Argenbright Security is an Atlanta based subsidiary of Securicor

Securicor

Securicor plc was one of the United Kingdom's largest security businesses. It was once a constituent of the FTSE 100 Index but merged with Group 4 Falck in 2004.-History:...

 that has operated security at airport

Airport

An airport is a location where aircraft such as fixed-wing aircraft, helicopters, and blimps take off and land. Aircraft may be stored or maintained at an airport...

s across the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, including Philadelphia International Airport

Philadelphia International Airport

Philadelphia International Airport is a major airport in Philadelphia, Pennsylvania, United States, and is the largest airport in the Delaware Valley region and in Pennsylvania...

 and Chicago

Chicago

Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...

's O'Hare International Airport

O'Hare International Airport

Chicago O'Hare International Airport , also known as O'Hare Airport, O'Hare Field, Chicago Airport, Chicago International Airport, or simply O'Hare, is a major airport located in the northwestern-most corner of Chicago, Illinois, United States, northwest of the Chicago Loop...

.

Through a contract with United Airlines

United Airlines

United Air Lines, Inc., is the world's largest airline with 86,852 employees United Air Lines, Inc., is the world's largest airline with 86,852 employees United Air Lines, Inc., is the world's largest airline with 86,852 employees (which includes the entire holding company United Continental...

, Argenbright operated passenger security checkpoints at Dulles International Airport, where five hijackers passed through before boarding American Airlines Flight 77

American Airlines Flight 77

American Airlines Flight 77 was American Airlines' daily scheduled morning transcontinental flight, from Washington Dulles International Airport, in Dulles, Virginia to Los Angeles International Airport in Los Angeles, California...

 on September 11, 2001

September 11, 2001 attacks

The September 11 attacks The September 11 attacks The September 11 attacks (also referred to as September 11, September 11th or 9/119/11 is pronounced "nine eleven". The slash is not part of the pronunciation...

. United Airlines also contracted with Argenbright to manage its security operations at Newark Liberty International Airport

Newark Liberty International Airport

Newark Liberty International Airport , first named Newark Metropolitan Airport and later Newark International Airport, is an international airport within the city limits of both Newark and Elizabeth, New Jersey, United States...

, where the hijackers on United Airlines Flight 93

United Airlines Flight 93

United Airlines Flight 93 was United Airlines' scheduled morning transcontinental flight across the United States from Newark International Airport in Newark, New Jersey, to San Francisco International Airport in California. On Tuesday, September 11, 2001, the Boeing 757–222 aircraft operating the...

 passed through.

Argenbright managed some security operations at Boston

Boston

Boston is the capital of and largest city in Massachusetts, and is one of the oldest cities in the United States. The largest city in New England, Boston is regarded as the unofficial "Capital of New England" for its economic and cultural impact on the entire New England region. The city proper had...

's Logan International Airport

Logan International Airport

General Edward Lawrence Logan International Airport is located in the East Boston neighborhood of Boston, Massachusetts . It covers , has six runways, and employs an estimated 16,000 people. It is the 19th busiest airport in the United States.Boston serves as a focus city for JetBlue Airways...

 for US Airways

US Airways

US Airways, Inc. is a major airline based in the U.S. city of Tempe, Arizona. The airline is an operating unit of US Airways Group and is the sixth largest airline by traffic and eighth largest by market value in the country....

, Delta Air Lines

Delta Air Lines

Delta Air Lines, Inc. is a major airline based in the United States and headquartered in Atlanta, Georgia. The airline operates an extensive domestic and international network serving all continents except Antarctica. Delta and its subsidiaries operate over 4,000 flights every day...

, Delta Shuttle

Delta Shuttle

Delta Shuttle is the brand name for Delta Air Lines' air shuttle service between LaGuardia Airport in New York City, Logan International Airport in Boston, Ronald Reagan Washington National Airport serving Washington, D.C. and Chicago-O'Hare International Airport...

 and America West. However, Argenbright did not manage the specific checkpoints that the hijackers passed through before boarding American Airlines Flight 11

American Airlines Flight 11

American Airlines Flight 11 was American Airlines' daily scheduled morning transcontinental flight from Logan International Airport, in Boston, Massachusetts, to Los Angeles International Airport, in Los Angeles, California...

. American Airlines

American Airlines

American Airlines, Inc. is the world's fourth-largest airline in passenger miles transported and operating revenues. American Airlines is a subsidiary of the AMR Corporation and is headquartered in Fort Worth, Texas adjacent to its largest hub at Dallas/Fort Worth International Airport...

 contracted its security operations at Logan to Globe Aviation Services. United Airlines

United Airlines

United Air Lines, Inc., is the world's largest airline with 86,852 employees United Air Lines, Inc., is the world's largest airline with 86,852 employees United Air Lines, Inc., is the world's largest airline with 86,852 employees (which includes the entire holding company United Continental...

 contracted with Huntleigh USA to manage its security operations at Logan, including the checkpoint where hijackers on United Airlines Flight 175

United Airlines Flight 175

United Airlines Flight 175 was United Airlines' daily scheduled morning transcontinental flight, from Logan International Airport in Boston, Massachusetts, to Los Angeles International Airport in Los Angeles, California...

 passed through. In November 2001, the Massachusetts Port Authority

Massachusetts Port Authority

Massachusetts Port Authority, or Massport, is a port district in the Commonwealth of Massachusetts. It operates seaports and airports in eastern and central Massachusetts, mainly the Port of Boston. Its headquarters is located in the Logan Office Center, adjacent to Logan Airport in East Boston,...

decided not to renew Argenbright's license to operate security at Logan.

Argenbright, founded in 1979 by Frank Argenbright, was sold to the British firm, Securicor, in December 2000 for an initial cash payment of $185 million.