The formula we use internally: gate-close time, minus 45 minutes at security, minus terminal walk, minus the 90th-percentile drive time for that hour — not the average.
Why the 90th percentile
Averages hide the days that actually make you miss flights. Planning against the bad-traffic case costs you twenty idle minutes at the gate and saves you a rebooking fee once a year.
Driver vs cab
For pre-dawn departures and any trip with luggage and family, a scheduled driver is more reliable than on-demand allocation. Book the night before, not the morning of.
