What is the minimum altitude for operating an airplane over a built-up area, excluding takeoff?

The minimum altitude for operating an airplane over a built-up area, excluding takeoff, is set at 1,000 feet above the highest obstacle. This regulation is designed to enhance safety for both the occupants of the aircraft and the people on the ground. By maintaining this altitude, pilots reduce the risk of collisions with buildings, towers, or other structures, thereby ensuring a buffer zone that allows for responsive actions in case of emergencies.

Flying at this altitude also takes into account potential emergencies where a safe landing area is unavailable. Establishing a clearance of 1,000 feet ensures that there is ample space to maneuver the aircraft and adapt to unforeseen circumstances. This altitude guideline applies uniformly across built-up areas, mitigating risks while promoting responsible flight operations.

The other options suggest altitudes that are either lower than what is mandated by regulations or excessively high, which would not only be impractical for flight operations but also impede normal air traffic procedures. Therefore, adhering to the specified 1,000 feet ensures compliance with safety protocols while effectively managing operational risks.