Tuesday, July 6, 2010
Is Glass Safer?
Making sense of the NTSB glass-cockpit report
Improving Safety In Glass Cockpits
By Tim Decker
|During the last eight years, the majority of GA aircraft, including Cessna, Cirrus, Diamond, Mooney and Piper, have switched from traditional analog cockpit instrumentation to glass cockpits. Many older aircraft are being retrofit with modern avionics that include IFR-approved GPS units, autopilots, primary flight displays (PFDs) and multifunction displays (MFDs), which give many of the same safety advantages that glass cockpits offer. However, a recent NTSB study concluded that glass-cockpit aircraft were no safer than conventional instrumented aircraft.
Disadvantages of traditional analog instrumentation are the multitudes of mechanical components: gyroscopes, delicate flywheels, gimbals, seals and motors. Diaphragms, tubes, gears, springs, pins, needles, pointers and housings make up other mechanical instruments. Gyroscopes lose accuracy during flight, and mechanical components wear out. Frequently repairing or replacing analog instruments is expensive.
One principal advantage of glass cockpits is the elimination of these delicate mechanical components. Instead, solid-state electronics found in glass cockpits are more reliable and less prone to wear and degradation because of normal aircraft operations.
The close grouping of the traditional “six pack” (airspeed, attitude, altimeter, turn & bank, heading, vertical speed) into a single display in a glass cockpit makes for a faster and more efficient cross-check. The addition of GPS, weather, airspace and traffic information adds to the pilot’s situational awareness and increases safety. All this is terrific, but a phenomenal improvement to safety that comes with glass is the solid-state Attitude Heading Reference System (AHRS), which is exponentially more reliable and accurate than vacuum-pump-driven attitude and heading systems.
The many advantages of glass come at a cost other than money: time. Time is required for training in order to develop proficiency. The NTSB recommendation for training on specific equipment is critical to realize the safety potential of glass cockpits.
A VFR pilot transitioning from steam gauges to glass needs to be comfortable with quickly finding and processing the traditional six-pack instrument indications, as well as engine, communication and navigation information on the PFD and MFD. An IFR pilot requires the same, plus an excellent understanding of how to use navigation and autopilot functions.
Without familiarization training, a simple change of a radio or navigation frequency can cause confusion, distract the pilot and take longer than using a stand-alone radio in a traditional cockpit. Entering a flight plan in the GPS and knowing how to quickly add or delete points in-flight require more training, and is essential for safe flight, especially in busy airspace or deteriorating weather conditions.
For the instrument pilot, an ATC clearance to intercept a Victor airway from an assigned heading is fairly simple using conventional instruments—tune the VOR frequency, dial the airway course, stay on heading until the VOR needle centers and then turn to keep the needle centered. Doing this same task using an IFR-approved GPS can be just as simple, but requires a completely different set of steps to accomplish—highlight the second waypoint of the intercept airway on the GPS flight-plan page, press the Direct button twice and press Enter to accept the “Fly leg X to Y?” message (Garmin 430/530/1000). Additional training is required in order to make the autopilot fly this autonomously, even though it’s very similar to autopilot intercept of VOR course (instead of GPS course).
Is the glass-cockpit training worth it? Definitely! Flying a conventionally equipped aircraft with a vacuum-driven attitude indicator and only dual VORs and possibly DME in hard instrument conditions is difficult and limits useful information available. A PFD and MFD combination displaying a moving map, terrain, weather and traffic information increases situational awareness tremendously. The added benefits of more reliable equipment is icing on the cake.
For pilots considering an upgrade to a glass cockpit who want to reap the numerous advantages of modern avionics, there are numerous training options. Many suppliers provide Internet-downloaded trainers free of charge, and there are free online interactive courses. Commercial DVDs and simulator training are extremely useful, too. Most importantly—realistic flight training using the specific system in busy airspace during less-than-ideal weather with an experienced glass-cockpit flight instructor is a must.
Tim Decker (timdeckerairshows.com) is an ATP pilot with CFI, CFII, and MEI ratings and has thousands of hours in the F-117, U-2 and other aircraft.
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