A320/1 Green Dot QRH/PFD Difference
Hi,
In the cruise, I understand that comparison of the green dot speed indicated on the PFD with that given for the current aircraft weight in QRH 4.01 "Operating Speeds" can provide an indication on whether the aircraft is in fact heavier than you believe it to be.
My question is, how reliable is this indicator? And is it possible to equate the difference in knots to a specific weight? For example, if you work out that your green dot speed should be 235 knots according to the QRH, but it indicates 250 knots on the PFD, can you equate the 15 knot difference to a specific weight and say "we're x tonnes heavier than we think we are"...
Thanks in advance,
ET