INVESTIGATORS sifted through the wreckage on Wednesday to discover what caused a Spanish airliner to crash on take-off from Madrid, killing 153 people.
Only 19 survivors have been recovered from Spanair Flight JK5022, which burst into flames during take-off on a flight to Las Palmas in the Canary Islands on Wednesday.
Spain has declared three days of mourning. Flags in Madrid flew at half mast on Thursday and the country observed a silent vigil at noon.
Spanair bosses do not know what caused the crash.
The firm said in a statement that the pilot of the US-built MD-82 airliner had initially reported a problem with a gauge that measures temperature outside the plane.
This delayed the take-off while the problem was repaired and the plane then crashed at the end of the runway during the second take-off attempt, burning and largely disintegrating.
Spanish newspapers speculated that one of the two engines had failed and may have caught fire during take-off.
The US National Transportation Safety Board said that it will send a team of investigators to assist in the probe.
Spanair has had other recent engine problems. The company has confirmed that an MD-82 was forced to make an emergency landing on Saturday on a flight from Lanzarote in the Canary Islands to Madrid because of problems with both engines.
The plane landed in the nearby island of Gran Canaria, the destination of Wednesday's flight.
It is not known whether the same plane was involved in both cases.
Spanair, which is Spain's second largest airline after Iberia, has eight MD82s remaining in its fleet.
Owner SAS put the unprofitable firm up for sale more than a year ago, but it failed to find a buyer.
Bosses have drawn up a cost-saving plan which calls for withdrawing older, less fuel-efficient planes like some of its MD-82s, eliminating some routes and axing a third of its 3,000-member workforce.
Hours before the crash, Spanish pilots' union SEPLA announced that Spanair pilots might go on strike against the proposed lay-offs, but it withdrew the statement after the crash.