Stabilized Approaches & Handling Autopilot Anomalies

by Michael J. “Mick” Kaufman
Published in Midwest Flyer December 2017/January 2018 issue

In my column for this issue of Midwest Flyer Magazine, I selected two topics that I think are of interest to our readers – “The Stabilized Approach” and “Handling Autopilot Anomalies.” The subject of stabilized approaches was one of the topics presented at the VFR/IFR seminars at Volk Field in Camp Douglas, Wis. in October, and presented by FAAST team member, Steve Mesner, of New Lisbon, Wis. The seminar was somewhat poorly attended due to weather and almost all of the pilots who attended drove to the program, as I did. Those who did attend were given briefings on military airspace with a new aviation acronym appearing (at least it was new to me) called a Temporary Restricted Area (TRA). Aviation weather and new briefing products were other topics covered.

As a flight instructor, we have all attempted to train our students to do stabilized approaches, whether they are flown VFR or IFR, and Steve pointed this out in his presentation. This is the desired way to teach, and as a pilot pursues a career as a professional pilot, this is the only way it is done.

Over the years, the philosophy of flying the traffic pattern has changed. As a student pilot of 50-plus years ago, I was taught to bring the engine to idle abeam of the touch down point and glide the rest of the way. If you should add power other than clearing the engine with a short burst of power on the base leg, it was a bad approach. The theory in those days was if a pilot made only power-off landings, he would be better prepared for a real engine failure. Having learned that technique, sometimes referred to as flying by the seat of your pants, has paid off for me as an instructor knowing how far to let a student pilot go, and be able to correct at the last second to save the airplane.

So, how does flying a stabilized approach apply to the instrument pilot? First, it is so important to develop a set of numbers for the aircraft you will be flying. I start with a chart (See FIG 1 on page 10) that you may have seen in some of my previous articles. If you do not have any input from a document, or another pilot familiar with this aircraft, you should develop one yourself. It is so much easier to fly a stabilized approach with the correct set of numbers. I am sorry to say that a majority of pilots try to fly their aircraft too slow, rather than too fast, while air traffic control (ATC) is asking most pilots flying light single and twin-engine aircraft to speed up due to traffic behind them. One of the reasons pilots elect to fly on the slow side is because of the categories listed on the bottom of the approach chart.

For example, an aircraft like a Bonanza could fly the approach at 90 knots, making it a category A aircraft or faster, which would then make it a category B aircraft

(FIG 2). In a few cases, the minimums are lower for Category A straight in approaches, but most apply to circling approaches. So why is faster better? On a precision approach of flying at what I refer to as the “ideal” airspeed, is any power adjustment necessary from the time of glide path intercept to the decision height, except for a manifold pressure reduction pre-planned half way down the descent path. This is due to the fact that as we descend, the engine produces more power on a normally aspirated piston engine aircraft, causing the airspeed to increase. If we attempted to fly on the slow side, we would be making numerous power adjustments on the glide path.

We can all recognize that the air is not always smooth as glass on approach, and the ideal airspeed will allow us to make corrections for turbulence while on the glide-path without sinking below the glide-path and unable to pitch up without getting too slow on airspeed or pitch down without gaining an excessive amount of speed. In Steve’s seminar, he mentioned we should be on a stabilized approach a minimum of 1000 feet AGL for an instrument approach or 500 feet AGL for a VFR approach, or otherwise, a go-around should be executed. So, could I recommend not flying a stabilized approach, and the answer is NO. I have done it intentionally, but would not recommend it to our readers.

Years ago, when it was still financially affordable to land at Chicago O’Hare International Airport, I was often asked by the controller if I could do 150 knots until on a one-mile final and this was in a Piper Arrow. The Arrow could not do 150 knots in level cruise, let alone on approach, except in a dive with the gear up. To do this maneuver, you needed a decent ceiling and visibility for this non-stabilized maneuver, which needed to be done in VFR conditions. At the mile fix, power came all the way back. You pitched up abruptly to bleed off airspeed to hit gear speed, dropped the gear, hit flap speed, then full flaps, pitched down and landed. I knew the airplane well, and this was a seat of the pants maneuver, which was similar to Bob Hoover’s style.

