Narrative:

On 3/tue/89 I was captain of air carrier flight xx from lax to smf. The first officer was xa. A FAA inspector, xb, was in the jump seat administering a route check. Sb was wearing a headset monitoring the radios. I noticed the #2 oil pressure gauge was reading 0 while holding short of runway 24L. I asked the first officer to research the problem in the aircraft manuals and the MEL. We notified lax tower of our problem and maintenance. Lax tower cleared us to cross 24L and hold between the runways while we worked on our problem. The gauge corrected itself while we were holding between 24L and 24R. After a brief discussion and deciding all engine indications were ok, we notified lax tower that we were ready for takeoff. First officer xa was contacting maintenance that we were ok and going to takeoff when tower issued a takeoff clearance. There was same radio congestion at the time of the clearance as well as the fact that we were talking to air carrier maintenance on our #2 radio, but I believed the clearance was for us since it was given immediately after we notified tower that we were ready for takeoff. Because of the congestion and to avoid possible confusion, first officer xa read back the entire takeoff clearance stating in similar if not exact terms that air carrier flight xx was cleared for takeoff, fly runway heading, maintain 5000' and 250 KTS. No correction was given to our readback, so I taxied the aircraft into takeoff position on runway 24R. I taxied into position slowly so we could complete checklists and get a good look at #2 engine as we set takeoff power. We initiated our takeoff and at about 70 KTS tower told us to stop takeoff. We immediately aborted the takeoff and cleared runway 24R. The controller said we had not been cleared for takeoff. I responded by saying that we believed we had been cleared for takeoff and had read back a complete takeoff clearance. The tower controller said that some radio xmissions we blocked but that the takeoff clearance was for an aircraft on runway 24L. She also said she couldn't let us go because gorman departures were stopped. We then received clearance to taxi back for takeoff. We accomplished the appropriate checklists and checked our brake energy limits. We made a normal takeoff and the rest of the flight was uneventful. Trying to resolved the oil pressure gauge problem in a timely manner while talking with lax tower and maintenance placed a brief but intense workload on both pilots. There was the additional pressure of an FAA inspection giving a route check in the jumpseat. This along with radio congestion and the busy workload of the tower controller created a situation of misunderstood and overlapping radio calls that allowed us to initiate a takeoff in error, when in fact all 3 individuals in the cockpit believed we were cleared for takeoff.

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Original NASA ASRS Text

Title: DUE TO VERY HIGH WORKLOAD AND SOME COM CONFUSION REPORTER ACFT BEGAN TKOF ROLL WITHOUT CLRNC AND SUBSEQUENTLY ABORTED THE TKOF.

Narrative: ON 3/TUE/89 I WAS CAPT OF ACR FLT XX FROM LAX TO SMF. THE F/O WAS XA. A FAA INSPECTOR, XB, WAS IN THE JUMP SEAT ADMINISTERING A ROUTE CHK. SB WAS WEARING A HEADSET MONITORING THE RADIOS. I NOTICED THE #2 OIL PRESSURE GAUGE WAS READING 0 WHILE HOLDING SHORT OF RWY 24L. I ASKED THE F/O TO RESEARCH THE PROB IN THE ACFT MANUALS AND THE MEL. WE NOTIFIED LAX TWR OF OUR PROB AND MAINT. LAX TWR CLRED US TO CROSS 24L AND HOLD BTWN THE RWYS WHILE WE WORKED ON OUR PROB. THE GAUGE CORRECTED ITSELF WHILE WE WERE HOLDING BTWN 24L AND 24R. AFTER A BRIEF DISCUSSION AND DECIDING ALL ENG INDICATIONS WERE OK, WE NOTIFIED LAX TWR THAT WE WERE READY FOR TKOF. F/O XA WAS CONTACTING MAINT THAT WE WERE OK AND GOING TO TKOF WHEN TWR ISSUED A TKOF CLRNC. THERE WAS SAME RADIO CONGESTION AT THE TIME OF THE CLRNC AS WELL AS THE FACT THAT WE WERE TALKING TO ACR MAINT ON OUR #2 RADIO, BUT I BELIEVED THE CLRNC WAS FOR US SINCE IT WAS GIVEN IMMEDIATELY AFTER WE NOTIFIED TWR THAT WE WERE READY FOR TKOF. BECAUSE OF THE CONGESTION AND TO AVOID POSSIBLE CONFUSION, F/O XA READ BACK THE ENTIRE TKOF CLRNC STATING IN SIMILAR IF NOT EXACT TERMS THAT ACR FLT XX WAS CLRED FOR TKOF, FLY RWY HDG, MAINTAIN 5000' AND 250 KTS. NO CORRECTION WAS GIVEN TO OUR READBACK, SO I TAXIED THE ACFT INTO TKOF POS ON RWY 24R. I TAXIED INTO POS SLOWLY SO WE COULD COMPLETE CHKLISTS AND GET A GOOD LOOK AT #2 ENG AS WE SET TKOF PWR. WE INITIATED OUR TKOF AND AT ABOUT 70 KTS TWR TOLD US TO STOP TKOF. WE IMMEDIATELY ABORTED THE TKOF AND CLRED RWY 24R. THE CTLR SAID WE HAD NOT BEEN CLRED FOR TKOF. I RESPONDED BY SAYING THAT WE BELIEVED WE HAD BEEN CLRED FOR TKOF AND HAD READ BACK A COMPLETE TKOF CLRNC. THE TWR CTLR SAID THAT SOME RADIO XMISSIONS WE BLOCKED BUT THAT THE TKOF CLRNC WAS FOR AN ACFT ON RWY 24L. SHE ALSO SAID SHE COULDN'T LET US GO BECAUSE GORMAN DEPS WERE STOPPED. WE THEN RECEIVED CLRNC TO TAXI BACK FOR TKOF. WE ACCOMPLISHED THE APPROPRIATE CHKLISTS AND CHKED OUR BRAKE ENERGY LIMITS. WE MADE A NORMAL TKOF AND THE REST OF THE FLT WAS UNEVENTFUL. TRYING TO RESOLVED THE OIL PRESSURE GAUGE PROB IN A TIMELY MANNER WHILE TALKING WITH LAX TWR AND MAINT PLACED A BRIEF BUT INTENSE WORKLOAD ON BOTH PLTS. THERE WAS THE ADDITIONAL PRESSURE OF AN FAA INSPECTION GIVING A ROUTE CHK IN THE JUMPSEAT. THIS ALONG WITH RADIO CONGESTION AND THE BUSY WORKLOAD OF THE TWR CTLR CREATED A SITUATION OF MISUNDERSTOOD AND OVERLAPPING RADIO CALLS THAT ALLOWED US TO INITIATE A TKOF IN ERROR, WHEN IN FACT ALL 3 INDIVIDUALS IN THE COCKPIT BELIEVED WE WERE CLRED FOR TKOF.

Data retrieved from NASA's ASRS site as of August 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.