How much more fuel efficient is a 777 than a747, a burn between ORD and London for example?

Question

If a 777 is much more effecent than an 747 and carries close to the same amount of people , why would the airlines continue to use the 747 . Does the 747 still have some advantages?

Answer 1

The A380 runs 80 miles per passanger gallon.
The 747 runs around 70.
I can't find a reliable figure for the 777, figures range from 65-140. If they could beat 80 then there's no way the A380 or the 787 would have been ordered by anyone. Not agreat answer.

potatochip: Maybe I'm taking your comment wrong, but losing 1 of 4 doesn't much affect the capability of the aircraft, BA are currently under scrutiny for continuing to LHR after losing an engine a few minutes into the climb out of LAX. A 777 would have dumped tens of thousands of dollars worth of polluting fuel and to have returned to LAX.

That contention on 4 engines being twice as likely to fail as 2 is specious. Probabilities multiply, but since they are less that 1 the result is less than either of the base probabilities. So if there was a 50% chance of one engine going wrong there will be a 25% chance of both going wrong, a 12.5% chance of 3 going wrong and a 6.25% chance of 4 going wrong.

The real figures are vastly different of course. I may expect to see an in flight shutdown once in 40,000 hours, so I don't expect to see a double failure in 1,600,000,000 hours. But if I have four I wouldn't expect to lose all of them in 2.56x10^18 hours.

Other than flying through a volcanic plume I have never heard of a 747 losing all four engines, and even in that case they got a couple restarted. I know of two twin engine twin failures, both in the mid eighties and the most famous being the Gimli Glider.

Answer 2

I agree with CX Fan with what was written. The 777 is definitely more fuel efficient and cheaper to operate than the 747. The 777-300 supposedly is a bit longer than the 747. But the 777-200 does not seat as many people as the 747.

I know some people prefer to fly the 747 because they think if one engine goes out, at least there are 3 more to compensate versus the 777 which would then be flying on 1 engine. Having an aircraft flying only on 1 engine can be a bit nerve-racking if flying over the Atlantic or Pacific Ocean since there are few places for emergency landings versus if flying over land. They forget that with 4 engines, there is double the chance there can be an engine failure.

If I fly First Class or Business Class, I would want to fly the 747 because I would want to sit on the 747's "bump" or upper deck. The 747 can evoke a sense of elegance and luxury since the early 747 upper decks were more of a hangout place with a bar than later versions which now carry passengers.

Answer 3

Although the 777 is more fuel efficient, it isn't easy for airlines to get rid of 747's. In many cases, the 747's are already paid for, so even if they're less efficient it's still cheaper to operate them than it would be to buy or lease a new 777.

Northwest has held on to their old DC-9's for the very same reason: they're paid for.

Answer 4

yes, the B747 has more passenger capacity and it is cheaper when airlines buy them second hand compare buying a B777-300ER/200LR when the airlines need the extra capacity to fly to dense destinations. Sometimes airlines buy the B747-400 to convert them into BCF (Boeing Converted Freighter) because that is more economical and is more efficient and more capacity than the earlier version. Also if the airline use B777-300ER to fly to London from Chicago, the 300ER may use around 20 percent less fuel compare to the B747

Just by comparing B777 to an A340, the B777 will have $18 million saving advantage in 10 year net present value for a typical airline