International air travelers may find themselves increasingly grounded at the last minute - as some did over the weekend - while European and US authorities tussle over the use of armed sky marshals.
"Hopefully it won't happen," says Anthony Council, a spokesman for the International Air Travel Association, which groups 270 airlines. "But when extraordinary situations happen, we need to take extraordinary measures. We need to keep our options open."
Washington has reserved the right to demand sky marshals on specific flights to the US, but European governments and carriers are reluctant to put guns on planes. Without an agreement between the two sides, cancellation of suspect flights appears the only alternative, say government and industry sources.
Ten transatlantic flights were canceled last weekend in light of what a spokesman for the US Department of Homeland Security called "specific and credible information that Al Qaeda would attack these flights on those dates." That followed a similar episode over the Christmas holidays, when 16 international flights were canceled or delayed.
Air France canceled flights from Paris to Washington Sunday and Monday on "the principle of precaution when there are signals," French Transport Minister Gilles de Robien said on RFO television. "We work very well with the Americans and they send us those signals."
The US government announced at the end of last year that suspect flights into US airspace would be turned back unless they carried an armed sky marshal. Though US undersecretary for border and transportation security Asa Hutchinson - meeting European officials two weeks ago - defused resentment at what some governments saw as a unilateral imposition, he found no European consensus on the issue.
The British and French governments have said they are prepared, in principle, to put sky marshals aboard planes carrying their flags, and the German carrier Lufthansa says it has used sky marshals on transatlantic flights since soon after the terrorist attacks on Sept. 11, 2001.
But airlines in Norway, Sweden, Finland and Portugal have publicly refused the measure, and other European governments are hesitant.
"The indications are that a European-level agreement is unlikely," says Tom Rowley, spokesman for Irish Transport Minister Seamus Brennan, whose government, currently presiding over the European Union, has explored the possibility of a single continentwide approach.
Apart from anything else, Mr. Rowley points out, only a few European nations have trained sky marshals, whose use is not customary on European airlines.
Transatlantic differences hinge partly on attitudes to firearms. "Most Europeans...think that guns are dangerous, and that having guns aboard planes increases, rather than decreases, the likelihood of innocent people getting hurt," wrote Amit Chanda and Kate Joynes of the World Markets Research Center, a London-based political research group, in The International Herald Tribune recently.
For those governments capable of providing air marshals, "the key issue is what risk level you are talking about when you say you want to use sky marshals," Rowley adds. "If there is any risk, the tendency is to cancel the flight, so when is a risk so minimal that you fly but still need a sky marshal?"
The Irish government, he says "is still trying to get more detail from the Americans" on such questions, and has yet to decide whether it will authorize sky marshals.
US officials say they are reluctant to provide such detail publicly, for security reasons. "Where we get specific information pertinent to specific flights, we would request the host country to provide an armed law enforcement officer," says Brian Doyle, a spokesman for the Department of Homeland Security. "This is not a broad-brush measure. If we have specific information we share it," he adds. "It is in [the airline's] hands to make a choice. It is their decision not to fly; we can't mandate that. But we can say that if you are going to fly here, we demand it [sky marshals] for security's sake."
Regardless of the British authorities' readiness to authorize such security measures, national flag carrier British Airways says it has not yet determined when they might be appropriate. "If there is a specific threat about a flight, we will cancel that flight," says spokeswoman Sophie Greenyear. "That is definite."
Airline owners and pilots say they would rather see heightened security before a flight takes off than an armed guard aboard. "We think you should stop terrorists long before they reach an airport," says IATA's Mr. Council. "The emphasis needs to be on intelligence gathering."
"The Americans see sky marshals as the way forward, but many of us in Europe see sky marshals as an irrelevance," said Jim McAuslan, head of the British Airline Pilots' Association, in a statement last month. "There is clearly a difference in culture between the USA and Europe."
"Our preference is not to have guns on board an aircraft," says Council. But if member airlines do allow armed sky marshals to fly, "we would like the captain to know, and to be reassured that the weapons would not do structural damage to the aircraft."
In the meantime, Council says, IATA member airlines "are doing their absolute best to do all that is asked of them" by the US authorities, for example by presenting them with advance information on passengers' names and departure and destination details to allow vetting.
"The problem is that several US organizations, and sometimes several departments within the same organization are asking us for this detail at the same time," he adds, which leads to confusion.
Nor do advance passenger lists always ease a flight's departure. Air France canceled six flights to the US over Christmas, but French officials said later that checks on passengers whose names had concerned US security officials found nothing to suggest a threat.