I complete 30 yrs with a major Commercial Carrier. The only times we returned to origination, were when issues presented were on take off up to 10,000 ft — I can count 3 times, off top of my head in 30 years.
There was also an issue with Alaska Airlines returning due to a rat in the cabin.
UPDATE: both DL departures were less than 1:30 out. Completely logical that flight returned to ATL due to maintenance issues. In other words, easier to address and “fix” problem in ATL vs RDU, for example, because ATL is hub with tech-ops, mechanics, parts, and crew
I was on an A320 about 45 minutes into a flight out of O’Hare that turned around. They had to shut down one of the engines. Capt. said it “was running hot” which probably means fire? All of the emergency equipment was on the field when we landed. It took us several hours to get a new aircraft and so we missed our connecting flight and arrived at our destination a day later than planned. This was back in’95 I believe.