A British Airways Boeing 777-200 just set a speed record on the New York-London route by using the jet stream to bring the wide body jet to within 16 mph of the speed of sound. BA114 completed the journey in 5 hours and 16 minutes and reached a maximum ground speed of 745mph. For those keeping score, the ground speed of sound is 761 mph. To compare the speed, the normal speed for a 777 is in the 560 mph range and the route takes about six and a half to eight hours. A Concorde would normally cross the Atlantic in two and a half hours at speeds over 1,300 mph. But it was as slender as a pencil…the 777 is many things, but “slender” it is not. However, at no point in time were the passengers in any danger, as Boeing has engineered so much strength into their jets that it would take severe stresses in many other directions before the airliner would be compromised.
The jet stream isn’t exactly easy to catch, either. It’s about ten miles wide and a couple of thousand feet thick, and it’s route is always in a state of flux. It can also be a source of clear-air turbulence, which can vary from slightly annoying to unbelievably terrifying. The jet stream that BA114 rode had winds in excess of 250 mph and was wider than normal, and is believed to be the reason why Scotland was recently hit with storms that packed winds in excess of 110 mph.
Maybe British Airways needs a new ad campaign. “Hauling Ass With Class” might be a little crude, but it would capitalize on this recent success…
BMT…Just think, the of pilots flying West with a SOG of maybe 400 mph. “Hey…I hope we made the correct fuel calc.”
At one time Boeing was looking at building the “Sonic Cruiser” which would hit these near supersonic speeds routinely. In the end capacity and fuel economy won out over speed and cool.
I don’t think our ride was that quick but, I will say the 777-200 is a very nice ride with BA hosting it.
Anybody know what critical mach is on a 777 ( don’t)? Probably a hundred miles-an-hour lower than mach 1, and I’m sure they stay well short of that no matter what. A right-place-right-time thing w/ the jet stream, I’m sure it was fun watching the clock tho’.
Flying from Tokyo to Los Angeles the info center on the plane showed us regularly cresting over 700mph, but usually hanging around 690mph. I was constantly watching the speed shown because I knew it was a heck of lot faster than “normal” cruising speed! Safe to say that pilot was keeping the jet in a nice westerly flow!
I noticed the same thing on a flight around xmas. Flying from seattle to orlando, connecting in DFW, the jet stream dipped right through and the brand new 737-900 we were flying on was cooking it deep into the 600’s, i knew this was abnormal, but my spouse was not impressed. We landed 30min early on a 3.5 flight 😀
What’s the speed of sound in the jet stream?
the same as the speed of sound out of it
The 747 was capable of just under Mach 1 back in 1970. Air Force 1 on 9/11 flew over 750 mph from Offutt AFB in Omaha to DC.
The jet stream and the rotation of the earth can make flying east to west a slow drag. More than a few times I picked up passengers taking nearly 7 hours flying New York to LA. Normal is around 5 1/2 hours. I tried to tell one customer who came in on the early flight that his flight home later that day would be swift. It was. He called me when he landed in New York 3 hrs 40 min later. Talk about a tail wind.
Obama will take credit for this.
The speed of sound changes dependent upon what the air pressure is at that elevation. The land speed record guys and gals generally refer to the speed of sound at sea level. Down there, sound waves have to travel through denser air, so it’s a bit slower than way up at cruising altitude for passenger jets. The difference isn’t much, the exact number escapes me, but it’s on the order of about 2-3 mph, so most people and entities that care about it just default to the sea level reading.
Don’t forget that when they’re talking about the speed of sound of an object, it’s with respect to it’s airspeed (the air around it) not how fast it’s going over the ground. Suppose a leaf blown by the wind is traveling at 5 mph over the ground and let’s also suppose the wind is blowing at 5 mph (also with respect to the ground. The speed of the leaf is 5 mph, but the leaf’s sped with respect to the air around it (it’s airspeed) is zero because it’s being carried by the air. So you see that the ground speed of an object can be substantially different from it’s airspeed. Now say that your’re in a commercial airliner flying at 560 mph indicated air speed (IAS) as in the story above. If there’s a 10 mph head wind, your ground speed will only be 550. Now suppose you have a 150 mph tail wind (i.e. jet stream) pushing you along. Your ground speed is now 710 mph, but your speed with respect to the air around you is still only 560. Since you’re only going 560 mph faster than the air around you, you don’t need to worry about the critical mach of the airplane because you’re nowhere close to it. 560 mph is only about mach 0.75 – which is around where that aircraft normally operates.
To answer a previous question, about critical mach, I don’t know exactly, but red line is 590 mph, so I’d imagine it would be just past that. Probably about mach 0.8 (610 mph) or so.