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solnabo
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1,140 Km/h For SAS A/c In Norway.

Fri Sep 30, 2005 5:47 pm

Read the Text-Tv this morning, a SAS domestic flight Oslo-Tromsö had strong tailwind and according to the pilot they reached speed of 1,140 km/h! Maybe Rita had to do w/ this strong wind. Guess it was B736, not sure though.

Anyone have more info about this?

Micke//SE  eek 
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HT
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RE: 1,140 Km/h For SAS A/c In Norway.

Fri Sep 30, 2005 5:52 pm

Read through this thread: Fastest Speed Traveled (by 747LUVR Sep 9 2005 in Aviation Polls & Prefs)

-HT
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solnabo
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RE: 1,140 Km/h For SAS A/c In Norway.

Fri Sep 30, 2005 6:11 pm

Thx for the thread HT, but how fast before a narrow body breaks? Curius.

(BTW, they got 30 min. ahead of sceduled time)

Micke//SE  wave 
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DTManiac
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RE: 1,140 Km/h For SAS A/c In Norway.

Fri Sep 30, 2005 6:29 pm

I am not sure, but isnt the airspeed the one that is relevant for overspeeding?

I have been on an LH A340 JFK-DUS in 1997 and the monitor showed a groundspeed of 1180km/h. In the beginning I thought that this couldnt be possible until I noticed that it was only the groundspeed. So if we had a tailwind of about 280 km/h the airspeed was around 900km/h which is certainly within the specification for an aircraft like the A340.

So it seems to me that the airflow over the airplane is similar to one travelling at 900km/h without any wind.

Frederik

[Edited 2005-09-30 11:35:13]
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star_world
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RE: 1,140 Km/h For SAS A/c In Norway.

Fri Sep 30, 2005 6:42 pm

Completely correct - the groundspeed is completely unrelated to the actual speed that the aircraft 'thinks' it's flying at - ie: how fast the air is flowing past it. I've regularly been on flights where the groundspeed was between 1100-1200km/h but the airspeed will always be within the usual range for that type of aircraft. In fact, last week I was on a flight JFK-LHR on a 744 and made the crossing in about 5hrs 15min, makes the journey very easy!

So rest assured that there's no risk of the aircraft 'breaking up' just because it has a very high groundspeed - in fact the crew probably wouldn't even notice unless they happened to glance at the groundspeed indicator - all the flight measurements are based on airspeed.
 
777
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RE: 1,140 Km/h For SAS A/c In Norway.

Fri Sep 30, 2005 9:59 pm

Sorry for the question but after reading this post I have a doubt:

I knew that flying at transonic air speed (between Mach 0.9 and Mach 1,1) is dangerous for the airplane in terms of vibrations and structure stress.

So, how can be possible to continuously fly at 1100/1200 km/h?
In fact even though you have a strong wind (for instance 200 km/h or more) probably you are still in the range of the transonic air speed...

Any explanation will be welcome!
 
DTManiac
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RE: 1,140 Km/h For SAS A/c In Norway.

Fri Sep 30, 2005 10:49 pm

In the case we discussed the airspeed isnt too high, although the ground speed is quite high. As far as I know you can have winds up to 300km/h or even more when flying right in the jetstream. That explains the high ground speeds.
If the airspeed increases up to a dangerous level, the pilot should receive an overspeed warning (acoustic and visual). Furthermore vibrations as you mentioned should occur.

Frederik
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beechnut
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RE: 1,140 Km/h For SAS A/c In Norway.

Fri Sep 30, 2005 11:16 pm

Quoting 777 (Reply 5):
So, how can be possible to continuously fly at 1100/1200 km/h?
In fact even though you have a strong wind (for instance 200 km/h or more) probably you are still in the range of the transonic air speed...

No you are not. The aircraft, 1100-1200 km/h groundspeed, will still be firmly in the subsonic range at its normal operating mach number of approx. M0.74-0.85 depending on type (that is, 74-85% of the speed of sound). The transonic speed range is well above the maximum operating mach number of an airliner (except the much missed Concorde of course! The Sonic Cruiser would have operated in the trans-sonic range, well above M0.9).

You have to remember two things: groundspeed is not related to airspeed; and sound travels through air. Therefore whether or not an airliner is trans-sonic or not depends on the speed relative to the air, not relative to the ground.

Mike G.
 
waterpolodan
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RE: 1,140 Km/h For SAS A/c In Norway.

Sat Oct 01, 2005 12:20 am

Here's a question I haven't seen asked before... I don't know what kind of wind patterns there are at 50,000 feet, but perhaps Concorde on occasion ran with a strong tail wind to give it an even higher ground speed? I know the Mach number is only calculated based on airspeed, so the Mach 2.02 that was on display in the passenger cabin wouldn't change, but it'd be interesting if they were going 100 or 200 mph faster ground speed than they thougth, the plane could make short work of JFK-LHR

[Edited 2005-09-30 17:23:31]
 
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AirPacific747
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RE: 1,140 Km/h For SAS A/c In Norway.

Sat Oct 01, 2005 12:51 am

Quoting Solnabo (Thread starter):
Read the Text-Tv this morning, a SAS domestic flight Oslo-Tromsö had strong tailwind and according to the pilot they reached speed of 1,140 km/h! Maybe Rita had to do w/ this strong wind. Guess it was B736, not sure though.

Anyone have more info about this?

Last year, I flew with SAS from Washington DC to Copenhagen on their A330-300 and we reached 1103 km/h.. also pretty fast  Smile