NORTH ATLANTIC OPERATIONS AND AIRSPACE MANUAL — CHAPTER 11
Monitoring of Operational Height-keeping Performance
11.3.6 The introduction of RVSM airspace into the NAT region has increased the necessity for consistent and accurate reporting by flight crews and ATC units, of all deviations of 90 m (300 ft) or more from the cleared flight level, whatever the cause.
Your Notes (not visible to others)
This question has appeared on the real examination, you can find the related countries below.