From the Lockerbie bombing to 9/11: How attacks on flights defined US air travel

Getting your By RIO YAMAT, AP Airlines and Travel Writer Taking a commercial flight from a U.S. airport generally requires a boarding pass to get anywhere near a gate, security screening controlled by the federal government and careful attention to the contents of carry-on bags. It The security system and screening procedures air travelers encounter today were built layer by layer, often after attacks or attempted attacks 'Attacks on aviation have an impact much greater than attacks on anything else because aviation commands the attention of the world as the thing that links the world,' said Mary Schiavo, an aviation disaster attorney. As the 25th anniversary FILE – Smoke billows from one of the towers of the World Trade Center as flames and debris explode from the second tower, Sept. 11, 2001. (AP Photo/Chao Soi Cheong, File) 9/11 requires authorities to consider aircraft hijackings in new ways No single day changed air travel more dramatically than Sept. 11, 2001, when 19 Before then, authorities presumed aircraft hijackers would seek to negotiate, not deliberately crash a plane as part of an attack, according to Schiavo, who served as the U.S. Department of Transportation's inspector general from 1990 to 1996. 'The focus at the time, generally, was not on suicide attackers,' she said. U.S. officials introduced changes before The Federal Aviation Administration immediately restricted gate access at airports to ticketed passengers and banned knives and box cutters from carry-on bags. The hijackers used small knives to threaten passengers, attack crew members and seize the planes. Congress created the With screening times and lines getting longer, TSA looked for ways to move pre-vetted travelers through more efficiently, said Sheldon Jacobson, a University of Illinois professor whose research on risk-based screening contributed to the design of TSA PreCheck. TSA increasingly used watchlist checks, voluntary background investigations and other information to sort passengers based on assessed risk. Travelers selected for additional scrutiny faced more intensive checks. Civil liberties advocates warned that opaque selection criteria and inaccurate watch lists would encourage discriminatory profiling based on race or religion. The range of security flaws that 9/11 bared came after authorities and the aviation industry spent more than a decade trying to address gaps that earlier attacks brought to light. FILE – Unidentified crash investigators inspect the nose section of the crashed Pan Am flight 103, a Boeing 747 airliner in a field near Lockerbie, Scotland, Dec. 23, 1988. (AP Photo/Dave Caulkin, File) A bombing high above Scotland puts a spotlight on checked bags and hidden explosives Almost 13 years before 9/11, a bomb destroyed a jumbo jet operated by a U.S. airline as it flew at 31,000 feet over Lockerbie, Scotland, The The FAA ordered U.S. carriers at airports in Europe and the Middle East to X-ray or physically search all checked baggage, to conduct additional random checks, and to confirm that checked bags belonged to flying passengers. Acting on recommendations from a presidential commission and legislation passed by Congress, the FAA assigned security personnel at major U.S. and foreign airports, established intelligence-sharing agreements, instituted tighter cargo controls, developed training standards for private screeners and researched explosives-detection and mitigation technology. The FAA also covertly tested airport and airline security systems by assigning a team 'to simulate the criminal and terrorist attacker modus operandi,' Garvey testified. On Sept. 10, 2001, the agency saw attacks with explosive devices as the most dangerous threat to an airliner and the people on it, she told the 9/11 Commission. 'The challenge is not formulating attack scenarios,' Garvey said. 'The challenge is figuring out how best to allocate finite resources in an environment of uncertainty.' FILE – Travelers walk through TSA security lines at George Bush Intercontinental Airport on March 30, 2026, in Houston. (AP Photo/Ashley Landis, File) Footwear and beverage bottles emerge as security concerns in the wake of foiled bomb plots Three months and 11 days after 9/11, TSA and airlines asked passengers after the Dec. 22, 2001, incident to remove their shoes voluntarily during security screening. Shoe removal became mandatory less than five years later, when TSA also restricted outside liquids and gels on commercial planes. The changes came after British authorities announced they had disrupted a plot to use liquid explosives concealed in beverage bottles to destroy seven transatlantic airliners. Authorities alleged the plotters planned to assemble and detonate devices in suicide attacks. Six men ultimately were convicted — TSA immediately banned nearly all liquids, gels and aerosols from remaining with travelers beyond security screening. The agency soon replaced the prohibition with the '3-1-1' rule that limits passengers to containers of 3.4 ounces or less that must fit in a single quart-sized, clear plastic bag. In July 2025, the Trump administration ended the The so-called 'underwear bomber' accelerates the rollout of body scanners On Christmas Day 2009, a passenger on Northwest Airlines Flight 253 tried to detonate explosives The traditional metal detectors in use at the time could not detect the plastic explosives under Abdulmutallab's clothes. TSA already was testing full-body scanners at some U.S. airports, and the averted disaster persuaded authorities to fast-track the technology. The radio wave scanners check for a wide range of prohibited items. Stepping inside one with feet apart and hands raised overhead now is a familiar ritual for most travelers. Related Articles Aviation security continues to evolve with new technology and equipment Security screening still is evolving at U.S. airports. TSA has been expanding 'Any one layer of security can be breached,' Jacobson said, 'but collectively, when you put them on top of each other, what you end up with is a very resilient system.'