The Civil Aviation report into the Aug. 20 accident was similar to a draft leaked to Spanish media three weeks ago. A total of 154 people died in the accident, Spain's worst air disaster in 25 years. Eighteen people survived.
The report said wing flaps — moveable panels on the trailing edge of a plane's wings that provide extra lift during takeoff — and slats were not properly deployed as the MD-82 aircraft trundled down the runway at Madrid's Barajas airport, headed for the Canary Islands.
A cockpit alarm that should have warned pilots of the danger failed to sound, according to a review of data from the plane's black boxes. The plane struggled to gain altitude and crashed in a grassy area next to the runway, bursting into flames.
"The investigation continues," the report says. "It will be necessary to carry out tests and an exhaustive examination of the recovered parts of the plane." The report did not say when a cause of the crash might be determined, but investigations into airline crashes can often take months or more.
A separate judicial investigation into what caused the crash found that the crew of the MD-82 reported a problem with the wing slats two days before the accident, and that they were repaired at the time.
Airport video of the takeoff showed that the plane used up much more of the runway than it normally should have as it tried to take off.