What altitude must the transferring ARTCC initiate coordination for when aircraft are at and above FL240 proposing to land at airports within a certain distance?

The altitude at which the transferring ARTCC must initiate coordination when aircraft are at and above FL240 and proposing to land at certain airports is indeed 75 nautical miles. This requirement is in place to ensure an effective and timely exchange of information between the centers, which is crucial for maintaining safety and efficient air traffic management.

When an aircraft expresses its intent to land, initiating coordination at this distance allows sufficient time for both the transferring and receiving ARTCCs to manage the aircraft's descent and approach safely. By doing so, controllers can ensure that separation standards are maintained and that any necessary adjustments to flight paths or altitudes can be made with adequate lead time.

The specified distance of 75 nautical miles for coordination helps in managing airspace more effectively, particularly in terms of ensuring that the approach to busy airports is handled smoothly. This distance encompasses a reasonable buffer for communication and response time between the involved air traffic control facilities.