What’s V2, Vref?

[Ref CAD 385]

What’s V2 (take-off phase)?

According HK CAD 385

V2 is Take-off Safety Speed

V2 -The target speed to be attained at the 35 foot (feet) height, assuming recognition of an engine failure at or after V1


Take-off Speeds Relationship

In order to satisfy JAR, depending on the aircraft type:

  1. V2 should not be less than 1.15 or 1.2 times Vs
  2. Furthermore, V2 should not be less than 1.13 times Vs1g in the take-off configuration

V2 ≠ Vref 

V2 is terminology used in take-off phase whereas Vref is used in landing phase. The reason why we discuss it here is that some may be wondering whether screen height is 35 feet or 50 feet


What’s Vref (landing phase)?

Vref is the Reference Speed

Vref – it normally refers to the minimum speed at the 50 foot (feet) height in a normal landing at a particular landing flap configuration.


Landing Speeds Relationship

Vref should normally be at least 1.3 times the Vs OR 1.23 times the Vs1g in the landing configuration.

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