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United States Department of Transportation United States Department of Transportation

Critical DMEs

A critical Distance Measuring Equipment (DME) is a DME facility that, when not available, results in navigation service which is not sufficient for DME/DME/IRU operations along all or portions of a specific route or procedure. The required performance assumes an aircraft's RNAV system meets the minimum standard (baseline) for DME/DME RNAV systems found in AC 90-100A, appendix 1, or the minimum standard for DME/DME/IRU systems found in AC90-100A, appendix 2. For example, terminal RNAV DPs and STARs may be published with only two (2) DMEs, in which case, both are critical.

If any critical DME facilities exist on an RNAV DP or STAR, they are identified on the relevant chart. NOTAMs should be checked to verify the operation of critical DMEs for navigation relying on DME. Pilots should assess their capability to navigate (potentially to an alternate destination) in case of failure of critical DME while airborne. The critical DME list is updated as charts are published. This list is searchable to determine which facilities are critical for portions or all of a procedure and/or route.

Right-click on Critical DME List (MS Excel) for May 16, 2024 and choose the 'Save Target As' or 'Save As' option, depending on your browser. Select the folder or directory on your system where you would like the file to be saved.

Questions or concerns please submit to: Aeronautical Inquiries.

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