Handling Broken Glass

With glass cockpits becoming more prolific, a wider spectrum of the pilot community is now engaged in flying them. Understanding the implications of malfunctions is an important responsibility of the PIC as higher levels of technology competence and preparedness are required.

While glass presents increased capabilities for pilots, it also offers a new set of problems when the equipment does not function as advertised. While coping may be a bit awkward in the VFR environment, it is a critical issue for IFR operations. Unfortunately, many of the current manufacturers of Technically Advanced Aircraft (TAA) and their avionics suppliers do not offer a complete understanding of the implications of various failures that may occur. This often makes the impact of failure not easily predictable and pilots may face difficult choices in aeronautical decision making and risk management when failures do occur.

Because the display panels and several critical components are duplicated to provide redundancy (such as with the G1000), debilitating failures are rare. Yet there are some units that represent single points of failure such as the Air Data Computer (ADC) and Attitude and Heading Reference System (AHRS) whose failure can create critical situations for the pilot. It is imperative that the pilot understand all of the components and what the options are when they fail.

In some instances failures result in fail-safe backup modes—such as switching a COM unit to 121.5. While these may seem prudent, they can present unexpected surprises if the pilot is not aware of the fallback configuration. Single pilot operations can be particularly impacted—procedures that work well when all is operating normally, may present significant problems when failures occur. The availability and use of memorized and written checklists can provide the pilot with an effective and appropriate means of coping with failures—assuming the checklists are comprehensive and immediately available.

At first glance, the aviating aspect of an AHRS or ADC failure may seem almost trivial as the back-up instrumentation is fully capable traditional round-gauge flight data presentations. The pilot may be tempted to continue as though there is little increased risk. But there are several implications here. For example, the scan now becomes one that, more than likely, has been rarely practiced and redirects the pilot to seldom referenced locations.

In the approach phase the workload and possible change of procedures can lead to distractions that could get you behind the aircraft—the domino effect of failure. While training for these possible situations is an obvious solution, there are limitations to many glass systems—such as the ability to mimic problems—that inhibits realistic failure preparation.

In my experience conducting IPCs, I have found that when the pilot loses the AHRS on the G1000 for example, and begins using the back-up Attitude Indicator, they tend to also revert to using the back-up airspeed and altimeter because they are in the immediate area of the new scan—virtually ignoring the rest of the information still available on the PFD. This disruption of the scan has the effect of introducing more complications to the piloting tasks.

Electrical failure is a major concern because of the heavy reliance of glass on it. When working electrical malfunction scenarios into initial training or an IPC, it is important to ensure the pilot has an awareness of the auto-load shedding features as well as the PICs responsibilities to oversee and augment the process.

The availability of a standby battery to provide up to 30 minutes of power may also seem adequate. But the pilot must understand the use and limitations of the Essential Bus—as the minimum load bus may be called.

During training, setting a timer and allowing the pilot 25 minutes to extract themselves from a critical situation is a worthwhile exercise. The pre-flight brief may define the location of VFR conditions allowing the pilot to select from available options.

Many pilots are not knowledgeable of the checklists in the POH—likewise the importance of the Kinds of Equipment List (KOEL). The KOEL lists the various components against the operations the aircraft is certificated to fly (Day-VFR/Night-IFR etc.) and identifies if that item must be functional to perform that operation. Thus, even before the flight begins, the KOEL can help keep the PIC from inadvertently violating an FAR, not to mention placing the flight at high risk. This is particularly true of the glass cockpit.

A thorough preflight and adherence to the checklist will ensure that required KOEL items are verified as operational. Even the periodic rehearsal of a failure by simply selecting a system or function and reviewing the appropriate POH checklist will help keep the pilot conversant with their location and use. Note that in the checklist, virtually all electrical failures resulting from a tripped breaker allow only one reset.

Knowing the correct response to a failure—and the alternatives—is half the battle in avoiding deeper problems. Even something as simple as the cabin heat can be involved in addressing specific failures.

Because some failures can induce a reversion of the PFD information to the MFD display, the pilot must know what other capabilities are lost. For example, under what circumstances might COM 1 or NAV 1 be compromised?

Ask your CFI for a list of questions that will get you into the POH and help you understand the systems and the consequences of their failures. This is especially true for the autopilot (AP).

Training for failures has become a challenging aspect of the glass cockpit. There are display masks that can overlay the PFD to help prepare the pilot for selected failures. It was easier when we only had to put the rubber suction cover over the desired instrument.

Perhaps no aspect of training is so dependent on well thought out scenarios than glass failures. CFIs need to exercise caution that they don't paint the pilot into a corner from which there is no escape—pilots occasionally do that themselves.

The following objectives must be mastered when training for broken glass: 1) control the aircraft, 2) proficiency in recognizing failures, 3) use all available resources (SRM), 4) make sound decisions (ADM—higher order thinking), 5) apply appropriate corrective action. Failure to achieve any of these is a serious shortcoming.

Simulators can play a key role in training for proficiency in glass failure. But it is critical that scenarios built to replicate failures avoid those areas that the sim does not reproduce realistically. Training that does not provide accurate representations of the conditions that will prevail, is dangerous.

No single aspect of glass cockpit training is more important than a good simulator that can help the pilot acquire the correct sequence of actions to achieve the five objectives noted above. I made the rounds of the various vendors at Oshkosh this year and was impressed with the number of glass cockpit sims that are now on the market. Some of these appear to address failures with reasonable fidelity.

However, all sims have their limitations. Make sure you understand them—especially when working failure modes.

Another strong point with the TAA is their ability to detect failures, as often the system will reveal a problem before the pilot might notice. This is particularly true of the loss of electrical or a bad AHRS (solid state gyro). Some modes provide more time to think and respond rationally. Advising the pilot of the failure and the removal of the erroneous information—with the big red X—is a major advantage of the high-tech TAA.

Another important aspect is the aural and visual warnings through the use of color coded annunciators to provide the appropriate visual alert level. Green, gray, yellow and red typically represent the severity of an annunciated message. Because the message is often accompanied by a flashing alert, pilots are encouraged to turn off the blinking cursor entry field when not actively engaged in data input. This provides increased awareness to any blinking field on the displays.

Even the unlikely failure of GPS navigation (most systems have two) could result in a ded-reckoning drift mode that can provide time for the pilot to work alternative navigation capabilities such as the VOR or vectors.

The TAA and its glass presentations have dramatically increased the utility of aircraft while reducing the risk in GA operations. But these capabilities come at a price of greater awareness of the systems and their failure modes.

Ted Spitzmiller is a FITS certificated CFII and FAASTeam rep. who has the pleasure of editing IFR Refresher magazine.

This article originally appeared in the October 2013 issue of IFR Refresher magazine.

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