NBC employed an outside contractor to conduct the simulation and in its apology Tuesday night, the network cited its use of an incendiary device to ignite an explosion and its failure to inform the viewers about the device. Go To Site

Despite a long and detailed on-air apology from NBC News, General Motors said yesterday that it had suspended advertising on all NBC News programs indefinitely but would continue buying spots on entertainment and sports programs. G.M.'s announcement came as NBC executives announced an "urgent and intense" review of how and why their news magazine program "Dateline NBC" decided to tamper with a G.M. pickup truck so that it would be certain to catch fire in a filmed collision.

NBC set out yesterday to close the book on its "Dateline NBC" debacle with a blizzard of high-minded statements, three firings, a demotion and the creation of a task force to avoid similar mistakes. But sources at NBC News wondered whether top network management understood how deep the news division's problems ran and how they led to the rigged test-crash of a General Motors Corp. pickup during a November broadcast.