https://en.m.wikipedia.org/wiki/Profess ... tion_(1968)
Was in high school so I don't have personal knowledge, but entered into aviation shortly thereafter. Knew many a military ATC'er who was called to work for the FAA to keep planes moving. When I went into federal employment in the mid 90's,the paperwork and initiation made it very clear that certain occupational fields could not strike.
There's ramifications still today. As many thousands of controllers were fired overnight, and thousands hired to replace them, a large part of the work force needs replacing at the same time. With a mandatory retirement age of 56 the FAA is in the midst of a tidal wave of retirements as the replacement controllers become eligible to or are forced to retire.