Originally Posted by
Farjer
...........is it possible to save fuel on a long-haul flight by slowing down a bit?.........
It's already been done, aircraft all over the world are now flying at slower speeds than before in the interests of fuel cost saving.
Typical Cost Indices currently used are already approaching Maximum Range Cruise, and after that, no further optimisation of fuel mileage is possible.
For most aircraft nowadays, even reducing all the way to MRC would only mean a further speed reduction of about M0.01, about 5 Knots of speed, we're almost there now!
Regards,
Old Smokey