South of 45 deg. N. Lat. — Contact Santa Maria OAC at least 20 min. before crossing the OAC boundary. Contact Santa Maria radio on HF. Pertinent information on clearances can be found on the Atlantic (H/L) 1 en route chart.
In 2006, nearly 400,000 flights crossed the North Atlantic, making that airspace some of the busiest in the world. Since normal land-based communications and radar surveillance are not available over the North Atlantic, horizontal and vertical separation of aircraft is ensured through a strict set of parameters and procedural disciplines.
Clearances for Pacific crossings are usually received on the ground prior to takeoff. If the clearance is delayed until after the aircraft is airborne, as is the case in the Atlantic, the clearance must be received before the aircraft crosses the oceanic entry point.
A good pre-departure technique when conducting oceanic operations is to test the HF radios long before takeoff. At minimum, before entering oceanic airspace, the crew must perform a functional test of HF radios, and ensure that all navigation equipment used for the trip is in working order.
Mach number technique must be used for all oceanic operations. The controlling agency can only plot the approximate position of aircraft, based on position reports. Pilots must maintain their Mach number within a tolerance of +0.01, unless a change is granted by ATC. After leaving oceanic airspace, the pilot is expected to continue to fly the flight plan Mach number until ATC authorizes a change in airspeed. Pilots must notify oceanic control if their ETA at the next reporting point changes by +3 min. when operating on a designated track, or by +5 min. when operating off the designated track system.
To handle the heavy air traffic between the U.S. and Europe, an organized track structure (OTS) is built every 12 hr. (due to constant weather changes). The entire Atlantic Control Area is divided as follows among control centers:
Reykjavik (to the North Pole)
Shanwick and Gander Oceanic
Santa Maria Oceanic — north of 27 deg. N. Lat.
New York Oceanic — North of 27 deg. N. Lat. but excluding the area west of 60 deg. W. Long. and south of 38 deg., 30 min. N. Lat.