The union is calling on the government, as the largest shareholder and instigator of the public private partnership, to face up to its responsibility and halve the debt NATS has been saddled with under the terms of the PPP.

On behalf of over 3,500 controllers and engineers in NATS, Prospect also welcomed the committee’s condemnation of the decision to cut back safety critical staff.

David Luxton, the union’s aviation officer, said: "As part of NATS’ cost cutting measures, the organisation plans to shed 450 system specialist engineering posts over the next five years, increasing to 900 posts over the next 10 years. Yet NATS needs specialist engineering skills to develop and expand.

"NATS’ debt level is crippling it both financially and organisationally, detracting from the primary focus of ensuring safe and reliable air travel.

"The government must step in now to ensure NATS’ financial stability so that it can meet its investment plans which are crucial to ensure air traffic safety in the face of the increasing volume of flights."

Prospect is also calling on the CAA’s economic regulator to allow NATS to raise its charges and give it the financial headroom needed to proceed with investment.