Originally posted by Zaphod58
reply to post by texasgirl
Currently there are special rules in place for UAVs to fly through public airspace. The only ones that are really flying around through any kind of national airspace are Global Hawks. Predators are so small that they are hauled anywhere long distance on a C-130, C-5, or C-17. When a Global Hawk does fly, they try to keep from going through congested airspace. When they do have to, they are in contact with ATC, just like any manned aircraft, and follow instructions like just a manned aircraft. The RQ-4 however, flies higher than any commercial or even private aircraft flies, so there is little to no chance of a conflict with another aircraft.
The FAA is in the process of testing two systems with future UAVs. One is the ADS-B (Automatic Dependent Surveillance Broadcast) that is also used on current commercial aircraft. It broadcasts a signal showing where the aircraft is, so any aircraft that has a receiver will know there is another aircraft in the area.
Far different from radar, which works by bouncing radio waves from fixed terrestrial antennas off of airborne targets and then interpreting the reflected signals, ADS-B uses conventional Global Navigation Satellite System (GNSS) technology and a relatively simple broadcast communications link as its fundamental components. Also, unlike radar, ADS-B accuracy does not seriously degrade with range, atmospheric conditions, or target altitude and update intervals do not depend on the rotational speed or reliability of mechanical antennas.
In a typical applications, the ADS-B capable aircraft uses an ordinary GNSS (GPS, Galileo, etc) receiver to derive its precise position from the GNSS constellation, then combines that position with any number of aircraft discretes, such as speed, heading, altitude and flight number. This information is then simultaneously broadcast to other ADS-B capable aircraft and to ADS-B ground, or satellite communications transceivers which then relay the aircraft's position and additional information to Air Traffic Control centers in real time.
The 978 MHz Universal Access Transceiver ("UAT") variant is also bi-directional and capable of sending real-time Flight Information Services ("FIS-B"), such as weather and other data to aircraft. In some areas, conventional non-ADS-B radar traffic information ("TIS-B"), can also be uplinked as well.
The other is being developed by the military to use on UAVs, that is a "see and avoid" technology. The UAV will have a small radar set installed, and when it sees another aircraft near it, it will take action to avoid any kind of conflict with that aircraft.
The goal for UAV introduction into the US NAS is an equivalent level of safety, including collision avoidance for UAV operation, when compared to piloted aircraft. Flight International quotes the FAA's Nick Sabatini on this issue.
Of the remaining regulatory and technological issues, the goal is the certification of a system of technology, feedback, analysis and control, which reduces the risk of an air to air collision, to the same level of risk currently enjoyed for manned flight, is of paramount interest and importance. The regulations governing DSA are contained within 14 CFR 91.113 "Right of Way Rules". ASTM has published a standard, F2411-04e for "DSA Collision Avoidance" and is available for purchase from ASTM International. David Grilley of Alion Science has recently published a paper with AUVSI which describes the problem and represents an analytical framework to evaluate systems that qualify as candidates for DSA within a small UA system.
The most common term for this capability is Detect Sense and Avoid (DSA). The military uses deconfliction. Progress has been made in DSA technology development, is continuing, and more advances are inevitable. The question is - What level of efficiency is sufficient to satisfy the "Comparable to Manned Aircraft" level of safety requirement for collision avoidance for UASs?
You know, I'm not so sure. There was a close call with a Cessna a few weeks ago in Colorado:
Maybe it's been corrected now?