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Autopilots

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Automation reduces pilot workload, but keeping sharp flying skills is paramount to avoid surprises.


Briefing when and where to use the autopilot, and to what degree, can increase situational awareness and decrease workload.
By Shannon Forrest
President, Turbine Mentor ATP/CFII.
Challenger 604/605, Gulfstream IV, MU2B

Pilots have mixed feelings when it comes to autopilot systems. At the professional level of experience, they generally harbor 1 of 3 philosophies. The first genre is the “hand flyers,” or those who prefer to use the autopilot as little as possible and would rather spend their time operating the flight controls manually.

If you ask a hand flyer to explain this preference, you’ll get a myriad reasons. A few express outright distrust of the automation. Often, there’s a “war story” forever embedded in a pilot’s psyche, underpinning a belief that the autopilot will inevitably behave badly.

Other pilots proclaim they just love to fly and they’re going to do it as much as possible. Sometimes, the only thing that forces the hand flyer to relinquish control to the computer is regulation or policy. For example, the RVSM requirement of having an autoflight system engaged upon climbing through FL290 overrules any desire to do otherwise.

The second group is the “part-timers,” or, more appropriately, the “10/1 club.” A pilot in this category chooses to hand fly from takeoff to 10,000 ft on the climb out, and from 1000 ft to the surface on the descent. There’s some subtle variation in the altitudes, but the general theory holds.

The 10/1 pilots tend to be proficiency-oriented and focused on maintaining some level of hand flying skills. They like to remain in control during what they deem to be more dynamic flight segments, while leaving the less work-intensive portion to the autopilot.

If the autopilot is engaged below 10,000 ft, it’s common for members of the 10/1 club to rest their hands on or near the flight controls. Lastly, there are the “99 percenters.” These pilots are perfectly comfortable (and even prefer) having the autopilot remain on as long as possible.

Some even wish the autopilot had the ability to taxi to and from the runway on its own, which would make them 100 percenters if that were possible. On takeoff, a 99 percenter turns the autopilot on after the landing gear leaves the runway, and it stays on until 200 ft above the ground when landing.

A mixed flightcrew It’s always interesting when pilots with differing autopilot philosophies operate together as a crew. The hand flyers and 99 percenters couldn’t be more diametrically opposed. If a 99 percenter is functioning as the pilot monitoring, the atmosphere can become tense as workload increases with the autopilot off.

The pressure really boils over when a pilot decides to hand fly a complex RNAV departure like the BOOCK 3 out of DCA (National, Washington DC). This practice always puts a 99 percenter on edge, as he thinks, “Is this guy going to hit the published altitudes, speeds, and turns within the tolerance? Why not just let the autopilot fly this thing?”

On the other hand, nothing irks a diehard hand flyer more than looking over at a 99 percenter with his hands on his lap and feet on the floor – and seemingly happy as can be – as the autopilot tracks the ILS down to minimums in instrument conditions.

The Garmin GFC 600 is configured with an LVL button that returns the aircraft to straight and level with one push.

It’s a generational thing

Generational disparity also affects automation philosophy. Some 30 years ago, hand flying was the norm, so it was extremely rare to see an autopilot in a general aviation (GA) training aircraft. If one did, it rarely worked, and flight schools didn’t want to pay to fix them, marking them instead with an “inoperative” sticker.

Many pilots who are still out there flying took instrument check rides that consisted of a hand flown Non-Directional Beacon (NDB), followed by a missed approach into a hold at the same NDB. The real “hard core” of the bunch will also point out that the Automatic Direction Finder (ADF) in the aircraft was a fixed card, not the slightly more advanced – but still archaic by today’s standards – Radio Magnetic Indicator (RMI).

For those who remember, the RMI took the instruction of “when the intercept angle equals the deflection,” and replaced it with “push the head, pull the tail.” In theory, the RMI simplified the approach. If these terms and phrases are completely foreign, consider yourself lucky.

In a world dominated by GPS, the NDB is now relegated to “Not Da Best.” Nowadays, most professional pilots – especially those in university programs – will learn to fly in a technologically advanced aircraft in which the autopilot plays a central role.

The infamous NDB approach has been replaced by a fully coupled precision LPV. Pilots exposed to automation early on will continue to rely heavily on it throughout their flying career – or at least that’s what the law of primacy tells us.

They also seem to trust the autopilot more than those who remember the rudimentary and less dependable devices of the past. The good news is that modern autopilot technology is remarkably stable, and retrofit options can enhance reliability.

The BendixKing AeroCruze 230 is the only autopilot in the market that is controlled by a touch screen. Altitude is set using a knob.

Autopilot categorization

Autopilots can be categorized as either a standalone system or part of an integrated avionics package. How much control the device has is reflected in autopilot nomenclature. A single-axis autopilot (sometimes called a wing leveler) controls only roll.

Combined roll and pitch are denoted as a 2-axis autopilot. Adding yaw (or more accurately yaw dampening) makes an autopilot a 3-axis device. In all cases, the autopilot must be able to determine the current state of the aircraft and what the pilot wants the state to be.

It achieves this in 1 of 2 ways – by sampling rate from a turn coordinator, or attitude from a gyro or digital Attitude and Heading Reference System (AHRS). Standalone autopilots are more likely to be installed in aircraft no longer in production, whereas new aircraft are likely to see autopilots embedded in a bigger avionics package.

