B777 300ER Fuel Burn
Some interesting findings:
-on this aircraft, a recent study compared (real life, not software predictions) data colected from flights operated either on company suggested CIs, on the lower 30s, wich translates into an average M.83 crz speed with other operated on typically LRC, CI around 180, giving M.84.
Given comparable TOW, atmospheric conditions, routes and aircrafts the only difference in operating at the lower CI is EXTENDED FLIGHT TIME!
The practice contradicts Boeing software predictions. Flying at a CI lower than say 150-180 does not actually provide any significant fuel savings. On the other hand, keeping the cruise around M.84 saves time without burning more fuel, thus reducing the overal trip costs.
These are cold FACTS, not guessing, with enough data to provide a definite trend.
Any clues?