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‘Zero’ Vs. ‘Sierra’

ForeFlight’s time and distance rings on the moving map can serve as a visual reminder of when to complete the in-range check as you approach the destination airport. Flying
Gemini Sparkle

Key Takeaways:

  • Pilots frequently experience confusion in ATC communications, particularly distinguishing the number "zero" from the letter "S" ("Sierra") in aircraft registrations, despite efforts for clear enunciation.
  • There is a significant disparity in safety records between commercial aviation and general aviation (GA), with a daily GA fatality rate contrasting sharply with minimal commercial air carrier deaths over a decade, prompting discussion on applying commercial safety improvements to GA.
  • The article addresses a reader's confusion regarding Angle of Attack (AOA) diagrams, clarifying that different FAA diagrams can illustrate distinct aspects of aerodynamic principles, such as defining AOA versus showing how flaps alter it.
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Because the final alphanumeric symbol in my aircraft’s registration is the number “zero,” (such as N67890), there is the occasional mixup by ATC, with a readback of “Sierra,” for the letter “S” instead of the number zero. This happens at times even though I am always careful to enunciate “zero” as clearly as I can (Zee-Row). Part of the occasional confusion is probably the fact that the zero comes at the end, where more often than not there is the expectation of a letter. I would venture a guess that there are more zero/sierra mixups than anything to do with the numbers three (which we are supposed to say as “tree”) or five (which we are supposed to say as “fife”). Although I suspect the chances of the FAA or ICAO (or whoever is in charge) changing the letter “S” designator to something other than “Sierra” is near zero. Any thoughts? Thanks.

William Cole – Petaluma, Calif.

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