What is the required vertical separation for aircraft above FL290?

The required vertical separation for aircraft flying above Flight Level 290 (FL290) is indeed 1000 feet. This standard is part of air traffic control regulations to ensure safe separation between aircraft at higher altitudes, where performance and operational factors can contribute to a more precise requirement for vertical spacing.

At these altitudes, 1000-foot separation is used in the en route phase of flight, as it is effective for minimizing the risk of collision while accommodating the performance characteristics of high-altitude aircraft. This separation remains a critical aspect of maintaining safety as aircraft may be operating at speeds and altitudes where changes in flight paths can quickly become significant.

In contrast, the other options present larger vertical separations, which are not necessary for aircraft above FL290 given the established regulations and safety practices in contemporary air traffic management.