The flight was due to leave at ten

Question

The flight was due to leave at ten means ----. The flight left at ten or the flight was behind schedule. Thank you.

Answer 1

'The flight was due to leave at ten.' as a sentence on its own tells you only that the plane was, in the past, scheduled to leave at that time. If that time is also in the past, it tells you nothing about the time the plane actually left, or even if it did leave, and if that time is still in the future, whether it is still scheduled to leave then.

You could add some more information after those words:

The flight was due to leave at ten so the family left their home at six thirty.

The flight was due to leave at ten and the passengers went to the gate at nine thirty.

The flight was due to leave at ten and that was the exact time it left.

The flight was due to leave at ten but was delayed by ten minutes.

The flight was due to leave at ten but was cancelled and the passengers had to stay in a hotel until the next day.

The flight was due to leave at ten but will now leave at twelve thirty.

Answer 2

'The flight was due to leave at ten' means The flight was expected/planned/arranged to leave at ten.

'Be due to' is usually used with a time expression

someone is due to do something (=they are expected to do it.)

due=expected to happen, arrive, etc.

-'When is the baby due?' -'The baby is due in January.'