Wednesday, May 6, 2009


I think most instrument pilots know about CRAFT: it's the acronym for the order of the elements of an IFR clearance:

  • Clearance limit;
  • Route;
  • Altitude;
  • Frequency;
  • Transponder code.

    My IFR Ground School has reached the point where we are starting to try to understand Air Traffic Control (ATC). Where do you begin understanding such a complicated system? I have always taught that the answer to every IFR puzzle begins "Well, in the event of lost communications, ..." That's where we began.

    The lost comm rules (14CFR91.185) have puzzled pilots for years. Most of it is logical: if you fly into a big hole in the clouds, continue under VFR, and land as soon as practicable. Call Flight Service and tell them what happened, and continue on your way VFR. You don't even have to shut down.

    You fly the highest (i.e. safest) of the minimum IFR altitude, the altitude you were cleared to, and the altitude you were told to expect. Still pretty simple.

    You fly the route you were cleared, or told to expect, or what you filed. OK.

    But when do you start down? The rule is complex, and I have heard a lot of silly interpretations over the year, some of them from my mouth, I am ashamed to say. "Just land and get out of their way" is the most common one. But what do the rules really say? And are they that hard to interpret?

    Yes, they are that hard to interpret. The difficult time is when ATC clears you to someplace other than the airport. They may or may not give you an Expect Further Clearance (EFC) time. You do different things in each case. Let's look at an example and see what the rules say.

    Let's fly from Provo, Utah (KPVU) to Idaho Falls, Idaho (KIDA). Checking shows that V21 goes from Fairfield VOR (FFU) to Idaho Falls VOR (IDA). The Departure Procedure takes you to FFU, so you file "FFU V21 IDA."

    This route crosses the Salt Lake City Class B airspace, and a typical clearance is "Cleared to the Fairfield VOR via the Provo Three Departure, Squawk 4321." The altitude and Departure Control frequency are on the chart, so ATC leaves them out. The chart also says "...Expect clearance for filed route and altitude within 10 minutes after departure."

    So far, the clearance limit is FFU, which is not an Initial Approach Fix for KIDA. The regulation is clear: your clearance limit is not an initial approach fix, and you do have an Expect Further Clearance (EFC) time. Start a timer when you're cleared for takeoff. If there is a communications problem, fly the departure procedure, hold at Fairfield until 10 minutes have passed, and proceed on your way. What has happened here is that ATC has given themselves 10 minutes to clear a path for you if something goes wrong. It's about 19 miles from KPVU to FFU via the Departure Procedure, so your 10 minutes will probably be up when you get to FFU.

    If nothing goes wrong, as you get close to Fairfield you hear something like "Cleared to the Idaho Falls airport via fly heading 330 to intercept V21, then as filed, climb and maintain 11,000." The heading is a radar vector, so if you lose communications you know to fly toward V21.

    Is this in the a gray area? The clearance limit, that is, the airport, is not an Initial Approach Fix. But since the airport is not an IAF, and you don't have an EFC time, if you lose radio contact you go to an IAF, then start the approach at your ETA. There should be an IAF in your flight plan route.

    Approaching Idaho Falls, you hear "Proceed direct Idaho Falls VOR, expect ILS approach." The clearance limit is an IAF and but you have no EFC time, so if you lose communications before Idaho Falls then you hold there until your ETA. You are given a route to "expect," too, so that's the route to fly.

    If it's busy, they'll spin you. "Hold South of the Idaho Falls VOR as published, maintain 11,000, expect further clearance at ... ." Now your clearance limit is an IAP, and you have an EFC. If the radios go bad, you leave IDA at the EFC and fly the approach.

    That's not so bad, is it? Of course it is. Not. But one way to learn is to imagine a few scenarios of your own. What if the destination is your favorite Class B airport? What happens if the destination is shut down by weather (I once had to divert from Laramie because the VOR had been hit by lightning, and all they had was a VOR approach. I didn't want to go there, anyway.) Playing "What if..." is a great way to sort this stuff out.

    Just remember to begin your answer with "Well, in the event of lost communications... ."

    Next: Unusual lost comm scenarios.

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