Mike is correct and DE is wrong. It bothers me that DE would be teaching an outdated procedure. I was told when the changeover occurred the practice of sqauwking 77 then 7600 was causing confusion and squawking 7600 from the outset was a lot more clear and to the point.
I want to say it was changed in the mid '90s. For the longest time, the old method is how I knew it. Along with PCA/TCA/ARSAs for airspace, and FTs/SAs/SPs/RSs for WX reporting that the US used prior to METAR.
Unfortunately, I missed out on the days of Fan Markers and colored airways....
Old - school.
