Start with the approval route

Before detailed design begins, a programme should understand who will approve the change, which organisation holds each responsibility and what evidence the chosen route will require.

Early Part 21 planning exposes gaps in privileges, unclear interfaces and unrealistic assumptions about classification or authority involvement. Finding those issues at the start is far less disruptive than finding them during a conformity review or final document check.

Make interfaces explicit

The strongest plans describe the working relationship between the operator, design organisation, production or maintenance organisation and any specialist suppliers. They also define how decisions, deviations and configuration changes will be recorded.

This does not remove every surprise. It does ensure that the programme has a controlled way to respond when the design or operating requirement changes.