Technique

Push

November 1, 2006

Your first move when the engine fails

The message had been delivered via cell phone just a few minutes before: There's been a terrible accident; we think it was Leo; there were no survivors. The details were, of course, sketchy, but it was day visual meteorological conditions at Falcon Field in Atlanta that morning. Calm winds, a long runway — and an engine failure after takeoff. The airplane stalled, lost the hundred feet or so it had gained since liftoff, and became a crumpled pile of parts on the ground.

Leo was the second of Dan Gryder's friends to lose his life at that airport: the same runway, the same accident, with the same result. Gryder, a flight instructor and owner of The Aviator Network, a flight-training operation in Griffin, Georgia, immediately sought some explanation as to why a competent, experienced pilot would be unable to cope successfully with such an emergency — especially when there were plenty of options ahead of him for a safe off-airport landing.

The preliminary accident report reads similarly to that of so many: After hearing a "change in engine noise," witnesses described the airplane leveling off, beginning a descent, then making a shallow turn, followed by a steep bank, loss of altitude, and "spiral" out of view.

Your classic stall-spin accident, right? The one you inoculate yourself against by practicing departure stalls, and taking heed when your instructor admonishes you not to turn back to the runway in this situation but to land straight ahead, right?

Well, it's not quite that simple. What if turning back had nothing to do with it? Have you ever practiced a power-on stall with an engine failure? Me either. Has anyone ever told you how much you have to push first to make that off-airport landing happen safely?

The guidance

Advisory Circular 61-21A was for decades the FAA-produced bible for flight training — you know it as the Flight Training Handbook. This tome was superseded in 1999 by the Airplane Flying Handbook (now in a second edition, published in 2004 as FAA-H-8083-3A). Although a wide variety of aviation authors have expanded on their framework for primary pilot texts, these books have been the references. Only in the latest revision (made in May 2004) is any mention made in the Airplane Flying Handbook of what to do if the engine fails after takeoff. In Chapter 5, "Takeoff and Departure Climbs," there are just two paragraphs on the scenario, with an emphasis on the urgency of the situation.

The FAA adds to its reference library with advisory circulars, and one in particular, AC 61-67, "Stall and Spin Awareness Training," should address more fully the "engine failure after takeoff" scenario. And it does — by admonishing pilots not to turn back to the runway.

Although this is a problem, it's not the first problem encountered by a pilot when the engine quits after takeoff. The first order of business is maintaining control of the airplane — and it may be all the pilot has time for. And capturing best-glide airspeed when you're already climbing out at a comparable speed — and a high deck angle — is very different from capturing it from cruise flight.

The most critical thing is to prevent a stall from occurring on the heels of the engine failure — and to maintain the energy to control your descent and landing flare. If you're like most pilots, this wasn't part of your primary training.

What's happening here?

When you first learned to fly, your instructor followed a syllabus, whether it was bound and full color or whether it existed only on Post-it notes. That syllabus was designed to help you acquire the skills and knowledge needed to become a safe pilot, and to accomplish the requirements for the private pilot certificate laid out in the practical test standards (PTS).

You made your way through stalls, including power-off (or approach-to-landing) stalls and power-on (or departure) stalls. Instructor's techniques vary, but most stall recovery procedures involve relaxing the back-pressure, which lets the nose come down to about the horizon, to regain airspeed. Your right hand is probably on the throttle (in most light aircraft) to ensure you have all the power in. The goal is to lose as little altitude as possible without inducing a secondary stall.

Setting up for a power-off stall is much the same. To recover, you reduce the angle of attack, bring in full power (and shut off the carb heat if necessary), clean up the airplane, and pitch to the horizon. Again, you're trying to minimize your altitude loss, because the stall itself is the primary problem.

A bigger problem

Now think about a different situation. You take off, climbing out at V X to maximize your altitude (and perhaps get a little higher over the houses that surround your airport). At about 200 feet agl, you're just crossing the airport boundary fence. And your engine quits.

You now enter new territory: You have the deck angle of the power-on stall, yet the power's off — and you're not getting it back. You have a healthy amount of rudder pressure in to counteract torque — so you're uncoordinated unless you neutralize the rudder. You haven't stalled yet, but you will if you keep the nose up. If you just pitch down to the horizon — which worked for you on all those practice recoveries before, and where you'll certainly want that nose to stay because the ground is coming up at you — you won't recover all the energy that you lost when the prop stopped moving. And you'll still stall. And if you continue holding rudder pressure, you may fall off into an incipient spin, even if you keep the airplane pointed straight ahead.

Better practices

Rich Stowell, the FAA's 2006 national Certificated Flight Instructor of the Year (see " Pilots: Rich Stowell," October Pilot), includes all varieties of stalls in his Emergency Maneuver Training syllabus. And under the topic "critical flight conditions," he adds another kind of stall practice to the mix: stalls from a V Y climb and power loss.

After talking with Gryder and Stowell, I went out to test these maneuvers.

I measured the difference between the time it took for the airplane to stall from level cruise flight (slowed to V Y) when the power was reduced to idle and the pitch attitude held in place, and the time it took to stall from a V Y climb when the power was reduced to idle and the pitch attitude similarly fixed.

In a Cessna 172S, the time it took to reach imminent stall in the first scenario was 12 seconds. The time it took to stall in the second scenario? Five seconds. It's even less if you're climbing at V X. If you wait to pitch down, if you allow precious seconds to pass as the gravity of the situation sinks in, you'll be edging into stall territory.

