Last year the UK long-haul carrier, which has six A340-600s, six A380s and 15 787-9s on order, said it was seeking 10 additional large aircraft - either A380s or 747-8s. It was also confident of exercising all eight of its 787 options.
But speaking to Flight in New York at a media event to mark the announcement that it had selected Rolls-Royce Trent 1000 engines to power its 787-9s, Virgin Atlantic chief operating officer Lyell Strambi said the airline is deferring these decisions until it has greater clarity on ownership changes at Heathrow's second largest slot holder BMI and, to a lesser extent, the next stage of transatlantic open skies.
SAS selling its 20% BMI stake and is in talks over the disposal with Lufthansa, which already owns 30%. BMI chairman Sir Michael Bishop, who holds 50% plus one share, also has a put option this year.
Virgin has a long-held ambition of merging with BMI to rival Heathrow incumbent British Airways, although Strambi is certain that BA itself could secure regulatory clearance to acquire BMI.
Strambi says: "From whatever combination slots become available to use, then that's going to influence the aircraft size that we need. We'd want to respond to that, so we'd like to have some idea as to which way that will go before we make a complete commitment.
"The challenge is that we may not get perfect information. We'll have to make a call at a certain time but when you have the opportunity to keep your options open for a little while then in a changing world that's not something to squander."
Virgin's fleet comprises 19 A340-600s, six A340-300s and 13 747-400s. Strambi says the A340-300s are likely to be the first for renewal, although he adds that a few of Virgin's 747s are "getting a little long in the tooth".