Narrative:

The captain and I were recently trained to fly the B737NG. After receiving the load message during taxi, I inadvertently entered the zero fuel weight on the gross weight line in the FMC. Since the fuel load was 38.5, the difference was extreme, resulting in V1-114, vr-115, and V2-125 instead of 138, 139, and 145. Flap retract soft speeds were also indicating lower than they should have been on departure. I know that the B737-700 is a remarkable performer and our passenger load was light, so the v-spds didn't register as out of line, although in retrospect they were. I was in the habit of verifying that the gross weight on the load is below the release weight, but was not in the habit of verifying that the FMC gross weight matches the load paperwork gross weight, although I am now when I enter the data in the FMC, along with verifying the gross weight. Rotation felt mushy, a little like being too nose heavy, but not as responsive in pitch. This led me to fly at higher speeds than bugged until cleaned up. I discussed with the captain how I felt that we felt a little miss-trimmed on takeoff. We leveled off at FL370 and had continuous light turbulence, so I looked at the cruise page and it said that FL410 was optimum with a huge fuel savings, so we climbed up and it smoothed out. Climb to FL410 was normal, but after leveling, the speed began a slow decay toward the (erroneous) low speed buffet yellow line. We requested lower and started descending just as a slight buffet at 7 KTS above the (erroneous) yellow line. I soon discovered my error and then entered the correct zero fuel weight and the flight continued normally. I now brief nearly everything on the takeoff page, mentioning the gross weight and that it is below release weight. There is a great potential to completely cut the captain out of the loop as far as data entry when it is an first officer leg and the captain is busy taxiing. I think adding the gross weight to the briefing has helped remedy this for me, as well as jarring my mind into thinking about performance, speeds and release weight.

Google
 

Original NASA ASRS Text

Title: DECAYED ACFT PERFORMANCE ON TKOF AND CLB, CRUISE ON A B737-700 WHEN THE FO INSERTS THE ZERO FUEL WT IN THE FMC VERSUS THE ACTUAL ACFT GROSS WT AT ZZZ.

Narrative: THE CAPT AND I WERE RECENTLY TRAINED TO FLY THE B737NG. AFTER RECEIVING THE LOAD MESSAGE DURING TAXI, I INADVERTENTLY ENTERED THE ZERO FUEL WT ON THE GROSS WT LINE IN THE FMC. SINCE THE FUEL LOAD WAS 38.5, THE DIFFERENCE WAS EXTREME, RESULTING IN V1-114, VR-115, AND V2-125 INSTEAD OF 138, 139, AND 145. FLAP RETRACT SOFT SPDS WERE ALSO INDICATING LOWER THAN THEY SHOULD HAVE BEEN ON DEP. I KNOW THAT THE B737-700 IS A REMARKABLE PERFORMER AND OUR PAX LOAD WAS LIGHT, SO THE V-SPDS DIDN'T REGISTER AS OUT OF LINE, ALTHOUGH IN RETROSPECT THEY WERE. I WAS IN THE HABIT OF VERIFYING THAT THE GROSS WT ON THE LOAD IS BELOW THE RELEASE WT, BUT WAS NOT IN THE HABIT OF VERIFYING THAT THE FMC GROSS WT MATCHES THE LOAD PAPERWORK GROSS WT, ALTHOUGH I AM NOW WHEN I ENTER THE DATA IN THE FMC, ALONG WITH VERIFYING THE GROSS WT. ROTATION FELT MUSHY, A LITTLE LIKE BEING TOO NOSE HVY, BUT NOT AS RESPONSIVE IN PITCH. THIS LED ME TO FLY AT HIGHER SPDS THAN BUGGED UNTIL CLEANED UP. I DISCUSSED WITH THE CAPT HOW I FELT THAT WE FELT A LITTLE MISS-TRIMMED ON TKOF. WE LEVELED OFF AT FL370 AND HAD CONTINUOUS LIGHT TURB, SO I LOOKED AT THE CRUISE PAGE AND IT SAID THAT FL410 WAS OPTIMUM WITH A HUGE FUEL SAVINGS, SO WE CLBED UP AND IT SMOOTHED OUT. CLB TO FL410 WAS NORMAL, BUT AFTER LEVELING, THE SPD BEGAN A SLOW DECAY TOWARD THE (ERRONEOUS) LOW SPD BUFFET YELLOW LINE. WE REQUESTED LOWER AND STARTED DSNDING JUST AS A SLIGHT BUFFET AT 7 KTS ABOVE THE (ERRONEOUS) YELLOW LINE. I SOON DISCOVERED MY ERROR AND THEN ENTERED THE CORRECT ZERO FUEL WT AND THE FLT CONTINUED NORMALLY. I NOW BRIEF NEARLY EVERYTHING ON THE TKOF PAGE, MENTIONING THE GROSS WT AND THAT IT IS BELOW RELEASE WT. THERE IS A GREAT POTENTIAL TO COMPLETELY CUT THE CAPT OUT OF THE LOOP AS FAR AS DATA ENTRY WHEN IT IS AN FO LEG AND THE CAPT IS BUSY TAXIING. I THINK ADDING THE GROSS WT TO THE BRIEFING HAS HELPED REMEDY THIS FOR ME, AS WELL AS JARRING MY MIND INTO THINKING ABOUT PERFORMANCE, SPDS AND RELEASE WT.

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.