A systems failure and pilots' error combined to cause the crash of the Spanair jetliner that killed 154 people in Madrid last year, according to a preliminary report released today.

Spanair MD82's flaps and slats were not extended as the aircraft was preparing for takeoff, but this was not noticed during the pilots' routine pre-departure check and the automatic on-board system did not alert the error, Spain's Civil Aviation Accidents Commission said in its report.

"The aircraft had the standard procedures and check lists in force ... which included the selection and confirmation of the correct configuration for takeoff," the report said.

"The pilots used these procedures as a reference, but for some reason -- whether an interruption from the aircraft's first return to the terminal due to a mechanical problem, pressure due to time delays or faults in the cabin crew's work methods --, these were not strictly followed," it added.

The Canary Island-bound flight shot off the runway into a ravine on takeoff and burst into flames on Aug 20, 2008. It was Spain's worst air crash in 25 years. Eighteen people survived.

The Commission also made seven recommendations to improve international air safety which will be sent to the European Air Safety Agency, the International Civil Aviation Organisation, and the Federal Aviation Administration in the United States.

The recommendations include pilots verifying the aircraft's take-off weight (TOW) before each flight rather than just the first of the day and a request to Boeing to review its TOW systems.

The MD-80 family is manufactured by McDonnell Douglas, which is now part of Boeing Co. Spanair is owned by Catalan investors and Scandanavia's SAS.

The Commission also recommended an annual international aviation conference to revise check lists, crew training and improvements in work methods to ensure that crews correctly configure their aircraft before takeoff and landing.