"Was air safety compromised? In many ways, yes. The military air controllers were unaccustomed to working with civilian aircraft and the complicated zones of the civilian system. New hires may have been rushed through programs to get them into work, without having sufficient training. A great quote:
"By the strike’s third day, [Captain Tom] Sheppard [chair of the Air Line Pilots Association (ALPA) Air Traffic Control Committee] began to worry about the exhaustion of replacement controllers and told [ALPA President J. J.] O’Donnell that, 'if the system continues at present staffing levels, fatigue of the people working will have a safety impact.' On day four he warned of 'a higher potential of danger.'...One controller who stayed on the job at Houston Center reported that safety had been 'set back 10 years minimum.'"
However, pilots kept flying. This is partially because they were unaware of ALPA's reports on safety, and partially just out of not wanting to get involved. This was the "kiss of death" according to many of the controllers on strike. ALPA would have crippled the nation's air system entirely if they joined in, and Reagan might've lost this battle. However, they didn't join, and despite the increased safety risk, O'Donnell insisted that the country's air system was perfectly safe. Another quote: PATCO disputed O’Donnell’s characterization in its own press conference on August 19, claiming that there had been fifteen near midair collisions in fifteen days. That very afternoon
two general aviation planes collided south of San Jose, California, killing the pilot of one of the aircraft, and seemingly underlining PATCO’s point. Strikers blamed the collision on controller fatigue, but FAA officials denied the charge. The fact that it involved two single-engine planes and produced only one fatality kept it from becoming a major story....So yes, air safety was definitely compromised despite the replacements by non-strikers, consolidation of zones and flow, cancellation of many, many flights, adding of new recruits, and use of military air traffic controllers. ....
Part of the reason incidents didn't occur in so big an amount was because of the lowered air traffic they allowed. The FAA had envisioned that air traffic would return to pre-strike levels in 1983, in the worst-case scenario. By the end of 1982, the FAA was far more understaffed still than pre-strike levels, and air traffic suffered as a result. There were still incidents, however, attributed to the new controllers.
On January 13, 1982, a plane crashed (it was snowing) into the icy Potomac leaving D.C for Florida. Initially it was believed to be only a problem of the de-icing failing, allowing ice to accumulate. 78 were killed, and only 5 survived. PATCO insisted that air controller error was to blame, from the get-go, and this was initially met with skepticism. But the NTSB hearings that opened on March 1 exposed the fact that the air traffic controller who cleared the doomed jet for takeoff, a supervisor who had resumed controlling traffic on August 3, had also cleared an Eastern Airlines jet to land behind Flight 90 on the same runway before the flight was airborne. So there were definitely doubts, and incidents, that made everyone feel the new system was far more questionable. The FAA, as a result, stepped up hiring, but did so in such a rushed manner that the NTSB (National Transportation Safety Board) asked it (in 1983) to stop its plans for expanding air traffic until it could raise the number of fully certified controllers, because it was rushing to try to get traffic back up quickly....
Sources:
Reagan, Ronald. An American Life. New York: Simon and Schuster, 1990. Print.
McCartin, Joseph Anthony. Collision Course: Ronald Reagan, the Air Traffic Controllers, and the Strike That Changed America. New York: Oxford UP, 2011. Print.
Wilentz, Sean. The Age of Reagan: A History, 1974-2008. New York, NY: Harper, 2008. Print."
What exactly happened when President Reagan fired all the striking air traffic controllers? How were they replaced? Was air safety compromised? : AskHistorians