June 2006Departments

Accident Analysis

Departure stalls

Don't skimp on practicing this important task

What is your least favorite maneuver to practice during your flight training? Many pilots answer this question with three words: power-on stalls. Some come to this firm conclusion on their own; others inherit the notion from flight instructors and even designated pilot examiners equally invested in avoiding realistic demonstrations. It isn't uncommon for flight instructors administering flight reviews or rental checkouts to fly with pilots whose previous training was based only on anemic simulations of power-on stalls--they practice more realistically for the first time and their eyes are truly opened.

They were vulnerable. Much more so than those who performed by-the-book recoveries from power-on stalls and appreciated the aerodynamic warnings being sent by an airplane that is in a nose-high mush, trying with all its might to yaw off to the left at high power and low airspeed, with decaying control effectiveness and ever-increasing buffeting. Then comes the actual stall. If the pilot isn't quick with hands and feet when the nose pitches down, the airplane may veer into a surprising yaw and roll to the right as angle of attack decreases and rudder effectiveness returns. You have to experience it to avoid it or control it later if you get careless some day during a takeoff climb. Low-power simulations don't cut it.

If rehearsed improperly at high power, the power-on stall can be more dramatic and puzzling than edifying. Perhaps the maneuver was entered at too high an airspeed, leading to ridiculous nose-up attitudes before even an imminent stall occurs, let alone a full stall. This is especially so in higher-powered airplanes. A careful look at the recommended method in the FAA's Airplane Flying Handbook should remedy that problem. However you practice, note that you should be able to pass a practical test in which it is required that a minimum of 85 percent of "available power" be used. (An exception is made for some high-performance aircraft.)

Recently I asked a colleague to name any flight-training maneuvers she disliked. I had a feeling I knew what the answer would be, and I wasn't disappointed. "Still hate power-on stalls," she replied. "Power-off stalls are not such a big deal."

Well, I didn't like them either when I was a student pilot. That was true because my awkward performance of a power-on stall recovery early in training showed me a Cessna 152 at its most spiteful--a moment of learning for which I am now grateful. I provoked that day's incipient spin in the company of a flight instructor whose calm response to my innocently clumsy recovery attempt filled me with vast confidence in his skill and knowledge. It also showed me the effectiveness of the control inputs he applied. When I "grew up as a pilot," I promised myself, I wanted to be like Alan. Had we avoided a full practice of the maneuver, I am sure I would have gone on lacking this understanding; perhaps never even turned to aviation as fully as I eventually did. All that from one botched power-on stall recovery!

If it seems overstated to claim that all this pivoted around the vertical axis of a stalled single-engine trainer, consider what inadvertent stalls during takeoffs and climbs have dished out to pilots on numerous occasions. According to the AOPA Air Safety Foundation's 2004 Joseph T. Nall Report (on accident trends and factors for 2003) 234 of 1147 pilot-related accidents occurred during takeoff and climb. Of these, 39 involved fatalities. (The 2005 edition of the Nall Report had just been released at press time.)

Three selected accidents, two from 2004 and a third from a decade earlier, illustrate what we are learning to avoid when we perform this training maneuver. Two persons died and one was seriously injured on June 23, 2004, when a Piper PA-28-181 Archer took off from Fort Lauderdale Executive Airport, Florida, lost power, radioed a "mayday" message, and crashed into a building.

The National Transportation Safety Board described the accident as having a series of causes cascading toward its conclusion. "According to witnesses on the ground, as the airplane climbed out the engine began to make a 'sputtering noise' and then stopped. The airplane was observed in a left turn by the tower controller, and descended out of sight. The pilot made no other radio transmissions. The airplane [flew] into the roof of the commercial building about one-half mile from the departure end of the runway," the report said. The problems started with fuel exhaustion, as detailed in the report's examination of the day's prior flying. This was compounded, after the engine quit, by the pilot's failure to maintain flying speed, resulting in "an inadvertent stall, and the subsequent collision with a building." The 199-hour pilot --who apparently was giving some of his attention to broadcasting "mayday" on his radio during the low-altitude engine failure --and one of two passengers perished in the crash.

