since the word “scheduled” isn’t in the title, I can lay claim to three flights between airports that are 5 miles apart

as a flight test engineer, I was on the first flights of a 727-200 and two 737-200s from Renton/RNT to Boeing Field/BFI

each flight actually lasted an hour and a half to two hours, as the pilots went through the normal first flight acceptance checklist and whatever dedicated test conditions needed to be performed

the first 737 flight (Apr 1980) involved a new exhaust mixer design for the JT8D-17 engine

the 72S (Sep 1980) and the other 737 (Apr 1981) each had a new airline-specific Performance Data Computer System