The final revisions to NATS' charges prior to completion of the PPP transaction were introduced on 1 April 2001. With effect from that date NATS' UK en route and North Atlantic traffic charges became regulated under a new charge control formula. Income equalisation balances owed to customers under the previous charging regime were settled in the financial year. In addition, the responsibility for levying the charge and bearing the costs for meteorological services transferred to the Civil Aviation Authority. For en route services, the NATS' rate per chargeable service unit was reduced from £49.25 to £46.24 to reflect this transfer of costs and the new charge control formula.
The UK unit rate, which additionally includes the charges levied by the Civil Aviation Authority and the Department for Transport (which collects the UK's contribution to the costs of running the Eurocontrol organisation) decreased from £52.71 in January 2000 to £50.68 in January 2001. The rate increased to £52.59 in April 2001, reflecting the adjustments referred to above.
The North Atlantic traffic charge increased from £55 per flight to £55.55 per flight in April 2001.