Key events in the Takata air bag recall

Japanese auto supplier Takata Corp. on Friday agreed to plead guilty and pay $1 billion in fines and restitution over a lengthy scheme to conceal a deadly defect in millions of air bags. Three former Takata executives were also indicted in the case. Automakers have recalled 42 million cars equipped with 69 million Takata air bag inflators, the largest automotive recall in U.S. history.

Here is a timeline of key events in the Takata recall.

Late 1990s: Takata begins making air bags with ammonium nitrate, which is used to quickly inflate the bag after a crash. But the substance is highly combustible.

2000: Takata executives Shinichi Tanaka, Hideo Nakajima and Tsuneo Chikaraishi realize that the air bags can rupture but they don't inform automakers, according to an indictment unsealed Friday.

2001: First recall issued relating to Takata's air bags, for the 2000-2001 model year Isuzu Rodeo and the Honda Passport. Takata says the passenger side air bags contain an improper amount of the chemical ammonium nitrate, which produces the gas that makes them inflate. Isuzu says the problem was caught quickly so it doesn't send recall notices.

2002: Honda recalls 2,686 Honda Accord and Acura TL sedans from the 2000 model year because their passenger air bags can inflate with too much pressure. Takata blames improper welding.

2008: Honda recalls 3,940 Accords and Civics nationwide from 2001 model year. Takata blames the handling of air bag propellant chemicals before assembly.

2009: Ashley Parham, 18, dies when the Takata air bag in her 2001 Honda Accord explodes after her car bumps into another car in a parking lot. Parham bleeds to death after shrapnel from the air bag slices open her carotid artery.

2009: Senior Takata executives learn that air bag reports were falsified, but take no action against lower-level executives until 2015.

2013: Toyota, Honda, Nissan, Mazda and General Motors recall nearly 3.4 million older-model vehicles worldwide due to defective Takata air bags. Takata blames two human errors during production: A worker forgot to turn on the switch for a system weeding out defective products, and parts were improperly stored, which exposed them to humidity.

2014: Lawmakers push for a nationwide recall of Takata air bags during congressional hearings.

May 2015: Takata admits its air bags are defective, expands recalls to 34 million inflators in the U.S.

November 2015: The National Highway Traffic Safety Administration imposes a record civil penalty of up to $200 million against Takata and requires it to recall all inflators with ammonium nitrate unless it can prove they are safe.

May 2016: The U.S. government more than doubles the size of the Takata recall to 68 million air bag inflators that must be replaced through 2019.

January 2017: Takata agrees to plead guilty to one count of wire fraud and to pay $1 billion in penalties, including $975 in restitution to automakers and injured drivers. The company's air bags have killed at least 16 people worldwide and injured at least 180.