Here's what it is, and how you use it...

Receiving (Or Requesting) a Cruise Clearance

The term "cruise" can be used by ATC to assign an IFR aircraft a block of airspace. It will sound something like this:

When ATC issues this clearance, the block of airspace between the minimum IFR altitude to the altitude in your clearance is yours to use. You can climb, descend, and level off at any intermediate altitude within the block of airspace, all the way to your destination under IFR. You're responsible for determining the minimum IFR altitude in your area. Traffic separation is still provided by ATC.

Note: once you report leaving an altitude within the block during descent, you may not return to that altitude without an additional ATC clearance.

Cruise Clearance = Cleared For The Approach

When given a cruise clearance, you're automatically given a clearance to execute an instrument approach at your destination airport. You don't have to request an approach and you won't hear the words "cleared for the approach."

Descent planning, all the way down from en-route altitude, is all up to you. Use your knowledge of minimum instrument altitudes to determine how low you can go en-route, on an approach transition, and during the approach itself. Depending on which type of instrument approach you fly, you may need to execute a procedure turn to re-align yourself with the final approach course.

Why Would This Clearance Be Issued?

While ATC can issue a cruise clearance, you can also request one. You'll find cruise clearances most commonly being issued by controllers in sparsely populated areas with little air traffic. Don't try requesting a cruise clearance through Chicago, because you're probably not going to get it.

A good example would be a late-night regional cargo delivery flight operating under IFR in the midwestern United States. These cargo contractors might be flying freight for UPS or FedEx, but operate using Metroliners or Cessna Caravans. They're flying at low altitude, often at night, to cities around the country without major airline service.

Another good use for this clearance is when you need to fly under IFR when layers of clouds along your route create an icing hazard. If you can't fly through icing conditions due to aircraft limitations, a cruise clearance could allow you to climb and descend around layers of clouds.

Have you ever been issued a cruise clearance? Tell us about it in the comments below.