PPRuNe Forums - Green Dot Speed

PPRuNe Forums (https://www.pprune.org/)

- Tech Log (https://www.pprune.org/tech-log-15/)

- - Green Dot Speed (https://www.pprune.org/tech-log/267848-green-dot-speed.html)

I recently come across the phase "green dot speed" I understand that it is the lowest L/D ratio for the given weight and condition of flight ? correct ?

when is it normally used ? Is it similar to Boeing flap up speed or v2 +100 ?

Also came across the Airbus perf charts ? what is T ref , T max, Grad 1 and Grad 2 ? How do u use the figures ?

According to the FCOM:

Quote:

Green dot speed.
Engine out operating speed in clean configuration.
(Best lift to drag ratio speed).
Corresponds also to the final takeoff speed.
Represented by a green dot on the PFD scale. Below 20000 feet equal to 2 × weight (tonnes) + 85
Above 20000 feet add 1 knot per 1000 feet

Quote:

when is it normally used ?

In approach mode, with speed managed and the aircraft clean, this is the target speed. It is also the target holding speed. In reality, if minimum clean speed is required, a speed a few knots above green dot is selected (i.e. speed is no longer managed).

Green Dot is minimum speed. Comparison in the Boeing world would be Vref 30+80 when clean, Vref 30+60 at flap 1, etc.

Tref, Tmax, and the Grads are performance terms. I may still have an Airbus performance document around if you are interested but Airbus performance is best left to a laptop...

Not quite extreme p

Green dot is in clean config only.