in search request page:
date_default_timezone_set("UTC");
$casodletu= date("H:i:s", time());
<td>Select Departure time:</td>
<td>
<select class="search" name="deptime">
<?php
{echo '<option value="'.$casodletu.' selected">Upcoming</option>';}
{echo '<option value="">All</option>';}
?>
</select>
</td>
in FrontSchedulesData class
insert in function findschedule
public function findschedule($arricao, $depicao, $airline, $deptime) {
$query = "SELECT phpvms_schedules.*, phpvms_aircraft.name AS aircraft, phpvms_aircraft.registration
FROM phpvms_schedules, phpvms_aircraft
WHERE phpvms_schedules.depicao LIKE '$depicao'
AND phpvms_schedules.arricao LIKE '$arricao'
AND phpvms_schedules.code LIKE '$airline'
AND phpvms_schedules.deptime > '$deptime'
.....
this will show for you departure after current GMT time.
Other (your modification of FrontSchedules.php is good).