When operating under IFR in non-mountainous areas, what is the required altitude above the highest obstacle?

When operating under IFR in non-mountainous areas, the regulation states that pilots must maintain a minimum altitude of 1000 feet above the highest obstacle within a horizontal distance of 4 nautical miles from the course to be flown. This requirement is aimed at ensuring safe clearance over obstacles such as buildings, communication towers, or other structures that may pose a hazard during flight.

This minimum altitude helps to provide a buffer against potential impacts with such obstacles while allowing for safe navigation through airspace. It reflects considerations for both safety and operational efficiency in non-mountainous areas where obstacles may vary in height and spacing.