Where Do We Lose It? The *Real* Threat!

Ask yourself a question: where do most stalls occur? Take a moment. Write down your answer.

Almost everyone probably wrote down “in the base-to-final turn.” The ubiquitous stall scenario is overshooting the turn from base leg to final approach, and (perhaps subconsciously) adding too much rudder to try to slew the airplane’s nose into alignment with the runway centerline in a skidding turn.

The resulting overbanking tendency may incite the pilot to apply aileron opposite the turn. The upward deflected aileron on the wing outside the turn decreases that’s wing’s angle of attack compared to the wing inside the turn. If the pilot also pulls back on the elevator control in this turn—another instinctive response to an overshoot—the inside wing may reach its critical angle of attack. It suddenly stalls while the outside wing is near its maximum coefficient of lift. The airplane snap-rolls toward the inside of the turn with nowhere near enough altitude for the startled pilot to recover.

A base-to-final turn gone bad is a deadly Loss of Control – Inflight (LOC-I) scenario. However, LOC-I in the base-to-final turn is one of the least common stalls in the accident record.  

The truth about stalls was quantified by AOPA’s Air Safety Institute in a 2017 study titled  “Stall and Spin Accidents: Keep the Wings Flying.” This report “analyzes 2,015 stall accidents between 2000 and 2014, and concludes with recommendations for prevention, recognition, and recovery from stalls while offering ideas on a shift in focus for stall awareness, prevention, and recovery.”

AOPA notes: “Perhaps surprisingly, more stalls occur during the departure phases of flight (takeoff, climb, and go-around) than in the arrival phases (approach, pattern, and landing).”

Using the AOPA-ASI data, which in turn derives from NTSB conclusions, I created some images that describe the true nature of traffic pattern stalls.

The first image details real-world stall data on the arrival end of a visual traffic pattern. The commonly cited base-to-final turn, and stalls in the turn from downwind to base leg, together account for only 3.8% of all NTSB-reported stall events. Now these stalls, when they do occur, are quite deadly: 66% of the downwind-to-base stalls are fatal, and 80% of base-to-final turn stalls result in death. That stands to reason; if a stall occurs in one of these places there is little room to recover. Still, these most commonly considered turns are low-probability, high-severity events.

Stalls on the downwind leg or the wings-level portion of the base leg almost never occur, only 0.8% of the reported LOC-I events in the circuit. A little over half of these resulted in death, still a low-probability, high-severity event.

Stalls after completing the turn to final approach are almost twice as common as stalls in the turns. Still, they account for only 6.1% of traffic pattern stalls, 40% of them fatal. This becomes a low probability but moderate severity type of event.

Stalls in the landing flare are much more common than any of the others on the arrival end of the pattern: 21.2% of the pattern stalls total. Close to the ground, these stalls usually do not devolve into spin rotation, and vertical movement stops before the airplane accelerates to a deadly descent. We call these stalls a hard landing—only 8% of stalls in the flare kill people. These are high probability but relatively low severity events.

Put them all together and LOC-I in a visual arrival account for 31.9% of all traffic pattern stalls. Another commonality: these are generally power-off stalls, the type most pilots and their instructors are far more comfortable practicing and tend to practice more often.

This second image plots AOPA-analyzed NTSB data to show stalls during a go-around and during the initial climb. This is the surprising part: takeoff and go-around stalls, power-on stalls, are far more common than power-off stalls during the approach and landing. About 18% of the reported stalls happened during a go-around. Because these LOC-I events are close to the ground, a quarter of these stalls are fatal…but three-quarters of them are not.

Many types of airplanes, when trimmed for final approach speed, have an elevator trim setting that is more nose-high than the takeoff trim setting. Some types are trimmed very nose high on final approach. Meanwhile, in many airplanes adding power causes an upward pitch movement.

So at the beginning of a go-around, many airplanes will pitch up into a high angle of attack. It may take forward pressure on the controls to fly the correct initial attitude and airspeed. Pilots who do not practice go-arounds routinely may not be prepared for the control inputs necessary to avoid a stall.

However, half of all traffic pattern stalls happen during takeoff and initial climb. 40% of these losses of control prove fatal. These are high probability, moderate severity events.

The major commonality here: these are power-on stalls. You know, the ones that are uncomfortable to fly, and may seem unrealistic is flown the way they are prescribed in the Airman Certification Standards. For the stalls that will get you, full power stalls during takeoff or a go-around, are often flown with some flaps and with (in retractable gear airplanes) gear extended.

Such an airplane, combined with nose-up trim, may reach the critical angle of attack at a pitch attitude much lower than is required to fly an ACS-style power-on stall (pg. 43). The “dirty” airplane configuration often results in a more dynamic, more dramatic departure from controlled flight than a clean, ACS-style power-on stall. And full power adds to the rapid departure from controlled flight, compared to the often reduced-power power-on stall taught at altitude—power application can introduce yaw and roll, and countering that movement with aileron (a common response) sets the pilot up for that same skidding-stall scenario we discussed back in the turn from base to final.

