Welcome Guest. Sign in or Signup

2 Answers

Instrument Approach Chart symbology

Asked by: 1091 views , ,
General Aviation, Instrument Rating

Some IAP's have a negative D above the runway sketch. I know what it means. Why do some approaches have the symbol while others do not?

2 Answers



  1. Jeff Baum on Oct 13, 2023

    From the Aeronautical Chart User Guide

    “Runway Declared Distance Information

    Runway declared distance information when available will be indicated by [“negative D”] and is shown to the right of the airport elevation in the sketch box. Declared distances for a runway represent the maximum distances available and suitable for meeting takeoff and landing distance performance requirements.”

    If there is no “negative D”, the declared distance information is not available. As an example U68 does not have any declared distance information listed in the Chart Supplement while KCOD does.

    -1 Votes Thumb up 0 Votes Thumb down 1 Votes



  2. Mark Kolber on Oct 13, 2023

    RDD means that something other than the full length of the runway is usable. For a simple example, runway 9/27 is 5000′ long. But 9 has a 500′ displaced threshold. There would be a negative D in the chart, indicating you should check the Chart Supplement. The CS would show a TODA of 5000′ for runway 9 but a LDA of only 4500′.

    If there is nothing that prevents the use of the entire runway for takeoff or landing, you would not see the symbol.

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes


The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.