Well-Equipped Though avionics technology offers a lot desirable options, careful consideration should be given to how many "bells and whistles" are actually necessary for the aircraft By Jim Sparks October 2000 What exactly is a...


Though avionics technology offers a lot desirable options, careful consideration should be given to how many "bells and whistles" are actually necessary for the aircraft

By Jim Sparks

October 2000

What exactly is a well-equipped aircraft when it comes to Avionics? When going out to buy a new car, "well-equipped" translates to "Includes ALL the bells and whistles." This can sometimes be the case with modern aircraft. Just like when buying a car and negotiating the option package with the dealer, common sense should prevail.
First of all, consideration should be given to the "Primary Mission." For example, a single engine private aircraft used for weekend excursions of only several hundred miles and daylight Visual Flight Rules (VFR) conditions, would not require the same Avionic package as a multi-engine machine used to transport passengers for hire on a scheduled basis. Consideration for Primary Mission should include the following questions:
Graphic• Is the aircraft a convenience or a necessity?
• What is the normal duration of flight?
• How much time is spent in instrument conditions?
• Does the aircraft require an automatic flight control system to achieve high altitude or high-speed flight?
• What is included in the basic instrument package?
• Will the selected equipment easily interface with the airframe and engines?
• Will maintenance requirements change?
• Is the selected equipment addressed in the Minimum Equipment List (MEL) to allow for a high dispatch rate?

A manufacturer's Master Minimum Equipment List (MMEL) will often lend to the reliability of the equipment. The more equipment listed can often translate into more things to go wrong. How much time is spent in areas with special flight requirements such as Reduced Vertical Separation Minimums (RVSM)? What about the level of complexity?
The demanding expectations of business aviation require systems with high reliability for a high dispatch rate plus a balance of simplicity and sophistication. Flight deck arrangement and maintenance accessibility are two other key factors in system selection.
Modern Avionic system architecture is based on the use of advanced built-in maintenance diagnostics along with a high level of redundancy in the primary components. By utilizing integrated concepts, complex wiring is reduced resulting in less possibility of failure not to mention significant weight saving.

Glass cockpit benefits
One of the challenges encountered by the designers of aircraft flight decks is to increase the awareness of the crew while reducing the clutter. The "Glass Cockpit" will in fact, cut pilot workload while increasing the amount of needed information for the crewmembers.
Electronic Flight Instrument Systems (EFIS) such as the Collins EFIS 4000 are comprised of four identical displays including two Primary Flight Displays (PFD) and two Multi-Function Displays (MFD).
Each pilot has the ability to control the two displays in immediate view. The PFD combines all the information included in the Basic "T," which contains:
• Barometric Altitude
• Attitude
• Airspeed
• Vertical Speed
• Horizontal Situation
When Instrument Landing is used, symbology automatically appears enabling the crew to maneuver the aircraft down the glideslope and relative to the runway centerline and can even illustrate the point where the main wheels touchdown. This data can often be shown in analog as well as digital formats. In addition to the basics, other important information such as speed cues based on Angle of Attack (AOA) and Stall margin along with acceleration monitors that enable the crew to determine engine thrust levels are at normal levels and no uncommanded braking is present. These capabilities provide the flight crew a significant increase in situational awareness. This higher level of safety is considered paramount by corporations when outfitting a business jet.
Even a single engine recreational aircraft can benefit from this technology. Even though there may not be room for four electronic displays in a small aircraft cockpit, the benefit of only two "tubes" to the pilot can be significant. In fact, EFIS Retrofit packages are currently available for many General Aviation products.
With a single propeller in the direct line of sight of the pilot, an acceleration indicator may qualify as "Bells and Whistles."

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