period when federal oversight of repair stations has been found lacking (see ASW, Jan. 21, 2003, Oversight Needs to Keep Pace With Expansion of Contract Maintenance).
Although adherence to approved procedures is one of the most effective defenses against errors, the Purdue study found that in 76 percent of the maintenance-related events, failure to follow established procedures was cited as a contributing factor.
Although inspection is often the last line of defense, the study found that inadequate or missing inspections were a contributing factor in nearly 20 percent of the maintenance-related accidents and incidents.
Organizational factors, such as inadequate procedures, documentation, training and supervision accounted for more than 15 percent of the maintenance-related contributions to accidents and incidents.
The study was undertaken with the encouragement of John Goglia, the resident maintenance expert on the National Transportation Safety Board (NTSB). The NTSB has found maintenance error contributed to a number of recent fatal air crashes, notably the Jan. 21, 2000, fatal crash of an Alaska Airlines [ALK] MD-83, the Feb. 16, 2000, crash of an Emery Worldwide Airlines DC-8 freighter, and the Jan. 8, 2003, crash of an Air Midwest Beech 1900D (see ASW, March 1). Together, these three accidents killed 112 people.
As a consequence of the investigations into these accidents, Goglia pushed for a wider examination of maintenance error. The Purdue study is a result of this concern that recent maintenance-related crashes are symptoms of a more widespread and sinister trend.
“Since coming to the safety board, and seeing the raw data, my gut was telling me the rate of maintenance-related problems was much higher than generally believed,” Goglia said. “This study tells us that all is not well.”
The Purdue study found that, indeed, there are worrisome trends that ought to prompt a hard look at the level of training and oversight of aircraft maintenance. The safety culture in aviation maintenance also is being scrutinized in a separate study under way at Missouri’s St. Louis University (see ASW, April 12). According to a draft copy of the Purdue study obtained by ASW, “Maintenance contributions to aviation accidents and incidents are increasing.”
“While the increase is not at an alarming rate, we should take action now to arrest this trend,” the report said. One of the more significant revelations in the report is that while incidents are trending toward fewer per year, the accident trend is in the opposite direction. Thus, while the total number of accidents and incidents remains relatively the same, the report notes that “the criticality of [the] outcome of such events is becoming more severe.”
The assertion that maintenance errors are on the rise is a contributing factor in the larger conclusion in the Purdue study: “As a whole, the air carrier industry is experiencing a slight trend toward becoming less safe as a mode of transportation.”
This finding flies in the face of the fervently held belief that the safety level is improving. For example, at the recent Federal Aviation Administration (FAA) Forecast Conference, Nicholas Sabatini, associate FAA administrator for regulation and certification, asserted that 2003 was the safest year ever (see ASW, March 29). However, Sabatini’s assertion was based on fatal accidents, of which there were only two in 2003, while the 50 other non-fatal accidents for 2003 pushed the total number of air carrier accidents last year to the highest ever recorded by the NTSB.
How the system’s performance is measured can largely drive perceptions about safety. Eiff and his graduate students, who did the grunt work in the Purdue study, looked at all accidents and all incidents in the NTSB database over a 20-year period from 1982 to 2002. The Purdue study focused on scheduled passenger operations; it excluded cargo aircraft and charter operations.
The purpose of the study was to determine if maintenance played a more prominent role in aviation accidents and incidents than was previously thought.
The Purdue researchers analyzed roughly 1,300 NTSB records of airline accidents and incidents. The study found that maintenance problems were factors in nearly a third (29 percent) of the events. One of the key assumptions in the study was that mechanical failures were maintenance-related. “While the reports do not directly link these mechanical failures to maintenance, it is reasonable to believe that many result from maintenance shortcomings,” the report said.
The study found that maintenance was a contributory factor in far more cases than previously thought. For example, a recently published Boeing [BA] safety summary attributes only about 3 percent of crashes to faulty maintenance. The Purdue study suggests that maintenance problems may be some 10 times greater.
A major reason for the difference is that the Boeing data includes only hull losses. Not all accidents are hull losses. In addition, according to Dustin Wilcox, one of the students involved in the Purdue study, “We looked at incidents as well, which might be described as accidents that got lucky.”
Goglia believes the findings of the Purdue study are closer to the reality. “The students who did the work did not change the NTSB findings in all those accident and incident reports,” Goglia said. “This was a straightforward exercise, extracting what the NTSB said and compiling it. That is significant, and a big reason why we need to pay attention to the results of this data-mining effort.” As an example, the data mining found more than 100 cases of nose landing gear failures to extend for landing.
In a telephone interview, Goglia said the study’s findings are consistent with other inquiries. For example, an engine manufacturer found that 50 percent of engine-related turnbacks (return to departure airfield) were caused by installation error, Goglia said.
What can be done? “We need to start putting some mitigations in place,” Goglia said. He recalled that after a spate of crashes from pilot error, primarily from a failure to follow procedures, aircrews were enjoined to stick to procedures.
Now, for maintenance, Goglia said, “We need to pound into everybody’s head the importance of following procedures.” Secondly, he said, the procedures themselves need to be evaluated for currency, consistency and ease of understanding. Following the Air Midwest crash, which was attributed to improperly rigged elevator control cables, the relevant section of the Beech 1900D maintenance manual was revised significantly (see ASW, March 1, , What a Difference an Accident Makes). >> Goglia, e-mail [email protected]; Eiff, e-mail [email protected] <<
Growing Concerns
Research at several airline operations suggested that:
- Growing numbers of aircraft delays were maintenance-related.
- An increasing number of aircraft turn-backs and diversions were due to maintenance.
- Several recent accidents and incidents occurred with maintenance as a causal factor.
Source: Purdue Univ.