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QNH and INS on a TAF?

Discussion in 'CFI Corner' started by comstsa, Mar 6, 2011.

  1. comstsa

    comstsa Well-Known Member

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    Does anyone know what "QNH" and "INS" on the TAF mean?
    ex: BECMG 0616/0618 33009KT 9999 NSW FEW015 QNH2999INS AUTOMATED SENSOR METWATCH 0609 TIL 0617 T10/0610Z T18/0621Z
  2. dasleben

    dasleben a> run "dasleben's_email"

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    QNH refers to the local altimeter setting. INS means that the number is in inches instead of hectopascals, which is what QNH is normally given in.
  3. comstsa

    comstsa Well-Known Member

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    hey thanks man.... can you tell me where I can find "QNH" in a book? does it actually stand for anything?
  4. Dugie8

    Dugie8 Well-Known Member

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    Here you is.

    QNH
  5. comstsa

    comstsa Well-Known Member

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    awesome... pretty interesting stuff. Its amazing what you find out on bad weather days.
  6. dasleben

    dasleben a> run "dasleben's_email"

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    Where is that TAF from? I don't think I've ever seen QNH shown on domestic TAFs. Military, maybe?
  7. queeno

    queeno Ward of the Guberment

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    heres one, most of you hi flyers use a QNE setting. at what alt would you set QNE in the USA and what would the setting be????????
  8. dasleben

    dasleben a> run "dasleben's_email"

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    29.92 inches climbing through 18,000 feet. :)

    The way I remember it:

    QNH = Altimeter setting at (H)ome.
    QNE = Altimeter setting (E)nroute (above transition altitude/level)
    QFE = (F)ield (E)levation showing 0' (scary).
  9. Chief Captain

    Chief Captain Well-Known Member

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    I only ever see such things at military fields. Nowhere else seems to forecast the QNH. Trying to figure out why exactly that information would need to be in a TAF...
  10. Autothrust Blue

    Autothrust Blue Smurf porn star

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    Yep - Military TAFs use that format. Point Mugu (our friendly neighborhood Naval Air Station) reports "QNH3010INS." They also report visibility in meters (e.g. 9999) in METARs.

    See also the format for Helsinki (-Vantaa), Finland:
    Code:
    EFHK 061950Z 31004KT CAVOK M05/M11 Q1024 0419//95 5419//95 1509//95 NOSIG
    EFHK 061738Z 0618/0718 33012KT CAVOK 
         BECMG 0623/0701 26005KT 
         TEMPO 0713/0718 5000 -SN BKN012
    ...where altimeter setting is given in millibars, specified as QNH. "QNH one zero two four." Visibility is also given in meters on the TAF between 0713 and 0718.

    Some foreign locales specify what kind of altimeter setting you're getting when you call them, e.g. "QNH one zero one zero."

    QFE is just dangerous. The Russians use it, I think the Chinese do too. (And they do metric altimetry (?!!) over there too, I think. Bad juju!)

    QNE = two nine, nine two (inHg) or 1013 (mb), above transition altitude/level (FL180 in the United States, but sometimes much lower in a lot of other places).
  11. will_fly_for_bandwith

    will_fly_for_bandwith Well-Known Member

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    Most of Europe (by that I mean the UK, France and Ireland) use QHN and QFE.

    Why do you think setting QFE is dangerous. IIRC in the UK you depart the field with the ASR's (altimeter Setting Region)QNH, set QFE when inbound (within 5 miles or so) to the field.

    The transition alt in the UK is at the surface at Heathrow (Class A at the surface) and increases as the floor of the Terminal Maneuvering Area increases (looks like US class B).

    The transition to flying QNH over here in the US took a few flights to get used to...
  12. dasleben

    dasleben a> run "dasleben's_email"

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    Yeah, all those old Soviet Bloc countries use it, too. Not a problem for some aircraft that can simply swap to meters at a press of a button. The 757/767 requires the use of a chart to convert to feet. :insane:

    It's potentially hazardous because obstructions in the area are shown on the charts in MSL, not height above field elevation. We're not allowed to use QFE at my company; you have to get a QNH equivalent instead.
  13. Autothrust Blue

    Autothrust Blue Smurf porn star

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    Southernjets too. "Krug, Southernjets 281, request QNH."
  14. queeno

    queeno Ward of the Guberment

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    Eastern and American both used QFE settings for approaches, i belive American stoped using it after the Bradley under shoot. i rode jump seat on AAL in the 80s and observed said operation.
  15. queeno

    queeno Ward of the Guberment

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    :clap::clap::clap::clap:
  16. MikeD

    MikeD Administrator Staff Member

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    We used it in Kuwait. Takeoff QFE, switch to QNE climbing through 3000, desceding through FL50, switch to QFE again. It was weird, but made no difference to me.
  17. Chief Captain

    Chief Captain Well-Known Member

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    The TA at EGLL is 6000ft if I recall. It is indeed class A to the surface, but that doesn't mean that the transition alt goes down to the ground too.
  18. Chief Captain

    Chief Captain Well-Known Member

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    Where's the danger? For all but a few airports, the altimeter will indicate higher than your actual height above MSL, so you'll still be clearing the obstacles.

    Does anybody know why AAL decided to use QFE? I could never understand the logic behind it, especially when their airplanes had radio altimeters.
  19. Hacker15e

    Hacker15e Member Of Extraordinary Magnitude

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    The TA in the UK is 3000' (FL30). The TL differs per QNH.

    In certain bits of controlled airspace ("Green airspace" on the charts), they stay on QNH.

    As a US military jet flying in the UK, I avoided green airspace as much as possible!
  20. Blackhawk

    Blackhawk Well-Known Member

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    Hmm. I don't think they weren't using it when I was there. I never remembered hearing it at Ali Al Salem or International.

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