British Airways has again canceled a London to Washington D.C. flight for security reasons. For the second time in 24 hours, British Airways flight 223 from London's Heathrow Airport to Washington's Dulles International has been grounded.
The air carrier made the decision after it received a strong recommendation to do so from the British government just hours before the scheduled departure.
Terrorism expert Paul Wilkinson from St. Andrews University says this shows that the threat is not going away and people will have to get used to heightened security measures.
"I think this episode illustrates the very high level of concern among the authorities about the possibility of an attack on a civil airliner going across the Atlantic and perhaps being used in the same way that the al-Qaida used airliners on 9-11," he said. "That is to crash them into buildings and cities in the United States. And that is such an enormous danger that I think these rather exceptional measures are certainly justified, and, I think, passengers and crews do understand the need for special security at this time."
Two days ago, the same British Airways flight was allowed to land in Washington, but it was escorted into the airport by two U.S. F-16 fighter planes, and passengers were questioned by officials on the ground for some three hours before being allowed to disembark.
Specifics on why flight 223 - which uses a Boeing 747 jumbo jet - might be of special interest have not been released here, but aviation expert Chris Yates says intelligence in general is getting better.
"There is this level of chatter out there," said Chris Yates. "As to how specific it is, to specific flights and such like, well, that is in the realm of the intelligence communities. We just do not know."
Airline staff members at Heathrow are moving the 300 passengers from Friday's grounded plane onto other British Airways flights and other carriers.
A Mexican flight to the United States earlier this week was also canceled.
Last week, six Air France flights between Paris and Los Angeles were also grounded. But the FBI said on Friday that names from airline passenger lists on those planes were wrongly identified as potential security threats.
The French government believes that mistake was partially due to errors in identifying some passengers with Arabic names.