Partial Panel Peculiarities

Probably the most difficult task on the Instrument Rating (IR) practical test is Area VII, Task D: Approach with Loss of Primary Flight Instrument Indicators. But why is the FAA so concerned about this? In their own words from the IR Practical Test Standards (PTS):

The FAA is concerned about numerous fatal aircraft accidents involving spatial disorientation of instrument-rated pilots who have attempted to control and maneuver their aircraft in clouds with inoperative primary flight instruments (gyroscopic heading and/or attitude indicators) or loss of the primary electronic flight instruments display.

As we transition from the typical light aircraft of the 20th century to the far more sophisticated glass panels of the 21st century, the philosophies of both training and testing are changing. From the classic 6-pack of flight instruments with electric turn coordinator and vacuum-driven attitude and heading indicators, to the multifunction displays with redundant attitude/heading reference sets, (AHRS), powered by redundant electric power supplies with backup attitude, altimeter, and airspeed indicators of classic design.

The addition of non-attached cockpit devices, such as the Garmin handhelds with their 5-instrument display, and uncertified backup units such as the Dynon D1 Pocket Panel, is also increasing the options available to pilots of aircraft legacy panels (or even pilots of glass panel planes if the lights ever do all go out).

Perhaps the first question to ask is what partial panelmeans. The Instrument Practical Test includes a task involving the loss of primary flight instrument indicators. The PTS says that this covers loss of the gyroscopic heading and/or attitude indicators (typically the attitude indicator, AI, aka artificial horizon and heading indicator, HI, aka directional gyro or loss of the primary electronic flight instruments display (usually the primary flight displayor PFD).

For classic 6-pack panels, this usually means the result of a vacuum pump failure which takes out the AI and HI. Simulation of these failures remains the classic instrument covers.

With glass panels like the Garmin G1000 or Avidyne Entegra Rev 9, the PTS doesnt specifically say what this means, so were left to some analysis based on possible system failures. For the G1000, Garmin provides a nice pamphlet on training for this situation (http://snipurl.com/guidefordpesandcfis). In addition to simply dimming the PFD to black as one simulated failure, it also sug- gests pulling the circuit breakers on the Attitude/Heading Reference Set (AHRS) and/or Air Data Computer (ADC) as means of simulating realistic failure modes.

However, Cessna recommends against pulling circuit breakers, and their guide suggests dimming the PFD or MFD, or dimming both to simulate failure of the underlying systems (AHRS/ADC). Another option is to make some custom overlays that can be hung from the knobs at the top of the PFD, with red X covers for the appropriate parts of the screen. Internet discussion boards suggest that several instructors have done this, but there does not seem to be any commercial availability.

In developing training scenarios, I think its important to tailor the training to the actual configuration of the aircraft with regard for the likelihood of multiple unrelated simultaneous failures. The purpose of the exercise is to prepare pilots for realistic failures in the aircraft they normally fly.

When working with a pilot whose aircraft has vacuum attitude/heading indicators but also an electric backup attitude indicator, I dont simulate the highly unlikely combination of vacuum pump failure along with a simultaneous failure of the electric AI. Likewise, if a standard 6-pack aircraft has a Garmin GNS530, I do not take away the 530 along with the two vacuum gyros. Instead, I want to see the pilot select the Nav1 page (HSI display) on the 530 and use that. Even if the aircraft doesnt have an installed GPS, if the pilot has a Garmin x96 or Aera handheld with the 5-instrument display, I want to see them use that.

Some may argue that this doesnt exercise all of the skills, which might possibly be needed. However, if instructors insist on taking away the backup tools, which the pilot is nearly certain to have available, the pilot will not be practicing the use of them, and the laws of exercise and primacy suggest the pilot may in the actual emergency not even attempt to use them.

In fact, I know several designated pilot examiners who, when testing the primary flight instrument failure task on an instrument rating checkride, will fail the applicant on judgment if they do not make use of every tool available in the cockpit, whether installed/IFR approved or not. They point out that while those tools may not be certified, in a critical situation, the pilot is not only encouraged but legally authorized to deviate from the rules about navigation/flight instrument system approval by 14 CFR 91.3(b), which excuses such deviation in an in-flight emergency.

Another consideration is just how far to take the exercise. To my thinking, when the primary flight display/instruments are lost in instrument conditions, the only consideration is getting the plane on the ground safely at the earliest time consistent with safety. One should not overfly a suitable field just because it doesnt have an instrument repair shop.

At the same time, one should understand, for example, that some vacuum pump failure modes may have the potential to cascade resulting even in engine failure. For that reason, partial panel missed approaches may not be appropriate-in that situation, it may be better to take ones chances with an ILS or LPV to the runway rather than going around and trying to continue flying without those instruments.

One other question often raised in discussions of partial panel situations is whether or not to declare an emergency. Many pilots fear using what they often call the E-word(they cannot even bring themselves to say emergencyin such a discussion). In some cases, they think that just declaring an emergency will necessitate written reports and forms to fill out. This isnt true, since the regulations (91.3(c) and 91.123(d)) only require such a report if the FAA asks for one, and ATC typically does not do so-they hate paperwork as much as pilots. In fact, failing to declare an emergency is more likely to get you in trouble than the declaration, since declaration of an emergency widens the scope of things controllers are allowed to do, and that means less chance of creating a conflict which does have to be reported by the controller.

Other pilots think the word "emergency" should be used only when there is an immediate threat of death, such as failure of the only engine or being on fire. The Pilot/Controller Glossary says the following:

EMERGENCY-A distress or an urgency condition.

DISTRESS-A condition of being threatened by serious and/or imminent danger and of requiring immediate assistance.

URGENCY-A condition of being concerned about safety and of requiring timely but not immediate assistance; a potential distress condition.

While a well-trained and proficient pilot shouldnt be in imminent danger just because the vacuum pump quits, such a system failure and consequential loss of primary flight instruments should make any pilot at least concerned about safety, and thus being in an emergency situation as the FAA defines it. Better to have available all the help you might want and end up not needing it, than to need it and not have the controller prepared to render it as fast as you may require it.

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