The US Navy trainer that teaches carrier landings, and the most visible member of the BAE Hawk family on ADS-B.
The T-45 is a BAE Hawk rebuilt for the deck: strengthened undercarriage, an arrestor hook, and the approach handling a pilot needs to put an aircraft onto a moving ship. It is the last aircraft a US Navy student flies before a fleet type, and its sorties come from Kingsville and Meridian in dense clusters.
The HAWK designator it reports under covers the whole family, not just the American variant. RAF Hawk T1 and T2 trainers, the Red Arrows, Canadian CT-155s and export Hawks from Finland to India all share it, so a European Hawk appearing here is the same designator doing a very different job.
In practice the traffic on this page is overwhelmingly US Navy. The Royal Air Force flies fewer of them and transmits less consistently.
It is a heavily modified one. The Goshawk has a strengthened airframe, catapult and arrestor gear, different flaps and a redesigned undercarriage. Enough is changed that it cannot be treated as an ordinary Hawk, but both report as HAWK on ADS-B.
They can. Red Arrows Hawk T1s share the HAWK designator, so when they transmit ADS-B they appear here alongside the naval trainers.
Carrier approach training is repetitive by nature. A student flies the same pattern many times in one sortie, and the aircraft turns round quickly for the next student.