Narrative:

We were instructed to hold on concrete pad and make room for air carrier jet to get around us. While maneuvering to comply, we switched to lax tower, and were given position and hold 24L. We commenced on runway items checklist, and before lining up, were instructed to cross 24L. I read back instructions and returned to checklist. As we approached the 24R hold line, I realized I had not registered in my mind whether we were given 'hold short' or 'position and hold.' I asked my first officer which it was, and was told 'position and hold', with no hesitation. I still had doubt, so I asked 'are you absolutely sure?' 'absolutely' came the reply, again with great conviction. I checked final, and it was clear as far as I could see (5 mi or more). So we continued the checklist, and taxied into position. After a few moments, the tower told us, 'your instructions were to hold short, turn left and exit the runway.' so we did. Afterward, my first officer continued to insist we were given 'position and hold'. I am still not sure one way or the other. Usually things as important as a runway change, etc, are preceded by an attention getter such as, 'cancel previous instruction, now taxi across 24L and hold short of 24R' with some emphasis. I remember thinking at the time that it was a pretty casual way to issue a fairly major instruction. Indeed, it may have been this thought that prevented my mind from remembering what my mouth read back. In retrospect, I should have exercised my command authority and told my first officer to hold short anyway while I verified the instruction. After all, I am not aware of any accident or violation that was the result of improperly holding short. Callback conversation with reporter revealed the following information: callback was structured as part of runway incursion study. Reporter says that ATC local controller gave no reason for departure runway change from 24L to 24R, but assumes that change was because they were going to the north after takeoff and could be turned without conflicting with 24L departures. After they taxied back off of 24R and facing back toward 24L again they were held for about 5 or 6 other departure aircraft to go ahead of them off 24L and then they were reclred for takeoff on 24L. About 1 min after they taxied off runway 24R a widebody transport air carrier landed that runway. Short distance from their gate to runway 24L/right does not allow enough time to complete all the checklists if they are in continuous motion as they were during this incident. Will suggest to company that procedure be changed to allow some checklist items to be accomplished prior to taxi from gate or ramp area.

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Original NASA ASRS Text

Title: COMMUTER TAXIED ONTO RWY WITHOUT CLRNC. PLTDEV. POTENTIAL CONFLICT.

Narrative: WE WERE INSTRUCTED TO HOLD ON CONCRETE PAD AND MAKE ROOM FOR ACR JET TO GET AROUND US. WHILE MANEUVERING TO COMPLY, WE SWITCHED TO LAX TWR, AND WERE GIVEN POS AND HOLD 24L. WE COMMENCED ON RWY ITEMS CHKLIST, AND BEFORE LINING UP, WERE INSTRUCTED TO CROSS 24L. I READ BACK INSTRUCTIONS AND RETURNED TO CHKLIST. AS WE APCHED THE 24R HOLD LINE, I REALIZED I HAD NOT REGISTERED IN MY MIND WHETHER WE WERE GIVEN 'HOLD SHORT' OR 'POS AND HOLD.' I ASKED MY FO WHICH IT WAS, AND WAS TOLD 'POS AND HOLD', WITH NO HESITATION. I STILL HAD DOUBT, SO I ASKED 'ARE YOU ABSOLUTELY SURE?' 'ABSOLUTELY' CAME THE REPLY, AGAIN WITH GREAT CONVICTION. I CHKED FINAL, AND IT WAS CLR AS FAR AS I COULD SEE (5 MI OR MORE). SO WE CONTINUED THE CHKLIST, AND TAXIED INTO POS. AFTER A FEW MOMENTS, THE TWR TOLD US, 'YOUR INSTRUCTIONS WERE TO HOLD SHORT, TURN L AND EXIT THE RWY.' SO WE DID. AFTERWARD, MY FO CONTINUED TO INSIST WE WERE GIVEN 'POS AND HOLD'. I AM STILL NOT SURE ONE WAY OR THE OTHER. USUALLY THINGS AS IMPORTANT AS A RWY CHANGE, ETC, ARE PRECEDED BY AN ATTN GETTER SUCH AS, 'CANCEL PREVIOUS INSTRUCTION, NOW TAXI ACROSS 24L AND HOLD SHORT OF 24R' WITH SOME EMPHASIS. I REMEMBER THINKING AT THE TIME THAT IT WAS A PRETTY CASUAL WAY TO ISSUE A FAIRLY MAJOR INSTRUCTION. INDEED, IT MAY HAVE BEEN THIS THOUGHT THAT PREVENTED MY MIND FROM REMEMBERING WHAT MY MOUTH READ BACK. IN RETROSPECT, I SHOULD HAVE EXERCISED MY COMMAND AUTHORITY AND TOLD MY FO TO HOLD SHORT ANYWAY WHILE I VERIFIED THE INSTRUCTION. AFTER ALL, I AM NOT AWARE OF ANY ACCIDENT OR VIOLATION THAT WAS THE RESULT OF IMPROPERLY HOLDING SHORT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: CALLBACK WAS STRUCTURED AS PART OF RWY INCURSION STUDY. RPTR SAYS THAT ATC LCL CTLR GAVE NO REASON FOR DEP RWY CHANGE FROM 24L TO 24R, BUT ASSUMES THAT CHANGE WAS BECAUSE THEY WERE GOING TO THE N AFTER TKOF AND COULD BE TURNED WITHOUT CONFLICTING WITH 24L DEPS. AFTER THEY TAXIED BACK OFF OF 24R AND FACING BACK TOWARD 24L AGAIN THEY WERE HELD FOR ABOUT 5 OR 6 OTHER DEP ACFT TO GO AHEAD OF THEM OFF 24L AND THEN THEY WERE RECLRED FOR TKOF ON 24L. ABOUT 1 MIN AFTER THEY TAXIED OFF RWY 24R A WDB ACR LANDED THAT RWY. SHORT DISTANCE FROM THEIR GATE TO RWY 24L/R DOES NOT ALLOW ENOUGH TIME TO COMPLETE ALL THE CHKLISTS IF THEY ARE IN CONTINUOUS MOTION AS THEY WERE DURING THIS INCIDENT. WILL SUGGEST TO COMPANY THAT PROC BE CHANGED TO ALLOW SOME CHKLIST ITEMS TO BE ACCOMPLISHED PRIOR TO TAXI FROM GATE OR RAMP AREA.

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.