Can longer paths consume less fuel than the (shorter) great circle path? Is the most fuel-efficient route between points A and B always along a great circle ?

Although somewhat counter-intuitive, this comment on an aviation blog seems to suggest that longer paths (in terms of geographic distance covered) can save fuel:


  Oceanic Flights these days are not restricted to the old “defined
  great circle routes”. Modern computerised flight planning systems
  definately take weather into account, and go searching for the best
  winds (tailwinds) or least adverse (headwinds). Particularly in the
  case of westbound flights across the Indian Ocean, where headwinds are
  often ferocious, the tracks actually flight planned, and actually
  flown, are often a long way off “great circle” routes.
That depends how you define longer in aviation. As you can look at it geographically or on the clock.

The hard answer is no, the most fuel efficient route is the one that has the aircraft in the air for the shortest amount of time. If you can take advantage of a big tail wind 20 miles south of the geographically shortest route or at a slightly higher altitude you may burn a bit of fuel getting there but on long haul flights you can make up for the burn, and even gain quite a bit by taking advantage of the winds 

Similarly headwinds can really kill your efficiency even over short distances.