ANNEX C 1 STUDIES, TRIALS AND TECHNOLOGY DEVELOPMENTS 1.1 DNA-FFVV WORKING GROUP (2001) AND STNA EXPERIMENTS/FLIGHT TRIALS (2003)

ANNEX C 1 STUDIES, TRIALS AND TECHNOLOGY DEVELOPMENTS 1.1 DNA-FFVV WORKING GROUP (2001) AND STNA EXPERIMENTS/FLIGHT TRIALS (2003) 1.1.1 On 12th February 1999, the crew of an Airbus A320 approaching Montpellier airport saw two gliders approaching them from opposite directions. Unfortunately, a collision with one of them occurred. This event triggered the establishment of a French DNA-FFVV working group to study the technical means of avoiding this type of scenario. 1.1.2 Flight trials were conducted using an ATR equipped with ACAS and a number of gliders, flown in clusters, equipped with Mode A/C transponders. The resulting data obtained demonstrated that the radar and ACAS system performance were greatly degraded due to garbling of the Mode A/C replies. 1.1.3 As a consequence, it was decided that the trials should be repeated using Mode S transponders. Due to the unique addressing of Mode S, it was expected that the heavy garbling, which had caused incorrect trajectories and inappropriate TCAS alerts in the 2001 trials, would be eliminated. The only other concern was that of the capability of the ACAS logic to deal with numerous intruder situations. 1.1.4 In 2003, five TB20 s were fitted with Mode S transponders. Gliders were not used due to problems encountered in 2001 with weather conditions. A mixture of Honeywell KT73 and Garmin GTX330 transponders were used and various configuration scenarios were flown. 1.1.5 Using classical multi-radar tracking, garbling existed and this led to incorrect trajectories and false altitude information being displayed. However, using Mode S radar the aircraft were perfectly tracked. The only concern was that of confusion caused by the overlap of the aircraft labels on the controller s screen and the cluster appearing as a single comet. Therefore, the controller had no idea how many aircraft were present in the cluster. 1.1.6 With regard to the ACAS functionality, if one of the transponders is eliminated from the results, because it did not comply with the ACAS standards for minimum range, then the detection rate was 100% for 98% of the time. This can be compared to 30% for co-altitude and 65% for vertical separation achieved in 2001 using Mode-A/C. Tracking and altitude tracking quality was excellent. Bearing information error averaged at 10, which is slightly higher than the accepted level. However, loss of bearing was rare; lasting only a few seconds and it occurred at high elevation angles. C-1 of 9

1.1.7 ACAS logic proved acceptable for all scenarios except head on, where 3 aircraft faced the ATR and were separated vertically by 500 FT (+500ft, co-altitude, -500ft). Another limitation was found with the ACAS display, which was not originally designed for traffic situational awareness but simply for anti-collision purposes. The working group have proposed new designs that provides an indication of other aircraft s heading and route. 1.1.8 In conclusion, the Mode S trials were extremely successful and proved the worth of fitting Mode S transponders to light aircraft. However, the benefits in radar control can only really be seen when Mode S radar coverage becomes generalised. In addition, the report concluded that a reduced functionality, and therefore reduced cost, Mode S transponder must be approved in order to make the technology available to GA communities. The study group also advised that the issue of battery power consumption by transponders should be investigated. 1.2 UK DEVELOPMENT OF A PROTOTYPE LOW POWER LAST 1.2.1 The UK CAA has been working with industry for several years to assess the technical feasibility of a low power LAST. Funding was provided to RACAL to develop a non-icao compliant 20W prototype based on Mode A/C. It is made up of two sections: mounted on the upper section is an integral antenna and display screen and situated on the lower front end panel is the main unit keypad. The transponder is light weight, battery powered and has a maximum peak power output of between 10 and 20W. 1.2.2 Progress has been slow but the prototype eventually undertook flight trials in May 2003. It is understood that these trials were successful and proved the concept. As reported by the UK CAA at a EUROCONTROL CIMSEL Focus Group meeting, the 20W LAST interacted with surveillance radars at ranges of up to 40nm and an ACAS II equipped BAC 1-11 at 12nm. ACAS II TAs were also successfully generated. It is further understood that a formal report of the flight trials is being produced. 1.2.3 Battery life trials using lithium batteries were not conducted during these flight trials. However, throughout the development, engineers sought more modern materials rather than developing existing transponder technology. In this way they were able to lower the power consumption of the unit. 1.2.4 No EMC studies have yet been conducted on the prototype LAST but the unit would need to be developed to meet the necessary electrical standards. The cost has also not been evaluated for the development of such equipment but the UK CAA has a target of around 800. 1.2.5 Since the flight trials of the Mode A/C prototype, funding from the UK Department of Trade and Industry has been made available to continue the feasibility assessment of a Mode S capable 20W LAST. Good progress is being made and the CAA is very hopeful that a marketable version could be available in 2008. There is also considerable interest in this product from the renewable energy industry and the Australian aviation authorities. C-2 of 9

