Q: What is done to ensure my panel will work properly?
A: After the avionics technician completes the panel wiring, but before the powdercoating, paint, silkscreen or leather wrap is done, the panel is brought to the test bench. If an aircraft harness is also part of the package, it is also brought to the bench and connected to the panel. If an engine is part of the package (if it is available at the time) it is connected as well.
 

We use a methodical approach to our testing procedure that ensures all systems are tested. The advantage of testing at this early stage is to correct any deficiencies that may be present, before the panel is powercoated or painted. First, a mechanical evaluation is performed, including center stack alignment, switch type and location verification, among other things. We then move to the function of each system, including the audio panel, the com radios, NAV receivers, GPS receivers, transponder and altitude encoder, autopilot, control sticks, engine monitoring, trim and flap system, warning annunciators, and any other equipment associated with the panel. Any discrepancies are noted to be corrected.
 

Then the panel is disassembled, and the metal parts are outsourced for powdercoating and silk-screening. The fiberglass is sent off to be painted or leather-wrapped. When the outsourced parts are returned, the panel is reassembled and returned to the test bench. We then test it all again, making sure any discrepancies noted in the initial test have been corrected. Final checks and inspections are made. The panel is then carefully packaged for shipment.

Q: What is WAAS and is it important to me?

A: WAAS provides significant benefits to the general aviation community. These benefits include safety enhancements, efficiency improvements, and cost savings for the general aviator. Examples of WAAS benefits to general aviation include the following:
 

WAAS Eliminates the Impacts of Global Terrain
Since WAAS, like GPS, is broadcast from above and not from the ground via a line-of-sight broadcast, pilots do not need to worry about losing the signal behind mountainous terrain or other obstacles. This feature makes WAAS very valuable when flying in terrain where such obstacles are prevalent. For example, one pilot sited difficulties faced in areas of Arizona where mountains often blocked reception of VOR broadcasts. Both GPS and WAAS signals would not be blocked in this situation. WAAS also adds the requisite accuracy and integrity to support instrument flight operations.

WAAS Provides a Nationwide Navigation Signal
The WAAS signal blankets the United States, effectively providing navigation capability in nearly all areas of the U.S. Due to the ubiquitous nature of the WAAS signal, pilots are not constrained by the location of ground-based navaids when planning their flight routes. Additionally, due to the high levels of reliability and availability built into the WAAS, pilots can feel a greater sense of confidence that the navigation signal will be there when they need it within the extensive WAAS coverage area. One piece of equipment (WAAS TSO receiver) can provide the aviator with reliable navigation anywhere within the WAAS coverage area.
 

WAAS Provides a High Quality Positioning Signal

WAAS has been heralded as the best source of high-quality positioning information available today. The availability of such a high-quality signal WAAS has been producing accuracies of 2 - 3 meters vertically and 1 - 2 meters horizontally. Although, by specification, the WAAS is required only to produce accuracies to 7.6 meters vertically and horizontally, constant monitoring by the FAA Technical Center and other organizations has shown that WAAS exceeds these requirements on a regular basis. Additionally, WAAS operates under very stringent integrity and availability requirements.
 

WAAS Enables Safe Navigation at Low Altitudes
The highly-accurate position determination and robust integrity of WAAS provides increased situational awareness in the air and enables low-altitude routes. Such routes provide protection from icing and positive guidance in obstacle-rich terrain. One example of how this benefit is making a significant impact is in Alaska where general aviation is a common mode of transportation. Capstone, an Alaska aviation project, is using GPS and WAAS to support such low-altitude route structures. Special Federal Aviation Regulation (SFAR) 97 allows trained pilots equipped with TSO C145/146 GPS/WAAS equipment to fly on lower than usual altitudes. The initial application of this SFAR has opened up 41, 000 feet of usable airspace spread over 1,521 nautical miles of existing routes in Southeast Alaska. Although this application of WAAS is just in the early stages of maturity, the benefits to be gained stand to be significant.
 

WAAS Provides Significant Capability for Relatively Low Cost
With WAAS commissioning taking place this year, WAAS certified avionics are beginning to make their way on to the market. There are currently a few pieces of certified avionics equipment on the market using WAAS for navigation. These units range in price from approximately $7K to $12K; however, they also provide much more than just WAAS navigation, including moving maps and terrain awareness warning systems. As additional receivers find their way to market, it is anticipated that options will grow to include avionics ranging from very simple, less expensive models to highly complex, more expensive ones. Although these units may not yet be in the price range affordable to all, these most recent units are still significantly less costly than comparable navigation equipment used on airliners. Additionally, a WAAS box will require a lot less real estate than the more complex avionics used by airlines. With WAAS, one box can provide en route instrument flight rules (IFR) capability and also enable precision approach capability anywhere in the U.S. where supporting procedures exist.
 

WAAS Increases Runway Availability by Enabling Lower Minimums
WAAS does not enable quite the same minimums as ILS, but comes very close. WAAS provides a highly-accurate and reliable vertical navigation position not provided by GPS. This vertical accuracy, combined with WAAS reliability, and the extensive WAAS coverage area, offers a unique opportunity to enable lower minimums at runways throughout the U.S. WAAS supports LNAV/VNAV and LPV approaches, both providing vertical guidance. Pilots using WAAS can fly to lower approach minima, in many cases down to 250 ft., without additional augmentation in the aircraft or on the ground to provide for safer vertical guidance on landing. WAAS gives aviation users the ability to make vertical guidance approaches at smaller airports with and without air traffic control towers, and where ground-based navigation equipment may not exist to provide vertically-guided approaches.
 

The inherent safety benefits of vertically-guided approaches, which lead to lower minimums, are significant and well-documented. To take advantage of these safety benefits, the FAA has already developed over 500 LNAV/VNAV procedures (as of March 2003) to complement the capabilities of WAAS, and plans to publish 300 new LNAV/VNAV procedures a year. Additionally, the FAA plans to publish the first LPV approaches this year. The accompanying graphic shows existing LNAV/VNAV procedures.

Performance Characteristics

As GPS satellites change position and ionospheric conditions fluctuate, WAAS coverage and performance experience slight fluctuations. WAAS is designed to perform within a stringent set of requirements. If WAAS performance falls below these requirements, WAAS must provide a notification to the WAAS receiver within seconds of any such anomalies. Most frequently, actual WAAS performance exceeds specifications. Although WAAS is specified to operate within an accuracy of 7.6 meters vertically and horizontally, it consistently delivers accuracies within 1 - 2 meters horizontal and 2 - 3 meters vertical throughout the majority of the Continental U.S. and portions of Alaska.