2011-12 · NASA ASRS report 984707
A B737NG flight crew recounted problems they encountered while attempting--and failing--to develop accurate takeoff performance data for an intersection takeoff at ORD; using computerized flight deck resources for which they concluded they had not been adequately trained.
We potentially departed [Runway] 14L Intersection U2 with invalid takeoff performance data. Upon taxi out; Ground gave us a confusing taxi clearance. I attempted to write it down; but the Controller was too fast. We asked for a re-issuance and were abruptly told to stop; let an RJ in front of us; and follow them to 14L. The Captain asked for read back of the specific route; but the Ground Controller directed us again to follow that RJ. I wound up glued to the airport page to make sure we were going the right way.Just prior to reaching 14L I noticed that 14L was not on our original takeoff performance data. I got a 14L takeoff performance data from ACARS. Then using the QRH I entered X/14L for the intersection and also the code for the wet runway conditions. The V speeds were corrected and entered in the FMC. The Captain also asked to remove the data for max power; which I did. The aircraft used an abnormal amount of runway getting to rotation speed. Enroute it became clear after discussion with the Captain and getting additional info once at our destination that we needed 14LX data; not 14L.We need increased attention to performance details. I have to say; our manuals don't say a lot about intersection takeoffs other than how to obtain and enter data. It frankly wasn't clear to me until now that 14L and 14LX in this case are two separate runways and two separate sets of takeoff performance data. We had recently been issued guidance on using the QRH in the FMC to correct V speeds for changing runway and weather conditions. I assumed the intersection entry would cover the fact that we were indeed using the intersection and the QRH V speeds would reflect that. I see now that unique performance data is needed for each runway; also another obvious choice to take the full length if in doubt since we did indeed have full length data.
Upon asking for clarification; we were instructed [by Ground Control] to stop short of next intersection. Ground then told the aircraft behind us to deviate around us [and] then instructed us to follow that aircraft. My professional pride was offended and I told the First Officer as much.I told the First Officer we needed performance data for Runway 14LX and he replied that we only needed to put 'X' on line 5L in the FMS and accept the FMS QRH V speeds. I was not 100 percent confident that was correct; but allowed myself to be convinced by following the QRH procedure in our QRH quick reference guide.Takeoff was uneventful except that we rotated at about 2;500 FT remaining marker. After landing I was still not convinced we had done things correctly and; from my hotel room; I called Dispatch to verify that the takeoff performance data we had used was valid. After my discussion with the shift Supervisor; I was convinced we took off without valid numbers.Believe me; I realize how serious the consequences of this error could have been. I assure you it will never happen again in any cockpit I occupy. I accept full responsibility for my mistake. However; I believe the training that we received regarding the QRH in the 737 FMS was woefully inadequate. A special Bulletin and a printed card stock procedure do not adequately cover the complexities of the system. We did not find a complete description of the QRH capabilities and limitations during any of our research. I believe more attention to what the QRH can do; and what it cannot do for the flight crew should be applied during initial and recurrent training.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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