DUBAI, United Arab Emirates (AP) — Disruptions to air travel are possible if Britain leaves the European Union in March without a deal, the head of the leading association for airlines around the world warned Thursday.

Alexandre de Juniac, director general and CEO of International Air Transport Association, said the risk to traffic flow is partly under control after the announcement of contingency plans.

However, he voiced concerns about the possibility of some disruption that could involve flight adjustments and cancellations in the period after a so-called "no-deal" Brexit because current guidelines relating to air travel between Britain and the EU reflect 2018 traffic levels. Passenger traffic is projected to grow 5.5 percent in Europe this year.

"I am not concerned that there will be a major disruption, but I am concerned that there will be disruptions in the coming weeks, in the coming months because it has not been calibrated properly," de Juniac told reporters in Dubai.

With less than three months to Brexit day on March 29, Britain has yet to agree on terms for its withdrawal from the EU, raising fears that the country could leave the bloc without a deal to ease the transition to a new future relationship— a scenario that could see serious dislocations to trade.

Even if a deal is secured, Brexit will involve the country leaving around 750 international treaties, among them arrangements governing the EU's aviation market. The British government has said that following Brexit it wants arrangements with other countries to allow air travel to continue unimpeded.

U.K. Transport Secretary Chris Grayling told the House of Commons on Thursday that there would be no disruption to flights in the event of a no-deal Brexit. The Civil Aviation Authority was working on creating a "properly functional British alternative," he said.

IATA, which represents some 290 airlines, relies on open borders, de Juniac said.

"When you close these borders, it's not good news for us," he said.

A study commissioned by IATA on the effects of Brexit stressed that Britain has the largest aviation industry in Europe with around 80 percent of all North Atlantic traffic passing through British or Irish airspace.