The passage of time is always highlighted by looking back at photos from the past. And, perhaps, aviation serves as one of the more obvious reminders of how much has changed from days gone by.

From propeller planes to jet engines to airlines no longer in existence—like TWA and Capital Airlines—historical photos offer a glimpse into the daily life of the past.

Blue Sky News took a trip through history this week by opening the archive, this time from Dale Zehnder, of St. Petersburg, Fla., who submitted his grandfather’s photos taken at Greater Pittsburgh Airport, the forerunner to Pittsburgh International.

TWA mechanics conduct maintenance on a Douglas DC-3 engine at Greater Pittsburgh Airport. (Photo by Noble Beheler)

Zehnder opened an old box packed up from his grandfather’s house and came across dozens of 1960s pictures of planes and mechanics at Greater PIT.

Noble Beheler was a company photographer for American Bridge Co. in Ambridge, Pa., but in his spare time, he took thousands of pictures around Pittsburgh, including the airport. Some of his aviation pictures show planes from airlines like TWA, Eastern, Capital, Allegheny, Mohawk and more.

Beheler died in 2005 at age 99 but thanks to his camera, all of us can step back in aviation history.

A TWA Martin 404 taxis at Greater Pittsburgh Airport. (Photo by Noble Beheler)