Emily Boase, the Prospect National Secretary representing 2,700 specialist air traffic controllers and engineers, also called on the CAA to consult the union as part of any investigations.
"Our members pulled out all the stops, putting in extra hours and coming in on their days off to resolve the problems and get people safely to their destinations," she said. "They worked hard to restore operations as quickly as possible and deal with the resulting backlog.
"But such flexibility is only possible if working practices and staff numbers are sufficiently robust. We have many concerns about the future ability to deal with such crises and recover from operational and technical incidents, in the light of the current cost-cutting programme being imposed by the European Union."
NATS used to be solely regulated by the CAA, but the EU now determines the overarching regulatory framework. In May NATS was told to significantly reduce charges for airlines for en-route air traffic services in the UK, with cuts of around 6 per cent of staff expected.
"Current cost efficiency targets mean that 80 air traffic controllers and 49 engineers must leave the organisation by the end of 2014, of whom some have already gone," said Boase. "If there is a CAA inquiry, it must consider whether such staffing cuts will lead to loss of specialist expertise, and what the impact on resilience would be."
There are currently two air traffic control centres in the UK – at Swanwick, Hampshire, and Prestwick in Scotland.
Boase added: "A two-centre strategy for air traffic control should be a key part of any future contingency planning. We urge the CAA and NATS to learn the lessons of last weekend or we could see even more chaos and disruption."