ALIFAX, Nova Scotia, March 27 — Canadian investigators have concluded that the 1998 crash of Swissair Flight 111, in which all 229 people on board were killed, was caused by sparks from faulty wiring that ignited flammable insulation above the cockpit, crippling the aircraft's electrical system.

A report released today by the Transportation Board of Canada stopped short of blaming any single factor for causing the fire that doomed Flight 111 within an hour after the plane, a McDonnell Douglas MD-11, took off for Switzerland from New York's Kennedy International Airport.

But the report strongly suggested that a hastily installed entertainment system that provided games for passengers in first class and business class was probably at least partly to blame for starting the fire, perhaps by overloading the aircraft's inadequate electrical wiring.

The 338-page report is likely to spur international airlines and regulators to improve wiring and maintenance and inspection standards, remove flammable insulation that remains in many aircraft and upgrade fire detection systems in cockpits.

A haunting description of a disastrous but preventable chain of events that began with a spark emerges from the otherwise technical report.

Sparks from chipped or otherwise defective wiring ignited a small creeping flame that gathered strength as it burned through the thermal-acoustic insulation blankets above the cockpit ceiling. No electronic warnings alerted the pilot and crew of the blaze before it burned through flammable foam material at the top of the cockpit's rear wall, causing the fire to gather fatal momentum. The report found no fault with the flight crew.

The aircraft crashed nose first at a steep angle into the chilled waters off Nova Scotia just 20 minutes after the pilot first smelled the fire.

"There was no requirement to have smoke or fire detectors above the cockpit," Vic Gerden, the investigator in charge, said at a news conference. "Such detectors could have provided critical information to the crew."

Mr. Gerden emphasized that the accident would never have happened if it had not been for the insulation blankets made out of metalized polyethylene terephthalate, or MPET, which he said were "readily ignitable" from sparks created by power passing through bad wiring.

"It is important to emphasize here that without the presence of this and other flammable material, this accident would not have happened," he said.

Since the Swissair accident, the Federal Aviation Administration ordered that the MPET insulation blankets be removed from all aircraft registered in the United States.

But the Canadian investigators said the aviation industry and regulators must go further to remove flammable materials from aircraft, and their report recommends that international regulators order the airline industry to install fire detection systems in cockpits and stiffen testing for wiring.

The investigation was the most extensive ever in Canada for an air disaster, taking four years and costing $40 million. More than two million pieces of the shattered aircraft were retrieved and 150 miles of electrical wire inspected.

Although the report determined exactly where the fire began — on the right side of the cockpit, a short distance in front of the rear wall — it did not conclusively pinpoint what ignited the initial spark.

Wire damage believed to be part of the initial ignition was found on one of the wires that supplied power to the in-flight entertainment system, which included video and gambling games and movies. But Mr. Gerden said that "it's important to emphasize here that it is unlikely that this entertainment system power supply wire was the only wire involved" in the ignition.

"We strongly suspect," he said, "that at least one other wire was involved, either an aircraft wire, or another entertainment system wire."

Swissair, which is now bankrupt, removed the gaming system, created by Interactive Flight Technologies, from all its aircraft after the crash.

Many family members of the victims have said they believe that the entertainment system was at fault for the crash, and that American regulators should never have approved the system.

"There is a lack of individual and corporate responsibility," said Mark Fetherolf, of Palm Beach, Fla., whose daughter was on Flight 111. "There also remains deep concern whether the recommendations of the report are adopted enthusiastically by the industry and regulatory bodies."