After British officials announced today they had thwarted a terror plot to blow up commercial jets in flight, the airline industry put in a tougher new security regime in a matter of hours.
Even though travelers at airports across the United States and Great Britain endured lengthy delays and changes to baggage allowances, reaction time in the United States was heralded a success.
But air travelers will have to have to rethink what they pack in their carry-on luggage to keep lines at airports moving, said John Nance, ABC News aviation consultant.
After the plot's details were announced, the airline industry "turned on a dime" to implement stricter security searches, Nance said.
"In four hours to be able to institute a new range of procedures is amazing," said Nance. "The lines are getting much smaller across the country as people get the message."
"It's now really easy to ramp up luggage inspection," Nance added, as he described the changes in security measures since the Sept. 11, 2001, terrorist attacks.
The announcement early today that British officials had thwarted a terrorist plot to kill thousands of people by detonating liquid explosives onboard flights headed to the United States led to a chaotic interruption in air services. Flights were backed up three to four hours at airports around the country, according to the Federal Aviation Administration.
The Homeland Security Advisory System Threat Condition was raised to "Severe" for all flights operating between the United States and the United Kingdom, and the threat condition on all other international and domestic flights was raised to "High."
But while today's passengers must patiently suffer the consequences, future travelers can possibly ease the check-in congestion if they follow the guidelines released by the Transport Security Administration and individual airlines.
Aside from adapting to the short-term changes associated with the current threat, Nance said people might have to change their approach to flying in the future because some of the changes in security measures are likely to be around for a while.
"The main thing to realize is that if you fly a lot, you've established a habit pattern. You have to take everything and lay it out on the bed and say, 'I'm going to reprogram myself,'" Nance said.
In the meantime, travelers will also have to make some more immediate changes to their packing and time schedule as they follow the TSA's new directives.
According to the TSA Web site, carry-on luggage is permitted for domestic and international flights from the United States, but the bags must not contain liquids or gels of any kind.
Exceptions are made for baby formula, breast milk or juice if a baby or small child is traveling; prescription medicine with a name that matches the passenger's ticket; and insulin and essential other nonprescription medicines.
Personal items like shampoo, toothpaste, suntan lotion and creams can be brought along if they're packed in checked luggage.
But caution is advised, as the new luggage restrictions differ, depending on the ultimate destination of the flight.
For passengers traveling from or through the United Kingdom, stricter regulations are in force.
On these flights, passengers are allowed no carry-on luggage except for small personal items like reading glasses, wallets and cell phones.
"They're steep measures, but obviously passenger safety is paramount," British Airways spokesman John Lampl said.
Some American airlines are also offering one-time ticket changes without penalties or additional fees.
Delta Airlines spokeswoman Betsy Talton said the airline would allow people traveling to or through the United Kingdom in the period from Aug. 10 to Sept. 1 to change their tickets.
Most airlines have also advised travelers to arrive a full three hours before their scheduled departures to allow for in-depth luggage searches and other security-related measures that could cause delays.
Airline officials declined to predict how long the delays were expected to continue.
"It's impossible to tell at this stage," Talton said. "Passengers should just abide by the TSA directives."