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ILS Y vs. ILS Z

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Commercial Pilot, Flight Instructor, Instrument Rating

What is the main difference between a ILS Y vs. a ILS Z ?  I know there are differences but what's the biggest difference?

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1 Answers



  1. John D Collins on Mar 24, 2019

    In most cases, the difference is the method for joining the approach. For example at my airport KUZA, Rock Hill, SC, there is an ILS Y or LOC Y RWY 2 which uses a TAA and GPS to join the approach and fly the missed approach. The ILS Z or LOC Z RWY 2 approach uses conventional ground based Navaids of VOR and DME for that purpose and has an MSA. Anytime the same navigation facility is used for the final approach, but there are multiple versions for whatever reason, an index letter starting at Z, Y, X .. is used to name the variations. There are other reasons than the one cited above, for example, the DA might be lower on one version, but require a higher than standard climb rate on the missed approach than the 200 ft/NM. You should be able to inspect the variations and choose the one that best fits your mission and the aircraft’s equipment and performance capabilities.

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