In-Flight Fires an Unresolved Safety Threat

Those fires and five others on the Bombardier regional jets were caused by moisture that seeped into the equipment, according to the National Transportation Safety Board.

Investigators found that two of the fires threatened the pilot's oxygen supply line. If the oxygen was ignited, the fire could have developed into a more hazardous situation," said Bob Swaim, an NTSB investigator who looked into the incident.

Pilots groups want manufacturers to develop and install sensors throughout aircraft to help pilots find the source of smoke.

And they would like the FAA to better fund efforts of its own scientists. FAA chemist Richard Lyon and his bosses say he has developed a super fire-resistant plastic. But the scientist has faced problems in getting chemical companies, aircraft manufacturers or the FAA to fund full-scale tests.

The last fatal crash blamed on an in-flight fire in North America was the Swissair accident in 1998. As a result, pilots are now trained to land a plane if they cannot quickly locate the source of smoke -- a reaction that the FAA's Hickey and others think contributes to the level of diversions.

"We are very pleased with that safety culture," Hickey said, adding, however, that the number of diversions is "a concern for me and a concern for the community."

Database editor Sarah Cohen contributed to this report.