Narrative:

Upon landing on 16R in seattle, wa, I taxied clear of 16R. We were given no instructions by ATC to either 'hold short or taxi across 16L.' initially, I had thought we were cleared across 16L and continued my taxi. As a habit, I always read aloud the clearance given by ATC to either 'hold short' or 'cleared across.' about half way across the hold short line, or half the acfts length, I stopped realizing that I hadn't read anything aloud. No part of the aircraft was on the actual runway. I was about to have my first officer verify our clearance when tower came on the radio and told us we were not cleared across and cancelled the takeoff clearance of an aircraft taxiing onto 16L. The tower then cleared us across 16L and had us contact ground. I believe that getting no clearance from the tower to hold short caused us, as the crew, confusion of our clearance. Because no clearance was given, I fell out of my routine of reading back the clearance, although I should have been aware no clearance was given and held short. Supplemental information from acn 513231: about 30 ft across the line and before the aircraft entered the runway the captain stopped the aircraft. She questioned whether we had been cleared across since she had not repeated any tower instructions per her normal habit pattern. I told her no. I became involved inside the cockpit and did not notice how far the captain had taxied the aircraft until we had crossed the hold short but before we entered the runway. Seatac tower, although not required, normally gives hold short or cross instructions to aircraft on or exiting the runway after landing. The lack of these instructions took the captain out of her normal habit patterns.

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Original NASA ASRS Text

Title: DHC8 FLC QUESTIONS SEA TWR ENTERING RWY 16L AS TWR CANCELS TKOF CLRNC TO ANOTHER ACFT ON RWY 16L.

Narrative: UPON LNDG ON 16R IN SEATTLE, WA, I TAXIED CLR OF 16R. WE WERE GIVEN NO INSTRUCTIONS BY ATC TO EITHER 'HOLD SHORT OR TAXI ACROSS 16L.' INITIALLY, I HAD THOUGHT WE WERE CLRED ACROSS 16L AND CONTINUED MY TAXI. AS A HABIT, I ALWAYS READ ALOUD THE CLRNC GIVEN BY ATC TO EITHER 'HOLD SHORT' OR 'CLRED ACROSS.' ABOUT HALF WAY ACROSS THE HOLD SHORT LINE, OR HALF THE ACFTS LENGTH, I STOPPED REALIZING THAT I HADN'T READ ANYTHING ALOUD. NO PART OF THE ACFT WAS ON THE ACTUAL RWY. I WAS ABOUT TO HAVE MY FO VERIFY OUR CLRNC WHEN TWR CAME ON THE RADIO AND TOLD US WE WERE NOT CLRED ACROSS AND CANCELLED THE TKOF CLRNC OF AN ACFT TAXIING ONTO 16L. THE TWR THEN CLRED US ACROSS 16L AND HAD US CONTACT GND. I BELIEVE THAT GETTING NO CLRNC FROM THE TWR TO HOLD SHORT CAUSED US, AS THE CREW, CONFUSION OF OUR CLRNC. BECAUSE NO CLRNC WAS GIVEN, I FELL OUT OF MY ROUTINE OF READING BACK THE CLRNC, ALTHOUGH I SHOULD HAVE BEEN AWARE NO CLRNC WAS GIVEN AND HELD SHORT. SUPPLEMENTAL INFO FROM ACN 513231: ABOUT 30 FT ACROSS THE LINE AND BEFORE THE ACFT ENTERED THE RWY THE CAPT STOPPED THE ACFT. SHE QUESTIONED WHETHER WE HAD BEEN CLRED ACROSS SINCE SHE HAD NOT REPEATED ANY TWR INSTRUCTIONS PER HER NORMAL HABIT PATTERN. I TOLD HER NO. I BECAME INVOLVED INSIDE THE COCKPIT AND DID NOT NOTICE HOW FAR THE CAPT HAD TAXIED THE ACFT UNTIL WE HAD CROSSED THE HOLD SHORT BUT BEFORE WE ENTERED THE RWY. SEATAC TWR, ALTHOUGH NOT REQUIRED, NORMALLY GIVES HOLD SHORT OR CROSS INSTRUCTIONS TO ACFT ON OR EXITING THE RWY AFTER LNDG. THE LACK OF THESE INSTRUCTIONS TOOK THE CAPT OUT OF HER NORMAL HABIT PATTERNS.

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.