Power-on stalls are practiced, says an FAA publication, "to simulate an accidental stall occurring during takeoffs and climbs," but a complicating factor is that not all takeoffs and climbs fit the classic mold or arise from the typical configurations. For example, a go-around in which the transition to a climb goes awry can cause a departure stall in an arrival configuration.

Eighteen days before the crash in Florida, a student pilot flying a Cessna 150 in Benton, Arkansas, was seriously injured in a departure-stall accident. The student, soloing after 45 minutes of dual instruction that day, went around after drifting away from the final approach course. Fine, so far. But he failed to maintain airspeed after realizing that he had forgotten to retract his fully extended flaps. Then he retracted them all at once. Quoting the NTSB, "The airplane started to drift left of the runway centerline while on short final. The student pilot crabbed the airplane into the wind attempting to line up on the runway centerline. The student pilot stated he had plenty of available runway remaining, but did not feel comfortable with the approach and decided to go around. After applying full power and pushing the carburetor heat to the cold position, he noticed the airplane 'was not gaining altitude that fast' and was still drifting to the left. He realized he still had 40 degrees of flaps selected and retracted the flaps to 0 degrees. Subsequently, the airplane struck trees approximately 100 yards left of the runway, at the midfield point, and came to rest in a nose-low position entangled within trees." What does this accident have in common with the foregoing? The element of distraction at low altitude during a departure climb. The decision to go around cannot be criticized, but its execution demands correct technique.

As is true with other stalls, departure stall recoveries are practiced and tested either in straight climbs or in climbing turns. The NTSB could not find metallurgical evidence to support a pilot's claim that the Bellanca 8GCBC he was flying in Summerdale, Alabama, experienced an aileron push-rod failure with resulting jammed controls on takeoff. But it quarreled with his claim about how he maneuvered his aircraft.

According to the pilot, control was not lost until "the airplane entered a left turn at 40 miles per hour." The NTSB responded to that assertion: "According to the operator's handbook, the airplane will stall between 51 and 52 mph with normal takeoff flaps and takeoff power; stall airspeed information in a turn was not determined, but typically the stall airspeed in a turn would be higher than 52 mph." Regardless of what happened, how well the pilot understood departure stalls became an issue in determining the cause.

Three stalls, but the origin of each was different: a fuel-starved engine in Florida, too much flap for a climb in Arkansas, and failure to maintain airspeed after liftoff in Alabama. Many other possible causes lurk under the general heading of departure stalls as well: an excessively aft center of gravity, sliding seats, a mistrimmed aircraft, or a distracted pilot losing control after turning around to argue with a rebellious child are examples.

The full or partial loss of engine power after takeoff always screams stall avoidance. That's why your instructor sometimes turns to you right after takeoff and asks, "What is the first thing you would do if the engine were to quit right now?" What she wants to hear you say is, "Lower the nose and maintain airspeed." Yes, looking for a place to land is important. But maintaining control and avoiding a departure stall has to come first, whether you're a hundred feet in the air or a thousand.

So if practicing departure stall recoveries thousands of feet above the ground seems unrealistic, or produces airshow-style attitudes without delivering the desired aircraft behavior, reexamine your method against that method described in Chapter 4 of the AFH. Did you slow to liftoff speed after clearing the area and configuring for takeoff or climb? Do so, then set the appropriate power. Then raise the nose "to an attitude obviously impossible for the airplane to maintain and is held at that attitude until the full stall occurs. In most airplanes, after attaining the stalling attitude, the elevator control must be moved progressively further back as the airspeed decreases until, at the full stall, it will have reached its limit and cannot be moved back any further." Then execute the recovery, ending in level flight.

Why reduce airspeed before advancing the throttle as recommended above? To avoid "an excessively steep nose-up attitude for a long period before the airplane stalls," the AFH explains. This may be the answer to many shortcuts taken in the practice of power-on stalls.

Take the medicine. Do the work. Then feel safer and more confident on your next takeoff.

Dan Namowitz is an aviation writer and flight instructor. A pilot since 1985 and an instructor since 1990, he resides in Maine.