This is the fourth in a series of articles dealing with learning to fly a Technically Advanced Aircraft (TAA).  By definition, TAA does not imply a glass cockpit, but a glass cockpit does imply a TAA since almost 90% of production aircraft rolling off the assembly lines of the 5 largest general aviation manufacturers have glass cockpits that meet the TAA definition.  FT decided to devote a series to helping you learn most efficiently and most effectively in the TAA trainers that you are likely to encounter at your local airport.  Ed

 

In part 3, we discussed learning the Technically Advanced Aircraft (TAA) navigation and flight planning process and keeping ahead of the aircraft in flight through the use of an intentional coordinated synchronization of the aircrafts electronics and the pilot’s intentions with a few detours introduced by air traffic control.  We found that there are two key challenges to safely learning to fly TAA: Programming knowledge and cockpit fixation and that addressing these during early training will make for a safer flying experience. 

 

As we have discussed, TAA aircraft have 4 basic components as outlined in the figure below:

 

TAA aircraft use a moving map GPS or like navigation system to depict and organize waypoint information, an integrated autopilot to couple to that navigation guidance to execute a predetermined flight-path or procedure, a flight management system (FMS) system as the primary interface between the pilot and the avionics, and an overriding computer program or data-controller to coordinate the flow of all those pieces together.  In part 1 and part 2 of this series, we discussed the Avidyne and G1000 Screen and moving map (PFD) and (MFD) portions of the system and how the processors of those subsystems make assumptions about how the information in the flight plan should be processed.  In part 3 we discussed the flight management process of how the pilots gets information into the navigation and flight planning portions of the system (bump-scroll-and twist) and some more about how the processors and system software of these systems coordinate the data in the flightplan with what the pilot sees on their map (MFD) and on their primary flight instruments of the PFD.

 

One thing that really sets the TAA aircraft apart from the aircraft that many pilots learned to fly in is the presence of a capable, coupled autopilot.  The various systems continue to bedevil pilots and worries educators that the lack of thorough knowledge of this important subsystem will lead to preventable accidents.  This installment will look at autopilot features of the most typical autopilots (Honeywell, Garmin, STEC) and shed some light on their features and functions for the novice pilot.

 

The typical TAA autopilot control panel

 

The presence of an integrated autopilot in the cockpit is not new.  General aviation aircraft have come with capable autopilot systems for many years.  What makes the TAA aircraft unique is how the autopilot is integrated.  TAA aircraft cockpits have autopilots that are connected with the other navigation and guidance systems through the use of the software and system processors which have very powerful capabilities to offer the pilot.  Previous autopilot systems had very limited integration to the rest of the avionics stack and there was no overriding automation to coordinate functions.  The pilot simply set desired courses or navigation signals on the horizontal situation indicator (HSI) or heading indicator with a heading bug and configured a series of switches on the autopilot control panel to obey those signals. If the pilot set in improper information, the autopilot would fail to arm or could possibly follow the improper settings to the detriment of the pilot or the chagrin of air traffic control.  It was pretty cut and dry.  The pilot needed to be the “brains” that coordinated what was on the instruments and what was set into the autopilot.

 

TAA aircraft have started down a road toward computer automation in the cockpit that allows the pilot to develop a very trusting relationship with the navigation and autopilot equipment that could quickly be spoiled by a simple failure of some of the electronics features.  The FAA and the insurance companies want to make sure that the pilot is fully in control of the automation and is supervising it at all times while allowing it to perform its programmed function.  Pilots who take an approach of a “blinking VCR clock display” to their avionics system can quickly get themselves over their head if a critical component of the system decides to take a rest at the wrong time.  The other major issue is the fact that these systems allow a low time pilot in training to suddenly have access to technology that was available only in jets and space vehicles only 20 years ago.

 

What does al this mean to the training pilot?  First, it requires the pilot to learn these systems and how to control them, override them, and manipulate them in the event of an emergency.  These training processes have never been offered in Private, and for that matter most instrument pilot curriculums, and now they must.  If flight instructors don’t understand them, then they will not teach them and we will begin to fill the skies with pilots who are trying to learn systems while they are taxiing the aircraft or while they are blazing across the ground at 4 miles a minute.

 

The current crop of autopilots found in TAA aircraft fall into two categories: Digital and Analog with digital faces.  The difference between these two is an amazing amount of technical capabilities.  The pilot must know the functions and capabilities of the autopilot installed in the aircraft that they fly.

