It solved, I put it here, hope that will help someone else:
<pre lang="c#">
TimeSpan time = flightTime.Add(TimeSpan.FromMinutes(30));
airportTimetable = (from r in db.ShuttleTimeTables
where r.TimeTypeId == 3 && r.Time >= time2
select r.Time)
.ToList()
.Select(x => new SelectListItem()
{
Text = x.Value.ToString(@"hh\:mm"),
Value = x.Value.ToString(@"hh\:mm")
})
.ToList();