Husqvarna
OAT = outside air temperature
QNH = altimeter setting to achieve altitude (above seal level), QFE = altimer setting to achieve height above an airfield
'Heavy' refers to a wake turbulence category and controllers must allow minimum separation between aircraft depending on the combination of wake turbulence categories involved.
V1 is a decision speed for an airliner during the take off roll.
A problem before the speed is reached may result in a rejected take off (stopping) depending on the severity.
After V1 the aircraft will take off and the crew will deal with the problem in the air. The decision speed is required, in simple terms, to ensure that an aircraft does not try to stop and run off the end of the runway because it is going too fast.
PS, I'm not a pro, but a private pilot with multi engine experience
