MH 370

[Anomalocaris]

For 2 reason.

1. He could go even farther south if he glided it down rather than just letting it plummet.

2. The plane would remain more intact and harder to find.

If the plane runs out of fuel it would not just plummet.  It would glide by itself at high speed.  FBW control system will still keep making adjustments required for fast stable glide.  Flaps allow the plane to glide slower and thus make safer and slower landings.  But it does not allow the plane to glide further from the point where it lost power.  If anything it steepens the glide slope and make the plane hit the water nearer to the point where it lost power.

With modern sonars, detecting a intact 777 on the sea floor would be relative easy.  Detecting a thoroughly broken up wreckage from violent water impact would be much more difficult. The fact that no large wreckage piece observable from the surface by sonar were found after 4 years of searching makes it seem more probable that the plane broke up pretty thoroughly upon water entry.