1.3 IFF/SSR ENVIRONMENTAL MODELLING 1.3.1 Environmental modelling of the SSR frequencies is routinely conducted by only a few European States, notably the UK and Germany, and EUROCONTROL. It is generally accepted that the modelling indicates that an increase in the carriage and operation of Mode A/C transponders by Light Aviation aircraft could produce an intolerable additional loading on the SSR reply frequency of 1090 MHz. However, it is believed that the increased carriage could be safely accommodated in Europe through the implementation of Mode S transponders in a predominantly Mode S environment. Unfortunately, no definitive modelling scenarios and results have yet been published and it is likely that further work will be required in this area before any increase in transponder carriage could be implemented. 1.4 OHIO VALLEY PROJECT 1.4.1 In the Ohio River Valley, a cooperative government/industry program called SF-21 has been assembled to develop enhanced capabilities for free flight, based on evolving communication, navigation and surveillance (CNS) technologies. The program is demonstrating amongst other things, the worth of a cockpit display of traffic that will provide improved information for controllers and flight crew. The new technologies being used include the Global Positioning System (GPS), Automatic Dependent Surveillance Broadcast (ADS-B), Flight Information Services - Broadcast (FIS-B), and Traffic Information Service Broadcast (TIS-B), to integrate with enhanced pilot and controller information displays. Safety improvements that these technologies make possible are being examined and, in certain cases, will facilitate the certification of these technologies. 1.4.2 One of the objectives of the program is to enable and expedite the See and Avoid principle and enhance the surveillance capability in non-radar airspace. In July 1999 and October 2000, flight trials were conducted to demonstrate the See and Avoid and aid to visual acquisition applications using ADS-B technology and cockpit display of traffic information (CDTI) 1.4.3 SF-21 is also exploring avionics development under a Test and Evaluation Surveillance Information System (TESIS), which is designed to evaluate alternative air carrier based avionics for ADS-B applications. Four avionics contractors are currently developing prototype units with a set of core capabilities. Each vendor is developing additional ADS-B applications. 1.5 CAPSTONE PROJECT IN ALASKA 1.5.1 CAPSTONE is a US technology focused Safety Program in Alaska which seeks near term safety and efficiency gains in aviation by accelerating implementation and use of modern technology such as ADS-B and linking multiple programs and initiatives under a common umbrella. C-3 of 9

1.5.2 The CAPSTONE project is divided into two phases. Phase I includes the installation of government-furnished GPS driven avionics suites in up to 200 commercial aircraft, along with a supporting ground based infrastructure. Compatible data link transceivers installed at strategically located ground sites are designed to facilitate air traffic and flight monitoring/weather information services. 1.5.3 In January 2000, Capstone began operational use of ADS-B to provide VFR and IFR surveillance services in non-radar airspace in southwest Alaska. This event marked the beginning of Air Traffic Control (ATC) use of ADS-B for separation, vectoring, and sequencing aircraft. This ADS-B surveillance information is also being routed to airline operators for flight following and to assist in search and rescue. 1.5.4 Phase II of program will incorporate technologies matured in the Phase I, while building on lessons learned to provide a more useable IFR infrastructure. This will focus on improved surveillance and traffic awareness amongst others. 1.5.5 On 31March 2003, Capstone initiated en route navigation using the world s first GPS/WAAS receiver certified for aviation use. Special FAA Regulation 97 provided authorisation for trained pilots to use the GPS/WAAS receivers as the sole means for en route navigation in Alaska. Already, this has produced an additional 41,000 feet of usable airspace along 1,521 nautical miles of the existing route structure in southeast Alaska. Approximately 200 aircraft, both fixed-wing and rotary, will be fitted with upgraded and certified avionics. This next generation of avionics will include ADS-B and explore new capabilities, including WAAS capable GPS, see and avoid/traffic warning system, and enhanced awareness and avoidance. These avionics will be compatible with the ADS-B ground and airborne infrastructure. Both the ground and airborne segments will be upgraded to meet the RTCA Universal Access Transceiver (UAT) MOPS. 1.5.6 It has been suggested that CAPSTONE equipped aircraft have had 40% fewer accidents than those not equipped. To determine whether this is a long-term trend, further data must be collected. 1.5.7 The avionics suite for CAPSTONE participation comprises a UAT radio data link system supporting broadcast services, a MX029 colour cockpit display (6 in size) and a GX60 TSOC129(A1) certified GPS navigation and communication solution (2 in size).the prime contractor for the supply of the ground based ADS-B technology for the CAPSTONE project is Sensis. Their ADS-B transceiver links the aircraft avionics with the existing ATC infrastructure. The link can be either Mode S Extended Squitter or UAT. It receives and relays the latitude, longitude, velocity, heading and ID information as determined by a global navigation satellite system (GNSS) such as GPS. C-4 of 9

