Eastbound flight timing (the "lost hour")

Flying east crosses into zones already ahead: destination clock advances more than flight time. Example: 3 h east across one zone boundary = 4 h on destination clock. Lost hour cuts daylight margin; plan for it on long eastbound flights, especially if landing must precede dark.

Arrival time formula (TC AIM GEN 1.5.3 Table 1.2):

• Destination local arrival = departure local time + flight duration + (destination zone offset minus departure zone offset).

Sunset check:

• Use destination sunset, not departure sunset.
• Get destination local sunset from an FSS; compare with planned arrival.
• Same trap with no zone crossing: west edge to east edge of one zone still eats margin, as sunset comes earlier by clock time.

Trap: adding only flight duration to departure local time, skipping the zone jump: a flight landing after dark looks like it has daylight to spare.

Practice