2-4-15

Emphasis for Clarity

JO 7110.65BB, Change 3, effective July 9, 2026 · Official text on faa.gov

Treat aircraft with similar sounding aircraft identifications by emphasizing appropriate digits, letters, or similar sounding words to aid in distinguishing between similar sounding aircraft identifications. Do not abbreviate similar sounding aircraft identifications.
Reference

FAA Order JO 7110.65, Para 2-4-20, Aircraft Identification.
FAA Order JO 7110.65, Para 2-4-9, Abbreviated Transmissions.
Treat aircraft with similar sounding call signs by restating the call sign after the flight number.
Example

“United Thirty‐one United.”
“American Thirty‐one American.”

Note

Similar sounding call signs procedures may apply to ICAO 3LD U.S. special, local, or military call sign.
Notify each pilot concerned when communicating with aircraft having similar sounding identifications.
Example

“United Thirty‐one United, Miami Center, Alaska Thirty‐one is also on this frequency, acknowledge.”
“Alaska Thirty‐one Alaska, Miami Center, American Thirty‐one is also on this frequency, acknowledge.”
Notify the operations supervisor‐in‐charge of any duplicate call signs or phonetically similar‐sounding call signs when the aircraft are operating simultaneously within the same sector.
Reference

FAA Order JO 7210.3, Para 2-1-14, Aircraft Identification Problems.