What is V1?
V1 is the takeoff decision speed. In simplified terms, it marks the decision boundary used when determining whether a takeoff should be rejected or continued after a critical failure.
A reliable V1 calculation depends on accelerate-stop and accelerate-go performance. This simulator tool does not contain certified runway-performance data, so its V1 is an educational estimate and runway condition does not directly rewrite the value.
What is VR?
VR is rotation speed: the speed at which the pilot initiates the pitch-up input for takeoff. It is influenced by weight, configuration and centre of gravity. A forward CG generally requires more control force and can increase the estimated rotation requirement.
Rotating before VR can reduce tail-clearance or performance margins. Rotating too late consumes runway and delays lift-off. In a simulator, use the value produced for the selected aircraft profile and conditions.
What is V2?
V2 is the takeoff safety speed target associated with initial climb performance after an engine failure. It must remain above VR in a valid ordered result.
The calculator derives V2 from the selected aircraft profile and adjusts it for weight, altitude, temperature, flap configuration and other modelled factors.
Why V-speeds change from flight to flight
Takeoff weight, flap setting, pressure altitude, outside air temperature, wind and CG can all change the resulting speed set. Aircraft variant matters as well: an A220, A320 and A330 should not share one generic table.
Runway length primarily determines whether the available distance and thrust margin are acceptable. Precise runway-limited V1 optimisation requires data beyond this simulator model.
- Aircraft type and engine variant
- Takeoff gross weight
- Flap configuration and CG
- Pressure altitude and temperature
- Wind and operational configuration
The required speed order
A usable set follows V1 < VR < V2. The calculator enforces that relationship when applying corrections, but users should still check for warnings, realistic units and the correct aircraft profile before copying values into an MCDU.