European Parliament 17 July 2002, WRITTEN QUESTION E-2132/02 by Bartho Pronk (PPE-DE) to the Commission. Working Time Directive and volunteers.

Although the information provided by Eurocontrol and the service providers points to a consistently high level of safety, the European system does have several shortcomings:
air traffic control capacity has not been sufficiently increased to deal with the growth in traffic;
control centres are not sufficiently interoperable at present, mainly because so many different systems are in use;