FAI Ultralight Definition

It is the take-off mass that is limited for DU class records. I was
the official observer for Gary's world records in the SparrowHawk. We
used the empty weight of the glider and weighed Gary and his gear
before the flight. I did a weight calculation and signed it and sent
it in with the rest of the paperwork. I don't know if a more accurate
weighing would be required if one was close to the limit. In Gary's
case, the take-off weight was 406.9 lbs., so the maximum weight limit
wasn't an issue.
Have fun and good luck with the records!
Doug Taylor


and the maximum allowed weight (mass) is shown as 245 kg. *This seems
to indicate that the mass at takeoff is all that matters.