Narrative:

While doing my cockpit preflight setup I found the captain's microphone cable wrapped around the sliding window release lever. I first pushed forward on the window release lever to make certain that it was latched and then attempted to remove the microphone from behind the release lever by pulling on the microphone cable. The microphone jammed between the release lever and the window frame requiring some effort to extract the microphone. This is a fairly normal occurrence on the air carrier medium large transport and I thought nothing about it at the time. On takeoff roll at approximately 100 KTS the captain's sliding window abruptly blew open. The takeoff was discontinued with minimal use of brake and reverse thrust. Aircraft was taxied clear of runway. While at a full stop on the ramp, a thorough inspection of the window was made. Nothing abnormal was found. The window repeatedly latched properly. Takeoff clearance was requested and given by the tower. The flight continued on to destination with all operations normal. After arriving at destination I discussed this situation with the captain who taking this aircraft out next. He advised me that he had recently had a similar experience. One of his first comments was to ask me if the microphone cable had been wrapped around the sliding door handle when I boarded the aircraft. He said that in his situation the release lever on the sliding door handle had been depressed by the microphone when he tried to remove it from behind handle. He did not notice it at the time but the window latch had been tripped and later the window opened apparently of its own accord. I had never heard of this situation before and thought this almost impossible at the time. I boarded my next flight early and intentionally hung the microphone over the sliding window release handle. My first effort to remove the microphone from this position was by pulling on the microphone cable. To my amazement the microphone was pulled down against the latch release lever and completely unlatched the window. The window not only unlatched, but slid completely open with no action on my part other than pulling on the microphone cable. I tried this procedure 10 times with my first officer observing the last few attempts. 8 out of 10 times the window unlatched and slid completely open. The other 2 times the window only unlatched and did not open until touched by hand. It is now my opinion that when I pulled on the microphone cable in an attempt to remove the microphone from its position behind the sliding window latch release lever, the window latch was inadvertently unlatched. In that particular instance the window did not completely open, but during the takeoff roll, whether by vibration, wind blast, or what ever, the necessary conditions were met to cause the window to finally slide open. A contributing factor to this situation is the position of the side wall mounted microphone retainers in the cockpit of the air carrier medium large transport. They are positioned in such a manner that when a pilot slides his seat back en route and places his ft (left ft for captain's and right ft for first officer's) on the forward ft rests, his knee (again left for left seat and right for right seat) hits the microphone push-to-talk button and the result is a blocked frequency caused by this 'stuck microphone.' this is a very common occurrence on this aircraft. For this reason many pilots will not use manufacturer supplied side wall mounted microphone retainers. Quite often the microphone is hung over the sliding window latch release lever because it is convenient and cannot cause a 'stuck microphone.'

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Original NASA ASRS Text

Title: ACR MLG FLC ABORTS TKOF AT SAN DUE CAPT'S SIDE WINDOW COMING OPEN. SIDE WINDOW LATCH MECHANISM TRIPPED BY PLTS PLACING MIKE CORD OVER WINDOW LATCH. PLTS PLACE MIKE CORD OVER WINDOW LATCH DUE POOR POSITIONING OF MICROPHONE HOLDER ON SIDE WALL -- WHICH MAKES IT EASY TO GET A 'STUCK MIKE.'

