Operational changes in flight
31.  An AOC holder must ensure that, where there is a need to alter the operational flight plan of a large aeroplane in flight and this alteration will require a change in the ATS flight plan —
(a)the appropriate air traffic services unit has agreed to the proposed change before the proposed change is transmitted to the pilot‑in‑command of the aeroplane; and
(b)the pilot‑in‑command has obtained all necessary air traffic control clearances before making operational changes to the aeroplane’s ATS flight plan.