$re = '/EGA-(?:(?!New=).)+(New=[:\d\/ ]+)/';
$str = 'structure(list(flight_history_id = c(280604281L, 280316415L,
280315758L, 280316495L, 280303866L, 280303866L, 280271465L, 280271465L,
280271465L, 280271465L), date_time_recorded = structure(c(10L,
4L, 3L, 2L, 7L, 1L, 9L, 8L, 6L, 5L), .Label = c("2012-11-12 05:50:23.547-08",
"2012-11-12 15:38:10.099-08", "2012-11-12 16:10:06.968-08", "2012-11-12 17:25:08.814-08",
"2012-11-12 17:58:14.268-08", "2012-11-13 05:16:41.01-08", "2012-11-13 06:51:45.831-08",
"2012-11-13 07:38:19.593-08", "2012-11-13 07:54:22.588-08", "2012-11-13 17:55:58.673-08"
), class = "factor"), event = structure(c(1L, 2L, 2L, 2L, 2L,
2L, 2L, 2L, 2L, 2L), .Label = c("Arrival Estimation", "Time Adjustment"
), class = "factor"), data_updated = structure(c(3L, 8L, 7L,
4L, 2L, 5L, 1L, 10L, 9L, 6L), .Label = c("AGD- New=11/13/12 10:22, EGA- Old=11/13/12 11:20 New=11/13/12 11:09",
"AGD- Old=11/13/12 07:40 New=11/13/12 07:38, EGA- Old=11/13/12 10:25 New=11/13/12 10:18",
"EGA- Based on Distance and Airspeed", "EGD- New=11/13/12 06:35, DGATE- New=A1, EGA- New=11/13/12 07:15",
"EGD- New=11/13/12 07:45, DGATE- New=11, EGA- New=11/13/12 10:25, AGATE- New=A1",
"EGD- New=11/13/12 08:55, EGA- New=11/13/12 09:45, AGATE- New=A1",
"EGD- New=11/13/12 19:05, DGATE- New=A7, EGA- New=11/13/12 20:50, AGATE- New=C5",
"EGD- New=11/13/12 20:20, DGATE- New=A1, EGA- New=11/13/12 21:00",
"EGD- Old=11/13/12 08:55 New=11/13/12 10:05, EGA- Old=11/13/12 09:45 New=11/13/12 10:55",
"EGD- Old=11/13/12 10:05 New=11/13/12 10:30, EGA- Old=11/13/12 10:55 New=11/13/12 11:20"
), class = "factor")), .Names = c("flight_history_id", "date_time_recorded",
"event", "data_updated"), row.names = c(862L, 5514L, 5527L, 5539L,
5545L, 5558L, 5564L, 5566L, 5570L, 5572L), class = "data.frame")';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php