Avionics News May 2012 - 41
Europe who already has typical U.S. equipment (VHF nav/comm and Mode C transponder) can do so by adding only a single HF radio, but will be limited to a specific route and unable to fly instrument flight rules in European airspace. With additional equipment, more flexible routing and IFR operations become available. A warning: This topic is complex and changes regularly. What follows will provide a rough outline of the general types of avionics required for international operations, but by no means is it comprehensive. Avionics shops and technicians should counsel operators to check for upto-date information. Links to a variety of useful sources are provided as well. COMMUNICATIONS While VHF voice radio remains the worldwide standard for aircraft communications over land, it is limited to line-of-sight operation (150 nautical miles or less, even at airline altitudes). For oceanic and remote area operations, other technologies are required. Traditionally, this has been filled by HF single-sideband voice radios, which actually are the latest versions
of technology dating back to the 1930s. While HF is not limited by line-of-sight, it is affected by various layers in the atmosphere (and even by solar activity) to a much greater degree than VHF. The equipment for HF also tends to be heavier and somewhat more complex than VHF. In particular, because of the long wavelengths involved (25 meters for a quarter-wave dipole at 3 MHz), antenna tuning is required. Satellite-based communications is an alternative to HF radio for long-range communications, but it has not completely replaced it. In 2011, the Federal Aviation Administration approved the Iridium satellite communications network as a method for implementing the Future Air Navigation System 1/A data standard as “a cost-efficient alternative” to existing methods, specifically for commercial and business operators. Even for small private operators, Iridium’s voice service can provide an effective and flexible backup to HF in transoceanic and remote areas.
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“Areas with high-traffic density, including most European controlled airspace, may require operators to have specific traffic detection and avoidance equipment.”