Hmmm ... now Spanair declares that, because both pilots left the cockpit for several hours, they were suppossed to check the TOWS alarms again for this flight.
And they said they did, according to Spanair. But they did it before the first return to gate.
And they didn't do it again afterwards, when they finally took off, as they had not left the cockpit for a long period, as their procedures called for.
They insist that the MD recommendation after Detroit to make this check prior to each take off, was never made mandatory, not even by the FAA in the USA, and that, regardless, they were never made aware of it and their procedures were approved by spanish civil aviation authorities.