B737 captain observes takeoff weight calculation errors.

Attributes
ACN	574240
Time
Date	200302
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : smf.airport
State Reference	CA
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : p31.tracon
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	ground : parked
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 230 flight time total : 16900 flight time type : 13700
ASRS Report	574240
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	non adherence : published procedure non adherence : far non adherence : company policies
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	other
Supplementary
Problem Areas	Company
Primary Problem	Company

Narrative:

Flight from smf. Count was actually 99 passenger (+6). Crew initially added 110 pounds to the takeoff weight of 90549. V speeds from opc were 117/117/127. These seemed low. We looked more closely and saw that zero fuel weight was never calculated. Faulty takeoff weight was given by adding 18202 fuel to operational (empty) weight. Our recalculated takeoff weight was really 111747 pounds. Not catching this error could result in tailstrike and/or stall on aircraft if the low zero fuel weight is entered in CDU. Flight from oak -- load sheet given had no passenger weights added to operational empty weight. Crew determined that actual weight was 16800 pounds (91 passenger) more. Precalculated our takeoff weight and V speeds. Original V speeds on faulty afw were 107/107/117. After catching the passenger weight omission, new speeds were 119/119/127. Every crew will catch 10000 pound addition errors occasionally. These 2 load sheets, 21200 pounds low and 16800 pounds low respectively, were not math errors, but were 'hurry up' omissions.

Original NASA ASRS Text

Title: B737 CAPT OBSERVES TKOF WT CALCULATION ERRORS.

Narrative: FLT FROM SMF. COUNT WAS ACTUALLY 99 PAX (+6). CREW INITIALLY ADDED 110 LBS TO THE TKOF WT OF 90549. V SPDS FROM OPC WERE 117/117/127. THESE SEEMED LOW. WE LOOKED MORE CLOSELY AND SAW THAT ZERO FUEL WT WAS NEVER CALCULATED. FAULTY TKOF WT WAS GIVEN BY ADDING 18202 FUEL TO OPERATIONAL (EMPTY) WT. OUR RECALCULATED TKOF WT WAS REALLY 111747 LBS. NOT CATCHING THIS ERROR COULD RESULT IN TAILSTRIKE AND/OR STALL ON ACFT IF THE LOW ZERO FUEL WT IS ENTERED IN CDU. FLT FROM OAK -- LOAD SHEET GIVEN HAD NO PAX WTS ADDED TO OPERATIONAL EMPTY WT. CREW DETERMINED THAT ACTUAL WT WAS 16800 LBS (91 PAX) MORE. PRECALCULATED OUR TKOF WT AND V SPDS. ORIGINAL V SPDS ON FAULTY AFW WERE 107/107/117. AFTER CATCHING THE PAX WT OMISSION, NEW SPDS WERE 119/119/127. EVERY CREW WILL CATCH 10000 LB ADDITION ERRORS OCCASIONALLY. THESE 2 LOAD SHEETS, 21200 LBS LOW AND 16800 LBS LOW RESPECTIVELY, WERE NOT MATH ERRORS, BUT WERE 'HURRY UP' OMISSIONS.

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.