Narrative:

At XXXX central, started the APU. Both captain and I were in our seats. As I was putting the APU online, 'a' flight attendant entered the flight deck to briefly speak with the captain. As they were wrapping up, operations agent handed me load manifest and I entered the data into the opc and FMC, and showed it to the captain. Entry door closed and I called for push. As we began the push, we started engine #1. Prior to starter cutout, there was a loud 'bang' and the captain in coordination with pushback crew set brakes. Pushback crew verified that the towbar shear pin had broken, and that the nose gear looked fine. We had been pushed back far enough to turn out and taxi without further push, so the towbar was disconnected and pushback crew departed. At that time, we completed the before start checklist, started #2 engine, completed the pretkof checklist down to the line, called for taxi, and continued the flight. This event was directly caused by our failure to accomplish the before start checklist. I had been thinking about the checklist, but when the load manifest was handed to me, I went into 'go' mode, calculated and entered the takeoff data, reviewed it with the captain, and called for push. I certainly should not have dealt with the takeoff data until checklist completed. I do believe that a contributing factor is the fact that there is a lot of pressure for the first officer to get the data done, and opc stowed, so that pushback may commence. I think that the new (relatively) procedure of completing all data prior to push, and pretkof checklist down to the line prior to taxi is a good thing. About the only negative is that the first officer is now very pressured to get data done. Usually, the load manifest arrives in the flight deck at push time, if not a min or two late. Now there is this big crush to get data done, and get pushed, etc. This in no way excuses or justifies the omission of the checklist. It just is a factor that put me into the 'go' mode and I never thought about the before start checklist again until the towbar shear pin broke. In the future, I will not calculate takeoff data until I verify that the before start checklist has been completed. If it costs an extra 30 seconds or min, that is a small price when compared to broken equipment and safety risk.

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Original NASA ASRS Text

Title: A B737-700 FO ADMITTED THAT HE AND THE CAPT FORGOT TO RUN THE BEFORE START CHKLIST, DUE TO A CHANGE IN PROC AND OTHER DISTRS.

Narrative: AT XXXX CENTRAL, STARTED THE APU. BOTH CAPT AND I WERE IN OUR SEATS. AS I WAS PUTTING THE APU ONLINE, 'A' FLT ATTENDANT ENTERED THE FLT DECK TO BRIEFLY SPEAK WITH THE CAPT. AS THEY WERE WRAPPING UP, OPS AGENT HANDED ME LOAD MANIFEST AND I ENTERED THE DATA INTO THE OPC AND FMC, AND SHOWED IT TO THE CAPT. ENTRY DOOR CLOSED AND I CALLED FOR PUSH. AS WE BEGAN THE PUSH, WE STARTED ENG #1. PRIOR TO STARTER CUTOUT, THERE WAS A LOUD 'BANG' AND THE CAPT IN COORD WITH PUSHBACK CREW SET BRAKES. PUSHBACK CREW VERIFIED THAT THE TOWBAR SHEAR PIN HAD BROKEN, AND THAT THE NOSE GEAR LOOKED FINE. WE HAD BEEN PUSHED BACK FAR ENOUGH TO TURN OUT AND TAXI WITHOUT FURTHER PUSH, SO THE TOWBAR WAS DISCONNECTED AND PUSHBACK CREW DEPARTED. AT THAT TIME, WE COMPLETED THE BEFORE START CHKLIST, STARTED #2 ENG, COMPLETED THE PRETKOF CHKLIST DOWN TO THE LINE, CALLED FOR TAXI, AND CONTINUED THE FLT. THIS EVENT WAS DIRECTLY CAUSED BY OUR FAILURE TO ACCOMPLISH THE BEFORE START CHKLIST. I HAD BEEN THINKING ABOUT THE CHKLIST, BUT WHEN THE LOAD MANIFEST WAS HANDED TO ME, I WENT INTO 'GO' MODE, CALCULATED AND ENTERED THE TKOF DATA, REVIEWED IT WITH THE CAPT, AND CALLED FOR PUSH. I CERTAINLY SHOULD NOT HAVE DEALT WITH THE TKOF DATA UNTIL CHKLIST COMPLETED. I DO BELIEVE THAT A CONTRIBUTING FACTOR IS THE FACT THAT THERE IS A LOT OF PRESSURE FOR THE FO TO GET THE DATA DONE, AND OPC STOWED, SO THAT PUSHBACK MAY COMMENCE. I THINK THAT THE NEW (RELATIVELY) PROC OF COMPLETING ALL DATA PRIOR TO PUSH, AND PRETKOF CHKLIST DOWN TO THE LINE PRIOR TO TAXI IS A GOOD THING. ABOUT THE ONLY NEGATIVE IS THAT THE FO IS NOW VERY PRESSURED TO GET DATA DONE. USUALLY, THE LOAD MANIFEST ARRIVES IN THE FLT DECK AT PUSH TIME, IF NOT A MIN OR TWO LATE. NOW THERE IS THIS BIG CRUSH TO GET DATA DONE, AND GET PUSHED, ETC. THIS IN NO WAY EXCUSES OR JUSTIFIES THE OMISSION OF THE CHKLIST. IT JUST IS A FACTOR THAT PUT ME INTO THE 'GO' MODE AND I NEVER THOUGHT ABOUT THE BEFORE START CHKLIST AGAIN UNTIL THE TOWBAR SHEAR PIN BROKE. IN THE FUTURE, I WILL NOT CALCULATE TKOF DATA UNTIL I VERIFY THAT THE BEFORE START CHKLIST HAS BEEN COMPLETED. IF IT COSTS AN EXTRA 30 SECONDS OR MIN, THAT IS A SMALL PRICE WHEN COMPARED TO BROKEN EQUIP AND SAFETY RISK.

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.