What was found
DURING CRUISE AT FL 390 THREE HOURS INTO THE FLIGHT, THE LEFT OUTER WINDSCREEN CRACKED. THE CREW DECIDED TO DESCEND TO FL 310. APPROXIMATELY 30 MINUTES LATER, THE LT PANE CRACKED A SECOND TIME. THE CREW ELECTED TO DESCEND TO 10,000 FEET. AS A PRECAUTIONARY MEASURE, AN EMERGENCY WAS DECLARED WITH THE TOWER. THE ACFT CONTINUED TO DALLAS AT REDUCED SPEED. LANDED AT KDAL AT 0018Z (0122-98) WITHOUT INCIDENT. UPON EXAMINATION AT DALLAS, THE OUTER PANE OF THE WINDSCREEN WAS MISSING APPROXIMATELY 25 PERCENT OF THE OUTER PLY SURFACE AREA. TC: 1,718.