Janet

This is the Janet flight taxiing to take off. Officially, this flight does exist.
You can find it listed in the various web sites that list take offs and landings. Generally its destination is set either KLAS, as if doing a round trip, or to another airbase in Nevada. It actually goes to Groom Lake aka Area 51. This particular plane is:
N-number :N4529WAircraft Serial Number :20785Aircraft
Manufacturer :BOEING
Model :737-275Aircraft
Year :1973
Owner Name : DEPARTMENT OF AIR FORCE
Owner Address : PO BOX 1504
LAYTON, UT, 84041-6504
Type of Owner : Government
Registration Date : 13-Feb-1996
Airworthiness Certificate Type : Standard
Approved Operations : Transport

Area 51 is the best known non secret secret in the US!