You should issue traffic advisories to radar identified aircraft when you feel that its proximity to another aircraft warrants it. The traffic advisory normally includes the azimuth from the aircraft in terms of the 12-hour clock, distance from aircraft in miles, direction in which traffic is proceeding and/or relative movement, and type of aircraft and altitude if known. For example:

• “Traffic 12 o'clock, six miles, eastbound, Piper Malibu at 8000.”
• “Traffic 9 o'clock, three miles, maneuvering, type and altitude unknown.”
• “Traffic 6 o'clock, two miles, same direction, overtaking you, Boeing 757, one thousand feet above you.”

When the traffic you are advising of does not have a verified mode C altitude, advise the pilot by using the phraseology “altitude indicates.” For example:

• “Traffic twelve o'clock, seven miles, converging, altitude indicates six thousand five hundred, type unknown.”

There are other times when traffic advisories are required. Those are covered in later lessons.

{Reference: FAAO 7110.65 2-1-21}