In the ATC system, they are classified under L01B.

ATC systems have traditionally been developed by individual States that concentrated on their own requirements, creating different levels of service and capability around the world.

Today's ATC systems do not rely on coverage by a single radar.

The sickout led officials to recognize that the ATC system was operating nearly at capacity.

This has not been done anywhere before and therefore the ATC system had to be specifically designed and developed to allow for this mixed operation mode.

ATC systems in the United States are almost always integrated with existing continuous cab signalling systems.

At no point can the ATC system override the maximum speed limit enforced by the cab signal system.

Two monitor the ATC system, one monitors passenger information, while the last is responsible for secondary systems, such as power supply.

In 1936, the Bureau itself took over the centers and began to expand the ATC system.

The ATC system was plagued by numerous glitches when first implemented, initially causing significantly more harm than good.