Full title: Southwest Airlines declares an 'operational emergency' due to grounded jets and 'threatens to fire mechanics who don't show up for work' as hundreds of planes are delayed or canceled Southwest Airlines has declared an 'operational emergency' due to grounded jets and threatened to fire mechanics who don't show up for work, according to reports. In a company memo seen by CNBC the carrier said notes from doctors were needed if they were 'alleging illness' after an unusually high number of planes needed maintenance work. Hundreds of their planes were delayed Friday, according to flight-tracking site FlightAware. Up to...