The total value of that commitment including the engines and the maintenance agreements is more than half the $3 billion market capitalisation of the company.
A leap to an Airbus A350-900 or the elegant -1000 for its wide-body future was seen as more unlikely than opting for a new iteration of the plane it knows and rates - the Dreamliner.
Chief executive Christopher Luxon told the Herald last November that a Dreamliner with more premium seats, therefore with fewer passengers and lighter, would be capable of reaching new destinations such as New York.
The airline will also announce which engine maker it has gone with later this month. It has the choice of new Rolls-Royce engines - improved versions of the Trent 1000 ones that have caused it big problems - or General Electric engines.
The airline's board had discussed the fleet replacement on six occasions.
Narrowing down the choices
The airline also assessed the yet-to-fly Boeing 777X as part of the process. This was seen as being too big for the routes it wants to fly and it being unproven in operation would have counted against it.
McDowall said the 777X was not out of the picture long term and could be a replacement for the airline's 777-300s.
The new aircraft will have new cabins with the airline doing work now on replacing its business class seats.