Rob Abbott, Aviation Director at Aveillant, UK-based radar company, explains how a key application for Aveillant’s 3D
Holographic Radar™ has been wind farms, to eliminate the effect that wind turbines have on air traffic control radars.
Solutions have traditionally focused on the problems caused by wind farms, rather than looking at the inability of radars to differentiate and remove wind turbine ‘clutter’ from images used by operators.
Rob says: “What if, rather than charging across the landscape to fix the wind farm, which in the last 10 years has led to raising aerial heads, hiding turbines behind a hill (known as terrain masking), painting them with radar suppression material or just blanking them out on the radar screen – what if we turned around, walked back to the root of the issue and saw the radar as the problem? Where would we be then? Exactly where Aveillant is today.”
Masking and blanking the area above and around wind farms is not “the answer”, although up until recent times this was been one of the only fixes available to an Air Navigation Service Provider (ANSPs). This doesn’t provide an accurate picture of airspace and reduces the coverage required, contrary to the needs of an industry that has to be risk averse and needs to operate safely and safeguard airspace in order to facilitate the European aspirations of flexible airspace usage. These approaches are sometimes accepted as ‘good enough’ because they are all that’s available and there is intense pressure to enable wind farm developments; however, in reducing risk, aviation is duty bound under the principles of ICAO safety management to use the As Low As Reasonably Practicable (ALARP) approach. Even recent advances in standard radar technologies, which look to reduce the impact of turbine break through, still mean the aircraft are not presented to the display if they are co-incidental to the turbines being removed in that location. The safety argument becomes one of probability of loss, rather than detection. Now with Holographic RadarTM ANSPs can, for less overall cost, have full, unrestricted coverage with no gaps due to blanking or masking, which begs the question, why would they choose anything else?
3D Holographic Radar™ is a major advance on the traditional rotating radar. Holographic RadarTM provides accurate measurement (or time on target) 100% of the time compared to rotating radar which is only on target 1% of the time. A staring, static array radar, Holographic RadarTM provides a constant view of airspace at all times, never losing sight of the target. Through intelligent characterisation of all objects in its range using hyper fine Doppler information, the radar can detect, differentiate and selectively remove clutter such as wind turbines, motorway traffic or trains, providing a clutter free view of what the operator wants to see.
Rob continues: “For the past four years, 3D Holographic Radar™ has been in development and it is now one of only two mitigation solutions with safety cases underway in the UK. In 2013, we held public trials of the radar at Prestwick Airport, where it was independently assessed to have a probability of detection above the wind farm of above 99%, compared to Civil Aviation Authority (CAA) CAP 670 recommendations of 90%. At the site, our 3D Holographic Radar™ also continued to operate in severe storms with winds in excess of 90 miles per hour. This and our independently reviewed verification methods, has proved to the industry that Holographic Radar™ is not only extremely robust but can also easily achieve CAP 670 compliance.”
Aveillant’s 3D Holographic Radar™ has been developed to be more cost effective across its lifecycle. It outlives the traditional PSR and without any moving parts, maintenance is reduced, simple and can be performed without any disruption to performance.
Commercially available now, 3D Holographic Radar™ is being implemented across the UK and further discussions are underway with many airports and ANSPs across Europe. It’s scalable to meet all coverage requirements, from small deployable units to regional solutions.
Rob says: “Our spectrum-efficient radar technology operates in L-band, as opposed to the congested S-band commonly used by the aviation sector and MOD. S-band is a sweet spot for mobile data transmission and so is in high demand by mobile phone operators. Ofcom is working to release 500MHz of radio spectrum below 5GHz, including 100MHz of S-band spectrum by 2020. This could leave many airports needing to modify or replace their radar with a difficult choice. The solution will not be to relocate wideband radars into L-band, there isn’t capacity in the band. Even with an optimistic six month project to replace many of the elements of an S-band radar, the problem will be increased due to loss of operation or mitigation cover during the period. A wind farm lifetime is 25 years and airports need to ensure any potential risks during that lifetime are covered, including changes to the wider ATM system, legislation and wind turbine design, changes like these could cause some ‘good enough today’ mitigations to fail or at the best be less effective.”
In addition to the spectrum release programme the replacement of the current Radio and Telecommunications Terminal Equipment Directive (R&TTE) 1999/5/EC by the Radio Equipment Directive (RED) is now underway and will be completed June 2017. Unlike the R&TTE the RED requires all equipment, including radar, to justify their use of spectrum and to be compliant. It is not beyond the realms of possibility that excessive use of S and X-band to do a task which can be achieved with only 2 Mhz of L-band could cause issues in delivery of contracts which need to be safeguarded for 25 years in order not to jeopardise either operation of the airport or revenue for the wind farm, especially in an environment where people are not comfortable in discussing where liability for these potential future charges should lay.
Rob continues: “We are executing a contract with the CAA to demonstrate the ability of Holographic RadarTM to provide a spectrum-efficient alternative to S-band primary air traffic surveillance radar. The future looks exciting for 3D Holographic Radar™.
The key now is to let the industry decide. Does it want to remain in the legacy world of conventional radar affected by clutter such as wind turbines or invest in a new approach? The feedback we are receiving from the market is that new technology is required, radar has to be fixed”.
Rob concludes: “We are often told that there is too much risk, a conventional radar is risk-free. I know at least four airports who would disagree, with some radar installations taking longer than three years to gain approval. Every project has risks and it is how you manage these risks that matters. Sometimes those people passionate enough to think they can change the world actually do. As Steve Jobs said, ‘The point is that new technology will not necessarily replace old technology, but it will date it. By definition. It will eventually replace it’. Thank you”.