Narrative:

While waiting for departure off runway 24 in mht--on taxiway juliet; behind another flight that had a delay--we were holding short of taxiway juliet 1 anticipating we would be cleared to takeoff with a back taxi as had a crj before us. We asked tower if we could back taxi full length; and he responded 'unable.' tower asked us if we would be good from juliet 1 and--assuming we would be ok due to the short distance between juliet 1 and the runway full length--we said it should be no problem. Tower then cleared us for takeoff while my first officer was still running new numbers from juliet one taxiway. While on runway and cleared for takeoff the new numbers came up on ACARS as invalid. In my judgment I had asked the first officer if he thought we were ok for takeoff and he replied 'I think we should be good' or words to that effect. We continued a normal takeoff and the aircraft rotated well within the balanced distance of runway. Assuming the short distance that was given up by the taxiway juliet 1 and runway 24 threshold I didn't think the data would have been invalid.I should have cleared the runway when no valid numbers were available.

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Original NASA ASRS Text

Title: When their access to the full length of the runway was blocked by a delayed flight the Captain of a commercial fixed aircraft opted to accept a takeoff clearance from an intersection a nominal distance from the end of the runway. When the First Officer unilaterally requested ACARS takeoff data from that intersection a response of 'invalid runway DATA' was returned. The Captain elected to command a takeoff and the First Officer complied.

Narrative: While waiting for departure off Runway 24 in MHT--on Taxiway Juliet; behind another flight that had a delay--we were holding short of Taxiway Juliet 1 anticipating we would be cleared to takeoff with a back taxi as had a CRJ before us. We asked Tower if we could back taxi full length; and he responded 'unable.' Tower asked us if we would be good from Juliet 1 and--assuming we would be OK due to the short distance between Juliet 1 and the runway full length--we said it should be no problem. Tower then cleared us for takeoff while my First Officer was still running new numbers from Juliet one taxiway. While on runway and cleared for takeoff the new numbers came up on ACARS as invalid. In my judgment I had asked the First Officer if he thought we were OK for takeoff and he replied 'I think we should be good' or words to that effect. We continued a normal takeoff and the aircraft rotated well within the balanced distance of runway. Assuming the short distance that was given up by the Taxiway Juliet 1 and Runway 24 threshold I didn't think the data would have been invalid.I should have cleared the runway when no valid numbers were available.

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.