Troubleshooting; Time Pressure; Situational Awareness; Communication Breakdown
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Weight And Balance; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Equipment / Tooling; Human Factors
Aircraft X was out when the Captain called me requesting Takeoff (TO) Data due to a [computer] Error. (The Chief's had sent out a message prior indicating there were issues with flights getting [computer] Errors). The Captain gave me the parameters he wanted the takeoff data for; and requested I send it to the printer. He asked for [the] runway; Anti-ice on; Wet; Zero Fuel Eight (ZFW) 122.3. We hung up; and I went to calculate the TO Data. I entered the flight; reactivated the release; updated the ZFW on the Flight Tab; Calculated the flight; and went to the Takeoff Weight (TOW) button to calculate the TO Data message which I then sent to the crew. After sending the message; I realized that assumed weight on the TO Data message seemed off. I checked the weights message to see what the TOG should have been. The TOG was approximately 1300 pounds above the assumed weight on the TO Data Message. I quickly sent a message to the crew asking them to double check the weight on the TO Data Message and asked them to confirm their TOG. Within a minute of sending that message the Aircraft took-off. As I continued to investigate why the there was a discrepancy; I realized that when I calculated the flight I forgot to set the Target Window to BLOCKF. Therefore; when I updated the ZFW (which was a several thousand pound decrease); it decreased my planned fuel and therefore decreased my TOG. Normally when calculating a TO Data Message; the crew tells me the TOG they want me to run it for; not the ZFW. In the future when calculating a TO Data message; I will always ask the crew to confirm what TOG they want it for; and will double check it against the weights message to ensure accuracy.
Dispatcher reported an error when imputing flight data and forgot to set the Target Window. The updated Zero Fuel Weight decreased the planned fuel and therefore decreased the Take-off Gross Weight.