Narrative:

We were taxiing for takeoff on 25R in las. When we were about a half mi from the end of the runway, the first officer answered a call from tower and went back to checking the numbers for takeoff and running the checklist and doing his PA to the flight attendants to be seated. As I taxied on to the runway the first officer copied our fuel amount and takeoff time. He then completed the before takeoff check and called it complete. I then called, 'your throttles' and I xferred control of the aircraft over to him as it was his leg. He then said 'are we position and hold?' I said 'no, we are cleared for takeoff, look at the light switches, they're all on.' he then said ok and took control of the aircraft (the landing light switches, on, is our reminder that we are cleared for takeoff). The first officer completed a textbook takeoff. The radio was completely silent except for that one call the tower made to us on the taxiway, quite a long time earlier. I observed no other aircraft on the runways 25R/25L side of the airport. The other runways in las vegas, runways 19L and 19R, are not visible from the east side of the airport and they are on a different frequency so we had no idea what was happening over there. As we climbed through 1500 ft AGL, the controller gave us a number to call. At that point I looked at the light switches and it hit me. I was in the only airplane in our fleet that has the light switches installed backwards. My heart sunk and I knew what had happened. When I got on the ground I called the controller and asked if everyone was ok. He said yes and that no one had a problem but that he would still have to report it. I asked why he didn't say anything to us when he saw us moving but he said he wasnT watching our runway. I realize he really wasn't supposed to watch us. I am just so glad no one was hurt. It could have been a disaster. I think our little helpful light switch technique to remind us of our clrncs should have been dropped immediately when our company acquired that old airplane with the backward switches or change those switches to match all the other airplanes. I also don't like the technique of the tower putting aircraft into position for 10 mins at a time while they depart a half dozen airplanes off of a crossing runway that has a different frequency. I kick myself for not using my CRM better and not asking for clarification from the tower when the first officer questioned whether or not we were cleared for takeoff. It was just that I had those little switches in the down position, the way they always have been for thousands of takeoffs. Relying on two little switches instead of a good first officer and the tower to clarify our clearance will be something I will never do again.

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Original NASA ASRS Text

Title: FLT CREW OF MD82 TOOK OFF FROM RWY 25 AT LAS WITHOUT CLRNC. DISTRS AND UNIQUE SWITCH POS ON THEIR ACFT ARE CONTRIBUTING FACTORS.

Narrative: WE WERE TAXIING FOR TKOF ON 25R IN LAS. WHEN WE WERE ABOUT A HALF MI FROM THE END OF THE RWY, THE FO ANSWERED A CALL FROM TWR AND WENT BACK TO CHKING THE NUMBERS FOR TKOF AND RUNNING THE CHKLIST AND DOING HIS PA TO THE FLT ATTENDANTS TO BE SEATED. AS I TAXIED ON TO THE RWY THE FO COPIED OUR FUEL AMOUNT AND TKOF TIME. HE THEN COMPLETED THE BEFORE TKOF CHK AND CALLED IT COMPLETE. I THEN CALLED, 'YOUR THROTTLES' AND I XFERRED CTL OF THE ACFT OVER TO HIM AS IT WAS HIS LEG. HE THEN SAID 'ARE WE POS AND HOLD?' I SAID 'NO, WE ARE CLRED FOR TKOF, LOOK AT THE LIGHT SWITCHES, THEY'RE ALL ON.' HE THEN SAID OK AND TOOK CTL OF THE ACFT (THE LNDG LIGHT SWITCHES, ON, IS OUR REMINDER THAT WE ARE CLRED FOR TKOF). THE FO COMPLETED A TEXTBOOK TKOF. THE RADIO WAS COMPLETELY SILENT EXCEPT FOR THAT ONE CALL THE TWR MADE TO US ON THE TXWY, QUITE A LONG TIME EARLIER. I OBSERVED NO OTHER ACFT ON THE RWYS 25R/25L SIDE OF THE ARPT. THE OTHER RWYS IN LAS VEGAS, RWYS 19L AND 19R, ARE NOT VISIBLE FROM THE E SIDE OF THE ARPT AND THEY ARE ON A DIFFERENT FREQ SO WE HAD NO IDEA WHAT WAS HAPPENING OVER THERE. AS WE CLBED THROUGH 1500 FT AGL, THE CTLR GAVE US A NUMBER TO CALL. AT THAT POINT I LOOKED AT THE LIGHT SWITCHES AND IT HIT ME. I WAS IN THE ONLY AIRPLANE IN OUR FLEET THAT HAS THE LIGHT SWITCHES INSTALLED BACKWARDS. MY HEART SUNK AND I KNEW WHAT HAD HAPPENED. WHEN I GOT ON THE GND I CALLED THE CTLR AND ASKED IF EVERYONE WAS OK. HE SAID YES AND THAT NO ONE HAD A PROB BUT THAT HE WOULD STILL HAVE TO RPT IT. I ASKED WHY HE DIDN'T SAY ANYTHING TO US WHEN HE SAW US MOVING BUT HE SAID HE WASNT WATCHING OUR RWY. I REALIZE HE REALLY WASN'T SUPPOSED TO WATCH US. I AM JUST SO GLAD NO ONE WAS HURT. IT COULD HAVE BEEN A DISASTER. I THINK OUR LITTLE HELPFUL LIGHT SWITCH TECHNIQUE TO REMIND US OF OUR CLRNCS SHOULD HAVE BEEN DROPPED IMMEDIATELY WHEN OUR COMPANY ACQUIRED THAT OLD AIRPLANE WITH THE BACKWARD SWITCHES OR CHANGE THOSE SWITCHES TO MATCH ALL THE OTHER AIRPLANES. I ALSO DON'T LIKE THE TECHNIQUE OF THE TWR PUTTING ACFT INTO POS FOR 10 MINS AT A TIME WHILE THEY DEPART A HALF DOZEN AIRPLANES OFF OF A XING RWY THAT HAS A DIFFERENT FREQ. I KICK MYSELF FOR NOT USING MY CRM BETTER AND NOT ASKING FOR CLARIFICATION FROM THE TWR WHEN THE FO QUESTIONED WHETHER OR NOT WE WERE CLRED FOR TKOF. IT WAS JUST THAT I HAD THOSE LITTLE SWITCHES IN THE DOWN POS, THE WAY THEY ALWAYS HAVE BEEN FOR THOUSANDS OF TKOFS. RELYING ON TWO LITTLE SWITCHES INSTEAD OF A GOOD FO AND THE TWR TO CLARIFY OUR CLRNC WILL BE SOMETHING I WILL NEVER DO AGAIN.

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.