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6 Answers

Lead Radials depicted on ILS

Asked by: 9925 views , , ,
Commercial Pilot, FAA Regulations, Instrument Rating

Question about lead radials (LR), specify the ones depicted on the ILS-2 in Maui (OGG).

I fly this approach often in an old-school 7-3 with only two VOR’s, no GPS or FMS.  Normally, we use the DME from the LNY 095 radial to determine when to begin our inbound turn. However, sometimes ATC will cut us in early on a vectored heading, so we are no longer referencing the DME off the LNY 095.   

Since we are on a vectored heading, the LNY DME is now slightly off, so last night I suggested we try using the depicted lead in radials, and this seemed to work well. However, in later discussion, my partner said that LR’s should only be used with a DME arc, but this approach has no arc associated with it.

We tried finding a reference to this in the FAA’s IFHB and IPH, but it only makes mention of LR’s when flying an arc, nothing about LR depicted on an ILS, such as the ones depicted on the ILS-2 in Maui.  

So, my question: Can we legally use the depicted LR’s on this approach as a reference point to begin our turn to intercept the inbound course? And if LR’s are only to be used with arc’s, why are they depicted on this chart? Is there a source reference for this?

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6 Answers



  1. Mark Kolber on Mar 19, 2017

    I have my educated guess about why the lead radials are there but will defer on that to someone with more knowledge of approach construction than I.

    But in terms of your partner’s comment, lead radials when depicted are there for the same reason, whether on a DME arc or a T type approach – to give guidance and turn anticipation for the approaching LOC intercept, just as described in the IPH section you read. So, while I have not come across one before, looking at the chart, I am not particularly surprised to see one providing turn anticipation information on this approach with its greater than usual LOC intercept angle and an appropriately sited VOR.

    Why wouldnt you use it if it is available? In the absence of GPS giving me that type of situational awareness, I sure would,

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  2. Best Answer


    John D Collins on Mar 19, 2017

    If you are flying the approach via one of the NoPT IAF/routes where the lead radials are depicted, you are expected to use the lead radial to begin your turn inbound to intercept the localizer. You need to be cleared for the approach and not on vectors.

    From FAA Order 8260.19G:

    8-2-5. Terminal routes general.

    h. Lead radials. In addition to the angle of interception requirements of Order 8260.3, paragraph 2-4-2a(1), a 2 NM lead radial (1 NM for Copter procedures) must be published with arc initial approaches when the DME is not collocated with the facility providing the procedural course guidance. The lead radial provides information for aircraft with single receiving equipment to change the receiver to the localizer or other facility providing the course guidance and to ensure the aircraft is within the clearance coverage area of localizer (LOC) facilities before changing frequency or accepting on-course indication.

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  3. Ken on Mar 19, 2017

    Mark – Thanks for the great response, and I agree, they wouldn’t be there if the FAA did not expect us to us them, but I sensed my partner was and is reluctant to use them again unless he comes across a reference that mentions their use outside of an arc procedure.

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  4. Ken on Mar 20, 2017

    John – Thank You for finding and sighting a FAA reference. I would have never found this on my own, you saved me countless google searches and much time 🙂 . I will show this to my coworker next time we fly.

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  5. Mark Kolber on Mar 22, 2017

    Ken, when I said “someone with more knowledge of approach construction than I,” guess whom I was thinking of? 🙂

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  6. Mark Kolber on Mar 22, 2017

    Come to think of it, a question for your partner: what did he think the lead radials were for?

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