BE to and BE about to

BE to and BE about to

[Reference: (Second Edition) Oxford Practice Grammar by John Eastwood Unit 26]

BE VERB
First form	Second form	Third form	Fourth form
Infinite form	Past form	Past participle form	Present participle form
Be Present cases (is, are, am)	Was / were	Been	being

We use be to for a future event that is officially arranged. It is often used in news reports.

↷ The Queen is to visit Portugal in November.

↷ The Student Games are to take place in Melbourne next year.

We could also use the present continuous here.

↷ The Queen is visiting Portugal in November.

We use be about to for the very near future.

↷ The plane is at the end of the runway. It is about to take off.

↷ Do you want to say goodbye to our visitors? They're about to leave.