On another occasion, I was flying a Cessna 310 into Richmond, Virginia on a low instrument meteorological conditions (IMC) day and was being vectored for the ILS approach. I was inside the outer marker and had contacted the tower and was cleared to land. The Cessna 310 has a very low gear speed, though I do not remember what it was, and I was aware of traffic following me on the approach. As I was breaking out right at minimums, the tower called for me to go around, and I did. I have been stewing about this incident for years, and the Volk seminar rekindled this fire. You see the go-around was called by the tower because the traffic behind me was overtaking me, and it was 45 minutes later before I actually landed, being vectored all around until they found a space I would fit in.

As part of the seminar, Steve played the audio recording from a fatal accident, which I encourage all of my readers to listen to: https://www.youtube.com/watch?v=xPo5yuLbvco

At the conclusion of this video, most of you will throw your hands in the air in disbelief as the participants did at the seminar wondering how the pilot let ATC crash her airplane. I do not want to say that all air traffic controllers are from the evil-empire because I credit them with saving my life in an emergency more than once. However, I have stated in several columns that we as pilots must be assertive when flying our aircraft, and had the pilot of this aircraft taken on the command role when asked to go around and used the words “UNABLE,” (a term made famous by Capt. Chesley Burnett “Sully” Sullenberger III of U.S. Airways Flight 1549, Miracle On the Hudson), she would be alive today.

I just returned from a Bonanza/Baron Training (BPT) seminar in Norfolk, Virginia, where I had the opportunity to fly with some of the students. I was very pleased to see that the gentleman I was assigned to fly with proved to be an excellent instrument pilot.

The day of our flight was IMC to marginal VFR, so we were able to do some practice approaches in real IMC. I have mentioned many times in my column of the deteriorating skills of pilots being able to hand-fly an aircraft on instruments, but this was not true of Wendell Todd, Jr. of Atlanta, Georgia. Wendell has a Century II autopilot in his aircraft, which is capable of holding a heading and tracking a VOR radial or GPS course, but no approach coupler or altitude hold. During the flight, which included a rest break, we flew almost 4 hours, and the cumulated autopilot time was about 5 minutes. We even shot two Non-Directional Beacon (NDB) approaches without any reference to a GPS, and one was a partial panel. It sure made me happy to see a pilot who would survive should the autopilot quit.

In the title of this column, I mentioned non-commanded autopilot anomalies, as they do not happen often, but they do happen.

Several weeks ago, I was doing the final recommendation ride as an instructor to a soon-to-become instrument pilot. We were at Oshkosh, Wisconsin doing the localizer (LOC) back course approach, and we were established on a stabilized approach on the autopilot, when we found ourselves in a 60-degree non-commanded roll to the left. The interesting thing on this was that the flight director did not command that roll. The pilot paying attention to what was happening disconnected the autopilot and recovered from the unusual attitude with minimum altitude lost. Puzzled as to what happened, we declared a missed approach and asked the tower to allow us to leave the area to sort out the problem. We reengaged the autopilot and all seemed well for about 10 minutes and then it happened again. This time when we reengaged the autopilot, nothing happened, and it appeared that something had quit completely.

For those who are familiar with a flight director system like this airplane had, I teach that the flight director is the smart part of the system and commands the servos to follow its directions. The servos of the autopilot are the muscle, and the pilot can hand fly the flight director and provide that muscle as well. So, here we had a rather unusual situation, but because of the vigilance of the pilot and his quick action, it showed a sign of a well-trained pilot. Should this situation have happened in hard IMC with a pilot with poor hand-flying skills, this would have been a fatal accident!

Till the next issue, keep those hand flying skills sharp!

EDITOR’S NOTE: Michael J. “Mick” Kaufman is a Certified Instrument Flight Instructor (CFII) and the program manager of flight operations with the “Bonanza/Baron Pilot Training” organization. Kaufman conducts pilot clinics and specialized instruction throughout the U.S. in a variety of aircraft, which are equipped with a variety of avionics, although he is based in Lone Rock (KLNR) and Eagle River (KEGV), Wisconsin. Kaufman was named “FAA’s Safety Team Representative of the Year” for Wisconsin in 2008. Email questions to captmick@me.com or call 817-988-0174.

DISCLAIMER:
The information contained in this column is the expressed opinion of the author only, and readers are advised to seek the advice of their personal flight instructor and others, and refer to the Federal Aviation Regulations, FAA Aeronautical Information Manual and other instructional materials before attempting any procedures discussed herein.

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