Narrative:

After arriving at the airport the first officer and all 3 flight attendants went to the aircraft to begin their duties while I remained in the office to review the paperwork. Approximately 10 mins later I overheard the first officer calling the operations center to tell them to shut down the external heater they were using to keep the aircraft warm because the cabin; jetway; and flight deck were saturated with the strong odor of exhaust gasses. It was too strong to endure. The first officer stayed long enough to start the APU and then he vacated the jet and all 4 of the crew returned to the operations center. At some point after this the external heater was shut down. I do not know how long this equipment had been running as the aircraft had spent the night at ZZZ. The first officer returned and began to tell me about the fumes. He mentioned that his eyes were burning and that it was a very unpleasant experience (being subjected to the fumes). As I was continuing my duties I kept a listening ear to the flight attendants who were discussing their physical reaction to the fumes they had just been subjected to. Approximately 15 mins later I volunteered to go to the jet to evaluate the fume condition and return to let them know if it was ok to board. Walking up the jetway I tried to be cognizant of any unusual odors. I found nothing out of the ordinary; and there was no residue detectable to me of any kind. After showing my bags I exited the jet to tell the rest of the crew that I thought it was ok to board. As the crew boarded the jet my impression of the crew's consensus was that the odor was no longer present and that they would be able to conduct their duties. We then proceeded to deice the wings; tail; and body of the jet. We executed the associated deicing checklist carefully. After the engine start I selected the wing and engine anti-ice on and we waited the prescribed time interval prior to bringing on the air-conditioning packs for takeoff. No abnormal smells were detected; we had more than our minimum 3 mins engine running time prior to taking the runway. At about 3000 ft AGL I heard multiple chimes. I asked the first officer to answer the chimes. One of the flight attendants called to report feeling extremely ill. Immediately I began to evaluate our options. My initial impression was that the cabin was contaminated and an immediate return was necessary. I spoke to the reporting flight attendant to verify the condition of the cabin. I was corrected; there was no visible contamination in the cabin; the passenger were not complaining; but all 3 flight attendants were feeling nauseous. I asked her if she thought their health status warranted an immediate return to ZZZ or whether she thought that continuing to ZZZ1 was advisable. She indicated that continuing to ZZZ1 would be ok; but that they did not want to continue on any further beyond ZZZ1. We had a deadheading captain seated in the cabin who would later tell us that at no time did he detect any abnormal cabin smells. The first officer and I were symptom free; he was on oxygen as a precaution. I elected to press on to ZZZ1 believing it to be the safest and most conservative option. One of the flight attendants came forward and used the oxygen mask. En route we asked for the paramedics to meet the arriving jet to attend to the flight attendants. After arrival the flight attendants were evaled by the paramedics. They were taken to the hospital for further tests. The 'a' flight attendant's test came back positive; she had abnormally elevated levels of carbon monoxide in her blood. We also had a passenger go to the hospital. The passenger's blood test was also positive. My blood was drawn and I also had abnormally high concentrations of carbon monoxide detected by the test. All 3 blood samples taken showed abnormally high levels of carbon monoxide. I believe the ranges were between 1.8% and 4.7%. After deplaning the passenger I opened the exterior doors and had the air conditioning system working to ventilate the aircraft with fresh air. Additionally the fire department had a carbon monoxide detector that was later used to check for the presence of carbon monoxide in the cabin or flight deck. The carbonmonoxide detector showed no evidence of carbon monoxide being present. But by that time the aircraft had been on the ground for more than an hour. Callback conversation with reporter revealed the following information: the first officer saw nothing obviously unusual about the condition of the air conditioning unit; the aircraft or the jetway. The aircraft was not unusually exposed to the entrance of ambient air which may have been befouled by the exhaust of the AC unit. He did note that the air was quite still and the unit had been on the aircraft for an extended period of time. He speculated that the unit's exhaust may have not dissipated as it usually would and may have been ingested into the conditioning air inlet and thus into the aircraft itself. Alternatively the possibility existed there was a fault in the AC unit allowing exhaust fumes to be ingested into the conditioned air delivered to the aircraft. The first officer felt it was significant that the captain had the second highest level of co in his system despite the fact he was never on board the aircraft while the exposure was most obvious. He attributes this to the fact that the burnt gas odor may have dissipated but the co level (odorless and tasteless) in the cockpit remained high. The captain never used an O2 mask while the first officer did both during his initial exposure and again when the cabin attendants complained of symptoms in flight. He further stated his airline is taking the incident seriously and has instituted a program to equipment their aircraft and jetways with co detectors.

