Jackson’s airport is one of the largest airports in the state of Mississippi. It is a fairly small airport, and part of the grounds belong to the Mississippi Air National Guard’s 172nd Airlift Wing which flies the C-17. Unfortunately, there are few spotting opportunities here due to the surroundings. The largest airline here is Delta, with mostly regional jet service to Atlanta although there can be mainline aircraft at times. There’s also American Eagle service to Dallas, Charlotte, and Washington DC and United Express to Chicago and Houston.
There are two parallel north-south runways at the Jackson airport and the parking garage sits between them. From the top level you can get a decent view of aircraft using each runway. This is probably the best bet for photography. Morning would be the best time to photograph the west runway while afternoon would be best for the east runway. There doesn’t seem to be a pattern as to which runway is in use; it can vary from day to day. There isn’t a lot of traffic here so it can be dead at times. The Air Guard frequently flies their C-17s on touch-and-go landings from the east side, since the north end of this runway is closer to their ramp. Also, the FBO is located on the east side so most of the business jets would be landing on this side or taxiing close to the parking garage coming from the west side.
Inside the terminal, there is a room called the Medgar Evers Pavillion which is lined with photos and memorabilia of the life of this Jackson native and 1960s civil rights icon. There are windows that overlook both sides of the ramp facing north. It may be possible to get some decent photos of aircraft here although you will have to deal with typical window glare. See below for a photo taken from this room.
Another spot is along highway 475 which runs parallel to the airport on the west side. There is a gravel turnoff which leads to an air traffic control antenna. There are signs posted for no trespassing but there is enough room to pull off the busy 4-lane road and not go beyond the sign. You’ll have a decent wide view of the west runway from here and photos will only be good in the afternoon. I would not recommend spending a long time loitering at this spot because police do patrol frequently.