The only place "Radar Heading" appears in MATS1 is "report radar heading to....". This appeared in MATS1 a number of years ago in response to an incident, when an aircraft turned back onto his own navigation on transfer to another unit.
I was the victim of the phrase "radar heading" about 5 years ago. I had (correctly) instructed a southbound aircraft to "continue present heading", to provide separation from a northbound aircraft. The southbound aircraft reached his next turning point, turned off the instructed heading and immediately came into conflict with the northbound. A rapid avoiding action turn resulted! During the investigation the pilot stated that he had not been told to fly a "radar heading", so he turned. Madness, I know, but that is what he said.
I have tried repeatedly to get the phrase "radar heading" either outlawed, or adopted as standard phraseology, I honestly don't mind which. The MATS1 editor who added the pharseology "report radar heading" was just plain wrong in my mind, all he did was muddy the waters even more.
