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5 Answers

Being cleared for the approach on ILS

Asked by: 3727 views Instrument Rating

Glide slope intercept(FAF) for ILS is 1500ft for ILS36 at KPIE airport, and ATC clears you as 'maintain 1600ft until established cleared ILS36 approach.'

Let us assum that you are currently at 1600ft, can I descend down to 1500ft or just intercept GS at 1600ft?

Also, why does controllers mention 'maintain 1600ft until established~' even when A/C is already established on localizer (CDI centered) ?

Connor.

5 Answers



  1. Brendan Donovan on Jan 27, 2017

    Connor,

    If you are established on the localizer and cleared for the approach you can descend to the published GS intercept altitude. If you like you can also maintain the 1600 and then intercept the GS and descend. Usually

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  2. Best Answer


    Russ Roslewski on Jan 27, 2017

    The KPIE ILS 36 has glideslope intercept at 2000, so you should not be cleared to intercept at 1500. If you were, that’s a foul on ATC’s part and you shouldn’t accept it. However, I will assume you mean the ILS 18, which does have GS intercept at 1500.

    “Let us assum that you are currently at 1600ft, can I descend down to 1500ft or just intercept GS at 1600ft?”

    You can do either, as either one is in accordance with your clearance. Realistically, I would just intercept the glideslope at 1600, that to me is better than descending 100 feet, leveling off, and then descending again – more power and trim changes than are necessary.

    “Also, why does controllers mention ‘maintain 1600ft until established~’ even when A/C is already established on localizer (CDI centered) ?”

    Typically you are on a vector to intercept final when the controller issues the clearance, so you are not yet established. The list of things the controller is required to tell you is in FAAO 7110.65W, para 5-9-4, and is typically summarized as PTAC:

    P – Position relative to the FAF
    T – Turn to XXX heading
    A – Altitude, Maintain XXXX until established
    C – Cleared for XXX approach

    So, while you may be already established, the controller may or may not know that, and even if they did, they issue the whole PTAC routine hundreds of times a day – so often that it literally just rolls off the tongue without much thought. So the one airplane that day that is already established when they get the clearance, likely gets the “Maintain 1600 until established” as a matter of routine. It doesn’t hurt anything, after all.

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  3. Mike on Jan 27, 2017

    Had similar question. Excellent info. Thank you

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  4. connor on Jan 28, 2017

    Thank you sir,

    I still do not know why he told me to descend down to 1600ft instead of 1500ft and cleared for me approach.

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  5. Russ Roslewski on Jan 28, 2017

    Could have been the minimum vectoring altitude (MVA) in that area, or some other reason. Unless you directly ask, there’s no way to know.

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