Hmm, that would be worth a trip to see. I remember a decade back a 124 came into MDT
and I went down to see it (well, I was a young sprout at the time so my aunt had to drive me to the airport), sat there all day hoping it would depart but it didn't leave until after dark.
There used to be a swell place to spot planes @ KMDT; my uncle and I used to park near the AMP hangar (not sure who owns that now), the employees didn't care and actually invited me in to tour their Beech and Saab one time, and we'd stand down in the field by the fence. I wouldn't think that'd be a good idea these days; the last time I went down there was well before 9/11/2001 and I can imagine there'd be suspicion about some bearded mid-twenties dude out there with a camera...
Not to mention the AMP hangar belongs to someone else now, and I'd just assume that means my welcome ticket to use their parking lot is expired!