Narrative:

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.

Google
 

Original NASA ASRS Text

Title: 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.

Narrative: 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.

Data retrieved from NASA's ASRS site 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.