Landing flaps

Hi.
Can you help me about when i must to use flaps 15 or 35 to land ?
I know i must to use flaps 15 for runway more 7000 feet and flaps 35 runway less 7000 feet.
But when there is strong wind and i would like to know from how many wind i must to use flap 15 to go around ?
Because if i have runway 6000 feet with snow condition and crosswind about 30 kts must i use flaps 15 or 35 ?

Comments

  • If the runway is contaminated the max Xwind is 14 Kt (Flybe) and with compacted snow 20 Kt.
    With 30 Kt Xwind you don't go there.

  • Ok thanks.but if the runway is 6000 feet 14 kts wind must i use flaps 15 or 35 ?
  • As said before, it depends of the operator but usually:

    15° Flap is recommended as the standard setting for a two-engined approach and landing for runways of 2000 m LDA or more. For runways of less than 2000 m LDA, 35° Flap is recommended and is mandatory when 1800 m or less.

  • I saw somewhere when we have short runway normaly we use flaps 35 but when there is strong wind we use flaps 15.so my question is from how many KTS we use flaps 15 ?
  • No you don't do that.
    The LDA is the distance AVAILABLE as written on the charts and it is the distance that you should take into account.
    Then you have the LDR (REQUIRED) where the wind, mass, temperature, altitude, etc. give you your landing distance which, of course, has to be less than the LDA.

  • I don't understand but thanks you for your help.
  • OK, I'll make it simple:
    On the charts you have a distance and you take that distance as the landing distance: LDA.
    2000 m or more Flaps 15. Less than 2000 Flaps 35.
    Do not take the wind into account for these calculations.

  • Yes I know about distance and flaps.
    My question is for example:6000 feet of dry runway
    With 20 kts of crosswind.
    Normally we use flaps 35 but with heavy wind we use
    Flaps 15 for better to go around because the heavy crosswind.
    So my question is from how many KTS of crosswind I must to use flaps 15 ?
  • edited November 2020

    This is the GENERAL RULE for landing the Q400 based on flap settings, and may differ based on an airlines SOP, not including times where flaps 35 will/may be necessary based on the runway length or other factors.

    Flap Setting for Landing.
    The choice of landing flap setting is either 15° or 35°. Operational considerations such as runway condition, surface winds and the type of approach affect the choice of landing flap. With passenger comfort being a very high priority the norm should be a Flaps 15 landing. To stay proficient using a Flaps 35 landing, flight crews should on occasion use this flap setting.

    The flap configuration for landing is determined by the PF. Consideration must be given to the runway length/conditions, wind direction/velocity, inoperative systems/components, etc. in making this determination. If Flaps 35 is selected, it should not be selected until landing is assured (e.g. no likelihood of a go-around). There is no performance data for a Flaps 35 go-around.

    Up to 10 knots of tailwind is approved landing (with flaps 35° only)

    Maximum Crosswind Component:
    Maximum crosswind component (measured at a height of 10 meters) approved for take-off and landing on a hard, dry runway is 32 knots.

  • As others have mentioned before, it depends on airline SOPs. At my airline, flap 35 MUST be used for any runway shorter than 5000ft, anything beyond that and its up to your personal preference. Personally, I use flap 35 at anything shorter than 7000ft-8000ft, depending on the landing weight and runway conditions, but the vast majority of times I use flap 15 simply because I think it lands nicer that way. A lot of guys use exclusively flap 15, and theres a few who absolutely swear by flap 35 landings. Its really up to you to determine what you prefer.

  • Thanks but my question is about heavy wind for short runway.
    Look on the picture it's majestic's text.
    Red rectangle for gust wind we use flaps 15 for best
    Performance to go around
  • As we said before SOP would differ from an operator to another.
    Qantas Link did not use Flaps 35:

    "At the time of the occurrences, QantasLink did not provide any landing configuration guidance or information additional to that provided by Bombardier. QantasLink did not specify a preferred or optimal landing configuration.

    As detailed previously, normal landings could be conducted with any combination of Flap 15 or Flap 35 and a propeller RPM setting of 850 or 1,020. The selected landing configuration was at the discretion of the captain.

    Flap 35 provides for a slower approach speed, reduced landing distances and a greater tail strike margin. Despite this, both training captains reported that most pilots preferred to use Flap 15 because the aircraft was more responsive, easier to handle and easier to land.
    Flap 35 was rarely used for other than training purposes."

    So you can make your own SOP to suit your taste.

  • So if i understand whatever strong wind or not whatever length of runway you use flaps 15 most of the time.
  • It depends of the airline.

    Personnally I use flaps 15 if the LDA is more than 1800 m and flaps 35 if less than 1800 m because I use Flybe SOP. Disregard the wind which is not taken into account.

    Sometimes it is not the runway lenght that you have to consider as LDA but the airport specifications.

    i.e. at LOWW at certain busy hours you are asked, when landing on 11, to vacate via A8 and there you have only 1170 m despite the runway is 3500 m long so you use flaps 35.

    Again do it as it suits you best.

  • @helico55 said:
    So if i understand whatever strong wind or not whatever length of runway you use flaps 15 most of the time.

    "Whatever strong wind": Yes. Don't think I've seen an SOP that accounts for wind in flap selection. You do not perform a missed approach at your landing flap either way, you will most always retract the flaps to 10 or 5 when initiating that maneuvre and they're not the slowest flaps in the world.
    A much more common reaction to strong crosswinds would be to opt not to land "Reduced NP" but instead at 1,020 RPM. Several operators do this when crosswind components exceed certain values that the operator has set and many operators will do this in gusty conditions regardless of direction.

    "Whatever length of runway": No. The available landing distance is what any operator and/or pilot will use as the main determining factor for what landing flap they will use. All operators choose different values here; as mentioned above, Flybe for example used 1800m as the cutoff value. Longer than that and you use Flaps 15, shorter than that and you use Flaps 35, wind not being considered at all here.

    My "personal SOPs" have me land 35 at fewer than 2000m LDA and 15 at more. jpgmultimodal also gives a great example about LOWW that shows how sometimes different operational considerations can become a thing but they lead back to the same calculation: "Is LDA longer than XXXX meters?"
    From my personal experience it also cannot hurt to do a training approach at Flaps 35 into a longer runway every once in a while when traffic permits, but that's a different story...

  • > @helico55 said:
    > So if I understand whatever strong wind or not whatever length of the runway you use flaps 15 most of the time.

    There have been several posts in this thread eluding to the fact that the use of flaps 15 or 35 is the preference of the crew (which are SOP or manufacture statements), providing it is not to a runway requiring the use of flaps 35 due to its length (5000' or less).

    You seem to think that high wind components play a factor in the flap setting it does not unlike some other aircraft whereby setting the flaps to its max setting could cause the overspeeding of the flap setting during a gusty/possible windshear event. This is not the case for the Q400.
  • My main question was about if i have short runway with strong wind and gust must i use flap 15 for better performance in case of go around.
  • edited November 2020
    What is one of the primary criteria for landing on a short runway? Flaps 35 right? So you use FLAP 35.

    The procedures in place for a go-around with the use of flap 35 are not much different than that of flap 15.

    Now if your determination of the approach with the use of flap 35 during a possible windshear event seems unsafe then there should be an escape maneuver in place to initiate the go-around.
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