Technology Focus: Satellite Weather in the Cockpit

In 2006, the FAA presented a workshop for the National Center for Atmospheric Research, informing participants that weather is more than twice as likely to cause general aviation fatalities than any other factor and is also the largest cause of general aviation fatalities in the United States, equating to 200 deaths annually. Weather uplinks in the cockpit, when combined with a thorough preview of the weather during pre-flight planning and other cockpit weather avionics, will help ensure that general aviation pilots increase awareness and reduce accidents.

Data link weather updates pilots with five to 15-minute bursts, providing localized timely weather data to the cockpit. There are a few options available to receive the satellite feed, from a ground-based VHF data link to atmospheric satellites, but two of the biggest players in the field for data link weather service are XM WX and, coming this spring, Sirius.

XM WX offers two aviation service packages and a choice of either FAA-certified or portable receivers. Avidyne, Rockwell Collins and Garmin have adopted XM WX on their integrated avionics systems. XM allows for receipt of weather data and XM audio through the same antenna and receiver. According to XM’s Web site, eight receivers can be connected to the one antenna. XM can also provide more than 120 channels of news, sports, talk and music. XM WX received the 2005 Editor’s Choice award from Flying Magazine.

Sirius will be airing this spring with WSI’s InFlight. WSI officials say that current InFlight customers must upgrade their systems, installing the new Sirius-enabled hardware and pricing is currently unavailable. However, WSI is a sister company of The Weather Channel and hopes to provide customers with an expanded signal and a solid relationship with Sirius. The new InFlight avionics will be an FAA-certified system.

Mitchell Johnson of Hangar One (hangaroneinc.com), a full-service FBO located in Carrollton, Ga., graciously walked AM through a general description of a typical installation of the Garmin GDL 69/69A weather data system receiver to be displayed on a GNS 530. George Desrochers, VP WSI InFlight, briefed AM on WSI’s next steps.

Garmin’s GDL 69/69A

Capabilities include, but are not limited to: high-resolution NEXRAD; METARs; TAFs; TFRs; lightening; and AIRMETs. XM Radio is available with the GDL 69A. The information can be displayed on a variety of devices, such as the Garmin MX20, GNS 530/GNS 430, Avidyne EX 500 and Bendix/King KMD 850. Garmin offers a service package for $29.99 a month and XM charges an activation fee of $75. The cost for the system is about $5,000, plus installation. As any good mechanic knows, a major alteration such as this type of installation must use approved data. This data can be acquired from a type certificate, supplemental type certificate, a designated engineering representative or FSDO field-approval. All major alterations require the use of the FAA Form 337.

Installation

After the plane is in the hangar, the first step is to engineer a wiring diagram specific for the installation. The manufacturer’s installation manual provides general wiring information, which must be adapted to each unique situation. Every wire on the diagram is given an identification label, which will correspond to the wire in the installation. During the engineering process, a mechanic performs an analysis of the aircraft’s electrical system and the load imposed by the system to be installed.

Next, a wiring harness is fabricated and careful measurements are made in the aircraft for wire lengths. The wires are then brought into the craft and routed. This could involve removing upholstery, carpets and sidewalls. This removal takes time and should be planned for and factored into the installation costs. The wire bundles should be routed with, and secured to, existing wiring. The GDL 69 sensor is a remote-mount unit installed on a shelf in the aircraft avionics compartment. To install the sensor rack to the shelf use riv-nuts, cert-nuts or nut plates. The sensor rack is secured to the shelf and the sensor installed.

Install the GNS 530, or other chosen display, in the radio panel in accordance with the display installation manual. Wires are routed to their destination and terminated into connectors at the equipment location. Circuit breakers are bused and power and ground connections made. Each new circuit breaker must be labeled. Many installers turn to specialized companies that refurbish and retrofit circuit breaker panel overlays, giving the final product a very professionally finished look.

The antenna is installed on the upper fuselage. Antennae installation is pretty straightforward on a non-pressurized aircraft and is done in accordance with the system installation manual (in conjunction with AC43.13-1B/2A). When installing an antenna on a pressurized fuselage, it is vital to use approved data. If there is no STC for the installed system in your model aircraft, then the easiest, most cost-effective source of approved data is a designated engineering representative. Depending on the Flight Standard District Office, an antenna installation onto a pressurized fuselage can receive field approval. It is important to understand the manufacturer’s installation instructions regarding antenna location. Most manufacturers give minimum distances from the system antenna to other antennae, skin sections and overlaps. For optimal system performance, follow the manual instructions.

