As more aircraft equip with ADS-B OUT–which broadcasts position, velocity, altitude and other information in unencrypted formats on easily received frequencies–business aircraft operators are concerned about whether they can continue blocking their aircraft from display on flight-tracking websites. While the FAA offers a way for operators to request blocking of particular aircraft from FAA radar data feeds, there currently is no physical means to block reception of mode-S transponder or ADS-B signals by a simple receiver.
European companies, especially in the East, are continuing to refine passive ground-based technologies with the potential to detect stealth aircraft. The best known of these is the detection and correlation of emissions from aircraft–such as from radars, radar altimeters and other navigation devices–using ESM/ELINT techniques, sometimes known as passive emitter tracking (PET).
The Namibia Wam system was supplied by Era, of the Czech Republic, and employs 36 widely separated and unmanned ground stations that listen for aircraft transponder replies to radar interrogations and then retransmit those replies to a central processing station. In Namibia, which has no radar, selected listening posts transmit pseudo, but otherwise identical, radar interrogations.
Italian electronic defense company Elettronica and Abu Dhabi-based Baynunah Aviation Technology recently established the ELTBAT Electronic Systems Development joint venture to act as a center of excellence in the Gulf region in the electronic warfare field.
UK air navigation service provider Nats and lobbying association Oil & Gas UK last month switched their North Sea multilateration system to the “operational” mode, thus improving offshore flight safety. Controllers can now see helicopters on their radar screens in areas that are beyond the 80-nm reach of land-based radar. The multilateration system uses signal transmitters and receivers fitted to 16 offshore platforms.
For many, multilateration (sometimes abbreviated Mlat) is one of those vague ATC terms that is always hard to define. Put simply, it is how a spread-out group of small, unmanned, ground-based “listening posts” continuously monitors aircraft transponder signals, and then collectively triangulates them to derive individual aircraft positions. Following that, they send those positions plus their idents, altitudes and other data to ATC.
Corporate operators heading for Colorado’s Craig, Steamboat Springs, Hayden and Rifle Airports this winter shouldn’t worry about diverting to Denver and having their passengers complete the trip by car. That’s because the Colorado DOT has purchased and installed a $5.7 million Sensis multilateration system to track aircraft accurately well below the mountain-affected line of sight of distant FAA secondary surveillance radars (SSR).
Era Systems last month announced it has been selected to provide an automatic dependent surveillance-broadcast (ADS-B) system to the Jamaica Civil Aviation Authority (JCAA). The JCAA will use the ADS-B network for operational testing in preparation for eventual nationwide, wide-area multilateration and ADS-B deployment.
Automatic dependent surveillance-broadcast (ADS-B) has emerged as what many describe as the surveillance technology of the future, but Asia Pacific air navigation service providers (ANSPs) are already taking advantage of its capability and cost-efficiency.
Although few pilots may know the word, multilateration is quickly becoming a household term among air traffic controllers and airport authorities. But pilots will ultimately be one of its major beneficiaries.
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