How air travel changed after 9/11

Security measures in place today did not exist 20 years ago

FILE - In this June 10, 2020 file photo, Transportation Security Administration agents process passengers at the south security checkpoint at Denver International Airport in Denver. Federal safety officials are investigating people who took part in last week's riot at the U.S. Capitol to decide whether they belong on the federal no-fly list. The move is one of several that officials outlined Friday, Jan. 15, 2021. (AP Photo/David Zalubowski, File) (David Zalubowski, Copyright 2020 The Associated Press. All rights reserved.)

Packing only small containers of liquids into one quart-sized bag. Arriving hours before a flight. Removing shoes to go through checkpoints.

These security measures have been accustomed in airports since the attacks on Sept. 11, 2001, changed air travel.

Two months after four hijacked U.S. airliners crashed into the World Trade Center towers, the Pentagon and a field in Pennsylvania, President George W. Bush signed into law the Aviation and Transportation Security Act, which created the Transportation Security Administration, a force of federal airport screeners that replaced the private companies that airlines were hiring to handle security. The law required that all checked bags be screened, cockpit doors be reinforced and more federal air marshals be put on flights.

SPECIAL SECTION | Remembering 9/11: 20 years later

In December 2002, the TSA met a key mandate of the law by deploying systems nationwide to screen all bags for explosives.

The TSA in August 2006 began requiring passengers to remove shoes to screen for explosives.

In September 2006 — a month after the implementation of the original liquids ban — the TSA amended its rules for liquids in passenger carry-on baggage, allowing airline passengers to carry liquids, gels and aerosols in containers of 3.4 ounces or less in a single, clear, resealable 1-quart plastic bag.

The TSA in March 2010 began to formally install advanced imaging technology units at U.S. airports — also known as “full-body scanners” — to detect threats.

In December 2011, TSA PreCheck operations began. The expedited screening program makes risk assessments about passengers prior to their arrival at an airport checkpoint, with the goal of allowing the TSA to focus resources on high-risk and unknown passengers. More than 10 million people have now enrolled in PreCheck, and the TSA wants to raise that to 25 million.

In July 2017, the TSA started implementing stronger screening procedures for carry-on items that require travelers to place all personal electronics larger than a cellphone in bins for X-ray screening.

Each new requirement has seemed to make checkpoint lines longer, forcing passengers to arrive at the airport earlier if they wanted to make their flights.

Currently, air travelers with TSA PreCheck must pay a fee, but they do not have to remove their shoes, laptops, belts, light jackets and their quart-sized bag of liquids in containers 3.4 ounces or less per item.

It’s called the 3-1-1 liquids rule, and it applies to all air travelers. But those going through standard screening must separate the quart-sized bag from carry-on baggage during the screening process. Exemptions to the 3-1-1 rule are medications and infant and child nourishments.

On its website, the TSA has a searchable database of what can and cannot be packed in carry-on bags and checked luggage.

And the coronavirus pandemic brought another major change in air travel protocols this year when President Joe Biden signed an executive order requiring face masks be worn on public transportation, including in airports and on commercial airplanes. The TSA responded by issuing guidance requiring travelers to wear face masks within security checkpoints and developing signage for airports.

The Associated Press contributed to this report.