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Original NASA ASRS Text

Title: B737-400 FLT AND CABIN CREWS SUFFER CARBON MONOXIDE OVEREXPOSURE DUE TO GROUND EQUIPMENT EXHAUSTING INTO CABIN PRIOR TO DEPARTURE.

Narrative: AFTER ARRIVING AT THE ARPT THE FO AND ALL 3 FLT ATTENDANTS WENT TO THE ACFT TO BEGIN THEIR DUTIES WHILE I REMAINED IN THE OFFICE TO REVIEW THE PAPERWORK. APPROX 10 MINS LATER I OVERHEARD THE FO CALLING THE OPS CTR TO TELL THEM TO SHUT DOWN THE EXTERNAL HEATER THEY WERE USING TO KEEP THE ACFT WARM BECAUSE THE CABIN; JETWAY; AND FLT DECK WERE SATURATED WITH THE STRONG ODOR OF EXHAUST GASSES. IT WAS TOO STRONG TO ENDURE. THE FO STAYED LONG ENOUGH TO START THE APU AND THEN HE VACATED THE JET AND ALL 4 OF THE CREW RETURNED TO THE OPS CTR. AT SOME POINT AFTER THIS THE EXTERNAL HEATER WAS SHUT DOWN. I DO NOT KNOW HOW LONG THIS EQUIP HAD BEEN RUNNING AS THE ACFT HAD SPENT THE NIGHT AT ZZZ. THE FO RETURNED AND BEGAN TO TELL ME ABOUT THE FUMES. HE MENTIONED THAT HIS EYES WERE BURNING AND THAT IT WAS A VERY UNPLEASANT EXPERIENCE (BEING SUBJECTED TO THE FUMES). AS I WAS CONTINUING MY DUTIES I KEPT A LISTENING EAR TO THE FLT ATTENDANTS WHO WERE DISCUSSING THEIR PHYSICAL REACTION TO THE FUMES THEY HAD JUST BEEN SUBJECTED TO. APPROX 15 MINS LATER I VOLUNTEERED TO GO TO THE JET TO EVAL THE FUME CONDITION AND RETURN TO LET THEM KNOW IF IT WAS OK TO BOARD. WALKING UP THE JETWAY I TRIED TO BE COGNIZANT OF ANY UNUSUAL ODORS. I FOUND NOTHING OUT OF THE ORDINARY; AND THERE WAS NO RESIDUE DETECTABLE TO ME OF ANY KIND. AFTER SHOWING MY BAGS I EXITED THE JET TO TELL THE REST OF THE CREW THAT I THOUGHT IT WAS OK TO BOARD. AS THE CREW BOARDED THE JET MY IMPRESSION OF THE CREW'S CONSENSUS WAS THAT THE ODOR WAS NO LONGER PRESENT AND THAT THEY WOULD BE ABLE TO CONDUCT THEIR DUTIES. WE THEN PROCEEDED TO DEICE THE WINGS; TAIL; AND BODY OF THE JET. WE EXECUTED THE ASSOCIATED DEICING CHKLIST CAREFULLY. AFTER THE ENG START I SELECTED THE WING AND ENG ANTI-ICE ON AND WE WAITED THE PRESCRIBED TIME INTERVAL PRIOR TO BRINGING ON THE AIR-CONDITIONING PACKS FOR TKOF. NO ABNORMAL SMELLS WERE DETECTED; WE HAD MORE THAN OUR MINIMUM 3 MINS ENG RUNNING TIME PRIOR TO TAKING THE RWY. AT ABOUT 3000 FT AGL I HEARD MULTIPLE CHIMES. I ASKED THE FO TO ANSWER THE CHIMES. ONE OF THE FLT ATTENDANTS CALLED TO RPT FEELING EXTREMELY ILL. IMMEDIATELY I BEGAN TO EVAL OUR OPTIONS. MY INITIAL IMPRESSION WAS THAT THE CABIN WAS CONTAMINATED AND AN IMMEDIATE RETURN WAS NECESSARY. I SPOKE TO THE RPTING FLT ATTENDANT TO VERIFY THE CONDITION OF THE CABIN. I WAS CORRECTED; THERE WAS NO VISIBLE CONTAMINATION IN THE CABIN; THE PAX WERE NOT COMPLAINING; BUT ALL 3 FLT ATTENDANTS WERE FEELING NAUSEOUS. I ASKED HER IF SHE THOUGHT THEIR HEALTH STATUS WARRANTED AN IMMEDIATE RETURN TO ZZZ OR WHETHER SHE THOUGHT THAT CONTINUING TO ZZZ1 WAS ADVISABLE. SHE INDICATED THAT CONTINUING TO ZZZ1 WOULD BE OK; BUT