Mountain wave PIREP

Discussion in 'Flight Following' started by Flying_Nun, Mar 14, 2019.

  1. Flying_Nun

    Flying_Nun Pre-takeoff checklist

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    Say what? Is 20 kts that critical in the flight levels?

    [​IMG]


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  2. FORANE

    FORANE Pattern Altitude

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    Is a B738 type the same as a 737 max 8?
     
  3. PaulS

    PaulS Final Approach

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    Reading about mountain waves, or gravity waves in Scott's new book, interesting stuff.
     
  4. MooneyDriver78

    MooneyDriver78 Pattern Altitude

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    At 37000’ that’s pretty close to its ceiling limit I would think, so their IAS would be pretty low.


    Tom
     
  5. 3393RP

    3393RP Pattern Altitude

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    It's a 737-800 NG, part of the -700/-800/-900 Next Generation series.
     
  6. PaulS

    PaulS Final Approach

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    Potential coffin corner issue??
     
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  7. Todd82

    Todd82 Pre-takeoff checklist

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    737 Max 8 is "B38M" in that nomenclature.
     
  8. mwagg737

    mwagg737 Pre-takeoff checklist

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    Depends on weight. Yes, could be a problem.


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  9. mtuomi

    mtuomi En-Route

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    Yes it is. It really is. Especially when you're heavy.
     
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  10. benyflyguy

    benyflyguy Pattern Altitude

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    So help me learn more about this. I read about it on Wikipedia but want to learn a bit more. Can you give an example perhaps?
     
  11. 1RTK1

    1RTK1 Cleared for Takeoff

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  12. mtuomi

    mtuomi En-Route

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    The envelope between redline and stick shaker gets pretty narrow high up when you're heavy.
    The plane I fly, for example, at 85'000lbs and FL410 has a speed envelope of 25kts between the redlines. You cannot even turn the plane without losing altitude at that point. 1.3g moderate turbulence would stall the plane.

    A more realistic scenario would be something like 80'000lbs and FL390. It's 67kts there, you cruise probably roughly halfway in the envelope, so 20kts loss will get you uncomfortably close to the stick shaker.
     
  13. PaulS

    PaulS Final Approach

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    Stick shaker, which is uncomfortably close to stall. Let's say you do stall, what happens then?
     
  14. mtuomi

    mtuomi En-Route

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    You push the nose down, you don't have any excess power. You will easily lose around 3000-4000ft of altitude on the recovery.
     
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  15. benyflyguy

    benyflyguy Pattern Altitude

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    so while airspeed is important.. is it more a function of loss of lift due to less dense air- hence needing more airspeed (IAS) to generate more “air” Over the wing.
    Until This moment. The idea of a plane zipping along at 450kts in level flight stalling was something I never even dreamed possible.
     
  16. mtuomi

    mtuomi En-Route

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    Yes, you have to remember that the plane zipping at 450kts probably has his indicated airspeed in the mid 200's in very thin air.