Obtaining official call signs
 

Back in the day flying formation in AA5 series aircraft we used call signs for flights that seemed to be accepted as a matter of course by pretty much any facility that we used them with, as long as they complied with the format of [name][number]. E.g. "cobra flight" did not work on the initial call, but "cobra niner niner flight" did. This was true even on the few times we were on an IFR/IMC and worked with tower, center, whomever.

This does not appear to be the case now. I've tried a few times with local facilities and they want to use "[tail number] flight". I called the local tower (LZU) to discuss formation ops and call signs and they pretty much said they need to use an official call sign if one is assigned, to avoid potential conflicts with other flights. His example was, what happens if "cobra" is assigned to F16 scramblers out of somewhere or other.

So, two questions. First, is it the official stance of FAA that only officially assigned call signs can now be used?

Second, has anyone gone through the effort of obtaining one i.a.w. A.C. 120-26K?

Call sign and atc
 

On the first call up we use the tail number then the call sign. For example N1234 Tango flight request overhead approach 20 right. From then on they call us Tango flight. Same on taxi and take off.

Same same.

In our area we don't have such a problem. We call ourselves "Alpha", "Blue", "Yellow", "White", "Whisky", "Sky", "Lake", "Snake", "Tiger", "Goofy", etc. At first call up we usually just use XX Flight of N.

At our local facility, we have a formal written LOA on file allowing us to use a specific flight call sign. A lot to do about nuttin'. Easier to use an n number-flight to be easy.

We used something similar: "Maverick Check"... "2" "3" "4"......"Tower, Experimental 24AZ, flight of four landing, requesting an overhead pattern."

Tower now knows how many are in the flight.