I heard a story from a BOAC 2nd officer a few (well a lot!) of years ago about him & his Captain discussing the feasibility of landing a VC10 without power. 2nd had then tried it at Khartoum but had had to add lots of thrust to get in. Capt had then gone into Nairobi starting at about 10 grand over the Ngong hills (Nairobi airport is at about 5 grand) and had sucessfully plonked it onto the end of the runway. Don't know if it was true though!
Of course there have been a couple of successful glide approaches from height with airbuses since!
Both a/c sustained some damage I believe, but excellent airmanship. All a question of having speed & height relative to runway.
But if you're low & slow & your 777 engines see fit not to spool up!
p.s. I believe pre-WWII the standard RAF practice was a glide approach, with drinks having to be bought in the mess for anyone having to open up on approach. With the advent of heavier monoplanes the undershoot accident rate got too high & powered approaches were mandated. Can anyone confirm?