Boarding a commercial airplane before Sept. 11, 2001 was a hassle-free exercise.
Travelers could go through the privately-run security checkpoints wearing shoes, belts and hats. You could bring as much liquid as you could fit in your carry-on bags. In most airports, family members or friends who wanted to accompany you at could go all the way to the gate without a problem.
That quick and convenient process ended after suicidal Al Qaeda militants took advantage of the rules to carry out the deadliest terrorist attack on U.S. soil.
In the two decades since 9/11, boarding a flight has become time-consuming and often stressful as authorities seek constant upgrades to security and identification measures at thousands of airports across the nation.
Air travelers largely accept the new reality as the price of flying safely — but the definition of “safe” in air travel is constantly evolving.
“We have a better security system, but now we have even more threats,” said aviation security expert Jeffrey Price.
Price’s biggest concern is the rise of domestic terrorism and two dangerous tools that people now have at their disposal: drones and cyberattacks.
Many U.S. travelers had likely never heard those two words before 9/11.
Before 9/11, passengers only paid attention to airport security in the first weeks or months after an attack or major threat, said aviation historian Janet Bednarek.
“But for the most part, it was something people did mechanically, and [they] didn’t pay much attention doing it. You could walk through the magnetometer with a pocket full of change and it wouldn’t go off,” Bednarek said, referring to metal detectors.
“It was very easy. All you needed was a boarding pass,” she recalled.
The system was so flawed that it was not hard to bring small weapons on a plane. Walk-through metal detectors were calibrated to detect items with at least the metal content of a .22-caliber handgun, a threshold the 9/11 hijackers appeared to know about.
The terrorists managed to board four airplanes that day with lighter objects including knives, box cutters and Mace, according to the final report by the bipartisan 9/11 Commission. It appears that they used knives with blades under four inches long to avoid detection, the report said.
However, even when small knives were detected during screenings, “they were usually returned to the traveler,” the 9/11 Commission reported — suggesting there was little chance the Al Qaeda killers would be turned away from their flights that day.
More than half of the 19 terrorists were identified for further inspection during pre-boarding screening — and that only applied to their checked luggage.
Airlines and airports used to avoid any security measures that might discourage people from flying — and spending their money — said Bednarek, a professor at the University of Dayton in Ohio. The strategy has since changed, with companies and authorities constantly boosting security for that very reason: to ensure people will keep traveling.
“People were terrified of flying after 9/11 and the security convinced people to fly again,” Bednarek said.
Things began to change shortly after the attacks. The Transportation Security Administration, created two months later, took over airport passenger security. It sought to implement 100% screening of checked luggage and deploy explosive detection systems nationwide.
Authorities have also fortified cockpit doors, strengthened no-fly lists and prohibited a series of potentially problematic carry-on items, such as liquids, gels and aerosols in containers of 3.4 ounces or larger. The rule on liquids came after authorities foiled a terrorist plot seeking to detonate liquid explosives aboard at least 10 aircraft traveling from the United Kingdom to the U.S. and Canada in 2006.
Airlines have also made it harder for non-ticketed people to go past security checkpoints. Today, they may allow visitors to accompany ticketed passengers in specific cases — such as following an underage or disabled person to the gate — but everyone must face the same screening as those with a boarding pass.
Another infamous terrorist plot that resulted in a screening change was the shoe bomb attempt aboard a flight from Paris to Miami in December 2001. That is the reason travelers are now asked to remove their shoes when passing through the security checkpoint.
Other tools introduced in recent years include CT scanners, automated screening lanes and chemical analysis devices.
Despite TSA’s successes, the agency of 60,000 employees has been criticized for a series of security holes identified in recent years. A 2015 internal report by the Department of Homeland Security revealed that airport screeners failed to detect mock explosives and weapons in almost every undercover test conducted in dozens of airports across the U.S.
The agency said it continues to evaluate and enhance its methods to adapt to the challenges involving security threats.
“Aviation security is much stronger now than it has ever been because TSA has taken numerous significant steps to address the evolving threat,” TSA spokeswoman Lisa Farbstein said.
One of the biggest TSA controversies to date happened in 2010 when the agency introduced its “full-body scanners,” designed to detect non-metallic weapons and other threats concealed under passengers’ clothing.
The measure sparked revolt across the country, with critics saying the scanners and rigorous pat-down searches that were offered as an alternative were too intrusive since TSA agents would get to see through people’s clothes. Some opponents even called for an organized boycott of the scanners on Nov. 24, 2010, which was dubbed “National Opt-Out Day.”
The campaign foundered, and Americans soon became used to the strict screening.
“People have, for the most part, accepted this as part of the flying experience,” Bednarek said. “It’s that degree of reassurance that you’re not going to be hijacked, you’re not on a plane that is going to (crash) into a building.”
But despite all the security measures put in place over the last several years, the nation is not 100% safe from terrorist threats.
Drones could be used to shoot large crowds at airports, attack aircraft or conduct surveillance to assist other terrorists conducting an assault, said Price, who teaches at Metropolitan State University of Denver.
Other threats Price worries about include potential attacks on politicians at airports or on planes and attacks by mentally disturbed people or those seeking attention. Private jets could also be turned into a weapons as they don’t face the same scrutiny as commercial airliners, experts have warned.
At the end of the day, Bednarek said, flying will always pose a risk — just like driving.
“It’s not completely safe every time you get inside your car and drive down the road, but it’s safe enough that you’re going to do it,” she said.
“It’s the same thing with flying. It’s never going to be 100% safe to get on an airplane, but as long as it’s safe enough, you’re going to do it.”