My third diagram interpreting AOPA’s report compares where we think we’ll stall to where we actually stall, based on NTSB accident history:

About half of all NTSB-reportable stalls are power-on stalls during takeoff and in a go-around. Almost 90% of all stalls—add the hard landings to the power-on stalls—happen over or beyond the runway. We think if we’re going to stall it will be in the pattern before the final approach. We actually stall over the runway and on the departure end.

We spend a lot of time and effort teaching the power-off stall, avoiding accelerating the stall (pulling back on the controls, which increases G load and therefore angle of attack for a given pitch attitude) and emphasizing rudder coordination to keep both wings at the same angle of attack, avoiding the snap-roll scenario. This emphasis may be why the most commonly cited stall scenario, the base-to-final turn, is in reality one of the least common stalls in the accident report. Don’t stop training, practicing and thinking about these stalls. Training and awareness work.

We need to add training and awareness of stalls that occur over and beyond the runway, and practice realistic simulations of a power-on stall in the landing and takeoff configurations, to guard against the most common stalls. Get as comfortable recognizing and recovering from these stall scenarios as you are with power-off stalls more commonly practiced, to avoid the traffic pattern loss of control threat.

Professional CFIs should take special notice of the *real* pattern threat – high power/high nose – and train these areas more assiduously for pilot proficiency and confidence. Fly SAFE out there (and often)!

Thanks to Tom Turner, a charter (and lifetime) member of SAFE, for sharing this important article here. This was originally published on Tom’s Mastery Of Flight Training website which publishes weekly “Flying Lessons” (subscribe for free). Tom is also the author of many books and articles as well as Executive Director and Chief Pilot of the American Bonanza Society.

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Flying Lesson: Scenario Training

Two scenarios from the airline world, and why they matter in single-pilot airplanes…

Scenario 1

The First Officer of a Regional Jet operating under a code-share agreement to a major airline, who is also a FLYING LESSONS reader, related a recent experience. About 10 minutes after departing from a major hub airport a flight attendant (FA) telephoned the cockpit informing the crew that a passenger was having a medical emergency. No one had responded to the FA’s query of the passengers to see if any had medical experience. The FA indeed had past medical experience and was caring for the passenger as much as conditions permitted. The FA recommended the crew land to deliver the passenger to skills medical assistance.

bigstock_Pilots_In_The_Cockpit_3489727The Captain agreed, and handed control of the aircraft to the First Officer (FO). The Captain (CA) then began coordinating with company dispatchers over the radio while maintaining contact with the FA to track the passenger’s condition. The FO assumed “single pilot” control of the jetliner, running checklists, setting up for a visual approach and “working the radios” with Air Traffic Control (ATC), and flying the airplane—alone—while the CA continued to monitor the medical emergency and relay information to company dispatchers.

With only about five months’ experience flying jet airplanes and with zero experience in single- pilot operations in a crew-required jet other than a couple of simulator “incapacitated captain” training drills during new-hire indoctrination, the FO programmed the avionics, configured the aircraft, prepped and briefed for the visual approach. Reported winds were almost directly across the runway, and while doing everything else alone the FO computed the wind to be “right at” the jet’s maximum crosswind component as limited by company procedures.

The FO flew the approach without monitoring or callouts from the CA, and made a “challenging” crosswind landing. By the CA’s own choice the CA was out of the loop until the airplane was on the ground and they were taxiing to a gate. An ambulance crew met the airplane at the gate and took charge of caring for and transporting the passenger.

According to the FO, the company’s manual calls for the CA to take charge of any inflight emergency. The CA apparently interpreted this to mean handing all flight responsibility to the FO and assuming personal control of company response communications while also remaining in contact with the FA who was caring for the passenger. The FO told me that this was indeed what is called for in the regional airline’s operating procedures.

Scenario 2

screen-shot-2016-09-07-at-5-05-57-pmThis one I probably don’t have to explain. I’m talking about the “Miracle on the Hudson,” as described in the recent theatrical release Sully. I was able to see the film recently, and am working on the assumption it accurately portrays at least the inflight portion of the story it tells (I suspect some other aspects of the story were embellished to heighten tension, notably the conduct of the NTSB investigation and hearing, which likely was treated with some license—a movie needs an antagonist, and there’s no tension from blaming the birds).

