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FAF on an ILS at the airlines

Discussion in 'Technical Talk' started by saxman, Jan 23, 2010.

  1. saxman

    saxman Well-Known Member

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    During our initial instrument training we were always taught that the final approach fix on an ILS is glideslope intercept. But when I got to my last airline, they told me this is now different. Since usually at big airports you are vectored on to the ILS much higher than than where the OM and multees cross is. And they said your FAF is where it is marked on the Jepp page, at the cross.

    So which is it for you other 121 guys out there.
  2. matt152

    matt152 Well-Known Member

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    I'm not at 121, but the FAF on an ILS is glideslope intercept at the minimum altitude. On NACO charts it is the "lightning bolt" in the profile view. On Jepp charts, this is where the line intercepts the precision approach path in the profile view (the solid line, not the dashed line). This may well be different from the nonprecision FAF, depending on the approach.
  3. subpilot

    subpilot Squawking 7600

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    It is at the outer marker, or glide slope intercept at the published altitude. If you are kept high then you will intercept glideslope earlier but this does not change the FAF. Make sure to crosscheck your altitude at the FAF!
  4. matt152

    matt152 Well-Known Member

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    There are approaches out there where the ILS FAF is not the same as the OM. You can be descending on the glideslope but not at the FAF on the ILS.
  5. scarface

    scarface New Member

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    Things may have changed since I've been out on minor medical, but I was taught that it was the final approach sement on an ILS, not the FAF. If the RVR goes down below mins prior to the final approach segment you've got to abandon the approach; if it goes down after the final approach segment you may continue the approach in accordance with FAR guidance.
  6. saxman

    saxman Well-Known Member

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    Here's what the Pilot/Controller Glossary says:

    but for Final Approach Fix (FAF) it says:
    So I'm confused. Sounds like both of those are saying different things.
  7. minitour

    minitour New Member

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    ILS21L KLUK.

    The marker is actually way inside the FAF for both the LOC only and ILS procedures.

    -mini
  8. subpilot

    subpilot Squawking 7600

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    Saxman: could it be that one definition is Jeppeson and the other is Government for the depected symbol? The wording on both seems to mesh just fine.
  9. subpilot

    subpilot Squawking 7600

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    I did have an "or" in there, but you are correct that the FAF is not always the outer marker. I guess I should have said it is normally at the outer marker. :)

    To the OP, just do as your new airline wants you to. I think most companies have there little differences to the norm for various reasons. What does it say in there Ops manual?
  10. dasleben

    dasleben a> run "dasleben's_email"

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    I'm not 121 anymore (I'm 135 now, but we treat this the same), but I consider the FAF on a precision approach to be glideslope intercept at the minimum intercept altitude. The maltese cross isn't applicable to precision approaches, and it'd be unrealistic to treat the ILS final approach segment as the FAF if you're cleared for the approach from, say, 4000'.
  11. CRJDriver

    CRJDriver Well-Known Member

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    :yeahthat:
  12. subpilot

    subpilot Squawking 7600

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    KLUK ILS21L

    So on the example above (using what mini gave us), The ILS FAF is at 3000' because it is the glide slope intercept at the published altitude plus there is a lightning bolt symbol denoting that on the profile view. Now when flying this is the 121 world, that is the official point that you are good to continue once past if the visibility goes below minimums. I would however use the NDB crossing (or I-LUK 8.5 DME) at 2902' to cross-check my altitude since the official FAF has no way to cross-check (no distance info).
  13. minitour

    minitour New Member

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    We used the 8.5 DME off of the LOC (and had Madera entered in the GPS too) to cross check our intercept last night. The NDB was in there, but I didn't even watch for the needle to swing, honestly. Honestly, I just glanced down and made sure we were over the GPS waypoint...but everything was set up. *lazy*


    -mini
  14. saxman

    saxman Well-Known Member

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    Both those definitions are from Jeppesen. They're on the same page in fact.
  15. subpilot

    subpilot Squawking 7600

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    :dunno: well the first one states "designated on Government charts " while the second state "designated in the profile view of Jeppesen Terminal charts ." Maybe Jeppesen copied and pasted the definition from the AIM?
  16. matt152

    matt152 Well-Known Member

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    Agreed.
  17. SIUav8er

    SIUav8er Narcosis

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    91, 121, 125, 135.... makes no difference!

    I am guessing that the airline wants you to treat intercepting the glideslope at any altitude (in terms of aircraft configuration/profile) the same as you would at the actual glide slope intercept altitude that is published on the chart. always cross check the altitude when passing over the point which GSIA is published!

    the cross published on ILS plates is the FAF for the Localizer, not the full ILS.
  18. deek

    deek New Member

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    but don't you start your stop watch when you hit the lighting bolt? I guess if you are vectored onto the ILS from say 4000' you just ride it down till you hit 3000' then start the timer?
  19. minitour

    minitour New Member

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    It would do you no good to time an ILS from any point other than where you'd time the LOC procedure. ...assuming there aren't different times published.

    The time thing is a distance/speed=Time thing. If you're using a different distance, then your time will expire before you get to DA(H).

    ...and who really times an ILS anymore?

    -mini
  20. deek

    deek New Member

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    so then you would time once across the NDB in the above example? I would imagine no one really times ILS approaches I would guess if you loose the GS you just go around in the 121 world.

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