V Speeds

V Speeds for Large Aircraft

Pilots of large aircraft or multiengine aircraft use additional key airspeeds. They calculate these speeds from aircraft performance charts before each takeoff, considering aircraft weight, weather conditions, runway length, and other factors.

	Vmc is the minimum control speed; the lowest speed at which the airplane is controllable when one engine is inoperative and the other engine is operating at full power.
	V1 is the takeoff decision speed; the speed at which the pilot decides whether to continue or abort a takeoff during the takeoff roll.
	Vr is rotation speed; the speed at which the pilot raises the nose to lift off the runway during the takeoff roll.
	V2 is takeoff safety speed; the speed used immediately after takeoff before accelerating to initial climb speed.If you're flying a large aircraft at high altitude, you'll also use

Mach number.

Aircraft that operate at high altitudes use Mach number, not airspeed, as a reference for aircraft performance and navigation, because the airspeed indicator is subject to many errors at high speeds in the thin air of the upper atmosphere. Mach number is calculated by a computer and displayed on the airspeed indicator.