Convert Flex date timestamp to UTC timestamp

var localDate:Date = new Date();
var localTimestamp:Number = localDate.valueOf() / 1000;
//date with valueOf function returns the milliseconds and divide by 1000 to convert to seconds
var timzoneOffset:Number = localDate.timezoneOffset * 60;
//Timezone offset returns the minutes and multiply by 60 to convert to seconds to use for timestamp
var utcTimestamp = localTimestamp + timzoneOffset;