THAT THEY DID NOT WANT TO CONTINUE ON ANY FURTHER BEYOND ZZZ1. WE HAD A DEADHEADING CAPT SEATED IN THE CABIN WHO WOULD LATER TELL US THAT AT NO TIME DID HE DETECT ANY ABNORMAL CABIN SMELLS. THE FO AND I WERE SYMPTOM FREE; HE WAS ON OXYGEN AS A PRECAUTION. I ELECTED TO PRESS ON TO ZZZ1 BELIEVING IT TO BE THE SAFEST AND MOST CONSERVATIVE OPTION. ONE OF THE FLT ATTENDANTS CAME FORWARD AND USED THE OXYGEN MASK. ENRTE WE ASKED FOR THE PARAMEDICS TO MEET THE ARRIVING JET TO ATTEND TO THE FLT ATTENDANTS. AFTER ARR THE FLT ATTENDANTS WERE EVALED BY THE PARAMEDICS. THEY WERE TAKEN TO THE HOSPITAL FOR FURTHER TESTS. THE 'A' FLT ATTENDANT'S TEST CAME BACK POSITIVE; SHE HAD ABNORMALLY ELEVATED LEVELS OF CARBON MONOXIDE IN HER BLOOD. WE ALSO HAD A PAX GO TO THE HOSPITAL. THE PAX'S BLOOD TEST WAS ALSO POSITIVE. MY BLOOD WAS DRAWN AND I ALSO HAD ABNORMALLY HIGH CONCENTRATIONS OF CARBON MONOXIDE DETECTED BY THE TEST. ALL 3 BLOOD SAMPLES TAKEN SHOWED ABNORMALLY HIGH LEVELS OF CARBON MONOXIDE. I BELIEVE THE RANGES WERE BTWN 1.8% AND 4.7%. AFTER DEPLANING THE PAX I OPENED THE EXTERIOR DOORS AND HAD THE AIR CONDITIONING SYS WORKING TO VENTILATE THE ACFT WITH FRESH AIR. ADDITIONALLY THE FIRE DEPT HAD A CARBON MONOXIDE DETECTOR THAT WAS LATER USED TO CHK FOR THE PRESENCE OF CARBON MONOXIDE IN THE CABIN OR FLT DECK. THE CARBONMONOXIDE DETECTOR SHOWED NO EVIDENCE OF CARBON MONOXIDE BEING PRESENT. BUT BY THAT TIME THE ACFT HAD BEEN ON THE GND FOR MORE THAN AN HR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE FIRST OFFICER SAW NOTHING OBVIOUSLY UNUSUAL ABOUT THE CONDITION OF THE AIR CONDITIONING UNIT; THE AIRCRAFT OR THE JETWAY. THE AIRCRAFT WAS NOT UNUSUALLY EXPOSED TO THE ENTRANCE OF AMBIENT AIR WHICH MAY HAVE BEEN BEFOULED BY THE EXHAUST OF THE AC UNIT. HE DID NOTE THAT THE AIR WAS QUITE STILL AND THE UNIT HAD BEEN ON THE AIRCRAFT FOR AN EXTENDED PERIOD OF TIME. HE SPECULATED THAT THE UNIT'S EXHAUST MAY HAVE NOT DISSIPATED AS IT USUALLY WOULD AND MAY HAVE BEEN INGESTED INTO THE CONDITIONING AIR INLET AND THUS INTO THE ACFT ITSELF. ALTERNATIVELY THE POSSIBILITY EXISTED THERE WAS A FAULT IN THE AC UNIT ALLOWING EXHAUST FUMES TO BE INGESTED INTO THE CONDITIONED AIR DELIVERED TO THE AIRCRAFT. THE FO FELT IT WAS SIGNIFICANT THAT THE CAPTAIN HAD THE SECOND HIGHEST LEVEL OF CO IN HIS SYSTEM DESPITE THE FACT HE WAS NEVER ON BOARD THE AIRCRAFT WHILE THE EXPOSURE WAS MOST OBVIOUS. HE ATTRIBUTES THIS TO THE FACT THAT THE BURNT GAS ODOR MAY HAVE DISSIPATED BUT THE CO LEVEL (ODORLESS AND TASTELESS) IN THE COCKPIT REMAINED HIGH. THE CAPTAIN NEVER USED AN O2 MASK WHILE THE FO DID BOTH DURING HIS INITIAL EXPOSURE AND AGAIN WHEN THE CABIN ATTENDANTS COMPLAINED OF SYMPTOMS IN FLIGHT. HE FURTHER STATED HIS AIRLINE IS TAKING THE INCIDENT SERIOUSLY AND HAS INSTITUTED A PROGRAM TO EQUIP THEIR AIRCRAFT AND JETWAYS WITH CO DETECTORS.

Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.