From Chris Coes
You point out that GPS is an essential element of some critical systems such as air traffic control (12 March, p 3 and p 44). There is, however, no need for cellphone masts and ATMs to rely on GPS. They both have easy access to high-bandwidth fixed line networks that could provide accurate time for synchronisation and auditing purposes. Lazy system design is responsible.
Camberley, Surrey, UK