1.6 GERMAN FILSER MODE S LAST 1.6.1 Out of all the avionics companies contacted as part of this study, only Filser has shown an interest in developing a LAST. Filser manufactures a number of transponder options for light and GA aircraft: a) The TRT600 is certified to ED0115, NTS-23 & CS-ETSO-2C112a standards, and is a LAST approved Mode S transponder manufactured for aircraft with a maximum operating weight of 5,700kg and a ceiling height of 15,000ft. It is a Class 2, Level 2, 57mm panel mounted transponder with a maximum operating output power of 150W at the device and 72W at the antenna. It is powered by 14VDC from the aircraft s supply and supports only elementary SSR functions. It has no Extended Squitter functionality. b) The TRT800 is similar to the TRT600 in size, max operating weight, ceiling height, power consumption and output power but does support Enhanced Surveillance, having Extended Squitter functionality. However, the TRT800 is not LAST approved. Both the TRT600 and 800 weigh around 0.7 kg. 1.6.2 In addition, Filser are also developing the following: 1.7 ADS-B c) An ADS-B receiver (RT60) 1090MHz, to recognise Extended Squitter d) A hand held version of the TRT600, powered by a rechargeable battery. This is not certified. 1.7.1 ADS-B is the periodic broadcast of aircraft identification, position, velocity and intent information used by ground systems or proximate aircraft. It allows both pilots and controllers to have a common situational awareness of all appropriately equipped users. ADS-B applications will enable new procedures, such as air to air, air to ground, ground to air, and on the airport surface, having the potential to increase safety and efficiency of the airspace system. 1.7.2 There are a number of GPS based ADS-B products currently under development that are suitable for light aircraft. However, as with all the technological solutions, in areas of high traffic density, such as glider clusters, it is difficult for pilots to comprehend the detailed situational picture, as well as maintain good visual See and Avoid principles. In fact, the technology may even prove to become an additional distraction from using the naked eye. C-5 of 9

1.7.3 As part of the CAPTSONE trials, the FAA has attempted to develop ADS- B technical standards for ADS-B technologies in parallel with the work carried out by the RTCA. They have carried out a number of flight tests, technology simulations and cost benefit analysis in order to determine the most suitable technology for ADS-B. In their opinion, there are only three real candidates: Very High Frequency Data Link Mode 4 (VDL-Mode 4); Mode-S Extended Squitter (ES); and the Universal Access Transceiver (UAT). 1.7.4 Their report concludes with determining the most suitable candidate for a particular aircraft category. General aviation that does not regularly enter busy airspace such as TMAs are classed as low and mid level GA. This category of aircraft is most interested in Flight Information Service (FIS) and the FAA analysis determined that UAT was the most capable link for providing FIS. It is also expected to be the least expensive option. However, in coming to that conclusion the FAA have made the following assumptions: e) As UAT international standards have not yet been agreed, that this category of aircraft rarely flies internationally. This may be true in the US but in Europe the situation is different due to the small land masses. f) That the risk of collision is predominately between other GA and non-commercial aircraft due to the altitude at which they fly. 1.7.5 UAT does offer air-to-air interoperability for low to mid end GA users but, in order to have complete situational awareness, a ground infrastructure is required to uplink the Traffic Information Service (TIS) in a broadcast manner. For high end GA users, which do operate in busy airspace and high altitudes, the FAA propose that Mode-S Extended Squitter is best solution because it achieves interoperability with existing commercial air traffic across international boundaries. 1.8 FLARM 1.8.1 FLARM is a small, low cost, low power device, designed specifically for glider pilots due to the number of lethal collisions involving gliders. FLARM broadcasts its own position and speed vector, obtained by integrated GPS, using a radio data link. At the same time it listens to other compatible FLARM devices in the vicinity. It is small, light and has low power consumption. FLARM is also affordable, easy to install and is commercially available now. 1.8.2 Intelligent track prediction algorithms predict short-term conflicts and warn the pilot acoustically as well as visually. FLARM incorporates a highprecision WAAS 16-channel GPS receiver and an integrated low-power radio transceiver. In addition, it contains a database of static obstacles like cables and antenna but these must be continually updated to function properly. Care must also be taken to load the appropriate terrain software for the location in which flights are conducted. C-6 of 9