Offerings from manufacturers

One of the more classic attitude units that’s being replaced with better technology (likely to be encountered in light to mid-sized twins) is the King KFC200. It consists of a large rocker switch to set climb/descent rate, 6 oversized push buttons to engage a mode, and a lever to turn the box on and off.

Undoubtedly, King autopilots are faded and chipped from years of use, but there’s hope. The BendixKing AeroCruze 230 Advanced Autopilot is a form-fit replacement for original KFC150 and KFC200 units.

BendixKing, a division of Honeywell, has a suggested retail price of $9800 for its AeroCruze 230, exclusive of installation, although it does allow owners to reuse existing servos and wiring to reduce costs. This off-the-shelf product is considered a 3-axis autopilot, and a yaw dampener is available separately.

It’s capable of coupled approaches and altitude preselect, and it has a unique feature that addresses mode confusion and unusual attitudes – a button that, when pressed, returns the aircraft to straight and level. This system will be especially popular with the iPad crowd because it’s controlled via a touchscreen.

Honeywell is often associated with fly-by-wire systems for Part 23 and transport category aircraft. However, when it comes to auto flight systems, the manufacturer’s offerings run the gamut. In July 2019, Honeywell acquired TruTrak Flight Systems, which specialized in autopilots for the experimental aircraft market.

Another provider of autopilots for new and legacy aircraft is Garmin. The Garmin GFC 600 Digital Autopilot is designed for aftermarket installation on a wide range of single- and multi-engine GA aircraft. Certification is currently under way for the King Air 90, Cessna Citation CJ (525) series, and Pilatus PC-12.

Manufacturer’s suggested retail base price (exclusive of installation) is $19,995. When coupled with a suitable navigation source, it can fly holds, procedure turns, missed approaches, and, of course, precision and non-precision approaches. The GFC 600 also includes some noteworthy safety features.

Electronic Stability and Protection (ESP), for example, uses autopilot servos, but functions independently to recover from pitch or roll deviations that exceed a prescribed limit. According to Garmin, the technology will “gently nudge the controls toward stable flight.”

In a worst-case scenario, like pilot incapacitation, the aircraft will return to level flight through flight director and autopilot engagement. ESP is just one part of the Autonomí family of products developed by Garmin. The most impressive offering in the Autonomí line is the Garmin Autoland, which received FAA certification for the G3000 integrated flight deck in 2020.

The G3000 Autoland is available in the Piper M600, Cirrus Vision Jet, and Daher TBM 940. With the press of a single button, the Autoland calculates variables, including range, runway length, terrain, and type of instrument approach, and uses the data to return the aircraft safely to the ground.

Collins Aerospace provides integrated FMSs for business, military, and GA aircraft. Pictured is the company’s FCS-7000 Flight Control System.

Newer developments

The industry has come a long way from the days of trying to give a nervous passenger an ad-hoc flying lesson over the radio after a pilot has had a heart attack in flight. For decades, airlines have had autoland capability, but that’s not the same thing as the autonomous landing performance currently being developed by avionics manufacturers.

Autoland has always relied on pilot monitoring and intervention if something goes wrong. Autonomous landing is based on enough safeguards and redundancies that a pilot is removed from the control loop.

Collins Aerospace even demonstrated that a McDonnell Douglas F-18 Hornet could be landed autonomously with 80% of its wing missing. Given where aviation technology is headed, using the term “autopilot” might even be doing manufacturers a disservice.

A more appropriate term is flight management, which is more about a philosophy than a device. Universal Avionics developed the first Flight Management System (FMS) in 1982. At the time, controlling an aircraft by means of a few keystrokes seemed ludicrous.

With any new technology come problems and, accordingly, mismanagement issues contributed to a string of incidents and accidents early on. First-generation FMSs were navigation-focused and not quite human-factor friendly. Today, both the Universal Avionics and Collins Aerospace FMSs use a multitude of inputs, such as terrain awareness, to enhance situational awareness and increase safety.

Controller–Pilot Data Link Communications (CPDLC) is a great example of a relatively new technology incorporated within the FMS to eliminate miscommunication.

Thirty years ago, the thought of receiving an air traffic control clearance – and sending it to the aircraft with a push of a button – was unheard of. Things have changed for the better.

Automation and CRM

There’s no doubt that having an autopilot is desirable. When Lawrence Sperry invented it just 9 years after the Wright brothers took flight, it saw immediate use, especially on long-range flights.

The question that must be asked is: What level of automation is appropriate? From a strictly Crew Resource Management (CRM) standpoint, the stock answer is: Whatever the pilot feels most comfortable with. However, there’s a caveat in a crewed airplane.

In this case, perhaps the most appropriate level of automation is what’s best for the crew under the current conditions. Keeping hand flying skills sharp is important, but so is keeping a civil relationship with the other crew member.

Willingness to speak up is critical if a pilot feels the level of automation is inappropriate for the situation. No one wants to be surprised by the “cavalry charge” aural alert of an autopilot being disconnected on an approach to minimums, so briefing whether the autopilot will be used – and to what degree – goes a long way toward increasing situational awareness and decreasing workload.

When in doubt between being a hand flyer and a 99 percenter, it’s always a safe bet to split the difference and join the 10/1 club, even if the membership is only temporary.


Shannon Forrest is a current line pilot, CRM facilitator, and aviation safety consultant. He has over 10,000 hours andholds a degree in behavioral psychology.

 

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