Airplanes bound for the U.S. from the U.K. and Europe are still not required to submit their passenger information to the Department of Homeland Security until they are wheels up and in the air.

That policy was changed temporarily in the wake of the heightened security alert and since last week all passengers on all flights from Britain to the U.S. were pre-matched to DHS terrorist watch lists before the planes took off. Now, there is a significant move to keep it that way.

"It shouldn't take an imminent terrorist attack and a Code Red alert to ensure that no international flight takes off for a U.S. airport before the terrorist watch list has been checked," said Rep. Ed Markey (D-MA).

This week's required passenger list checks, however, have caused long delays and a large amount of cancellations of flights at Heathrow, which will make implementing any permanent change to the regulation very difficult.

Under normal circumstances, international flights from the U.K. and elsewhere in Europe must turn over their passenger information to DHS shortly after the flight has taken off. The airlines do check passenger information against their own databases, but they often do not have as much information as DHS databases.

If a passenger is discovered by DHS to be on the no-fly list after the plane has taken off, the flight is often turned around or diverted to a less populous area. For example, when Yusuf Islam, formerly known as singer Cat Stevens, was flying from London to Washington in 2004, U.S. officials learned that his name was on the no-fly list, and his flight was diverted to Maine, to avoid flying over the Boston-New York corridor.

After the current threat subsides, the international regulations will return to this system, though a DHS spokesman says there is no timeline as of yet for when they will revert to the old method.

DHS added that there is a significant move to change the regulation so that all U.S.-inbound flight passenger lists are checked before take-off, but no final regulation has yet been approved.

The proposal is currently in the 30-day public comments stage and then will be reviewed before a change in the regulation is made.

"The rule should be: 'No wheels up until the no-fly list has been checked off,'" said Rep. Markey. He called DHS's recent effort to rewrite the rule "long overdue."