It is a Boeing 737-200 and it has been in service for 43.7 years.
There are still DC-3's in commercial operation, and production of those ended in 1942.
http://www.buffaloairways.com/ is one operator.
Common definition of a "commercial operation" for airlines is scheduled operation, not charters.
So... That boeing just may be the oldest flying airliner on scheduled routes.
Are there any such planes used for regular scheduled (passenger) airline services? It appears to me that Buffalo Airways is charter and cargo only.
Jets don’t like that.
For back country missions the only thing maybe better than a DC-3 is a Basler... and that is a modernized DC-3 with reinforcements and turboprops for more power. They suck a lot more fuel than a plain DC3 though, which can be problematic as some of these fields they have to fly fuel in.
I've talked to a bunch of people that get flown around by their company for 2h meetings at airports within Germany every day. If these wouldn't happen and would be done via video conferencing or other means that would be an improvement. Business will find a way to make it work.