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Thread: Some questions

  1. #1
    Join Date
    Jan 2008
    Location
    Northwest
    Posts
    26

    Default Some questions

    1. The heat rising off the mountains (thermals?) seem to be a big reason for turbulence around areas like Las Vegas. So does cloud cover help reduce those waves hitting the plane?

    2. When traveling from the Northwest to Orlando is it generally smoother to go over the Rockies or the Phoenix/Dallas lateral? Does the answer depend on the time of year? I know the Rockies are prone to bad turbulence, but does that only apply for landing and take offs or cruising high above?

    3. I’ve never been in a storm at cruising altitude, only lower, do they occur around 30,000 feet?

    4. Once in a while on familiar routes the plane “dives” (rather than steadily lowering) upon initial decent, is it simply to make up time?

    5. On which plane type of 737-300 or higher do you feel the least turbulence? Seems like 757s are very shaky?
    Last edited by Brave; 10-29-2011 at 01:02 PM.

  2. #2
    Join Date
    Sep 2010
    Location
    AMS, LUX
    Posts
    278

    Default

    1: Tough one. Maybe so. If there is a cloud layer, the earth beneath will warm up slower because the cloud layer is reflecting the heat back up again. The thermal radiation below the cloud layer will reflect back to earth again. That's why it is generally warmer at night when it's overcast.
    2: In winter the jetstream is stronger, so at higher altitudes there could be more turbulence, but this depends on many other factors as well. If conditions are right, there could be significant mountain wave action at high altitudes.
    I'm not familiar with the Rocky's at lower altitudes, but I can imagine when there is heat and/or strong winds it will be pretty bumpy out there.
    3: Over 50.000 feet in the tropics, but you will never fly through them. Pilots will always circumnavigate the big storm clouds (Google: Cumulonimbus) as the vertical movement of air in the cloud could damage airplane structure and cause severe to extreme turbulence. Sometimes the cells are embedded, which means you are at high altitude flying in a cloud layer which surrounds various storm cells.
    4: Mostly autopilot behavior. The flight management computers compute an idle thrust path from cruise altitude to the runway. If it picks up the computed flight path it tends to lower the nose not really in a smooth way. It's definitely not to make up time, which is very hard as well in the US because of all the busy airports. There are ways of operating the autopilot more smoothly (for example in V/S mode)
    5: Size matters, that's for sure. But also the way the autopilot is compensating for turbulence. I'd say boeing 747-400, but that's not an objective choice ;-)

  3. #3
    Join Date
    Apr 2007
    Location
    SLC
    Posts
    205

    Default

    With regard to #2, I've been on flights into many small airports in the Rockies over the years, and yes...they're usually always bumpy. Flying from DEN to any of the small cities in a small airplane is always an adventure. Mountain wave action, combined with thermals in the summer, etc. always makes for a wild ride. I can honestly say I've never had very smooth flight into cities like Grand Junction, Montrose, Gunnison, Aspen, etc.

    #5...I think I could have guessed your answer on that one! I will say that's my favorite aircraft. Mostly because of it's story and history, but the ride is usually nice. Especially upstairs! My second favorite aircraft is the 757. And in third place is (surprisingly) the CRJ-900. That thing feels like a rocket during takeoff and climb. So fun.
    Check out my route map: http://my.flightmemory.com/hunter75
    Read about my trips: HunnerWoof

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