For IFR separation, what must be maintained?

For IFR separation, what must be maintained?

• A. Assigned flight level
• B. Minimum IFR altitude
• C. Cruise altitude
• D. Last reported position

Answer: (A)

The key idea is that IFR separation is ensured by keeping aircraft at specific, assigned flight levels. Air traffic control assigns each airplane a particular flight level, and pilots maintain that level to preserve vertical separation from other aircraft. Only when ATC clears a change in altitude can the flight level be altered, ensuring the required spacing is maintained throughout the flight. Minimum IFR altitude, by contrast, is about obstacle clearance, not maintaining separation between IFR aircraft. Cruise altitude is a planned level for efficiency and fuel, not the mechanism that guarantees separation. Last reported position helps track where an aircraft is, but separation relies on staying at the assigned flight level (and other separation procedures), not just where the aircraft was last seen.

The key idea is that IFR separation is ensured by keeping aircraft at specific, assigned flight levels. Air traffic control assigns each airplane a particular flight level, and pilots maintain that level to preserve vertical separation from other aircraft. Only when ATC clears a change in altitude can the flight level be altered, ensuring the required spacing is maintained throughout the flight.

Minimum IFR altitude, by contrast, is about obstacle clearance, not maintaining separation between IFR aircraft. Cruise altitude is a planned level for efficiency and fuel, not the mechanism that guarantees separation. Last reported position helps track where an aircraft is, but separation relies on staying at the assigned flight level (and other separation procedures), not just where the aircraft was last seen.