For a Northeast-bound route, the cruising altitude should be which parity?

For a Northeast-bound route, the cruising altitude should be which parity?

• A. Even
• B. Odd
• C. Both
• D. None

Answer: (B)

When selecting enroute cruising altitudes, there’s a parity rule: eastbound and northbound routes use odd thousands of feet, while westbound and southbound routes use even thousands. A northeast-bound route sits in the east/north quadrant, so it follows the same odd-parity rule. That means you should choose an odd-thousand altitude (for example, 3,000; 5,000; 7,000, etc.). This system keeps adjacent routes at different altitude levels to maintain vertical separation and reduce conflicts.