Narrative:

The following event occurred during the 10TH flight segment which was during the 16TH flight hour within the prior 48 hours. All ten of the prior segments were flown under the influence of a major WX system along the west coast of the united states. This WX system produced late flts, extended/long duty periods, short turn around times, rushed crew changes to different aircraft, along with additional flight planning and duties for deicing of aircraft. We were 10 hours, 30 mins into our duty period and had just completed our third rushed aircraft changes in four flight segments. Prior to pushback air carrier a, abc, was advised by sjc ground control to plan runway 12R. During pushback we were positioned on ramp/taxiway Z. When we called for taxi clearance we were instructed to 'taxi to runway 12R via yankee.' we taxied via taxiway Z, left on taxiway G, right taxiway Y, and proceeded to the end of taxiway Y, which with a left turn becomes taxiway left and held short of runway 12R. We were the only aircraft at this position, holding short of runway 12R at taxiway left waiting takeoff clearance. Taxiway left positions aircraft at the displaced threshold of runway 12R, the normal takeoff position for runway 12R. Taxiway left also crosses runway 12R, turns right and becomes taxiway M which provides only access to the end (full length) of runway 12R. Across and at the end of runway 12R, about 1000 ft from our position were 2 aircraft, an air carrier B flight positioned behind our company flight, xyz. While holding short for takeoff I observed the air carrier B flight and assumed he was put in that area for flow control. With visibility impaired by the dark and light rain I did not notice any other aircraft in the vicinity of the air carrier B aircraft. After observing several arrs, sjc control tower instructed air carrier a, XXX, taxi into position and hold runway 12R.' what we heard was 'air carrier a, abc,' which the first officer acknowledged 'air carrier a, abc, position and hold runway 12R' and after visually clearing the approach path we entered runway 12R at taxiway left. Simultaneously air carrier a, xyz, acknowledged a clearance for position and hold which blocked the entire readback/hearback verification procedures to the controller. Xyz entered at the end of the runway 12R at taxiway M. Once the controller observed both aircraft entering the runway he stated that the clearance was for xyz not abc. Abc was instructed to continue across runway 12R and taxi via taxiway M to the end of runway 12R. Who was cleared into position and hold? We heard abc, but maybe we misled ourselves, being in the normal takeoff position for runway 12R and assuming we were the only air carrier a flight waiting a takeoff clearance. Most likely it was for xyz, but they could have been misled because they were #1 at the end of runway 12R. Did the tower controller mean xyz but say abc by accident? During late evening operations the sjc tower staffing requires controllers to perform multiple combined duties vastly increasing their workload and the possibility of errors. We have similar call signs involved, both ending in same number. There was no confusion or guessing in our cockpit, like, 'was that for us?' we both heard the clearance, nothing was said between the two of us questioning it or leading each other to its content. Who was the clearance for? In my mind there is no doubt, it was for abc. Most likely, the clearance was for xyz. Anti-blocking radios anyone?

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Original NASA ASRS Text

Title: FLC OF MD83 TAXIES TO HOLD SHORT AREA OF DISPLACED THRESHOLD OF DEP RWY AND HOLDS WAITING FOR TKOF CLRNC. THEY ARE NOT AWARE OF COMPANY ACFT AT ACTUAL END OF RWY ALSO WAITING FOR TKOF CLRNC. WHEN CLRNC ISSUED THEY ARE SURE IT IS FOR THEM AND AFTER READBACK BEGIN TAXI ONTO RWY. CTLR SIGHTS BOTH ACFT MOVING AND CLRS RPTR ACFT TO CROSS RWY AND TAXI TO END.

