ATC units at EGPK

Three units, three jobs

Prestwick TWR (Tower) — runs the runway. Issues takeoff, landing and taxi clearances. On VHF 118.155 (as of current AIP; always double-check).

Prestwick Approach (APP) — sequences traffic inside the Prestwick CTR/CTA. On 120.555. You'll hear aircraft told to "descend to altitude 3000 feet, QNH 1013, report field in sight".

Scottish Control (area en-route) — actually based at Prestwick, but handles high-level traffic crossing Scottish airspace, not the airport itself. Different facility.

The handoff flow

Arrival:

Scottish → Prestwick APP → Prestwick TWR → ground

Departure:

TWR → APP → Scottish

Each handoff is a frequency change: "contact Prestwick Tower one-one-eight decimal one-five-five, good day."

Why you care as a spotter

If you're listening on a scanner (legal to listen, illegal to transmit), knowing which frequency matches which phase of flight lets you line up photos. You'll hear "report final" on tower before you see the landing lights.