Narrative: WHILE DOING MY COCKPIT PREFLT SETUP I FOUND THE CAPT'S MICROPHONE CABLE WRAPPED AROUND THE SLIDING WINDOW RELEASE LEVER. I FIRST PUSHED FORWARD ON THE WINDOW RELEASE LEVER TO MAKE CERTAIN THAT IT WAS LATCHED AND THEN ATTEMPTED TO REMOVE THE MICROPHONE FROM BEHIND THE RELEASE LEVER BY PULLING ON THE MICROPHONE CABLE. THE MICROPHONE JAMMED BTWN THE RELEASE LEVER AND THE WINDOW FRAME REQUIRING SOME EFFORT TO EXTRACT THE MICROPHONE. THIS IS A FAIRLY NORMAL OCCURRENCE ON THE ACR MLG AND I THOUGHT NOTHING ABOUT IT AT THE TIME. ON TKOF ROLL AT APPROX 100 KTS THE CAPT'S SLIDING WINDOW ABRUPTLY BLEW OPEN. THE TKOF WAS DISCONTINUED WITH MINIMAL USE OF BRAKE AND REVERSE THRUST. ACFT WAS TAXIED CLR OF RWY. WHILE AT A FULL STOP ON THE RAMP, A THOROUGH INSPECTION OF THE WINDOW WAS MADE. NOTHING ABNORMAL WAS FOUND. THE WINDOW REPEATEDLY LATCHED PROPERLY. TKOF CLRNC WAS REQUESTED AND GIVEN BY THE TWR. THE FLT CONTINUED ON TO DEST WITH ALL OPS NORMAL. AFTER ARRIVING AT DEST I DISCUSSED THIS SITUATION WITH THE CAPT WHO TAKING THIS ACFT OUT NEXT. HE ADVISED ME THAT HE HAD RECENTLY HAD A SIMILAR EXPERIENCE. ONE OF HIS FIRST COMMENTS WAS TO ASK ME IF THE MICROPHONE CABLE HAD BEEN WRAPPED AROUND THE SLIDING DOOR HANDLE WHEN I BOARDED THE ACFT. HE SAID THAT IN HIS SITUATION THE RELEASE LEVER ON THE SLIDING DOOR HANDLE HAD BEEN DEPRESSED BY THE MICROPHONE WHEN HE TRIED TO REMOVE IT FROM BEHIND HANDLE. HE DID NOT NOTICE IT AT THE TIME BUT THE WINDOW LATCH HAD BEEN TRIPPED AND LATER THE WINDOW OPENED APPARENTLY OF ITS OWN ACCORD. I HAD NEVER HEARD OF THIS SITUATION BEFORE AND THOUGHT THIS ALMOST IMPOSSIBLE AT THE TIME. I BOARDED MY NEXT FLT EARLY AND INTENTIONALLY HUNG THE MICROPHONE OVER THE SLIDING WINDOW RELEASE HANDLE. MY FIRST EFFORT TO REMOVE THE MICROPHONE FROM THIS POS WAS BY PULLING ON THE MICROPHONE CABLE. TO MY AMAZEMENT THE MICROPHONE WAS PULLED DOWN AGAINST THE LATCH RELEASE LEVER AND COMPLETELY UNLATCHED THE WINDOW. THE WINDOW NOT ONLY UNLATCHED, BUT SLID COMPLETELY OPEN WITH NO ACTION ON MY PART OTHER THAN PULLING ON THE MICROPHONE CABLE. I TRIED THIS PROC 10 TIMES WITH MY FO OBSERVING THE LAST FEW ATTEMPTS. 8 OUT OF 10 TIMES THE WINDOW UNLATCHED AND SLID COMPLETELY OPEN. THE OTHER 2 TIMES THE WINDOW ONLY UNLATCHED AND DID NOT OPEN UNTIL TOUCHED BY HAND. IT IS NOW MY OPINION THAT WHEN I PULLED ON THE MICROPHONE CABLE IN AN ATTEMPT TO REMOVE THE MICROPHONE FROM ITS POS BEHIND THE SLIDING WINDOW LATCH RELEASE LEVER, THE WINDOW LATCH WAS INADVERTENTLY UNLATCHED. IN THAT PARTICULAR INSTANCE THE WINDOW DID NOT COMPLETELY OPEN, BUT DURING THE TKOF ROLL, WHETHER BY VIBRATION, WIND BLAST, OR WHAT EVER, THE NECESSARY CONDITIONS WERE MET TO CAUSE THE WINDOW TO FINALLY SLIDE OPEN. A CONTRIBUTING FACTOR TO THIS SITUATION IS THE POS OF THE SIDE WALL MOUNTED MICROPHONE RETAINERS IN THE COCKPIT OF THE ACR MLG. THEY ARE POSITIONED IN SUCH A MANNER THAT WHEN A PLT SLIDES HIS SEAT BACK ENRTE AND PLACES HIS FT (L FT FOR CAPT'S AND R FT FOR FO'S) ON THE FORWARD FT RESTS, HIS KNEE (AGAIN L FOR L SEAT AND R FOR R SEAT) HITS THE MICROPHONE PUSH-TO-TALK BUTTON AND THE RESULT IS A BLOCKED FREQ CAUSED BY THIS 'STUCK MIKE.' THIS IS A VERY COMMON OCCURRENCE ON THIS ACFT. FOR THIS REASON MANY PLTS WILL NOT USE MANUFACTURER SUPPLIED SIDE WALL MOUNTED MICROPHONE RETAINERS. QUITE OFTEN THE MICROPHONE IS HUNG OVER THE SLIDING WINDOW LATCH RELEASE LEVER BECAUSE IT IS CONVENIENT AND CANNOT CAUSE A 'STUCK MIKE.'

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.