The “ACS Slow Flight” Controversy

The Airman Certification standard (ACS) replaced the Practical Test Standard (PTS) for the certification of private (and instrument) pilots as of June 15th this year. The primary thrust of this testing transformation was to update the knowledge testing questions and philosophy, replacing ancient, irrelevant test questions in the data bank with more timely, calibrated questions correlated to the areas of operation in the flight test. The intention (and some involved parties say “FAA promise”) was to not modify the flight test maneuvers or completion standards during this process. It does appear though that on the way to the alter, one critical vow was transformed and quietly embedded into the new ACS. Now that it has been discovered, this slow flight modification is creating quite a dust-up in the flight training community.

Doug Stewart in Flying Magazine; “Prior to the ACS, the PTS specified slow flight as ‘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,'” Stewart said. “The ACS now specifies slow flight as, an airspeed, approximately 5 – 10 knots above the 1G stall speed, at which the airplane is capable of maintaining controlled flight without activating a stall warning.”

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The new FAA SAFO highlights this controversy and presents the FAA position. The FAA does not want pilots in training flying with the stall warning horn blaring with the supposition this will lead to ignoring this critical warning device. [FAA ACS FAQ] This new FAA focus developed directly from accidents such as the Colgin 3407 crash in Buffalo, where the pilot decelerated rapidly into a high AOA configuration and aggressively held the plane in an aggravated stall defeating the stall protection safety devices and resulting in 50 deaths. To me this seems like a one off pilot error more than a symptomatic problem with the entire flight training process. From the Wall Street Journal May 11, 2009;

An aerial view of the site where Continental Connection Flight 3407 crashed into a home on Long Street in Clarence, N.Y., is seen Saturday morning, Feb. 14, 2009. (AP Photo/The Buffalo News, Derek Gee) ** TV OUT, MAGS OUT,  FOREIGN OUT, MANDATORY CREDIT **
An aerial view of the site where Continental Connection Flight 3407 crashed into a home on Long Street in Clarence, N.Y., is seen Saturday morning, Feb. 14, 2009. (AP Photo/The Buffalo News, Derek Gee)

The captain of a commuter plane that crashed Feb. 12 near Buffalo, N.Y., had flunked numerous flight tests during his career and was never adequately taught how to respond to the emergency that led to the airplane’s fatal descent, according to people close to the investigation.

Capt. Marvin Renslow had never been properly trained by the company to respond to a warning system designed to prevent the plane from going into a stall, according to people familiar with the investigation. As the speed slowed to a dangerous level, setting off the stall-prevention system, he did the opposite of the proper procedure, which led to the crash, these people said.

GAPioltStallAwarenes1976Practicing and demonstrating pilot knowledge, skill and control in this slow flight area of airplane operation is critical to flight safety and is the holy grail for most CFIs and DPEs. There is great training value in mastering (and regularly practicing) slow flight with the stall warning horn operating, coordinating your plane carefully at the maximum angle of attack right up to the aerodynamic stall. The FAA’s own 1976 FAA Stall Awareness Study clearly demonstrated that “extra stall and slow flight training was effective in preventing unintentional spins.” Inflight-Loss Of Control is the major causal factor for fatal accidents in aviation so understanding and controlling this phase of flight is critically important to pilot safety. If a pilot never experiences and trains in this critical phase of flight their reaction might be an inappropriate panic response like Cpt. Renslow.

Send your comments supporting retaining slow flight in it’s previous (slower) form as an essential part of flight training to the ACS focus team at the FAA Aviation Working Group. Please mention your flight training experiences and viewpoints. They meet on September 14th (that should be an interesting meeting…) Have fun, fly safely, and best wishes for a wonderful holiday weekend.

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Author: David St. George

SAFE Director, Master CFI (12X), FAA DPE, ATP (ME/SE) Currently jet charter captain.

7 thoughts on “The “ACS Slow Flight” Controversy”

  1. So the FAA wants to inculcate in every student pilot an automatic ‘push the stick forward’ response to every bleating of a stall warning horn. Well, I get a loud, blaring stall warning horn on (almost) every landing, and I’m certainly NOT going to push the stick forward then! Methinks the promulgator of this FAA policy has forgotten how to fly anything smaller than an airline jet.

    1. Funny you should mention high AOA landing. The PC-12 has a warning/shaker/pusher system. If you land with a nice nose high attitude it starts to get concerned yelling “stall” and some pilots have even gotten the “shaker and pusher” to their peril. Consequently, many PC-12 pilots hold the “interrupt” switch to prevent an “FAA takeover” of their landing!

  2. I want to reinforce that SAFE encourages individuals to communicate directly with the ACS Focus Team, and that Doug Stewart’s letter writing campaign is his own initiative. and not organized by SAFE.

  3. There seems to be an epidemic of commercial airliners and military aircraft that have crashed as a result of a pilot induced stall/upset and improper recovery from the stalled condition.

    Pilots instinctively react to unfamiliar situations in the manner in which they were trained. Upset Recovery Training (URT) goes a long way to give pilots the experiences they would not otherwise see and allows valuable insights into how airplanes tend to behave when operating outside of their normal operating envelope. Correct habit formation for stall/spin avoidance and recovery is essential for any pilot. I fear, however, that we have a systemic flaw in the standard slow flight and stall recovery technique which the FAA requires of ATP pilots. The ATP approach to stall recovery training scenario both involve an imminent stall at low altitude, as on final approach, and recovery dictates a minimum loss of altitude. Preventing a stall becomes secondary to immediately stopping a descent by pitching-up, adding power and performing a go-around maneuver. The problem with this is that most fatal stall/loss of control incidents involve a stall at higher altitudes where excess altitude can and should be traded for airspeed and aircraft control. This, however, is not normally trained in the air transport industry. The result is that pilots of large airplanes are loosing control of their aircraft at high altitudes and holding their airplanes in a stalled condition all the way to the crash cite. I have seen this numerous times where a pilot inadvertently stalls the airplane at high altitude and reacts to the stall warning horn by trying to power-out of the stall while releasing little or no elevator back pressure. Operating at high altitude means less power available to break a stall and continued backpressure only deepens the stall. It’s frightening to observe this especially when the pilot is obviously confused as to why the airplane is not recovering the same as it did in performing the standard approach to stall recovery.

    An accident case in point is Colgan Air Flight 3407 where the pilot of a Dash 8 Q400 reacted to a stall warning while the aircraft was in the approach configuration and at about 2300 feet, plenty of altitude to recover if only the pilot had pushed rather than pulled the yoke forward.
    As early as 1989, I became increasingly concerned that our pilot training at my airline company as it did not include stall recovery at altitude and feared that the stall training scenario at low altitude would lead to a negative habit transfer if a pilot became confronted with a stall warning at high altitude. Later, I also saw this in the Army’s standardization and training so I developed a class on “Stall Avoidance Training” for our RC-12 students at Ft Huachuca. http://www.macleans.ca/news/world/deadly-stalls-haunt-airlines-as-airasia-investigation-unfolds/

    1. After Colgin 3407, all the FAA PTS were modified to emphasize a “positive reduction in AOA” as opposed to the previous “minimum altitude loss.” But how many pilots still perform stalls as initially trained? I fear the current specification will not allow slow flight to be deep enough into the induced drag curve to demonstrate “mushing with power” where you must lower the nose to reduce drag and obtain a climb (that is an eye-opener) It takes a very competent educator to handle this training correctly and build understanding (and why SAFE works hard to improve aviation educator excellence) Thanks for your comments!

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