A total altitude change of more than how many feet is considered an error requiring reroute or vector?

• A. 3000 feet
• B. 5000 feet
• C. 6000 feet
• D. 4000 feet

Answer: (D)

Altitude adherence is monitored to maintain safe separation and orderly flow. When an aircraft’s actual altitude deviates from its assigned altitude, there’s a defined tolerance. If the total altitude change exceeds 4,000 feet, it’s treated as an error that requires intervention, such as rerouting the aircraft or issuing a vector to bring it back to the assigned altitude. This 4,000-foot threshold balances allowing normal climbs/descent changes caused by winds or flight planning with the need to catch larger deviations that could affect separation and path integrity. Smaller deviations can usually be corrected with minor adjustments, but beyond 4,000 feet, a formal remediation is triggered to restore the intended trajectory.