100% of ultimate load, which is 150% of limit load. The limit load is what goes into the flight manuals and is what the aircraft is certified to withstand. The

100% of ultimate load, which is 150% of limit load. The limit load is what goes into the flight manuals and is what the aircraft is certified to withstand. The ultimate load is a safety factor on top of limit load and is what the engineers design for. The writer has some of the numbers mixed up. Transport category positive load limits are 2.5 to 3.8 (depending on max takeoff weight), not 1.3. I don’t know where the 1.3 number came from, but it might be from the loads required to be demonstrated during flight tests (1.3g pull-up at 1.3x the stalling speed in the landing configuration IIRC).