A combination of factors probably caused this week's deadly plane crash in Madrid and a seemingly minor glitch that thwarted a first takeoff attempt will require further study, Spain's civil aviation chief said yesterday.

Manuel Bautista said failure in one of the Spanair MD-82's two engines - if such a failure did occur - should not, alone, have been enough to bring down a modern aircraft because they are designed to fly on just one if necessary.

"A set of causes probably came together to cause the accident," Mr Bautista said.

The crash killed 153 of 172 people aboard.

An investigation is under way, with help from the United States and the airplane's manufacturer, and Mr Bautista said it was too early to say if human error was involved.

Mr Bautista said he has seen - but would not comment on - video footage from Madrid airport that shows the doomed airliner trying to take off. The newspapers El Pais and ABC said it shows no engine explosion, contrary to some witness accounts.

The video is reported to show the plane using up virtually the entire runway as it tries to take off, then struggling to gain altitude. The airliner eventually crashed, skidded, burned and largely disintegrated.

Only 19 people survived Wednesday's crash of the flight bound for the Canary Islands, Spain's worst air disaster in 25 years.

While taxiing, the plane abandoned a first takeoff attempt because of a problem with what the airline called an air intake temperature gauge near the cockpit. The gauge was essentially turned off, which is an accepted procedure, and the plane was cleared for takeoff, according to Spanair. It crashed on the second attempt at takeoff.

Experts say such a gauge problem is a relatively minor glitch unlikely to have caused the crash. But Mr Bautista would not rule out a link.

"A problem with a temperature sensor may not matter at all, or it can be very important, depending on what other circumstances accompany it," Mr Bautista said. "We will have to see what other issues were present."