March 28, 1931 United Air Lines Inc. is incorporated.

March 20, 1939 United signs industry's first collective bargaining agreement, with mechanics and related ground service employees.

July 1993 Pilots, flight attendants and machinists unions agree to wage and benefit concessions in exchange for majority ownership of UAL.

Dec. 15, 1993 Unions reach a tentative agreement to buy the carrier in a $5.15 billion cash-and-concessions deal that would give them at least 53 percent ownership under an employee stock ownership plan.

May 24, 2000 Announces it has agreed to buy US Airways for $4.3 billion in a deal that would give United larger operations along the East Coast and nearly triple its daily flights to more than 6,400 a day.

Aug. 26, 2000 Agrees to grant industry-leading pay to its pilots after a summer of labor turmoil that resulted in thousands of flights being delayed or canceled.

July 27, 2001 United Airlines and US Airways Group call off their merger after the Justice Department says it would sue to block it.

Sept. 11, 2001 Two United planes are among the four hijacked by terrorists and crashed -- one in Shanksville, Pa., the other hitting the World Trade Center.

Sept. 19, 2001 Announces 20,000 layoffs in wake of terrorist attacks and decline in air travel.

Sept. 27, 2001 Indefinitely suspends its quarterly dividend, replaces chief financial officer.

October 28, 2001 Chief executive James Goodwin replaced by board member Jack Creighton on interim basis, two weeks after saying the airline "will perish" sometime in 2002 if it cannot stem huge losses that have worsened dramatically since Sept. 11.

Nov. 1, 2001 Reports $1.16 billion quarterly loss, biggest in its 75-year history.

Feb. 1, 2002 Announces $2.1 billion loss for 2001, a record for any airline.

Feb. 18, 2002 Reaches tentative contract agreement with the union representing its 12,800 mechanics and aircraft cleaners, averting by less than 36 hours a strike that could have grounded the airline.

April 19, 2002 Reports $510 million first-quarter loss.

June 24, 2002 Asks the federal government for $1.8 billion loan guarantee.

Sept. 2, 2002 Oil executive Glenn Tilton named chairman and CEO.

Oct. 18, 2002 Stock sinks to $1.42 per share on the New York Stock Exchange, its lowest level in at least 40 years.

Oct. 18, 2002 Reports $889 million third-quarter loss.

Nov. 4, 2002 Stock soars 24 percent as company reaches a tentative $2.2 billion cost-cutting deal with pilots.

Nov. 27, 2002 Mechanics reject a plan to contribute $1.5 billion in wage concessions that were part of UAL's effort to stay out of bankruptcy. In separate votes, two other factions of the machinists union approved the proposal.

Dec. 2, 2002 Mechanics agree to vote on a revised contract that sweetens terms on benefits but still calls for wage cuts of 6 percent to 7 percent.

Dec. 4, 2002 Federal Air Transportation Stabilization Board rejects United's request for $1.8 billion in federal loan guarantees.