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Thread: Boeing 737/747 cruise speed

  1. #1
    Join Date
    Jan 2012
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    Smile Boeing 737/747 cruise speed

    Just a curious question about FSX cruise speeds being set to ridiculous settings ie 747 is 370 knots and 737 is 340 knots. Anything over those speeds sets off
    the over-speed alarm. Any way to disable this? Keep the shiny side up and the rubber side down!

  2. #2
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    Aug 2005
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    I guess you do not understand the difference between Ground speed and Indicated air speed. If you have a look at a GPS when at cruise you will find the two are not the same. When above around 30000 ft most planes use MAC and fly around .78. Planes use differential air pressure to measure air speed, and the air gets thinner as you climb so the indicated air speed gets less. around 2% per 1000 ft. So a plane doing 370 kts IAS at 40000 ft is actually doing around 666 kts ground speed, not taking into acount wind speed and direction. I think you need to do some reading. And the reason they use MAC is because as the air gets thinner the speed of sound gets lower, little red striped bar on speed indicator, you need to be below this if you dont want your plane to fall apart.
    Intel 4790k@ 4.6 1.223V Gigabyte GAZ87X-UD3H, Gigabyte GTX 680 2Gig GPU, 8 Gig Cas 11 2100 Mhz ram, Win 7 64 Bit

  3. #3
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    Cruise speeds are usually messured in Mach numbers as the indicated airspeed varies per altitude.
    A 747 cruises around Mach 0.84 and a 737 around Mach 0.78.
    The overspeeds are pretty accurate in FSX. Obey them or you're wings come off

  4. #4

    Default

    Thank you for this information Gentlemen. I didn't know any of this and so it has been quite informative to me.
    Den.

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