You're flying under instrument flight rules in the clouds. Air traffic control has just assigned you a lower altitude as you approach your destination airport. Suddenly, zero visibility magically turns to fifteen miles visibility as you punch through the bottom of the cloud layer, and you see the runway. A clean breakout. The weather is beyond adequate for a visual approach, so you key up and say, "Approach, Five Mike Bravo, airport in sight, cancelling IFR." The controller responds with routine in his voice, "Five Mike Bravo, roger. IFR cancellation received. Radar service terminated, squawk VFR, frequency change approved. Good day." You land, secure the airplane, and are approached by a stranger on the ramp. He asks, "What'd you break out at?" A few more casual questions are asked about your approach, and just when you think you've made a new pilot buddy he says, "I'm an FAA Aviation Safety Inspector. Expect to receive a Letter of Investigation from Flight Standards shortly." Doh!
Okay, maybe I'm being a bit extreme. But I've heard of things similar to this hypothetical situation actually happening to pilots. If you're wondering what in the world was illegal about that flight, come along with me and let's explore a few things. I like to keep things simple. So, let's get simple here. When you're operating an aircraft in the National Airspace System, you're operating under one of two sets of flight rules: Visual Flight Rules (VFR) or Instrument Flight Rules (IFR). I'm omitting Special VFR and Defense VFR because they are so seldom used. When you're operating under VFR you must comply with one set of rules, and when you're operating IFR you must comply with a different set of rules. With me? Simple, right? There's no halfway gray world between VFR and IFR where some rules apply from here and some rules apply from there. Quite simply, you're either VFR or IFR, and it's extremely simple for a pilot to know which set of rules he's operating under at any given time.
You're operating under VFR anytime you do not have an IFR clearance, or anytime you terminate or "cancel" your IFR clearance. You're operating under IFR anytime you have been released into the National Airspace System with an IFR clearance until you land and/or cancel that IFR clearance. Simple. Now, let's return to the hypothetical flight at the beginning and apply this logic to that situation to find out where the regulations were violated. When you broke out of the clouds and saw the airport you immediately canceled IFR. ATC immediately acknowledged receipt of your IFR cancellation, so that means at that moment you instantly reverted to operating under VFR (remember, you can't operate under both at once). Assuming you were flying in Class E airspace that means the VFR cloud clearance requirement of five hundred feet below clouds was likely violated, unless you were in a vertical dive. You were, perhaps, only one hundred feet below the clouds when you abruptly transitioned to VFR operations. That's a violation, plain and simple. I heard a pilot on frequency just the other day who broke out of the clouds mid-transmission and canceled IFR immediately. I guess he didn't understand the nature of cancelling IFR. When you cancel IFR, you cancel all of it. Not part of it, all of it. IFR goes sailing into the slipstream, and if you can't maintain legal VFR weather minimums at that moment, you're in violation of the regulations.
The proper way to handle our hypothetical flight would've been to continue the descent, if possible, until five hundred feet below the cloud bases and then cancel IFR. Just ask yourself, "Am I in VFR conditions right now?" If not, cancelling IFR is not an option. You'll need to request an instrument approach procedure to get you to the airport legally (and safely if the conditions are marginal). Even then, though, the same rules apply. Breaking out on the localizer doesn't grant you permission to cancel IFR. Not until you're in compliance with legal VFR weather minimums. These rules are in place for your protection. They prevent IFR guys exiting a cloud from colliding with VFR guys lurking just outside the boundary of a cloud. The rules exist to allow IFR pilots leaving instrument conditions time to re-establish visual contact with the outside world with enough time to avoid any potential conflicts with VFR traffic not being controlled by ATC. That's why in Class B airspace where all aircraft (VFR and IFR) are being positively controlled by ATC the VFR cloud clearance requirement shrinks to simply "clear of clouds." The regulation then becomes a matter not of collision avoidance but of preventing loss of control accidents involving non-instrument rated pilots. I concede the point that if you just canceled IFR that there shouldn't be anyone within a matter of miles of you for at least a minute or two, but that's not what's important. What is important is that you are no longer guaranteed separation from other traffic, and that means an increase in risk. Not to mention it's illegal and could get you into enforcement trouble. Besides, waiting another few hundred feet during descent to cancel IFR is almost never an inconvenience.
While pre-maturely cancelling IFR is a minor infraction, it's still enough to cause legal and/or safety problems. You never know who might be watching or listening. I think the reason pilots pre-maturely cancel IFR is because they fundamentally misunderstand exactly what it is they're doing when they key up and cancel. Remember, keep it simple. You're either VFR or IFR, never both. Make sure you can comply with the set of rules you're about to transition into before cancelling IFR.
