Defensive IFR

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This article originally appeared in Aviation Safety, Feb. 2005.


Controllers are just like pilots: All are human and make mistakes. Most are good, know the rules, do everything they can to make your flight efficient and safe, and make sensible judgments. Only a tiny fraction are highly paid chair-warmers too lazy or bored to have opened the book (FAA Order 7110.65) for a refresher on the finer points of their craft. For pilots, what this means is that amidst what is overwhelmingly professional and courteous ATC service, you'll hear the occasional boneheaded clearance, instruction or suggestion with which no sensible pilot should comply. That's why we have readback procedures and is one of the reasons the word "unable" exists and why you should use it without fear of retribution when necessary or appropriate.

Trust, But Verify

The image depicts the minimum vectoring altitudes (circled in red) for the San Diego TRACON overlaid on the area en route IFR low-altitude chart. The accident occurred just southeast of the JLI VORTAC.

No better recent example can be found to illustrate the point that it's your butt on the line than on May 10, 2004, when Piper Seminole N304PA collided with terrain near the Julian, Calif., VORTAC (JLI) and was destroyed. Both pilots aboard the twin were killed. The planned flight was from Phoenix, Ariz., to Carlsbad, Calif. Nighttime visual conditions prevailed, although the flight was operating on an IFR flight plan. The cleared routing for N304PA was: Gila Bend, V66, Imperial, V458, Julian, then direct to Palomar. N304PA was number four in a train of five airplanes flying the same route for training. The airplanes were separated by about five to 10 minutes. The airplane directly ahead of N304PA was N434PA, another Seminole. According to the NTSB, ATC communications and radar data show that N304PA reported level at 8000 feet MSL to the San Diego North Radar (SDNR) controller at 2043:48. The SDNR controller instructed the pilot to fly a 260-degree heading after crossing JLI and then intercept the Palomar localizer. The pilot read back the clearance. At 2045:47, the SDNR controller told the pilot of N434PA to descend to 6000 feet. The pilot of N434PA acknowledged the clearance. At 2047:55, the SDNR controller transmitted, "Seminole four papa alpha descend and maintain five thousand two hundred." The pilot of N304PA responded, "Down to five thousand two hundred for three zero four papa alpha." According to the controller, this clearance was intended for N434PA. The controller did not recognize that the clearance had been acknowledged by N304PA rather than N434PA. At 2052, the San Diego AFSS contacted the SDNR sector reporting that they were receiving a strong ELT signal from near the JLI Vortac. Why the controller missed the readback from the wrong airplane is anyone's guess. And, certainly, better situational awareness on the part of the two pilots aboard the Seminole probably would have prevented this accident. But the point is that once you close the cabin door and the wheels leave the ground, you're mostly on your own to ensure the wheels safely touch down again.

Little Voices

Control Tower

Anytime you're not flying straight and level well above terrain, the little voice in your head should be asking yourself some basic questions: Where am I going? Where am I going after that? What altitude should I be at now? The next leg? What am I going to do if this doesn't work out? For example, let's say you're droning along en route to your destination when you become aware the weather there has gone down the tubes. At the least, you need to stop and get some more fuel with which to tackle the weather, so you tell ATC you'd like to divert to nearby Cowpie County International. You request a "vector and lower" and the TRACON controller you're handed off to makes a transposition error on your altitude. He meant to set you up to join the feeder route for the VOR approach at 5300 feet, but instead tells you to "descend and maintain 3500 until established" and clears you for the approach. You read back the clearance and grab the approach plate to get your bearings. Will you notice that the altitude you've been given does not match the feeder route? Will you see that the altitude to which you're descending is below the minimum safe altitude (MSA) circle on the plate? A little voice in your head should be asking if you're where you should be for the approach. That's one of the reasons why each published feeder route has a minimum altitude and the plate itself has the MSA information. Twice I have received clearances that made no sense. Both times I was glad my instrument instructor drummed into me the need to physically trace my entire route on a map before takeoff. One of the bad clearances was actually to a fix over the Atlantic Ocean. I still remember sitting in my plane that night, wondering what I had written down wrong to think I was cleared out over the water. After conferring with the tower, I shut down the engine, trekked up to the tower cab and sat down with the controller to trace out my clearance on a chart. He was positively stunned, especially since he'd given out that same clearance more than 1000 times without any problems. Apparently, the TRACON or someone down the line always amended those clearances well before they became a problem. And, to date, no one had to implement lost comm procedures while flying the bad clearance.

Know Your Rights

Tower Controller

But how many pilots would do the same? How many are willing to analyze an ATC clearance or directive on-the-fly then stand up on two hind legs and refuse an unsafe or out-of-line instruction? Part of the problem is that we tend to accept the authority of anything uttered by a controller as the last word. After all, he wouldn't be a controller if he didn't know what he was doing, right? The antidote, of course, is knowledge and experience. The knowledge comes from knowing the FARs and AIM procedures; we can assure you most controllers and pilots don't. Experience comes from flying and using the system and applying that knowledge. And that's why an annual flight review or IPC without some discussion of real-world procedures and regs is a sham, lending truth to the notion that what you don't know can hurt you.

Am I Paranoid Enough?

Some may say it is not practical to be constantly paranoid and suspicious of everything ATC asks or commands. And it may seem like overkill to focus on these types of errors when so many pilots are still making much larger and dumber mistakes, like flying well below an MDA to take a peek or launching into icing conditions with nothing more than a lukewarm pitot tube. Of course, flying defensively is about more than nitpicking clearances. At the end of the day, it's your butt that matters, not the controller's.

Who's The Boss?

By Jeb Burnside The irony of all this is that it's your chair moving at 150 knots, not the controller's. When your airplane slams into that unseen ridge, he'll probably feel really bad. You probably won't feel a thing. Maybe it's the anarchist gene in me, but I'm not spring-loaded to believe everything the government -- or a controller -- says. Yet as pilots, most of us react in the opposite way when confronted with ATC clearances and instructions that disrupt our plans and sound fishy or ill-advised. We go along. We comply. We're happy to help. Why? For the simple -- and understandable -- reason that we assume controllers know their business and, as only sometime-users of the system, we similarly assume our knowledge is flawed. So we go along with ATC's wishes, sometimes to a fault. The ultimate authority, of course, is FAR 91.3, the PIC imprimatur that gives you ultimate authority over the safety of the flight. Controllers don't exactly have their own version of this and even if they did, your authority trumps ATC's. On the other hand, there's FAR 91.123, which requires compliance with ATC instructions and directives and requires the pilot to seek clarification if he doesn't understand ATC's wishes. The ultimate escape valve, of course, is emergency authority, which overrules anything ATC has to say. If it was this simple, though, rejecting clearances would be easy. Instead, there are massive gray areas here. For example, rejecting a directive to land your Skyhawk short behind a landing 737 and opting instead to land long for wake avoidance reasons might screw up the local controller's flow, but that's not your problem. No right-thinking ATC facility would make an issue of it. The same applies when given a clearance for an immediate takeoff? Should you rush your takeoff and departure routine just because it might save two minutes? Putting the shoe on the other foot, suppose you were following another aircraft to land, the tower controller calls for a go-around and you reply, "Unable." You certainly have the authority to do so but you'd better have a good explanation at hand, such as a rough engine, smoke in the cockpit or some other emergency-like condition. The FAA will take a dim view of promiscuous use of "unable" and we suspect an administrative law judge will know the difference between legitimate PIC balking and pure bs. Some of what ATC does falls into the realm of "suggestions." Comply at your own whim and risk. Refusing the request won't cost you any enforcement points while granting it could cost a lot more.
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