I have been flying a small Cessna airplane that has a COM/NAV NARCO MK12 equipment with CDI (lateral needle only).

This CDI does not incorporate a horizontal needle to provide vertical guidance, so there is no glide-slope indication for ILS.

Last time I tuned the LOC frequency of an ILS procedure and the CDI captured the LOC signal. The audio panel also captured the O M I markers.

My question is if it is legal to execute an ILS approach "with LOC" only limitations, as published in the approach plate (since the airplane does not have any GS information).

  • 1
    $\begingroup$ If you're asking what's "legal" then please tell us which country or regulations you're asking about. It would also be helpful to know a specific approach that you're interested in, so that we can see exactly the scenario that you explained. $\endgroup$
    – Pondlife
    Feb 17, 2019 at 0:08

1 Answer 1


No, you cannot execute an ILS approach without an ILS glide slope indication as the primary form of vertical guidance.

Even if you could supplement it with alternatives (WAAS, GPS software, etc), they are not recognized as the appropriate standard of vertical guidance required for an ILS approach.

Many airports that have an ILS also have LOC (localizer-only) approaches. If such an approach is published, you could certainly fly it with only the use of the localizer, but then again, it is not an "ILS approach" it is a localizer approach.

The localizer -only approach will have different minimums which will be based on your altitude at a published minimum descent altitude rather than a decision height.

If no localizer approach is published, then you'd need to find another method or airport.

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    $\begingroup$ Often the localizer-only approach is published on the same plate as the ILS. In the US these are titled something like "ILS or LOC RWY 30". $\endgroup$ Feb 16, 2019 at 23:59
  • $\begingroup$ Yes, thank you, that is a good point to include. $\endgroup$ Feb 17, 2019 at 0:03
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    $\begingroup$ Frequently localizer only approaches use another ground-based source like a VOR cross-radial to indicate step-down fixes, so it could be challenging to fly with only one Com radio. $\endgroup$
    – JScarry
    Feb 17, 2019 at 16:06

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