Where Do Stall/Spin Accidents Happen The Most? 

Posted on January 25, 2018

Thanks to Boldmethod for sharing…

Source: Where Do Stall/Spin Accidents Happen The Most? | Boldmethod

Boldmethod

Nobody thinks it will happen to them. But before you know it, there you are. Low, slow, and approaching a stall.

And how well you react in those few seconds makes all the difference in the world. Often times, it’s the difference between a safe recovery and a fatal crash.

Where Do Stall/Spin Accidents Happen The Most?

The Air Safety Foundation conducted a study of 450 stall/spin accidents from 1993 to 2001 to see where they happened, and how they compared to other types of accidents. And to keep the focus on GA, they only looked at accidents where aircraft weighed less than 12,500 pounds.

So where did the accidents happen? At least 80% of them started from an altitude of less than 1000′ AGL.What’s the significance of 1000′ AGL? It’s the traffic pattern altitude at most airports.

That brings up the major problem with stall/spin accidents down low. The altitude loss in a stall recovery for most GA aircraft is estimated to be 100-350 feet. Which, in many cases, gives you enough room to recover from a stall in the pattern.

But spins are a whole different animal. In the 1970s, NASA studied altitude loss in spins of several aircraft, one of which was the Piper Arrow.

What they found was eye opening. The Arrow had an average loss of 1,160′ in spin entry through recovery. And, keep in mind, that’s in an aircraft flown by a test pilot.

It doesn’t take a math genius to figure out the problem here. If you’re flying a 1,000′ AGL traffic pattern and you get yourself into a spin, you’re not going to have enough altitude to recover, no matter how quick your reaction, or your recovery technique.

Who Do Stall/Spin Accidents Happen To?

“But this would never happen to me.” The thought has probably already crossed your mind. So who are these stall/spin accidents happening to?

According to the ASF study, student pilots and ATPs were the least likely pilots to have a stall/spin accident. That leaves the majority of stall spin accidents to private and commercial pilots.

It makes sense that the most experienced pilots, ATPs, are some of the least likely to get themselves into a scenario like this. But student pilots? They have the least flight time and experience. This study, and many like it, propose that students are still under enough supervision, and are still cautious enough, to keep themselves away from a stall/spin scenario.

But private and commercial pilots like you and me (which are the vast majority of GA pilots) are the prime candidate for a stall/spin accident.

There are a lot of reasons that could be the case. Lack of proficiency and complacency are two of the leading factors. (When’s the last time you practiced stalls, or better yet, turning stalls?)

What’s Being Done To Prevent Stall/Spins?

So what’s being done to help prevent stall/spin accidents? The FAA’s new rules for slow flight in the ACS are a clue.

In the old Private Pilot PTS, slow flight was performed at “an airspeed at which any further increase in angle of attack, increase in load factor, or reduction in power would result in an immediate stall”.

So in the old way of doing things, you would ride the stall warning horn and aircraft buffet throughout the maneuver.

Now, with the new ACS, thing have changed. And they’ve been modified even further since June 12th.

According to the ACS for slow flight, you now need to “Establish and maintain an airspeed at which any further increase in angle of attack, increase in load factor, or reduction in power, would result in a stall warning (e.g., aircraft buffet, stall horn, etc.).”

And here’s how the FAA suggests pilots set up the maneuver:

One way to set up for the maneuver is to slow the airplane to the stall warning in the desired configuration and note the airspeed. Next, reduce the pitch or AOA slightly and eliminate the stall warning indication, adjust power to maintain altitude, and note the airspeed required to perform the slow flight maneuver in accordance with the standard. For example, the pilot may first note the stall warning indication at 50 knots. A slight pitch down to eliminate the stall warning, while adjusting the power to maintain altitude, might then cause the airspeed to increase to 52 knots. That 52 knot airspeed would be the base airspeed to perform the slow flight maneuver. The pilot can adjust pitch and power as necessary during the maneuver to stay within the ACS airspeed standard without the stall warning indication. By setting up the maneuver this way, the pilot can achieve similar AOA for the maneuver, regardless of weight or density altitude, and meet the objectives of the slow flight task. If a stall warning occurs while maneuvering in slow flight, the expectation is the pilot will take the appropriate action to correct it.

So why the change?

The FAA recently said this: “The FAA does not advocate disregarding a stall warning while maneuvering an airplane. With the exception of performing a thoroughly briefed full-stall maneuver, a pilot should always perform the stall-recovery procedure when a stall warning is activated.”

The FAA clearly doesn’t want pilots to be complacent about the stall warning horn. By changing the maneuver, their hope is that the stall warning horn will be as ear-piercing as ever, grabbing your attention as you approach a stall. In addition to that, there have been cases of student-instructor training accidents that resulted from slow flight. By speeding up the maneuver, the FAA is, in theory, making the training environment safer.

Only time will tell if the change is effective.

Boldmethod

Staying Alert, Especially Down Low

This, like most things in aviation, always comes back to the basics.

There’s no substitute for flight proficiency. And when things start to fall apart in the pattern, going around and giving yourself another chance is almost always the best option.

So the next time you’re flying, climb up to altitude and practice some stalls and slow flight. And if it’s been a long time since you’ve done either, grab an instructor so they can give you feedback on how you did.

A little practice and proficiency can go a long way. And it can keep you reading about accident studies like this, instead of becoming one of the NTSB’s statistics.