See https://en.wikipedia.org/wiki/Sully_(film)

Here’s a synopsis of the story, from the website linked above: On January 15, 2009, US Airways pilots Captain Chesley “Sully”

Sullenberger and First Officer Jeffrey Skiles board US Airways Flight 1549 from LaGuardia Airport to Charlotte Douglas International Airport. Barely three minutes into the flight, at an approximate altitude of 2,800 feet (approx. 850 m), the Airbus A320 hits a flock of Canada geese, disabling both engines. Without engine power or airports within a safe distance…Sully decides to ditch the aircraft on the Hudson River. Sully manages to land the aircraft in the Hudson without any casualties.

It’s a very good movie, and it also highlights an issue I mention frequently in FLYING LESSONS: the delay between the onset of an abnormal or emergency condition that causes even a highly proficient pilot (or crew) to delay actions necessary to get the aircraft safely on the ground (or water), because of the “startle factor” and denial of an unexpected event followed the typical pilot’s actions to attempt to remedy the situation before finally deciding decisive action is needed.

As part of that reaction the crew accomplished memory steps of the published emergency procedures, additionally taking an educated leap to accomplish some of the procedures out of order to improve the chances of success…the movie does not explain why, but Sullenberger turned on the Auxiliary Power Unit (APU) sooner than the sequence of checklist steps called out, presumably to provide some additional thrust as well as assure continuation of electrical power (the APU is a fairly strong jet engine of its own, mounted in the tail, that would add some to the A320’s glide ratio).

Throughout the emergency the two acted as a crew. Sully took the flight controls (Skiles was Pilot Flying on that leg) and commanded his FO to run the Dual Engine Flameout checklist. After quickly determining that a “controlled water touchdown” on the river was their best option they probably referenced the Ditching checklist, but that was not portrayed in the movie. They advised the passengers and started the well-trained reaction of the cabin crew. A good leader, once all was done and they were committed to the water landing, Captain Sullenberger asked his First Officer if he had any ideas—knowing that no one pilot can always have all the ideas alone.

LESSSONS for the single-pilot

I emphasize that in both cases—the Regional Jet and US Airways 1549, the flight ended without fatalities. In both cases the crew appeared to do everything the “book” told them to do. In the case of the Regional Jet all but one passenger and crew were delayed, but were able to fly out on the same aircraft later the same day. In both cases what’s really important, leaving no one at the scene of a crash, was the result.

But what do you think is the big difference between the way these two events were handled by the flight crews?

Think about that for a moment……

I’ll wait.

OK, here’s my take: In the case of US Airway 1549, the cockpit crew worked as a team. Although the situation, as it turns out, was unprecedented, they processed checklists the way they had been trained just in case there was something that could have fixed the problem or at least improved their chances. In the heat of the moment it would have been easy to forget to do something that calmer minds had documented in the checklists years before, when the stress was not affecting their thinking and they had time and other resources to come up with the best possible procedure. Sully and Skiles did what they had been trained to do. Most importantly, in my view, they flew the airplane as close to normal as they could, removing as many variables as possible. When they had completed everything training and experience prepared them to do, they went beyond their training and did what they had to do for the passengers and crew to survive.

In the case of the Regional Jet, at the onset of a medical emergency the crew abandoned almost everything it had been trained to do. The FO was left to fly single-pilot in an airplane and using techniques he had never done before, flying a high-workload return to a busy hub airport to land at the edge of the airplane’s approved crosswind envelope without the help and quality control check of a second pilot. Frankly, other than assure an ambulance crew was waiting for the passenger when they arrived at the gate the CA added absolutely nothing to the passenger’s care or chances of surviving the medical condition—that was up to the flight attendant. However, the CA could have done a whole lot more to assure a safe and expeditious arrival at the gate for all the passengers, including the one needing attention, by remaining engaged as part of the cockpit crew and retaining command of the high-workload return and challenging crosswind landing.

Yes, the FO handled this all well. But if he had not, the NTSB investigators might have been as unforgiving of the captain and the crew as they were portrayed in the movie describing the other event.

Here’s the LESSON for the vast majority of FLYING LESSONS reader, who do not fly as part of a cockpit crew, or if they do, may at times fly single-pilot as well. In an abnormal or emergency situation, do everything you can to make the remainder of the flight as normal as possible.

Use your training. Follow your checklists. Don’t try to land faster than normal, or slower than normal, or on a shorter or busier runway than normal, unless you absolutely have no choice.

Fly like Sullenberger and Skiles, following procedures that just might work until you confirm they do not. Only then, use your experience to go beyond your training.

Don’t abandon everything you’ve practiced and try to make up new techniques and procedures, especially while you’re under extreme stress and don’t have time to detect all of the status that may affect the outcome of your flight. Practice your normal, abnormal and emergency procedures until you know them well, then review and practice them regularly. You can’t expect to be successful operating outside the normal envelope in an extreme situation if you aren’t very familiar with where the edges of that envelope lay.

You might try to abandon your training. It might turn out OK. But your actions will be hard to defend—and if anyone get hurt, your guilt hard to assuage—if something does go wrong.

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