Which is faster, the 777 or the 747?
 

Flew LHR-JFK on Sunday on UA905 (777). Since I was listening to tower communications I heard and watched BA177 (a 747) take off about 3-4 planes in front of us, and I was thinking that they would definitely arrive in front of us at JFK and fill up immigration at T7.

However, when we arrived in JFK, we actually landed ahead of BA177 which surprised me. I always thought the 747 was the fastest passenger jet, but in this case we had definitely made it across the Atlantic faster. Although we were late out of the gate in London and there was a lot of taxiway congestion, maybe the UA pilots decided to fly faster than usual to make up time? Maybe we had a faster routing? Or maybe the 777 cruise speed is faster? Anyone know....


Adam

Boeing.com gives all the technical specs on their site. Here are the spec for the 744 and if you click around you'll get them for the 777. Yes, the 747 is capable of cruising faster and yes, the plane that can fly the fastest doesn't always get in first for a variety of reasons. http://www.boeing.com/commercial/747...technical.html

There was an earlier discussion of 747, 767, and 777 cruising speeds where the 747 was reported faster than the 777. So it may have been an air traffic issue. Do airlines designate cruising speeds for particular routes or equipment, or is it largely at the flight crew's discretion?

The operations department or an on-board computer will do most of that (e.g., verify weight & balance, calculate trim settings, etc.)

Also consider weight. A heavy 747 will likely lose out to a lightly loaded 777.

Fuel savings are a major consideration in setting airspeed- in the 1970's 747's crossed the pond faster than today.

Among aircraft whose nominal cruising speeds are within a couple of percent of each other, which includes all modern passenger jets, that number is likely to be way down the list in terms of who actually arrives first. For one thing, an optimum (in terms of fuel consumption at a given speed, or equivalently, speed at a given fuel consumption) flight path involves gaining altitude as fuel is used. Whether or not one can do that depends on what other traffic is in the area, such as another aircraft already up there where you'd like to be. If that other aircraft happens to be the nominally-slower one that took off a few minutes earlier, there goes the infinitesimal edge that a trivially higher cruising speed spec might provide.

And that's assuming both aircraft were given exactly the same routing. If they weren't, they'll hit different winds and weather, and all bets are off.

You guys can talk about winds, optimal fuel consumption, loads, etc. 'til the cows come home, but what most likely happened here is the 777 captain had to hurry or he'd miss his flight home and the 747 captain needed an extra 10 minutes of flight time to have his hours in for the month. :)

Most commercial airplanes flying from airport ABC to airport XYZ (or whatever) get in the ABC-XYZ queue and basically fly at the same speeds.

MisterNice

No, that's why ATC has different altitudes to work with (soon to be more when reduced vertical separation kicks in domestically early next year) so airplanes don't have to follow each other and faster ones can get ahead of the slower guys.