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AOPA on ADS-B 2015

In 2015, on behalf of AOPA UK, I produced a positioning paper about ADS-B. Whilst not coming out and saying ADS-B wil be required technology, the CAA have recently said in a news release about electronic conspicuity "we see ADS-B enabled and interoperable platforms as the most likely commonly adopted technology in the U.K."

Almost 4 years ago, this is what AOPA was saying:

Aviation, by its very nature, crosses borders and oceans and success requires global airborne and ground solutions. Implementing a globally harmonised Communication / Navigation / Surveillance (CNS) infrastructure is essential and specifying these solutions is an immediate priority.

Automatic dependent surveillance Broadcast (ADS-B) provides unparalleled traffic information which enables a “cooperative surveillance environment” between pilots and controllers. ADS-B makes possible the air-to-air and air-to-ground receipt of aircraft position, velocity and other data about the location of the aircraft. Tracking being more accurate, controllers are better able to manage the aircraft at congested airports, resulting in additional gains in capacity and pilots are able to plan for other traffic in the skies.

ADS-B will be the future surveillance technology to be implemented in Europe and it is also being implemented in other key aviation strongholds around the world. However, there is a lack of alignment with regards to technical requirements in Europe as compared to these other key implementers. The technical review of ADS-B mandate should include the following aspects.

I- Expand the Implementation of ADS-B

In Europe, the ADS-B is only required on aeroplanes weighing more than 5.700kg (or flying faster than 250kts). In order for ADS-B to be useful in congested airspace and to enhance safety for larger aircraft, all aircraft in mixed airspace need to be equipped with ADS-B out. Further, as remotely piloted aircraft grow in numbers, ADS-B provides a key to their safe implementation.

To assure the benefits of ADS-B equipage can be realised in Europe, the ADS-B mandate should be extended include all aircraft in mixed airspace (Class A-B-C airspace, airspace above 10,000 feet MSL, within 20nm of the busiest airports in Europe).
As increasing implementation to all aircraft in mixed airspace has the potential to add requirements on a tremendous number of aircraft where the cost of implementation far outweighs the benefits, financial incentives should be widely available. Additionally, concepts such as "ADS-B light" and FLARM should be reviewed to determine if there are simpler solutions that can satisfy the needs of the aviation community.

The ADS-B ETSO currently provides for a graduated approach of different equipment including a “light” equipment standard in the B0 and B1 classes. The B1 is the lightest standard invoked by the U.S. FAA by regulation within ADS-B airspace, but allowances also exist for a modified “B0” equipment class as identified in the TSO-C199 TABS equipment standard published by the FAA in 2014. Testing is currently underway using a B0-standard by the UK CAA as well regulators outside Europe including Australia to determine if “Non-Transponder Equipment” (NTE) ADS-B in context of a transponder is appropriate for use. Equipment built to meet the “B1” standard currently retails for approximately US$2,000 including the required installation kit such as antenna and control head.

The ADS-B mandate does not currently include the deployment of the ADS-B UAT standards (operating on 978 MHz) which would also have enabled weather and Flight Information Services for Broadcast (FIS-B) to the aircraft. The benefits of a “dual link” deployment, which would also require an ADS-R capability (Rebroadcast from ground equipment), should be explored to enable this capability or, alternatively, leverage the UAT link for uplink services only while requiring aircraft to be equipped with 1090MHz capable broadcast capability (i.e., ADS-B OUT). This kind of approach might create a large incentive for the entire aviation community to adopt both ADS-B out and ADS-B in.

Any expansion of the mandate must assure for a proper implementation window. Considering the scale of European aviation that could be potentially impacted, technical information to develop appropriate solutions must be in place and then appropriate time provided to design, certify and install those solutions, before any new mandate should go into effect.

II- Clarify the ANSP obligations

In order to assure ADS-B equipage can achieve all of the potential benefits, a cohesive ground implementation must be implemented. The current mandate requires air navigation service providers (ANSPs) to implement ADS-B by 2018, to support an expectation that the ground infrastructure must be working and in place before aircraft are required to carry this equipment. It is critically important that in doing this, ADS-B is integrated into the air traffic management process and a uniform and integrated level of ADS-B ground coverage is in place across Europe.

To assure ANSPs can meet obligations to assure a uniform and integrated level of ADS-B ground coverage across Europe, it would be appropriate to include a detailed review of implantation as the next steps in the SPI plan are reviewed.

III- Further analyse the 1090/1030 spectrum capacity

To assure that ADS-B on the 1090/1030MHz frequency can function properly, especially in the high density air traffic environments found in much of Europe, it will be important to consider the airborne broadcast power levels and the integration of the ADS-B ground infrastructure which will rebroadcast traffic information.

The 1090/1030 spectrum currently supports ACAS (TCAS II) and Secondary Surveillance Radars; i.e., Mode S / 1090ES equipped aircraft. ADS-B is an expansion of the message set currently required within 1090ES to also include additional parameters such as aircraft velocity, accuracy and integrity. Cooperative work has been underway to ensure appropriate protections of the link including the 2002 study undertaken with two scenarios (“Los Angeles 2020” and “Core-Europe 2015”). The studies identified spectrum constraints. Similar experiences with spectrum constraints were identified in the Netherlands recently.

Additional work underway by the U.S. FAA in 2008-2011 expanded the study to ensure the viability of the 1090-link through 2035 and identified options to help mitigate congestion on the link. The alternatives identified by the FAA include shifting ACAS to hybrid surveillance, passive wide-area mult-lateration (no SSR), and near-term changes such as the removal of “Terra Fix”. Europe should work with the U.S. FAA on its experience and work to mitigate congestion on the 1090 link and determine which options are appropriate for the European surveillance environment.

It is critically important that ADS-B not end up in a scenario similar to data link where flawed architecture dooms the program to be repeated. It will be important to assure that ADS-B implementation considers all issues related to frequency capacity and any additional issues related to real world implementation of ADS-B in Europe which could cause difficulties if not properly managed.

IV- Clarify the aircraft certification requirements

Aircraft should equip with ETSO-C166b (or later acceptable version) equipment, which is the appropriate level of equipment based on operational experience in other parts of the world. Assuring this level of requirement will enable global interoperability and a strong likelihood for success in the European airspace. EASA should be empowered to determine acceptability of equipment and to issue any deviations that can be permitted within the functional ADS-B system.

V- Conclusions

We are committed to supporting this development if the CAA is able to undertake an activity which would address the issues of ADS-B outlined above.

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