Event CHI93IA372

Factual narrative

On September 21, 1993, at 1017 eastern standard time (EST), a Boeing 737-3B7, N527AU, operated by USAir as Flight 1614, and piloted by an ATP certificated flight crew, diverted from its scheduled route between Philadelphia, Pennsylvania, and Kansas City, Missouri, to Indianapolis, Indiana, after five airplane occupants reported hypoxic symptoms. Visual meteorological conditions prevailed at the time of the incident. The 14 CFR Part 121 flight had been operating on an IFR flight plan. The airplane was not damaged. The flight crew and passengers reported no injuries. The flight departed Philadelphia, Pennsylvania, at 0740 EST. The captain of the flight stated, in his written account of the incident, that "... one of the rear flight attendants came into the cockpit and complained that she felt dizzy. She (the flight attendant) said that the three rear F/A's felt the same way." Oxygen was administered to the flight attendants and they returned to their duties. The captain stated he directed the first officer to go into the cabin and investigate the situation. The first officer returned to the cockpit and reported he was not able to identify what was causing the flight attendants symptoms. The first officer stated he "was experiencing a slight headache which (he) previously did not have," upon his return to the cockpit. The captain stated the first officer said "... a few of the 81 passengers were experiencing the same symptoms." The flight attendants reentered the cockpit on an individual basis and showed the two pilots their fingernails which were turning blue. The captain stated he requested an air traffic control clearance for an unscheduled stop at Indianapolis, Indiana. Upon landing the captain requested the crash, fire, rescue (CFR) units to check the cabin for carbon monoxide (CO). The captain's statement does not show whether or not the CO testing was accomplished by the CFR personnel. The flight attendants and four passengers were taken to a hospital in Indianapolis, Indiana. All were checked for CO poisoning with negative results. Once of the flight attendants stated she had been determined to have "...inhaled toxic fumes of unknown origin." The written statements of the flight attendants are appended to this report. The passenger's hospital medical reports stated: "Possible toxic inhalational exposure." These reports were provided to the NTSB by USAir. The passengers and flight attendants were seated near the rear section of the airplane. According to the company's engineering report on the incident, no smoke or fumes were reported by the first officer, flight attendants, or passengers. The report states: "...the aircraft was run on the ground with the FAA and the local fire department on board. Oxygen percentage was at a normal 20.5%, and all readings were within established parameters. The aircraft was checked for possible fuel, hydraulic fluid, halon, and rain repellant leaks. The baggage was examined to ensure that no dangerous chemicals had inadvertently gotten into the cargo compartment and leaked. There was no evidence of any leakage." The aircraft was ferried to the company's maintenance facility at Pittsburgh, Pennsylvania. During the flight the cabin air was checked for organic vapors. The maintenance report states: "No unusual readings were noted." The maintenance report is appended to this report. USAir reported that the airplane has not had a similar event since the original one on September 21, 1993. DURING FLIGHT THE FLIGHT ATTENDANTS COMPLAINED OF HYPOXIA SYMPTOMS. THE FIRST OFFICER INVESTIGATED THE AIRPLANE'S CABIN WITH NEGATIVE RESULTS. THE FLIGHT ATTENDANTS REPORTED THEY HAD HYPOXIA SYMPTOMS TO THE FLIGHT CREW A SECOND TIME AND THIS TIME THEIR FINGERNAILS HAD TURNED BLUE. THE CAPTAIN REQUESTED, AND RECEIVED, AN ATC CLEARANCE TO DIVERT TO AND LAND AT INDIANAPOLIS. HOSPITAL EXAMINATION OF THE FLIGHT ATTENDANTS AND FOUR PASSENGERS REVEALED NO CARBON MONOXIDE POISONING. THE HOSPITAL REPORTS STATED THERE WAS 'POSSIBLE TOXIC INHALATIONAL EXPOSURE.' THE AIRPLANE WAS CHECKED FOR CARBON MONOXIDE AND ORGANIC VAPORS DURING GROUND RUNUP AND FERRY FLIGHT TO THE COMPANY'S MAINTENANCE CENTER WITH NEGATIVE RESULTS. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12