Page 261 - UK Air Operations Regulations 201121

Part CAT - ANNEX IV - Commercial Air Transport Operations

(B) 2 000 ft above 6 000 ft.
MTCAs are always shown in feet. The lowest indicated MTCA is 3 100 ft.
(2) Minimum grid altitude (MGA)
MGA represents the lowest safe altitude which can be flown offtrack. The MGA is
calculated by rounding up the elevation of the highest obstruction within the
respective grid area to the next 100 ft and adding an increment of
(i) 1 000 ft for terrain or obstructions up to 6 000 ft; and
(ii) 2 000 ft for terrain or obstructions above 6 000 ft.
MGA is shown in hundreds of feet. The lowest indicated MGA is 2 000 ft. This value
is also provided for terrain and obstacles that would result in an MGA below 2 000 ft.
An exception is over water areas where the MGA can be omitted.

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