What do MOCAs assure between radio fixes?

MOCAs, or Minimum Obstruction Clearance Altitudes, are crucial in ensuring obstacle clearance and signal coverage between radio fixes. By providing a minimum altitude that pilots must maintain, MOCAs guarantee that aircraft remain at a safe height above obstacles in the terrain, such as mountains or tall buildings, thereby reducing the risk of mid-air collisions with these structures.

Additionally, MOCAs are designed to ensure that aircraft are within the service volume of navigational aids, such as VORs (VHF Omnidirectional Range), which are often used for navigation. This helps to maintain reliable communication and navigation signals as pilots fly from one radio fix to another, particularly in mountainous or challenging terrain where signal reception could be compromised at lower altitudes.

The other options do not capture the primary intent and function of MOCAs effectively; they focus on aspects such as fuel efficiency, direct communication, or flight scheduling, which do not pertain to the safety and navigation responsibilities fulfilled by MOCAs.