The factors that affect a helicopter's endurance are:

• All-Up-Mass
• Altitude and temperature
• Centre of Gravity
• External loads
• Selected True Airspeed

Therefore, for a given mass, configuration (in terms of CG and external loads) and fuel on board, the endurance depends on Altitude, Temperature and True Airspeed.

Also, the TAS for maximum endurance, V_{MAX END}, is the minimum power required speed, V_MP, and is always the speed which corresponds to the bottom of the power required curve and gives the minimum fuel flow (kg/hr).

Thus, when altitude increases, the power required curved moves up and right and as a result TAS increases. This combined effect decreases the helicopter's endurance.

When flying for maximum endurance, a helicopter is flown at the true air speed and altitude that will ensure the maximum airborne time for a given amount of fuel or the minimum fuel consumption for a given amount of time.