"...the Regulator only allows NATS to make a profit in order to fund the investment program." Is your statement factually correct or not? Just a 'yes' or 'no' will do, thanks.
Like any attempt to summarise a very complex subject on a web forum it's both factually correct and factually incorrect and also like any complex subject there is no yes or no answer. As I've tried to explain the Regulator has allowed pass through of the capital investment programme so it has allowed NATS to make a large part of the profit to fund the agreed investment programme. If it won't allow NATS to include all the pension payments in the charging regime it isn't going to allow NATS to redirect the investment money to pay the pension payments either. I'm sure it would be quite happy for NATS to use any part of the profit not already earmarked for investment to pay pensions but that's a very small part and if you think it's enough to pay the sort of sums we're talking about you are going to be very disappointed.