Small US avionics contract has big ramifications

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A little-known US avionics company has secured a key role for itself in a project with the potential to be one of the most important in the US drive towards ‘free flight’.

Aviation Data System Innovations (ADSI) is to provide the avionics for one of the three datalink technologies being trialled by the US Cargo Airlines Association (CAA) later this year.

The CAA programme is intended first to provide a more sophisticated alternative to the conventional traffic alert and collision avoidance system (TCAS), but eventually to produce a usable version of the automatic dependent surveillance-broadcast (ADS-B) technique needed to enable ‘free flight’ to be introduced.

A critical element of the project is the comparison of three candidate datalink technologies with different technical characteristics: Mode S; VHF datalink Mode 4 (VDL-4 or STDMA); and the embryonic Universal Access Transponder (UAT).

Behind the dry assessment of the trio lies a fierce battle for long-term global acceptance with substantial industrial and political implications.

Loosely speaking, Mode S and UAT are effectively US systems, while VDL-4/STDMA was Swedish-invented and could potentially secure for Sweden, or certainly for Europe, a vital role in the development of the Future Air Navigation System (FANS).

Mode S operates in the 1090MHz band and is already used for TCAS applications; VDL-4 is a VHF system which uses the self-organising, time-division, multiple-access technique; and UAT is a newly developed hybrid concept developed by Mitre of the USA, combining TDMA characteristics with operation in the 966MHz band

In a new twist in the saga, ADSI, which acted as consultants to the interests backing VDL-4 through the tortuous ICAO approval process, has won the contract to provide VDL-4 avionics for the CAA’s ADS-B programme.

ADSI principal, Prasad Nair, says the company is a wholly owned offshoot of Project Management Enterprises (PMEI) of Bethesda, Maryland.

He claims to have developed the basic Swedish STDMA concept into a version of VDL-4 that is "more robust and acceptable as an international standard".

Nair says that it became clear to ADSI and the Swedish CAA, which has been championing STDMA, that further work was needed to make the technology internationally acceptable.

As a result, ADSI has been trying "on our own initiative, unrelated to the European efforts, to create a US manufacturing base [for STDMA products".

Nair says that that attempt has "not been successful yet" because of the lack of an interested US partner, but ADSI has struck a deal with a Danish manufacturer of STDMA-related products to fulfill the CAA contract.

The requirement is for 20 examples of what ADSI calls its EFR-CA-200 model, which is an ARINC 429-standard, 3MCU (modular concept unit) box, currently certified to RTCA DO-178 Level D standards, but due to be Level C once the initial batch is delivered.

There seems little doubt that the attractiveness of STDMA for aviation purposes is likely to lead to some robust talking over proprietary rights but, for now, Nair insists that a "non-exclusive licence" he has acquired from STDMA-inventor Håkan Lans is adequate.

"Like it or not we compete with the other [STDMA] transponder manufacturers," he says, in a reference to the fact that a Swedish-produced transponder is already being trialled in Europe.