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Thread: IFR descent rates

  1. #1
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    Default IFR descent rates

    Going into Munich, I heard that 1500 or greater was a special command, and from personal experience, any descent past 1000fpm is very noticeable, would feel uncomfortable on an airliner probably. What would a "standard" descent rate be for a 767/777?

  2. #2

    Default RE: IFR descent rates

    1000fpm in an airliner is VERY doable and actually borders on the MINIMUM for a typical descent, rather than the maximum. 1500 fpm is not uncomment and 2500+ fpm is not unheard of and happens on many commercial flights.

    That being said, 1500 fpm IS extreme in many single engine bug-smashers (i.e. Cessna 172). I typically will limit my descents to 1000 fpm or less, if possible.


  3. #3
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    Default RE: IFR descent rates

    Hi Grzegorz,

    ATC often requests a descent beginning at or near the computed TOD or Top of Descent for the route programmed into the flight computer. (FMC). The TOD is computed using normal performance numbers with current altitude and target altitude along with distance to go. Speed restrictions (<250KTS under 10,000 feet or design target speeds) limit the max fpm in normal descent profiles.

    Commanded descent rates could be anywhere from 500 to 4000 FPM (or greater) in order to keep the aircraft on schedule for the computed descent path.

    I don't have any 767 data with me but I can tell you the Boeing 777's numbers:

    (EDIT TABLE)
    Target Speed-------Clean------Speedbrake
    310KTS-----------2300---------5500
    250KTS-----------1400---------3500

    For passenger comfort the pressurisation systems will not exceed 500fpm climb or descent rates, even with a much higher rate either being commanded by the pilots or programmed into the flight computer.

    Regards,
    Kelly

  4. #4

    Default RE: IFR descent rates

    >Going into Munich, I heard that 1500 or greater was a special
    >command, and from personal experience, any descent past
    >1000fpm is very noticeable, would feel uncomfortable on an
    >airliner probably. What would a "standard" descent rate be for
    >a 767/777?

    what personal experience is that? a jet typically descends at 2-3000 fpm on a 3deg glide slope at idle or epr 1 descent. uncomfortable? the pressure controller usually maintains 3-500 fpm on the descent so i do not know where this statement is coming from also.

    if the speed brakes are out, then these descent rates can go much higher. a 5 deg down deck angle can give 4-5000 fpm and be hardly noticed by the passengers (except the loud noise over the wings).

  5. #5
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    Default RE: IFR descent rates

    Hey Jeff. Back to the forums ... how are you doing? Any mountain-flying in Colardo this summer? :)
    Greetings
    Florian alias PHCO

    www: www.transamericarally.florianjindra.net - Continuation August 2008

  6. #6
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    Default RE: IFR descent rates

    Thanks!

    RS - I only heard the 1500 fpm or greater from ATC. I didn't know why 1500 was specifically mentioned, but I'm just saying what I heard. When I mentioned the 1000 fpm, I am talking about piston GA (i.e. Skyhawk).

  7. #7

    Default RE: IFR descent rates



  8. #8
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    Default RE: IFR descent rates

    In the US, ATC usually issues a climb/descend to altitude only with no specific rate. The controller knows average performance according to general type (turbojet, turboprop, piston) when giving altitude change clearances in order to maintain separation and in the case of descending, to get us into the airport's airspace at the right height. The actual descent rate is up to the flight crew or programmed by the FMC in the case of an airliner.

    Maybe things are different in European airspace ??

    regards,
    Kelly

    PS - Munchen is a beautiful city !


  9. #9

    Default RE: IFR descent rates

    what kelly said is absolutely correct.

    atc may also ask for "expedited" climb, which is never truly declared. in my mind it means more than 2000fpm.

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