If an aircraft becomes non-RVSM compliant and ATC allows it to remain in RVSM airspace, what must the pilot state to each new controller?

When an aircraft is no longer compliant with Reduced Vertical Separation Minimums (RVSM) and is allowed to remain in RVSM airspace, it is crucial for the pilot to communicate this status to air traffic control. Stating “negative RVSM” clearly informs each new controller that, although the aircraft is operating within RVSM airspace, it does not meet the necessary requirements for RVSM compliance. This alert is vital as it ensures that air traffic control is aware of the aircraft's limitations and can provide appropriate separation from other aircraft that are RVSM-compliant.

Using this specific phrase helps maintain situational awareness and safety, allowing ATC to manage the airspace effectively. It serves to differentiate the aircraft from others that can safely operate with reduced vertical separation, ensuring all parties involved have a clear understanding of the operational status of the aircraft in RVSM airspace.