Narrative:

Departure with an incorrect calculation of aircraft climb gradient performance. We departed runway 16L on a modified profile in order to clear all obstacles on the SID. Runway 16R was closed. The modification to profile was to delay clean-up of flaps until above obstacle ht. Lesson one, the company fom does not stipulate modifying profile, but only allows the profile to be flown exactly as described in the fom. Modified climbs can't be calculated. We reviewed the climb data provided by the aircraft performance computer. The computer showed our takeoff performance for conditions, confign, cargo weight and balance, and the runway selected. Our performance was acceptable with obstacle climb capability as being the limiting factor for takeoff. I had always believed the aircraft performance computer would automatically calculate climb gradient for departure SID as well. Lesson two: it does not! We looked at the SID and felt that an old B727-100 might have a hard time getting out of reno, as heavy as ours was for that SID, so we briefed and flew the modified profile which gave us ample climb performance. Lesson three: the correct procedure is to manually enter the profile into the aircraft performance computer after reviewing takeoff and weight and balance. A performance chart will be generated for various altitudes on departure. That chart is then compared to the required climb performance on the SID. Our aircraft performance was legal. Our use of the aircraft performance computer and therefore our departure, was not.

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Original NASA ASRS Text

Title: B727-100 CREW DEPARTED RNO AND DID NOT HAVE THE REQUIRED SECOND OR THIRD SEGMENT ENG OUT-CLB REQUIREMENTS. THE COMPANY DOES NOT PROVIDE THE CREW WITH THE REQUIRED PERFORMANCE CALCULATIONS. THE COMPANY REQUIRES THE CREW TO CALCULATE THIS PERFORMANCE ON A LAPTOP COMPUTER.

Narrative: DEP WITH AN INCORRECT CALCULATION OF ACFT CLB GRADIENT PERFORMANCE. WE DEPARTED RWY 16L ON A MODIFIED PROFILE IN ORDER TO CLR ALL OBSTACLES ON THE SID. RWY 16R WAS CLOSED. THE MODIFICATION TO PROFILE WAS TO DELAY CLEAN-UP OF FLAPS UNTIL ABOVE OBSTACLE HT. LESSON ONE, THE COMPANY FOM DOES NOT STIPULATE MODIFYING PROFILE, BUT ONLY ALLOWS THE PROFILE TO BE FLOWN EXACTLY AS DESCRIBED IN THE FOM. MODIFIED CLBS CAN'T BE CALCULATED. WE REVIEWED THE CLB DATA PROVIDED BY THE ACFT PERFORMANCE COMPUTER. THE COMPUTER SHOWED OUR TKOF PERFORMANCE FOR CONDITIONS, CONFIGN, CARGO WT AND BAL, AND THE RWY SELECTED. OUR PERFORMANCE WAS ACCEPTABLE WITH OBSTACLE CLB CAPABILITY AS BEING THE LIMITING FACTOR FOR TKOF. I HAD ALWAYS BELIEVED THE ACFT PERFORMANCE COMPUTER WOULD AUTOMATICALLY CALCULATE CLB GRADIENT FOR DEP SID AS WELL. LESSON TWO: IT DOES NOT! WE LOOKED AT THE SID AND FELT THAT AN OLD B727-100 MIGHT HAVE A HARD TIME GETTING OUT OF RENO, AS HVY AS OURS WAS FOR THAT SID, SO WE BRIEFED AND FLEW THE MODIFIED PROFILE WHICH GAVE US AMPLE CLB PERFORMANCE. LESSON THREE: THE CORRECT PROC IS TO MANUALLY ENTER THE PROFILE INTO THE ACFT PERFORMANCE COMPUTER AFTER REVIEWING TKOF AND WT AND BAL. A PERFORMANCE CHART WILL BE GENERATED FOR VARIOUS ALTS ON DEP. THAT CHART IS THEN COMPARED TO THE REQUIRED CLB PERFORMANCE ON THE SID. OUR ACFT PERFORMANCE WAS LEGAL. OUR USE OF THE ACFT PERFORMANCE COMPUTER AND THEREFORE OUR DEP, WAS NOT.

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.