Which statement is true about Class A separation as described?

• A. The 1000 ft separation applies between FL180 and FL290
• B. The 2000 ft separation applies between FL290 and FL410
• C. There is no required separation in Class A
• D. Separation is only required above FL410

Answer: (A)

In Class A airspace, all operations are IFR and ATC provides vertical separation between aircraft. The standard vertical separation is 1,000 feet, and this applies across the Class A altitude band, including the portion from FL180 up to FL290. That’s why stating that a 1,000-foot separation applies there is correct. The idea that you’d use 2,000 feet in that range isn’t consistent with Class A separation practice, and separation is required throughout Class A, not only above FL410. So the key point is that ATC maintains 1,000 feet of vertical separation between IFR aircraft within Class A, including the lower portion up to FL290.