 

First the 1^st generation of TAA autopilots; Analog. The S-TEC 55X is a very common autopilot platform found in most Cirrus Avidyne Entegra equipped aircraft and many 2004 and 2005 Mooneys with G1000 panels.  The Bendix-King-Honeywell KAP140 autopilot is found in 2004-2006 Cessnas and Diamonds equipped with the Garmin G1000.  Both of these autopilots feature advanced functions and are reasonably integrated into their host glass panel cockpits.  The challenge is understanding the limits of overriding automation that is built into the interface to keep the pilot from getting into trouble.  Both of these autopilots depend upon a hidden turn coordinator which provides these systems with analog rate information.  That means that if the connection to these hidden components fail, the autopilot can lose its ability to determine how to make standard rate turns.  In addition, these units depend upon a sensor to sample ambient static information to help them determine how to climb, descend, and how to hold altitude.  The KAP140 equipped aircraft requires the pilot to input an altimeter setting into 3 places in the aircraft; the autopilot, the G1000 system, and the standby altimeter.  The S-Tec autopilot does not require an altimeter setting to be input into the control panel because it can get this information from the glass cockpit at the time of autopilot engagement so these aircraft have two.  The pilot must maintain a watch over these systems to avoid a situation where the autopilot attempts to keep a predetermined vertical climb rate set at a lower altitude from stalling the aircraft at a higher altitude.  This stems from the lack of digital information flowing back and forth from the glass system processors and the autopilot.  If there is not sufficient or valid information then the overriding computer programs that guide and coordinate the systems cannot perform basic advisory functions or corrective functions for the pilot leaving the pilot to fend for themselves.  There are other limitations with these systems.  There are a number of instrument procedures that these units simply cannot execute.  An example is a simple holding pattern depicted on nearly all instrument approaches.  The early versions of these units do not have the integration necessary to fly these procedures and require the pilot to use hand fly the aircraft during these procedures or to use the heading mode and drive the aircraft around the holding pattern like a go cart at a racetrack. Thus, the pilot must keep a constant vigilance over the systems watching to make sure that autopilot is doing what it was intended to.  This need for pilot oversight leads to an increased training requirement despite the fact that the increased level of cockpit technology might imply to the pilot that their function has been reduced to one of a cockpit automation manager.

 

The digital autopilot, such as the Garmin GFC 700 installed in Beech, Columbia, and 2007 and subsequent Diamond, Mooney, and Cessna aircraft incorporate a high level of automation coordination between the systems.  This system can not only watch over the pilots operational parameters and provide certain advisories, but they are also capable of flying very complex instrument procedures; 19 to be specific, such as holding patterns, procedure turns, and a wide variety of other procedures that experienced pilots will be thrilled with.  Are these more capable and considerably more expensive autopilot units worth it?  Ask an aircraft dealer for a test flight and watch these units go and you will see for yourself.

 

Several last items regarding autopilots that the training pilot needs to know.   First is the concept of Axis control.  Typical single engine autopilots control the aircraft on two axes; pitch and roll.  Every action that the autopilot can do for the pilot depends upon its ability to control special servos along the control cables leading to those respective flight controls or trim tabs.  The roll modes are the easiest to understand.  The autopilot is instructed to following a heading or a navigation signal by the pilot’s selection of the “HDG” or the “NAV” button on the autopilot control.  The pilot will know that the AP has armed in that mode by a steady indicator on the AP control or the PFD AP mode display strip common on both the Garmin G1000 and the Avidyne.  Blinking indicators on the AP control unit or a display reflecting “ROLL” tells the pilot that the unit has not achieved the desired state and in fact may never correctly arm without further intervention by the pilot.  Many times the pilot must use HDG mode to drive the aircraft to a point close enough to the desired navigational signal so that the NAV mode will arm.  Pilots should watch these indications closely to make sure that the AP is in the mode they think it is. 

 

Regarding the pitch mode, the pilot must be careful to understand all of the possible modes of the pitch channel of the AP.  Usually, there are two modes on the pitch channel; vertical speed (VS) and altitude hold (ALT).  If the autopilot has an altitude intercept feature, then the autopilot can be configured to climb or descent at a specific rate of speed and then level off at some preconfigured altitude.  Most of the errors we see students make regarding the use of the AP is in this area.  A pilot that is expecting their AP to level off at a preset altitude can be surprised when the AP keeps right on going past that altitude.  This happens by not arming the AP correctly or by disarming it by accident.  Work with your instructor and determine the precise set of steps required to properly arm an autopilot to accept a level off command and then mentally count down the last several hundred feet as that altitude gets close so that no surprises occur. Later model aircraft (2007 and subsequent) have done a much better job in helping pilots to avoid unexpected results and modes from their AP.

 

Every autopilot has one way to turn it on and multiple ways to turn it off.  Know exactly how to turn off the AP in your aircraft and always verify that it is off prior to takeoff and landing.  Perform the prescribed autopilot and trim check prior to each flight as instructed in the autopilot supplement that came with your aircraft.  Some aircraft checklists do not describe this process in detail enough and then pilots begin to skip this step.  This checking process is your final defense to determine that your autopilot is ready for your flight.

 

Conclusion

 

You should now have a better understanding of the autopilots used on glass cockpit aircraft such as the Garmin G1000 and the Avidyne Entegra.  The pilot must learn these systems and become completely skilled at preflight testing, normal and emergency operation modes and their instructors must test their ability to know the autopilot limitations and how to recover from AP stalls and unexpected or uncommanded responses.  The pilot will find that the skillful use of the autopilot is not difficult and in fact can be the key to staying ahead of the ever faster TAA aircraft by allowing them more time to monitor cockpit, navigation, weather, and air traffic conditions. Q