WASHINGTON -- Under-inflated tires caused a Learjet crash 18 months ago that killed four people and seriously injured Blink 182 drummer Travis Barker and celebrity disc jockey DJ AM, federal safety investigators said Tuesday.

The National Transportation Safety Board also said that a design flaw in the Learjet 60 and a decision by the flight's captain to abort takeoff in Columbia also were at fault in the accident.

Investigators told the board they found that operators of air charters often aren't aware how rapidly the tires of some business jets can lose pressure, and aren't checking tire pressure frequently enough.

"This accident didn't have to happen," said NTSB Chairwoman Deborah Hersman. The crash, she said, should be a warning to everyone in the aviation industry that "there are no small maintenance items, because every time a plane takes off, lives are on the line."

The board also said the Federal Aviation Administration and Learjet Inc., a subsidiary of Bombardier Aerospace of Canada, didn't take aggressive enough action to correct a design flaw involving the Learjet 60's thrust reversers, despite knowing that the flaw played a role in a similar 2001 accident in Alabama in which two people were seriously injured.

Barker and DJ AM, also known as Adam Goldstein, had just wrapped up a concert in Columbia and were taking off from a local airport in their chartered jet with two of Barker's staff members and two pilots on Sept. 19, 2008.

As the plane hurtled down the runway at about 150 mph, all four tires exploded only seconds apart. Pieces of the tires, hurled at high speeds, damaged the plane's hydraulic system, causing the brakes to fail.

Barker and Goldstein were the only survivors. Goldstein died of a drug overdose a year after the accident.