An antenna installation, particularly on pressurized aircraft, requires a skin doubler. Often the factory-supplied doubler is not appropriate (especially for a pressurized cabin). It is common for the installation shop to fabricate and install a custom doubler for each job. This practice may add several hours to the installation, so time should be considered during planning. The doubler should overlay and attach to some existing aircraft structure. Pick up the appropriate existing rivets, lay out the rivet patter, locate and drill the rivet holes, the center hole and four screw holes. Antenna doublers normally use counter-sunk rivets. When using 1/8" rivets on skin thicknesses smaller than.040", dimple the countersinks. Apply a film of pro-seal between the doubler and skin when installing.

To ensure a good electrical bond between antenna and airframe, the antenna footprint should be stripped of paint. Hold the antenna in place, draw the outline and mask with aluminum tape. Strip the paint and clean the area thoroughly with water. Apply alodyne to stripped metal to restore corrosive protection. The antenna is now ready to be installed. The antenna should be sealed with a thin bead of proseal, which dries like a very hard rubber, rather than RTV, which is more like silicone. The antenna cable is now routed and connected.

Before applying power to the newly installed system, check that power, ground and lightening connections are on the appropriate pins on all connectors. When installation is complete, the aircraft owner initiates the service subscription. Finally, follow the test procedures in the installation manual.

An installation of this type typically takes less than a week, but the more complex the installation, the longer it will take to complete. There are some more extensive avionics refurbishments that could take a month or more to complete.

Maintenance for the GDL 69

For each system, the manufacturing provides instructions for continued airworthiness. These instructions will assist in future maintenance. If a problem occurs with the system, follow the procedures in the ICS’ and the installation manual. If you aren’t getting the required test results, try to determine if it is the unit, the installation wiring or the subscription service. "If the problem can’t be identified, maybe the owner has not paid for the subscription. A signal won’t come until the subscription fee is paid," Johnson said, and all too often mechanics are finding that this is the case.

If there is a problem with the unit, return it to Garmin for repair or, if under warranty, get a new one from them. If it’s the wiring, check for continuity or shorts to ground. Inspect the unit, rack, connectors. "Smell it, feel it, visually and physically inspect it," says Johnson. Is it getting power? Does it have grounds? Modern avionics systems installed in high-quality shops are extremely reliable and fault free. The installer working in concert with the equipment manufacturers quickly resolves any problems that do occur.

WSI’s InFlight

InFlight was co-developed with NASA and when the hardware transition is complete, it will receive its broadcast from the Sirius Satellite radio constellation. The Sirius signal enables InFlight to reach further into Canada and deeper into the Caribbean and Mexico. Capabilities of InFlight include, but are not limited to: WSI NOWrad Radar; METARs; TAFs; TFRs; storm tracking and lightning. Canadian radar data is on the current feed and will continue. The system is compatible with any portable display that runs Windows and many panel mounted displays. InFlight offers unlimited usage service packages, starting at $479 per year and the cost of the systems runs about $5,000. These prices will change when the new system is completed. WSI is offering existing and former WSI InFlight customers a $1,200 voucher. The voucher allows a $1,200 rebate on either the AV300 or AV350 system, but is not applicable to customers selecting the Pay-As-You-Fly subscription packages. The only difference between the two systems is that the AV350 delivers both weather and Sirius radio content. The rebate offer expires on December 31, 2007.

A System in Transition

As technology develops, upgrades in hardware can become a necessity. WSI began work on the InFlight upgrade more than a year ago and sought a data link weather service provider that would offer long-term viability and an expanded coverage footprint. Sirius offered frills too, including audio entertainment in the cockpit. However, the current AV200 receiver and antenna will need to be removed and the upgraded equipment, AV300 and antenna, installed.

Service from Sirius will be available when the new hardware is expected to arrive later this spring. The new hardware is compatible with the Sirius feed and with AV100 and AV200 product lines. Also, the new AV300 receiver will fit in the same space that the AV100 and AV200 occupied, and there will be a drop-in replacement for the current AV100/AV200 antenna. The new antenna is slightly larger, but, according to WSI’s InFlight VP, Desrochers, the hole pattern, mounting pattern and connection are the same as the existing antenna, cutting down on installation time. WSI’s current satellite, the MSat II and the Sirius satellite will both operate through the fall when the switch to Sirius should be completed.

The satellite transition for current WSI customers should last from the spring of 2007 to the fall 2007. During this time, customers can order a transition kit from their dealer and install the new hardware and antenna. WSI offers a dealer extranet site and a customer service department that will help ease the transition for both mechanics and pilots. They are also leading a workshop during the upcoming Aircraft Electronics Association Convention and Trade Show in Reno, Nev., at the end of next month.

Further information regarding WSI’s InFlight is forthcoming; Desrochers said final details would be issued within the next few months.