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Old 02-09-2020, 09:42 PM
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Fastest subsonic trans-Atlantic crossing - 4' 56


https://www.wbur.org/npr/804266975/b...-under-5-hours

By using a spectacular jet stream, they cut well over an hour off the time from NY to London. They may have been traveling over 800 MPH ground speed. 4 hours and 56 minutes!
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Old 02-10-2020, 01:38 AM
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That’s impressive. So how fast was the tailwind?
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Old 02-10-2020, 02:08 AM
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Apparently, the supersonic (i.e. Concorde) record is just under 3 hours. That strikes me as a lot of palaver and expense to save 2 hours.
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Old 02-10-2020, 02:18 AM
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Meanwhile, the associated weather on the ground:

https://www.bbc.co.uk/news/uk-51439152
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Old 02-10-2020, 06:27 AM
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Originally Posted by capn carl View Post
that’s impressive. So how fast was the tailwind?
150 mph
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Old 02-10-2020, 08:30 AM
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150 mph
Max airspeed for a 747 is reported to be about 570 MPH, so if they were hitting a max of 800 MPH ground speed at some point, then their tailwind was (at least briefly) 230 MPH.

AIUI, the extremely violent clear-air turbulence that occasional afflicts commercial flights is related to mixing at the edges of the high-speed jet stream with more stable adjacent air. Does flying in such a crazy-fast jet stream present any exceptional hazard? was this any sort of risky endeavor?
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Old 02-10-2020, 08:41 AM
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What I'm wondering is what the actual gate-to-gate time was. Because in my experience, you have to wait in line at JFK before the plane can taxi to the runway, and then on landing, the plane seems to taxi around for half an hour or more before eventually finding its way to the gate. Particularly annoying if my bladder is bursting.

Also slightly surprised that this was a 747. I think the US-based carriers have all stopped flying them.
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Old 02-10-2020, 08:55 AM
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Also slightly surprised that this was a 747. I think the US-based carriers have all stopped flying them.
https://boards.straightdope.com/sdmb...d.php?t=846599

Yes, there are no US based airlines that use 747 for passenger flights, but they are still in service on many routes by foreign carriers.
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Old 02-10-2020, 11:26 AM
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Apparently, the supersonic (i.e. Concorde) record is just under 3 hours.
And then there is this:

Quote:
The SR-71 also holds the "speed over a recognized course" record for flying from New York to London—distance 3,461.53 miles (5,570.79 km), 1,806.964 miles per hour (2,908.027 km/h), and an elapsed time of 1 hour 54 minutes and 56.4 seconds—set on 1 September 1974, while flown by U.S. Air Force pilot James V. Sullivan and Noel F. Widdifield, reconnaissance systems officer (RSO).[122] This equates to an average speed of about Mach 2.72, including deceleration for in-flight refueling. Peak speeds during this flight were likely closer to the declassified top speed of over Mach 3.2. For comparison, the best commercial Concorde flight time was 2 hours 52 minutes and the Boeing 747 averages 6 hours 15 minutes
https://en.wikipedia.org/wiki/Lockhe...ckbird#Records
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Old 02-10-2020, 08:22 PM
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I hope there weren’t any Twilight Zone fans on the flight. There’s an episode where a plane from London to New York starts accelerating suddenly and that causes it to go back in time.
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Old 02-11-2020, 02:14 AM
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Originally Posted by Machine Elf View Post
Max airspeed for a 747 is reported to be about 570 MPH, so if they were hitting a max of 800 MPH ground speed at some point, then their tailwind was (at least briefly) 230 MPH.

AIUI, the extremely violent clear-air turbulence that occasional afflicts commercial flights is related to mixing at the edges of the high-speed jet stream with more stable adjacent air. Does flying in such a crazy-fast jet stream present any exceptional hazard? was this any sort of risky endeavor?
Planes fly in the jet-streams all the time. There is a chance of turbulence around the edges of the jet, mostly on the lower polar side, but it's rare for the turbulence to be severe.
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Old 02-11-2020, 09:11 AM
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Planes fly in the jet-streams all the time. There is a chance of turbulence around the edges of the jet, mostly on the lower polar side, but it's rare for the turbulence to be severe.
That's not the question. Does flying in a faster than usual jet stream turn what is normally an annoyance into something dangerous.
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Old 02-11-2020, 09:51 AM
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That's not the question. Does flying in a faster than usual jet stream turn what is normally an annoyance into something dangerous.
This, yes. To extend the question, commercial flights sometimes encounter turbulence so severe that it injures or kills passengers (generally the ones who are not wearing seatbelts and hit their heads on the ceiling). Such dangerous turbulence is admittedly very rare, but would this unusually fast jet stream present a significantly greater risk of that happening?
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Old 02-12-2020, 02:42 AM
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stendec

Last edited by Gatopescado; 02-12-2020 at 02:44 AM.
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Old 02-12-2020, 08:03 AM
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stendec
Cool story, brah.
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Old 02-12-2020, 04:08 PM
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Originally Posted by Machine Elf View Post
This, yes. To extend the question, commercial flights sometimes encounter turbulence so severe that it injures or kills passengers (generally the ones who are not wearing seatbelts and hit their heads on the ceiling). Such dangerous turbulence is admittedly very rare, but would this unusually fast jet stream present a significantly greater risk of that happening?
It's probably more on point to ask if there is a greater risk of unforecast severe turbulence in a stronger jet-stream. The pilots and planners get given SIGWX (significant weather) charts like this, https://www.aviationweather.gov/data/iffdp/2108.pdf. The jet-streams are shown as bold black lines with the windspeed depicted by triangles and lines. A triangle is 50 knots and a line is 10 knots. There appears to be a jet-stream in the middle of that chart that's over 300 knots! There are also areas shown by dashed lines which represent clear air turbulence (CAT). You wouldn't normally plan through forecast severe turbulence but flying through moderate turbulence and adjusting altitude to find the smoothest "ride" is pretty common. The danger then is that you could encounter severe CAT when the forecast was for none or just moderate. I don't know whether this is more likely to happen, ie the turbulence is not as predictable, in a stronger jet-stream. I suspect not.
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Old 02-12-2020, 06:10 PM
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What I'm wondering is what the actual gate-to-gate time was.
To answer my own question, the plane spent 28 minutes taxiing at JFK and five minutes in London, for an overall flight time of 5 hours and 27 minutes.
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Old 02-12-2020, 10:22 PM
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Cool story, brah.
It is, actually.

https://en.wikipedia.org/wiki/1947_B..._Dust_accident

Sew your name into your undies, people.
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