Interpretation 17

This is in response to a request for interpretation submitted by the Central Service Area, on behalf of Fort Worth Air Route Traffic Control Center, regarding FAAO JO 7110.65, Paragraph 7-2-1c, Visual Separation.

1. Can an aircraft at FL180 be cleared to descend through an aircraft at 17,000 feet using visual separation?

2. Can an aircraft be cleared to climb through an aircraft at 17,000 to FL 180 or above?

3. What happens when FL 180 is unusable due to the altimeter?

1. Yes, an aircraft at FL 180 is allowed to transition out of Class A airspace using visual separation if the visual maneuver will be a descent through the altitude of another aircraft at or below 17,000 feet MSL. The reasoning is that separation exists before the aircraft descends and visual is not applied until the descent starts. At that instant, the aircraft will also be out of Class A airspace.

2. Yes, an aircraft is allowed to climb into Class A airspace after visually separating from an aircraft no higher than 17,000 feet MSL. The reasoning is the instant before the aircraft breaks the plane into Class A airspace visual is no longer being applied and “separation after” will exist.

3. When FL 180 is not an assignable altitude and FL 190 or above is useable, any visual separation maneuver out of FL 190 or above would begin in Class A airspace. This is not an allowable application, therefore nullifying transition out of Class A airspace. The reasoning is that FL 180 is still a discernible altitude just not an assignable altitude.