Well done, Mike! - Tables & charts everywhere I bet!
(We did the Opus Dei job)
Good points, Flightwatch.
under_exposed,
<<would a boeing 747 with 2 engines gone be in a similar situation to a B777/A330 with half its engines gone? (i.e. 1 failed) except better able to cope with another engine fail than a B777/A330>>
Performance schedule A aircraft such as these must be able to suffer an engine failure at any time without requiring a forced landing. 4 eng aircraft must therefore be able to lose 25% of power on take-off and twins must be able to lose 50% of their power which is why twins with both running go like the proverbial off a navvy's lustrous leaning device
The loss of an engine on a twin at any time constitutes an emergency and (usually) requires a landing to be made at the nearest suitable airfield. (in simple terms for the pedants
)
Nevertheless, both aircraft would have full flight and go-around capability. Remember that on take-off you are starting with zero energy but on a go-around you are at, say, 50ft and 150 knots so you're pretty well placed.
Now, to answer your question: Following a second engine failure on, e.g. a B747, the aircraft will continue to fly but at a reduced level so safety altitudes have to be reviewed and could limit radius of operation. Unlike the loss of one, this is considered to be an emergency situation. Approach and go-around require careful handling and pre-briefing. The minimum control speed with two failed on one side will be in the region of 152 knots. After selecting gear down drag increases considerably and a successful go-around is not assured and, in any case, the first part of the go-around continues downhill acquiring speed and raising draggy flap before climbing away.
So no, a B747 with two out is not in the same condition as a B767 with one out.
I've never tried a simulated approach on one engine on the B747 however one I have tried: a simulated two engine approach with severe structural damage and reduced control authority is probably around the ballpark for an undamaged aircraft on one. Once the aircraft is configured for landing it is only going down and a go-around is not possible but it is controllable. Probably a good idea to radio ahead for a change of underwear though
p.s. If I've made any errors or omissions I'm sure they will be pointed out
