What action must pilots take when operating under the SLOP in U.S. Domestic Airspace?

When operating under the Strategic Lateral Offset Procedure (SLOP) in U.S. Domestic Airspace, pilots are permitted to apply SLOP without notifying Air Traffic Control (ATC). This procedure allows pilots to fly laterally offset from the centerline of their designated route, which can enhance separation from other aircraft and increase safety, especially in busy airspace.

The essence of SLOP is that it is a voluntary procedure meant to be used at the pilot's discretion. It is specifically designed for use in certain operational situations where enhanced separation is beneficial, and because it is a part of standard operating practices, the need to notify ATC is generally waived. This affords pilots the flexibility to implement the procedure quickly and efficiently without the need to engage in additional communication that could delay their operation or increase workload unnecessarily.

The other choices present requirements or stipulations that do not align with the established protocols for SLOP in the context of U.S. Domestic Airspace.