Narrative:

An unpredicted snowstorm had dropped several inches of snow in yyz. When we arrived at the aircraft at AB30 we determined that deicing of the aircraft prior to engine start was necessary. However, procedure at yyz to deice was at a distant pad and the aircraft could not be towed to that location. I decided to broom off the nacelles and engine inlet so that we could safely taxi the aircraft to the deicing pad. After that was accomplished, we started the engines and taxied to the deice location. We were deiced at that time. During the deicing of the aircraft, all bleeds (engine and APU) were selected off to prevent any fumes from the deicing fluid from entering the cabin. We encountered some unexpected fluid that entered the cabin and cockpit through the windows and doors during this procedure and a hasty cleanup was performed. I would like to mention that this procedure was one that I was unfamiliar with, which unfortunately started to divert our attention. After deicing was completed, the aircraft was reconfigured for taxi with all the appropriate checklists completed. The takeoff for this flight was a bleeds off takeoff requiring the APU bleed air to be used for aircraft pressurization. The taxi from the pad to the departure runway that day was short. When the first officer began the bleed air sequence, smoke began to fill the cockpit when the APU bleed was turned on. This smoke was immediately recognized as residual deice fluid and the APU bleed was turned off. When this was done the smoke stopped. I then decided to perform a depressurized takeoff, which is an approved company procedure. However, when the APU bleed air was off, deice fluid again began to seep through the cockpit windows. The first officer was directed to put on the engine bleed to pressurize the cabin until we were cleared for takeoff and at that time the bleed air would again be placed in the off position to accomplish the depressurized takeoff. The end of the runway was approaching and although not called for, the before takeoff checklist was read. Assuming that we were cleared into position, I continued the taxi as the first officer was preparing the bleed air system for the depressurized takeoff. In reality we were not cleared into position and a runway incursion occurred resulting in the go around of another aircraft. Our aircraft was stopped prior to entering the runway, but after the hold short line for that runway. Other aircraft was sent around at an estimated 500 ft and 1/2 mi from the threshold by toronto tower. We were then cleared into position and subsequently cleared for takeoff. The remainder of the flight was uneventful. As captain of the aircraft, I assume sole responsibility for the incursion onto the runway. Contributing factors for this situation are many. The biggest problem I think is the fact that the first officer read the checklist unprompted which led me to believe that we had been cleared into position. It is our company procedure that the checklist will be called for by the captain and only after we have been given instructions from the tower to be cleared into position or cleared for takeoff. Although I also am monitoring the tower frequency, I should have picked up that we were not cleared into position as I was busy trying to determine that everything was set right for the depressurized takeoff. I am equally convinced my copilot was doing the same. Valuable lessons have been learned. Supplemental information from acn 466122: inadvertently taxied aircraft onto runway 6R. Taxiing on unfamiliar airport after fresh snowfall obscured many taxi features. Crew used ATC to maximum extent practicable with safety, including use of progressive taxi. Our first indication that we had committed the incursion was when tower told an air carrier to 'go around, traffic on runway.' crew queried tower as to whether we had been cleared to 'position and hold' and were informed that we were not. This incident, to me, underscores the need to punctiliously verify actions performed by flcs, particularly during odd or irregular operations or sits. Multi-tasking and the fact of unfamiliar airport operations in this case may have been contributing factors.

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Original NASA ASRS Text

Title: A B737-300 FLC TAXIES THEIR ACFT PAST THE HOLD SHORT LINE FOR RWY 6R AT CYYZ, ON.

