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Dispatched with an inoperative left engine reverser the flight crew of a B737-700 computed their takeoff performance utilizing the onboard computer with the relevant MEL item selected and the result required a maximum thrust takeoff due to the MEL. On the next leg the computing process was initiated in a different fashion; the MEL dropped out of memory; and the computer provided takeoff numbers predicated on reduced thrust. The error was not discovered until at cruise on the second leg.
| Attributes | |
| ACN | 1123702 |
| Time | |
| Date | 201310 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Takeoff |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Laptop Computer (performance planning etc.) |
| Person 1 | |
| Function | Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 138 Flight Crew Type 11000 |
| Person 2 | |
| Function | First Officer |
| Experience | Flight Crew Last 90 Days 197 Flight Crew Type 1300 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Procedural MEL Deviation - Procedural Published Material / Policy Deviation - Procedural Weight And Balance |
Narrative:
Our aircraft had an MEL for the number one engine thrust reverser inoperative; which had been previously documented. On the first leg from XXX; the opc was correctly programmed resulting in a max power takeoff. All ground ops at our next departure airport were normal resulting in a reduced power takeoff on runway 19L. Upon reaching cruise; something jarred my memory about the requirement to perform a max power takeoff with an inoperative thrust reverser. I then reviewed the opc again and found out for some reason the MEL button was no longer highlighted. It was my belief that once an MEL had been selected on the opc that it would be retained for subsequent use. We then began a trial and error with the opc along with a review of the manual to determine what could have possibly happened. During this exercise; we discovered that during the opc programming on the ground at our first stop the onboard performance system page had been selected when going from landing data to takeoff data versus just selecting the module menu page. This resulted in the MEL being dropped. Although this was a programming error; I still should have caught the MEL not being highlighted. We talked numerous times on the first leg about the thrust reverser; especially on landing; but for some reason we both completely missed the reduced takeoff commanded by the opc for our subsequent departure.we get mels so infrequently; especially ones that require opc input. My [limited] knowledge on how the opc retains mels may have made me a little complacent on what the opc provides us. We were on top of the MEL the first leg but failed to follow through with the same diligence for the second.
Original NASA ASRS Text
Title: Dispatched with an inoperative left engine reverser the flight crew of a B737-700 computed their takeoff performance utilizing the onboard computer with the relevant MEL item selected and the result required a maximum thrust takeoff due to the MEL. On the next leg the computing process was initiated in a different fashion; the MEL dropped out of memory; and the computer provided takeoff numbers predicated on reduced thrust. The error was not discovered until at cruise on the second leg.
Narrative: Our aircraft had an MEL for the Number One Engine thrust reverser inoperative; which had been previously documented. On the first leg from XXX; the OPC was correctly programmed resulting in a max power takeoff. All ground ops at our next departure airport were normal resulting in a reduced power takeoff on Runway 19L. Upon reaching cruise; something jarred my memory about the requirement to perform a max power takeoff with an inoperative thrust reverser. I then reviewed the OPC again and found out for some reason the MEL button was no longer highlighted. It was my belief that once an MEL had been selected on the OPC that it would be retained for subsequent use. We then began a trial and error with the OPC along with a review of the manual to determine what could have possibly happened. During this exercise; we discovered that during the OPC programming on the ground at our first stop the Onboard Performance System page had been selected when going from landing data to takeoff data versus just selecting the Module menu page. This resulted in the MEL being dropped. Although this was a programming error; I still should have caught the MEL not being highlighted. We talked numerous times on the first leg about the thrust reverser; especially on landing; but for some reason we both completely missed the reduced takeoff commanded by the OPC for our subsequent departure.We get MELs so infrequently; especially ones that require OPC input. My [limited] knowledge on how the OPC retains MELs may have made me a little complacent on what the OPC provides us. We were on top of the MEL the first leg but failed to follow through with the same diligence for the second.
Data retrieved from NASA's ASRS site as of July 2013 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.