With the window opening on February 1 to book Olympic game arrival and departure slots at London City airport, business aviation officials worry that warnings to secure positions early to cope with extensive security precautions are not being heeded.

Authorities have urged business aviation operators to reserve slots far ahead of the games period because of tightened security restrictions for non-scheduled aircraft flying into London and increased slot controls for airfields surrounding London. Around 10,000 aircraft movements by business jet operators are expected to be required during the two weeks of the games – 40% more than normal summer months in London.

But with only six months to go before the games commence, not even half that number has been reserved yet, according to Airport Coordination (ACL), the company responsible for slot management at London’s airports.

That does not mean, though, that demand will fall short of expectation. “I am confident we will see a large surge in bookings only 2-3 weeks ahead of the games,” says Adam Twidell, CEO of PrivateFly. That situation could be problematic, though, he acknowledges. “The question is, how will ACL and the required anti-terrorist security checks be handled during this late surge?”

London City is a particularly difficult situation, because it is the airport with closest proximity to the main event sites. Although some slots will be made available the airport will remain severely restricted for business jet operators.

One of the big questions still hanging over operators is how to deal with strict U.K. Department for Transport (DfT) rules on what aircraft are allowed into the restricted zone. Airports and operators need to demonstrate that all inbound flights originate from destinations where the level of screening is acceptable to the DfT. “Airfields that have lesser security and passenger screening in place pose a risk of sending rogue aircraft into the Olympic airspace during the games,” an airport official tells Aviation Week. Exactly how security of a foreign airport is determined “still needs to be clarified with the DfT,” he adds. Securing bookings until those issues are resolved could pose a challenge.

Nevertheless, there are at least some signs the business aviation community is trying to comply. Early bookings for Biggin Hill, Farnborough and Luton airports are being made, says an ACL spokesman. Of the 39 airports in England for which ACL is managing Olympic slots this summer, 35 normally are not slot controlled.

Still uncertain is whether RAF Northolt, to the west of London, will factor into the business aviation traffic. The government was planning to take full control of the facility to stage special operations units, police helicopters and a Eurofighter Typhoon fighter detachment, but there is growing pressure for some business aviation traffic to be allowed in, if for not other reason than to host high-level overseas state visitors.

Despite a rather tepid pace of bookings so far, Twidell remains confident the demand will emerge in the end. “Shortened lead times has been a clear trend throughout the recession,” he notes, adding that there are ample “loose enquiries” being made.