On an approach plate, what does 'Highest Obstacle' refer to?

• A. The highest altitude allowed on the approach
• B. The highest obstacle within the approach area
• C. The highest course deviation allowed
• D. The highest permissible wind speed

Answer: (B)

The highest obstacle is the tallest obstruction within the approach area that could affect obstacle clearance on the approach. This value is shown to alert you to the maximum vertical challenge you must account for as you descend and as you plan for the missed approach if needed. It isn’t about the maximum altitude you’re allowed to fly, nor about how far you can deviate from the course, nor about wind speeds. Knowing the highest obstacle helps determine safe minimum altitudes and ensures you stay clear of terrain and structures along the instrument approach path.