1.8.3 Although the RF communication protocol is to be published royalty free, the success of such a system depends on its adoption as a standard piece of equipment for all light aviation. In addition there are issues such as the legality of the digital radio and potential infringements with intellectual property rights. However, in Austria, Germany and Switzerland a licence to operate FLARM is not required. Perhaps more importantly, FLARM is not interoperable with ACAS, SSR or ADS-B. 1.8.4 It is believed that some gliding competition directors in Germany are considering making FLARM compulsory for participants from 2005. FLARM could also, in principle, be used on microlights, hang gliders and para gliders. 1.9 STROBE LIGHT DETECTION 1.9.1 Due to the concerns over whether the See and Avoid is still adequate, the UK CAA unilaterally came up with a technological solution to improving air safety, in terms of preventing air collisions, that would support the look out principle. 1.9.2 The CAA decided to conduct a number of flight trials to test the feasibility of fitting light aircraft with a simple anti-collision device. This device was a sensor fitted to the cockpit that was sensitive to the frequency of the radiation of energy from an aircraft s strobe light. The sensor was connected to a simple display that alerted the crew with light diodes as to the direction of any potential intruder. A feasibility study was conducted that confirmed that there was sufficient time to react when alerted if a GA/GA collision was to occur. In fact, it also proved viable for potential GA/military collisions. This device was very simple and very cheap to manufacture. 1.9.3 However, there were a couple of problems associated with the strobe light detection equipment. The first was that the aircraft had to be fitted with a strobe light to be detected. Therefore, it was not suitable for detecting aircraft such as gliders. The second was that many GA aircraft are single engine propeller driven. With the device situated on the glare shield, the propeller provides a similar amplitude modulation to that of the strobe light, thus interfering with the device functionality. The device could have been positioned out of the view of the propeller, for example on the wing tip, but this would have meant installing cables which would have significantly increased costs. 1.9.4 Currently, with the advent of mobile phone technology and cheap radio electronics, this device could be made to operate wirelessly. However, it appears that the momentum behind the project has now been lost in favour for a transponder solution. C-7 of 9

1.10 ADELARD 1.10.1 For ATM, the main catastrophic accident is that of a mid-air collision. A collision model, called Adelard, has been developed to compute the lose encounter rate. This computes how often two aircraft are likely to come into close proximity. However, the model is complicated by safety barriers such an ACAS and STCA, which are designed to prevent loss of separation. Nevertheless, the estimated figures for accidents computed by the model were tested against real figures and the results appear consistent with actual experience. Target levels of safety were then applied to particular phases of flight and airspace. This model may be of further use in assessing risk in the ATM environment. 1.11 BEKLAS 1.11.1 BEKLAS was a study carried out in 2003/4 to improve the recognition of small aircraft. The analysis examined the current problems faced, examined accident investigations and human factors, looked at the potential technological/operational solutions and researched other antcollision projects being conducted. BEKLAS was funded by the Bundesminiterium fűr Verkehr, Bausund Wohnungswesen (BMVBW) 1.11.2 The analysis of the current problem consisted of analysing over 50 sources of data and literature for airspace structure, near miss reports, accident reports and statistics, limitations of the human eye, current operations and technical anti-collision systems. They found that the number of accidents reported to the BFU had remained fairly consistent since 1980, though the trend did see a slight reduction in number. Since 1999 there appears to be an upward trend in the number of near misses and collisions, and in particular collisions. By far the main factors responsible for collision accidents are poor airspace observation and poor recognition. 1.11.3 BEKLAS examined certain human factors, such as the decision processing of the pilot in a potential collision scenario and optical aspects related to the human eye. 1.11.4 In terms of safety improvements, BEKLAS has examined the ACAS and TCAS systems, improving the visual lens hood of the aircraft windscreen/canopy, examining the flight operations of GA, military and commercial aircraft and examined other anti-collision projects. Such projects include FLARM and IDOCAS, which was a study that focussed on avoiding collisions between helicopters and fixed obstacles. C-8 of 9

1.11.5 BEKLAS concluded that there was no suitable short term solution available to all air traffic participants. It also stated that there was little alternative to the See and Avoid principle and, therefore, the visibility of small aircraft should be enhanced through design features. For instance flight trials were conducted using LED lamps and mirror film patches on the control surfaces of gliders. They also determined that recognising a dot on the horizon and processing this information was an area that could be developed and improved through education. 1.12 MARCONI TCAS SYSTEM FOR FAST JETS 1.12.1 In 1998, Marconi Electronic Systems published a feasibility study on the development of a collision warning system (CWS) that was originally customised for military, low-flying, fast-jet operations. The design principle of the system could be broadened for use on rotary wing, light commercial and general aviation because of its light weight design, low cost and the fact that little integration was needed with other aircraft equipment. C-9 of 9