Take-off Speeds of Jet Airplanes

A number of speeds are defined and taken into consideration during the take-off of an airline jet. The need to establish these speeds is a consequence of increasing safety concerns in commercial aviation and a struggle to attain higher efficacy. The following explanation of speed limitations during the three steps listed above is in line with the FAA regulations.

  • Thedecision speed (V1of an aircraft is a reference to predict take-off ability with respect to the failure of a critical engine.

In simpler words, if the engine fails before V1, the pilot can stop the airplane within the stop distance and if it fails after, the pilot must necessarily take-off.

  • Rotation speed (VR)is the speed of an airplane at which its nose wheel leaves the ground.
  • The take-off safety speed (V2)is the speed at which the aircraft operates when in the “initial climb” phase. Maintaining this speed ensures a safe operating margin between V2 and stall speed of an aircraft. It also provides a safe speed to operate on, in the event of an engine failure.

Incorporating these speeds into the three subdivisions of take-off:

  • Jet airplanes accelerating during the “take-off roll”, take note of Vto decide whether to take-off or not.
  • At VR, the pilot rotates to lift the nose wheel and increase the angle of attack.
  • At VLOF (lift off speed), the main wheels “lift off” the ground and the  jet airplane enters “initial climb”.
  • In this phase, the aircraft flies at V2to operate within a safe margin with respect to stall speed and possible engine failure.

There are many other speeds involved during the take-off phase in the flight of jet airplanes, such as minimum control speeds, max brake energy absorption speed and maximum tire speed. However, the above listed have a more prominent role in the take-off phase of an aircraft.

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