V Y in most light singles can be pretty close to best-glide airspeed; V X is often several knots below best glide, as it is in the 172S, and only marginally above the corresponding wings-level stall speed. At most, V Y is about 20 knots more than best glide — but the moment the engine stops, that airspeed starts going away. And in your shock, you give up airspeed to maintain your "climb." With that deck angle (in some high-performance singles it can be up to 10 degrees pitch up on the attitude indicator), and the airplane trimmed for the climb, the airspeed ticks away quickly.

The longer you keep the nose in the climb attitude, the more you will need to pitch down deeply below the horizon to regain airspeed and arrest the sink rate — up to 10 degrees below the horizon, depending on the airplane, its configuration, the sink rate, and the density altitude. Pitching down this much can require a significant amount of stick or yoke travel — for example, in Gryder's tailwheel Cessna 150, it takes about 3 inches of travel, overcoming aerodynamic and trim forces in the process. It takes a push.

Your flight path has already headed down — you can start to feel it in the seat of your pants — and your wing is still at a climb angle, making your angle of attack significantly higher than it was when the engine was running.

And no matter what is rising up to greet you — trees, buildings, a herd of cattle — if you don't make that push, the airspeed will quickly bleed off into stall territory. Regardless of what you see ahead, you have to reduce the angle of attack.

In my flight testing, the pilot in the right seat also noted that by the time I'd recaptured best-glide airspeed, we had lost at least 200 feet. Getting that energy back so you can flare may be the only thing you have time to do.

Catherine Cavagnaro, who gives spin and aerobatic training at Ace Aerobatic School in Sewanee, Tennessee (see " Spin Masters," August Pilot), also points out that if you have the airplane configured with takeoff flaps, the pitch down can be even more dramatic — and those flaps can exacerbate a spin condition if you stall, depending on the airplane.

Adding the load

Keep in mind, too, a couple of things. You need to bring the nose down significantly below the horizon to regain your airspeed straight ahead. As Stowell points out, "The airspeed indicator may lag by several seconds, so it is crucial to memorize the sight picture of gliding flight in your airplane. Airspeed by itself is imprecise as an indicator of stall, so lowering the nose instantly increases your stall margin."

Keeping the wings level also increases your margin from the stall, especially when you consider that turning flight always means higher stall speeds: The very act of the turn, even the shallowest bank, will increase the load factor and the stall speed. If you can feel the load factor increasing — and you feel this by sensing how your relative weight in the seat increases — you're entering dangerous territory. You have to trade back some of the energy by dropping the nose farther, reducing the angle of attack, and getting your margin back. You've gotta push first, or there's no doubt you'll become part of the accident data.

Looking at the data

As it turns out, there's no single category that "engine failure after takeoff" accidents fall into. Instead, they lie buried in at least three separate categories within the GA accident data. Because these accidents happen with the takeoff, some are classified as — yep — "takeoff" accidents. Because some are the result of mechanical failures (as opposed to fuel starvation or exhaustion, for example), some are classified under this category. Accidents may also go into the "maneuvering flight" bucket, if the pilot is believed to have attempted a turn back to the airport — once you start to turn, you're maneuvering, the way the NTSB sees it.

According to a search of the AOPA Air Safety Foundation's Accident Database covering the past five years, accidents fitting the profile occurred more than five times a year in airplanes weighing less than 12,500 pounds. In addition, at least three accidents occurred involving instructional flights in which the instructor was demonstrating or observing a student managing a power loss after takeoff at low altitude, with an attempted return to the airport. All of these instructional accidents were fatal.

However, there's another side to the story, by definition one that the accident data don't include. Because the typical accident profile involves a power failure and happens in close proximity to an airport (and potentially open areas around it), there is an opportunity for a pilot to successfully manage the power loss and land the airplane without damage. These "success stories" would not necessarily fall within the criteria for reporting as an accident or incident, and thus be off the radar.

Even though the maneuver isn't in any PTS, some astute primary instructors have trained their students to cope with this specific combination of power loss and impending stall — without teaching them to turn back to the runway (that's another set of accident data — those instructional flights gone wrong) or making the demonstration at low altitude.

The combination of how the accident data are sorted and the invisible nature of certain success stories leads us to wonder how prevalent the situation (an engine loss after takeoff) and the solution (appropriate management of angle of attack [airspeed] and aircraft control) really are.

As we went to press, I learned of a similar accident involving a student pilot: just after takeoff, an engine failure, on a solo flight. The pilot survived this time, but the airplane was destroyed.


Access the AOPA Air Safety Foundation's Accident Database online. Links to additional information about departure emergencies may be found on AOPA Online.


E-mail the author at julie.boatman@aopa.org.


Departure Emergency Stalls

At a safe altitude (we suggest at least 3,000 feet agl) and perhaps with an instructor, practice the following maneuvers. Follow guidelines in your airplane's pilot's operating handbook to ensure no limits are exceeded. Also, avoid abrupt power reductions in high-performance aircraft. Keep in mind that when you transition from a climb, you may still be holding in rudder correction to counteract the torque, creating an uncoordinated situation that could lead to an incipient spin if the stall recovery isn't prompt. In each maneuver, pay close attention to the pitch-down force required to maintain — or in the case of a real power loss, regain — airspeed.

Power-off stall, clean configuration. This will establish a baseline from which to determine how the pitch attitude, deck angle, timing, and stall profile change in the next two maneuvers.

Climb profile to best-glide attitude. Establish a climb at V X, pull the power, and pitch to recover best-glide airspeed promptly. Note your altitude loss; you can work to minimize this while acquiring best glide in a timely fashion.

Climb profile to a power-off stall, clean configuration. Start with one from a climb at V Y, then do another one from a climb at V X. Measure the amount of time between the power reduction and the incipient stall. Remember to neutralize the rudder.

Climb profile to a power-off stall, takeoff configuration. Use the normal takeoff flap setting, and try one with the gear up, and one with the gear down. — JKB