FIRE OF UNKNOWN ORIGIN


“Hidden Fire.” 1983 Air Canada Flight 797 (McDonnell Douglas DC-9-32). An Air Canada DC9-32 was en route from Dallas to Toronto with 41 passengers and 5 crew when cabin crew discovered smoke in the left aft lav. The lav was equipped with auto extinguishing waste bins, but no smoke alarm. Inspection revealed no visible fire. CO2 extinguishers were discharged into the lav with negative results. Smoke rapidly filled the cabin and cockpit. An emergency landing was accomplished in approximately 17 minutes from discovery of smoke. FAs passed out wet towels for passengers to breathe through.


NTSB ruled the fire as “of undetermined origin” and estimated the fire had burned for at least 15 minutes before smoke was detected and continued as a “hidden fire” until a flash fire erupted just as the last survivor exited; 23 passengers died, all 5 of the crew survived.


Due to the fire being “hidden,” the NTSB determined the time taken to evaluate the nature of the fire and to decide to initiate an emergency descent contributed to the severity of the accident.


WHAT IS SAID VS. WHAT IS HEARD (UNDER STRESS)


Delta Air Lines Flight 2030 On September 17, 1999, about 2230 eastern daylight time, a McDonnell Douglas MD-88, N947DL, operated by Delta Airlines as flight 2030, experienced an in-flight fire and made an emergency landing at the Cincinnati and Northern Kentucky International Airport in Covington, Kentucky. After landing, an emergency evacuation was performed. The airplane sustained minor damage, and none of the 2 flight crewmembers, 3 flight attendants, 3 off-duty flight attendants, or 113 passengers were injured.


Shortly after takeoff, several flight attendants detected a sulfurous or “lit match” smell and reported it to the flight crew. Following the captain’s instructions, flight attendants checked the lavatories, but were unable to locate the cause of the smell. Two off-duty flight attendants retrieved Halon fire extinguishers when flight attendants noticed smoke in the forward section of the coach cabin. Flight attendants reseated a passenger in row 11 to another row when he stated that his feet were hot. This individual’s carry-on bag, which had been on the floor beside him, next to the right sidewall and above the floor vent, was scorched. Flight attendants also reported seeing an orange or red, flickering glow beneath the vent at that location.


Flight attendant No. 1 went to the cockpit to inform the flight crew of these observations and asked the captain whether to spray Halon into the vent where she had seen the glow. The captain instructed her not to use the Halon extinguisher, indicating he was concerned about spraying Halon in the cabin. Meanwhile, another flight attendant had already discharged a Halon fire extinguisher into the vent and observed that the glow was no longer visible. Thereafter, the smoke began to dissipate and did not return, indicating that the fire had been extinguished by the Halon. When flight attendant No. 1 returned from the flight deck, she became alarmed that a Halon fire extinguisher had been discharged because the captain had instructed her not to do so. During its investigation of this incident, Safety Board staff discovered that the source of the smoke in the cabin was a smoldering insulation blanket in the cargo compartment adjacent to a static port heater. Electrical arcing from the heater ignited the blanket, and the smoldering became a self-sustaining fire that grew in size.


Inflight Fire and Smoke 6


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