Glass Cockpit Partial Panel

Most turbine airplanes have three-screen panels, with a PFD for both front seats. In the event the pilots-side PFD dies he/she is expected to continue using the PFD on the other side of the airplane, although the option of manually selecting PFD information on the center screen always exists as well. Pilots brought up flying traditional round-gauge IFR might not even consider the reversionary mode to be "partial panel" at all. This valuable feature makes partial panel flying easy...if the partial panel results from failure of the PFD hardware. Because it is an important advance in ease of flight in the case of primary flight instrument failure (i.e., those directly in front of the pilot), it gets top billing as a safety advantage of glass cockpit airplanes. Except for a little parallax (viewing the instrument from the side, not head-on) everything is exactly as it normally appears for the partial-panel flyer, and all functions (including the autopilot) remain fully operable. The biggest difference is that large-scale moving map, engine and fuel management, checklists, charts and other functions are relegated to a small window in the corner of the most recent-model MFDs when in reversionary mode, and are not available at all in some earlier installations. Pilots who grow too dependent on these functions, or who eschew paper checklists and navigational charts in favor of electronic versions on the "big screen" will find themselves outside their comfort zones in the event of a PFD hardware failure.

Tom Turner

Monday, December 29, 2008 at 12:00 AM ET

Verified

Key Takeaways:

Glass cockpit aircraft can experience three primary partial panel failure modes: PFD hardware failure (often mitigated by reversionary mode), AHRS/ADC sensor failure (resulting in "Red X" displays), and total electrical failure.
Each failure type presents distinct challenges, from minor operational adjustments during a PFD hardware failure to critical reliance on minimal backup instruments and approximate power settings during a total electrical outage.
Training for these failures is often limited, with instructors commonly focusing on easier-to-simulate PFD failures; thus, pilots must deeply understand their aircraft's systems, practice frequently, and develop personal procedures for all potential partial panel scenarios.

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Modern “glass panel” avionics give pilots an unparalleled level of situational awareness. But what happens when a hardware or software failure, a sensing issue or a total electrical outage takes away that awareness? Which capabilities remain and which dont? How can instructors present failure modes with maximum realism to prepare pilots for real-world failures?

There are three distinct failure modes resulting in partial panel flight in glass cockpit airplanes:

1. Hardware failure of the Primary Flight Display (PFD);

2. Attitude Heading Reference System (AHRS) or Air Data Computer (ADC) failure rendering part or all flight instrument data unavailable;

3. Total electrical failure or system outage.

Lets look at each in turn, including causes of the failure, what partial panel capabilities remain, and how experienced instructors present the failure mode in training.

PFD Hardware Failure