The rapid acceptance of multilateration is unprecedented in the history of air traffic control systems. However, it has also had the unprecedented effect of user demand outstripping the pace of traditional aviation rule making, just as the technology itself has, in many locations, outstripped the implementation of more costly, but less efficient, traditional aids, like secondary radar.

The good news is that leading ANSPs have demonstrated that it is not necessary to wait for traditional aviation rulemaking to catch up in order to realize the benefits of multilateration. They have shown that operational certification of MLAT-based applications is readily achievable today. Because it has been repeatedly proven by authorities that have certified MLAT performance to be equal to or better than SSR.

So how can multilateration be certified for civil aviation use today?

Essentially, it is because national regulatory authorities agree that multilateration has demonstrated that it meets — and in many ways exceeds — all the certification criteria for secondary radar already specified by ICAO. In turn, this means that national regulators can certify the conformance of a multilateration installation against the established standards of the radar it is intended to replace. In no cases have multilateration systems been rejected by regulators for non-compliance with ICAO secondary radar standards.

Are ICAO Standards being updated to formally recognize multilateration?

Yes. This process is well underway in ICAO’s Aeronautical Surveillance Panel (ASP) and its Separation and Airspace Safety Panel (SASP), both staffed by international surveillance specialists, with formal issue of ICAO Standards And Recommended Practices (SARPS) expected within the next year. Parallel supporting activities are ongoing at Eurocontrol’s Multilateration Task Force, Eurocae’s WG70 and at ICAO regional meetings and individual ANSPs. Since multilateration’s current and future role is to supplement or replace secondary radar, it has been accepted that, following the new “performance-based” philosophy, its characteristics must equal those of secondary surveillance radar. The approach being taken by ICAO and other groups is therefore to develop multilateration legislation to bring it into compliance with current ICAO secondary radar standards, reflecting the practice already adopted by national regulators.