Matthew Waugh

Have you ever busted an altitude, descended through an intermediate altitude on descent by a couple of hundred feet, or popped a couple of hundred feet over your assigned altitude on climb-out? No, me neither, and that’s my story and I’m sticking to it. However, if you can, hypothetically, see how that could happen, then you may be interested in incorporating Altitude Critical Areas (ACA) into your flying.

Altitude Critical Areas come from writings by Robert Sumwalt in Professional Pilot Magazine and from some further discussion in the book “Cockpit Resource Management” by Thomas P. Turner.

Altitude Critical Areas are sort of the sterile cockpit concept for piston powered general aviation. The idea of the sterile cockpit for airlines is that below a certain altitude, often 10,000 feet, no conversation that is unrelated to the phase of flight is allowed. No discussing last night’s TV or where to go for dinner at the next layover. But let’s face it, if we implemented a sterile cockpit below 10,000 feet in any of our airplanes we’d never talk to anybody from take-off to landing most of the time.

An ACA is the final 1,000 feet before your level-off altitude during a climb or a descent. When you’re flying within the ACA you work to minimize any distractions that may divert your attention from your primary job of manipulating the controls, power and trim to level-off the airplane.

Distractions might include such things as ATC calling with a new route clearance “advise when ready to copy”, in the ACA, tell them to “stand-by”. It may be your passenger wanting to know “what’s the name of that lake we just passed over”, in the ACA, ask them to just hold on a minute. It could be your instructor anxious to discuss with you the finer points of engine leaning during the climb, in the ACA, just tell your instructor you’ll discuss it once you’ve leveled off. If you minimize the distractions while you’re flying in the ACA you’ll be far less likely to be doing something else as your airplane blasts through your assigned altitude.

Of course there are always going to be legitimate distractions you’ll need to attend to while you’re in the ACA. If ATC calls and wants you to “continue descent and maintain 2,000 feet”, well it doesn’t exactly make sense to ask them to hold on, level off at 6,000 and then ask them “so what was that last transmission?” If your passenger wants to know if it’s normal for smoke to come out of the cockpit ventilation system (and assuming it isn’t) you might want to let a little of your attention review what’s going on. If your instructor needs to urgently explain to you the concept of detonation and what those funny noises the engine is making, well you might want to take the time to cover that issue before one of the cylinder’s launches itself through the cowling. The goal is to minimize distractions, not eliminate them entirely.

There’s also one more special ACA you may want to incorporate, and that’s when the aircraft is within 1,000 feet AGL, and especially when you’re within 1,000 feet AGL and 5 miles of an airport. On your way in, or on your way out.

If you’re out practicing maneuvers, turns around a point, S-turns across a road, then before you descend to start your practice brief yourself. “We’ll be descending below 1,500 feet to perform this maneuver. That’s within 1,000 feet of the ground. We’ll keep sharp lookout for any unexpected towers and maintain a regular check of our altitude to make sure we’re not too low.” Say it out loud, if your instructor’s with you then it’ll remind you both of what you’re about to do, and if you’re on your own nobody will know you’re talking to yourself.

Arriving at an airport, before descending below 1,000 feet AGL make sure you’ve got all your cockpit chores complete. Charts you won’t need put away (or at least stuffed out of the way), seat belts checked and tight, flight plan closed (if you’re closing it in the air), landing light on, passengers briefed. During the arrival it’s heads up, looking outside. Studies of the midair collision problem indicate that nearly all midair collisions occur during daylight hours and in VFR conditions. Perhaps not so surprising is that the majority happen within five miles of an airport, in the areas of greatest traffic concentration, and usually on warm weekend afternoons when more pilots are doing more flying. What with radio calls, finding traffic, flaps, gear if you’re so inclined there’s plenty to do in the Airport ACA without fumbling around the cockpit tidying up.

So brief your use of the ACA before departure. “We’re going to be departing straight out on runway 6. The ACA height is 1,800 feet and up to that height we limit our conversation and activity to only those items needed during the climb.” If your passenger (or instructor) says, “great, what’s an ACA”, you may want to add some more detail.

Tell your passengers “it’s very important that we level-off at the altitudes ATC expects us to, so as we approach these altitudes I’ll call out “one thousand feet to go” and then please limit our conversation to anything immediate, such as if you should spot another plane.” Make sure you call out “one thousand feet to go”, if there’s somebody with you, they can check your math, if you’re alone it’s less lonely if somebody is talking, even if it’s you.

Upon arrival brief again, “We’re going to be arriving from the south and the ACA height is 1,300 feet. Once we’re below that height we’ll limit our conversation and activity to only those items needed for our arrival until we’re on the ground and clear of the runway”. Make sure you do limit your activity, if you get into the ACA and remember you should have called for a rental car, either climb back up out of the ACA or forget about it until you get on the ground.

You can use the ACA if you’re IFR or VFR, the consequences of an altitude bust IFR are slightly worse, but it’s always more enjoyable to arrive at the altitude you said you would and it’s definitely more enjoyable to make an arrival at an airport without collecting any additional airplanes on the way. If you use the ACA concept, brief what’s going on out loud, and follow the principles involved then I think you’ll have a happier, safer flight.