Narrative: AN UNPREDICTED SNOWSTORM HAD DROPPED SEVERAL INCHES OF SNOW IN YYZ. WHEN WE ARRIVED AT THE ACFT AT AB30 WE DETERMINED THAT DEICING OF THE ACFT PRIOR TO ENG START WAS NECESSARY. HOWEVER, PROC AT YYZ TO DEICE WAS AT A DISTANT PAD AND THE ACFT COULD NOT BE TOWED TO THAT LOCATION. I DECIDED TO BROOM OFF THE NACELLES AND ENG INLET SO THAT WE COULD SAFELY TAXI THE ACFT TO THE DEICING PAD. AFTER THAT WAS ACCOMPLISHED, WE STARTED THE ENGS AND TAXIED TO THE DEICE LOCATION. WE WERE DEICED AT THAT TIME. DURING THE DEICING OF THE ACFT, ALL BLEEDS (ENG AND APU) WERE SELECTED OFF TO PREVENT ANY FUMES FROM THE DEICING FLUID FROM ENTERING THE CABIN. WE ENCOUNTERED SOME UNEXPECTED FLUID THAT ENTERED THE CABIN AND COCKPIT THROUGH THE WINDOWS AND DOORS DURING THIS PROC AND A HASTY CLEANUP WAS PERFORMED. I WOULD LIKE TO MENTION THAT THIS PROC WAS ONE THAT I WAS UNFAMILIAR WITH, WHICH UNFORTUNATELY STARTED TO DIVERT OUR ATTN. AFTER DEICING WAS COMPLETED, THE ACFT WAS RECONFIGURED FOR TAXI WITH ALL THE APPROPRIATE CHKLISTS COMPLETED. THE TKOF FOR THIS FLT WAS A BLEEDS OFF TKOF REQUIRING THE APU BLEED AIR TO BE USED FOR ACFT PRESSURIZATION. THE TAXI FROM THE PAD TO THE DEP RWY THAT DAY WAS SHORT. WHEN THE FO BEGAN THE BLEED AIR SEQUENCE, SMOKE BEGAN TO FILL THE COCKPIT WHEN THE APU BLEED WAS TURNED ON. THIS SMOKE WAS IMMEDIATELY RECOGNIZED AS RESIDUAL DEICE FLUID AND THE APU BLEED WAS TURNED OFF. WHEN THIS WAS DONE THE SMOKE STOPPED. I THEN DECIDED TO PERFORM A DEPRESSURIZED TKOF, WHICH IS AN APPROVED COMPANY PROC. HOWEVER, WHEN THE APU BLEED AIR WAS OFF, DEICE FLUID AGAIN BEGAN TO SEEP THROUGH THE COCKPIT WINDOWS. THE FO WAS DIRECTED TO PUT ON THE ENG BLEED TO PRESSURIZE THE CABIN UNTIL WE WERE CLRED FOR TKOF AND AT THAT TIME THE BLEED AIR WOULD AGAIN BE PLACED IN THE OFF POS TO ACCOMPLISH THE DEPRESSURIZED TKOF. THE END OF THE RWY WAS APCHING AND ALTHOUGH NOT CALLED FOR, THE BEFORE TKOF CHKLIST WAS READ. ASSUMING THAT WE WERE CLRED INTO POS, I CONTINUED THE TAXI AS THE FO WAS PREPARING THE BLEED AIR SYS FOR THE DEPRESSURIZED TKOF. IN REALITY WE WERE NOT CLRED INTO POS AND A RWY INCURSION OCCURRED RESULTING IN THE GAR OF ANOTHER ACFT. OUR ACFT WAS STOPPED PRIOR TO ENTERING THE RWY, BUT AFTER THE HOLD SHORT LINE FOR THAT RWY. OTHER ACFT WAS SENT AROUND AT AN ESTIMATED 500 FT AND 1/2 MI FROM THE THRESHOLD BY TORONTO TWR. WE WERE THEN CLRED INTO POS AND SUBSEQUENTLY CLRED FOR TKOF. THE REMAINDER OF THE FLT WAS UNEVENTFUL. AS CAPT OF THE ACFT, I ASSUME SOLE RESPONSIBILITY FOR THE INCURSION ONTO THE RWY. CONTRIBUTING FACTORS FOR THIS SIT ARE MANY. THE BIGGEST PROB I THINK IS THE FACT THAT THE FO READ THE CHKLIST UNPROMPTED WHICH LED ME TO BELIEVE THAT WE HAD BEEN CLRED INTO POS. IT IS OUR COMPANY PROC THAT THE CHKLIST WILL BE CALLED FOR BY THE CAPT AND ONLY AFTER WE HAVE BEEN GIVEN INSTRUCTIONS FROM THE TWR TO BE CLRED INTO POS OR CLRED FOR TKOF. ALTHOUGH I ALSO AM MONITORING THE TWR FREQ, I SHOULD HAVE PICKED UP THAT WE WERE NOT CLRED INTO POS AS I WAS BUSY TRYING TO DETERMINE THAT EVERYTHING WAS SET RIGHT FOR THE DEPRESSURIZED TKOF. I AM EQUALLY CONVINCED MY COPLT WAS DOING THE SAME. VALUABLE LESSONS HAVE BEEN LEARNED. SUPPLEMENTAL INFO FROM ACN 466122: INADVERTENTLY TAXIED ACFT ONTO RWY 6R. TAXIING ON UNFAMILIAR ARPT AFTER FRESH SNOWFALL OBSCURED MANY TAXI FEATURES. CREW USED ATC TO MAX EXTENT PRACTICABLE WITH SAFETY, INCLUDING USE OF PROGRESSIVE TAXI. OUR FIRST INDICATION THAT WE HAD COMMITTED THE INCURSION WAS WHEN TWR TOLD AN ACR TO 'GO AROUND, TFC ON RWY.' CREW QUERIED TWR AS TO WHETHER WE HAD BEEN CLRED TO 'POS AND HOLD' AND WERE INFORMED THAT WE WERE NOT. THIS INCIDENT, TO ME, UNDERSCORES THE NEED TO PUNCTILIOUSLY VERIFY ACTIONS PERFORMED BY FLCS, PARTICULARLY DURING ODD OR IRREGULAR OPS OR SITS. MULTI-TASKING AND THE FACT OF UNFAMILIAR ARPT OPS IN THIS CASE MAY HAVE BEEN CONTRIBUTING FACTORS.

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.