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3 Answers

Terminology Help. Define “By” ?

Asked by: 5294 views
Airspace, Flight Instructor

Sometimes ATC gives instructions to pilot like following 1) climb to fl 380 by 2130z. 2) decent to fl 230 by kobok. Does the word "by" in the above sentences means "prior to, before" or "at, punctually"?

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3 Answers



  1. Kent Shook on Oct 27, 2010

    “Prior to, before.”

    In the first case, at 2130z you should already be at FL380, or just arriving at FL380. In the second case, you should be at FL230 when you cross KOBOK.

    Usually, though, that’s how such an instruction will be issued: “N12345, cross KOBOK at FL320.” That is the terminology listed in the Pilot/Controller Glossary. http://www.faa.gov/air_traffic/publications/atpubs/PCG/

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  2. Matthew Waugh on Oct 27, 2010

    As Kent points out, it’s not correct phraseology, so nobody really knows what that individual controller means by it.
    If you revert to the basic English language then I would understand it to mean “meet the limitation but if you want to meet it early, be my guest”. But it’s exactly that ambiguity problem that the FAA solves by providing phraseology for those requests.
    So next time a controller asks you to “descend to fl 230 by kobo” ask him/her if they would like you to “descend to cross kobo at FL230”. If they keep doing it note the time and the frequency and contact the facility and ask for the quality specialist. They’ll be happy to reinforce the controllers understanding of correct phraseology.

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  3. Anais on Oct 28, 2010

    Thank you both.
    Further question is why sometimes ATC does not use standard glossary so that make the communication more clear?

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