TO ACT BY THE BOOK - to adhere to the rules or the official wa | ✈️Aviation English

TO ACT BY THE BOOK - to adhere to the rules or the official way of doing something.

E.g.
This airline always ACTS strictly BY THE BOOK.
In case of emergency ATCOs have to ACT BY THE BOOK.
This is a private deal - we don't have to do everything by the book.