Narrative:

On taxi out at las first officer said he thought he smelled something burning. I smelled nothing, but we turned off the packs and gasper fan as they are where I have had problems in the past with smells. I then saw a thin trail of smoke coming from the APU generator control unit behind the first officer's head. I asked him to reach around and pull the handle out. He tried to reach around, but it was difficult to reach. About that time he got a good whiff of smoke and then put on the oxygen mask. After about 2 mins he was able to remove the generator control and put it on the floor. The smoke stopped immediately, and after opening windows dissipated quickly. Later at the gate, the medics treated first officer for smoke inhalation. First officer was able to continue after switching airplanes. The one thing I would have done different is to have had us both put on oxygen masks at the very first sign of smoke. When we practice this procedure in the simulator, you are always in-flight. When I was on the ground, I didn't have the same sense of urgency. Perhaps there should be more taxi problems in the simulator. Callback conversation with reporter revealed the following information: either the B737-200's APU or generator control unit had been written up the day before this incident. The captain (reporter) was not sure which, but he remembered that work had been done on the system, and it had been cleared. When the smoke was initially detected, the captain was not too alarmed, as this was the third time that he had experienced smoke in the cockpit. In hindsight, he feels he was too complacent about the smoke. If this had occurred in the air, they (flight crew) would have immediately donned masks. As it turned out, this complacency about the smoke was a major factor in what followed. The first officer was not only treated for smoke inhalation back at the gate, but had to seek medical help the following day. The captain now feels that the smoke was toxic, and that the first officer should not have continued flying. When the flight crew discussed the incident, they both thought it was odd that they did not go for the masks right away. The first officer was a former fireman, and was quite surprised at his failure to first get the oxygen on.

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Original NASA ASRS Text

Title: A B737'S MALFUNCTIONING GENERATOR CTL UNIT CAUSED TOXIC SMOKE IN THE COCKPIT DURING TAXI. THE FO REMOVED THE GENERATOR CTL UNIT, BUT WAS AFFECTED BY THE HARMFUL SMOKE IN THE PROCESS.

Narrative: ON TAXI OUT AT LAS FO SAID HE THOUGHT HE SMELLED SOMETHING BURNING. I SMELLED NOTHING, BUT WE TURNED OFF THE PACKS AND GASPER FAN AS THEY ARE WHERE I HAVE HAD PROBS IN THE PAST WITH SMELLS. I THEN SAW A THIN TRAIL OF SMOKE COMING FROM THE APU GENERATOR CTL UNIT BEHIND THE FO'S HEAD. I ASKED HIM TO REACH AROUND AND PULL THE HANDLE OUT. HE TRIED TO REACH AROUND, BUT IT WAS DIFFICULT TO REACH. ABOUT THAT TIME HE GOT A GOOD WHIFF OF SMOKE AND THEN PUT ON THE OXYGEN MASK. AFTER ABOUT 2 MINS HE WAS ABLE TO REMOVE THE GENERATOR CTL AND PUT IT ON THE FLOOR. THE SMOKE STOPPED IMMEDIATELY, AND AFTER OPENING WINDOWS DISSIPATED QUICKLY. LATER AT THE GATE, THE MEDICS TREATED FO FOR SMOKE INHALATION. FO WAS ABLE TO CONTINUE AFTER SWITCHING AIRPLANES. THE ONE THING I WOULD HAVE DONE DIFFERENT IS TO HAVE HAD US BOTH PUT ON OXYGEN MASKS AT THE VERY FIRST SIGN OF SMOKE. WHEN WE PRACTICE THIS PROC IN THE SIMULATOR, YOU ARE ALWAYS INFLT. WHEN I WAS ON THE GND, I DIDN'T HAVE THE SAME SENSE OF URGENCY. PERHAPS THERE SHOULD BE MORE TAXI PROBS IN THE SIMULATOR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: EITHER THE B737-200'S APU OR GENERATOR CTL UNIT HAD BEEN WRITTEN UP THE DAY BEFORE THIS INCIDENT. THE CAPT (RPTR) WAS NOT SURE WHICH, BUT HE REMEMBERED THAT WORK HAD BEEN DONE ON THE SYS, AND IT HAD BEEN CLRED. WHEN THE SMOKE WAS INITIALLY DETECTED, THE CAPT WAS NOT TOO ALARMED, AS THIS WAS THE THIRD TIME THAT HE HAD EXPERIENCED SMOKE IN THE COCKPIT. IN HINDSIGHT, HE FEELS HE WAS TOO COMPLACENT ABOUT THE SMOKE. IF THIS HAD OCCURRED IN THE AIR, THEY (FLC) WOULD HAVE IMMEDIATELY DONNED MASKS. AS IT TURNED OUT, THIS COMPLACENCY ABOUT THE SMOKE WAS A MAJOR FACTOR IN WHAT FOLLOWED. THE FO WAS NOT ONLY TREATED FOR SMOKE INHALATION BACK AT THE GATE, BUT HAD TO SEEK MEDICAL HELP THE FOLLOWING DAY. THE CAPT NOW FEELS THAT THE SMOKE WAS TOXIC, AND THAT THE FO SHOULD NOT HAVE CONTINUED FLYING. WHEN THE FLC DISCUSSED THE INCIDENT, THEY BOTH THOUGHT IT WAS ODD THAT THEY DID NOT GO FOR THE MASKS RIGHT AWAY. THE FO WAS A FORMER FIREMAN, AND WAS QUITE SURPRISED AT HIS FAILURE TO FIRST GET THE OXYGEN ON.

Data retrieved from NASA's ASRS site as of July 2007 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.