Takeoff Performance Tables

The instructions for using the required takeoff field length and runway length limit weight in the PMDG 737NG takeoff performance documentation are incorrect.In the required takeoff field length table, positive wind values are for headwinds, while the negative wind values are for tailwinds. (As an aside: you will need special operational approval from the FAA if you want to take off in winds greater than 10 knots if operating under FAA authority.) This table is used to determine the wind corrected runway length to be used as an entry into the runway length limit weight table. For example, for a 737-600 operating on a 5,600 foot runway with a 20-knot headwind, the corrected field length would be 7,152 feet. With a 10-knot tailwind, the corrected field length would be 5,610 feet.To use the runway length limit weight table, step one is to determine the corrected field length from the required takeoff field length table as I've just described above. Enter the table with the corrected field length (NOT the runway length), then follow the instructions provided in the PMDG documentation. For the examples above, with a 20-knot headwind at 30 degrees C, the maximum field length limited takeoff weight would be 159,800 lb. With a 10-knot tailwind, the field length limit weight would be 150,860 lb (if I've done my math right -- using linear interpolation in the table). But since the climb limit weight is 149,500 lb, you would be limited to 149,500 lb in either case.Note that the tables are only good for one airport pressure altitude (presumably sea level).Don S.