Changeover system

Auto-Changeover Control Tower CNS

At London Heathrow LHR, FTI's self healing Fibre Network connects the Comms, Navigational Aids and Surveillance systems to the Control Tower.

There are two Fibre Network Rings, one around the North and the other for the South Runway. A break in the Fibre Network Ring will self heal in less then 2 sec, to meet the ICAO Standard for a CAT IIIb Instrumentation Landing System. The self healing Fibre Network assists in maintaining the high utilisation of both LHR Runways, where Aircraft separation can be down to 2.5 nautical miles.

Ethernet network in turn does not ensure constant propagation delay, because latter is not required by most data applications. Thus, Ethernet and other packet-based networks make better utilization of available network capacity, as no part of total capacity is constantly reserved for voice calls. Many operators still nowadays rely upon TDM networks as their transmission backbones, because these networks have reliably served over the years delivering voice, telemetry and data traffic.

However, the future of communication networks is no doubt IP/MPLS, because TDM networks cannot support steadily increasing capacity demand by new applications.

Therefore, most network operators and utility providers running TDM networks are migrating their communication infrastructure to IP/MPLS now or at least are planning upgrades in the next years.