Narrative: THE FOLLOWING EVENT OCCURRED DURING THE 10TH FLT SEGMENT WHICH WAS DURING THE 16TH FLT HR WITHIN THE PRIOR 48 HRS. ALL TEN OF THE PRIOR SEGMENTS WERE FLOWN UNDER THE INFLUENCE OF A MAJOR WX SYS ALONG THE WEST COAST OF THE UNITED STATES. THIS WX SYS PRODUCED LATE FLTS, EXTENDED/LONG DUTY PERIODS, SHORT TURN AROUND TIMES, RUSHED CREW CHANGES TO DIFFERENT ACFT, ALONG WITH ADDITIONAL FLT PLANNING AND DUTIES FOR DEICING OF ACFT. WE WERE 10 HRS, 30 MINS INTO OUR DUTY PERIOD AND HAD JUST COMPLETED OUR THIRD RUSHED ACFT CHANGES IN FOUR FLT SEGMENTS. PRIOR TO PUSHBACK ACR A, ABC, WAS ADVISED BY SJC GND CTL TO PLAN RWY 12R. DURING PUSHBACK WE WERE POSITIONED ON RAMP/TXWY Z. WHEN WE CALLED FOR TAXI CLRNC WE WERE INSTRUCTED TO 'TAXI TO RWY 12R VIA YANKEE.' WE TAXIED VIA TXWY Z, L ON TXWY G, R TXWY Y, AND PROCEEDED TO THE END OF TXWY Y, WHICH WITH A L TURN BECOMES TXWY L AND HELD SHORT OF RWY 12R. WE WERE THE ONLY ACFT AT THIS POS, HOLDING SHORT OF RWY 12R AT TXWY L WAITING TKOF CLRNC. TXWY L POSITIONS ACFT AT THE DISPLACED THRESHOLD OF RWY 12R, THE NORMAL TKOF POS FOR RWY 12R. TXWY L ALSO CROSSES RWY 12R, TURNS R AND BECOMES TXWY M WHICH PROVIDES ONLY ACCESS TO THE END (FULL LENGTH) OF RWY 12R. ACROSS AND AT THE END OF RWY 12R, ABOUT 1000 FT FROM OUR POS WERE 2 ACFT, AN ACR B FLT POSITIONED BEHIND OUR COMPANY FLT, XYZ. WHILE HOLDING SHORT FOR TKOF I OBSERVED THE ACR B FLT AND ASSUMED HE WAS PUT IN THAT AREA FOR FLOW CTL. WITH VISIBILITY IMPAIRED BY THE DARK AND LIGHT RAIN I DID NOT NOTICE ANY OTHER ACFT IN THE VICINITY OF THE ACR B ACFT. AFTER OBSERVING SEVERAL ARRS, SJC CTL TWR INSTRUCTED ACR A, XXX, TAXI INTO POS AND HOLD RWY 12R.' WHAT WE HEARD WAS 'ACR A, ABC,' WHICH THE FO ACKNOWLEDGED 'ACR A, ABC, POS AND HOLD RWY 12R' AND AFTER VISUALLY CLRING THE APCH PATH WE ENTERED RWY 12R AT TXWY L. SIMULTANEOUSLY ACR A, XYZ, ACKNOWLEDGED A CLRNC FOR POS AND HOLD WHICH BLOCKED THE ENTIRE READBACK/HEARBACK VERIFICATION PROCS TO THE CTLR. XYZ ENTERED AT THE END OF THE RWY 12R AT TXWY M. ONCE THE CTLR OBSERVED BOTH ACFT ENTERING THE RWY HE STATED THAT THE CLRNC WAS FOR XYZ NOT ABC. ABC WAS INSTRUCTED TO CONTINUE ACROSS RWY 12R AND TAXI VIA TXWY M TO THE END OF RWY 12R. WHO WAS CLRED INTO POS AND HOLD? WE HEARD ABC, BUT MAYBE WE MISLED OURSELVES, BEING IN THE NORMAL TKOF POS FOR RWY 12R AND ASSUMING WE WERE THE ONLY ACR A FLT WAITING A TKOF CLRNC. MOST LIKELY IT WAS FOR XYZ, BUT THEY COULD HAVE BEEN MISLED BECAUSE THEY WERE #1 AT THE END OF RWY 12R. DID THE TWR CTLR MEAN XYZ BUT SAY ABC BY ACCIDENT? DURING LATE EVENING OPS THE SJC TWR STAFFING REQUIRES CTLRS TO PERFORM MULTIPLE COMBINED DUTIES VASTLY INCREASING THEIR WORKLOAD AND THE POSSIBILITY OF ERRORS. WE HAVE SIMILAR CALL SIGNS INVOLVED, BOTH ENDING IN SAME NUMBER. THERE WAS NO CONFUSION OR GUESSING IN OUR COCKPIT, LIKE, 'WAS THAT FOR US?' WE BOTH HEARD THE CLRNC, NOTHING WAS SAID BTWN THE TWO OF US QUESTIONING IT OR LEADING EACH OTHER TO ITS CONTENT. WHO WAS THE CLRNC FOR? IN MY MIND THERE IS NO DOUBT, IT WAS FOR ABC. MOST LIKELY, THE CLRNC WAS FOR XYZ. ANTI-BLOCKING RADIOS ANYONE?

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.