Division SERA.3110 Cruising levels

The cruising levels at which a flight or a portion of a flight is to be conducted shall be in terms of:

1. (a)

   flight levels, for flights at or above the lowest usable flight level or, where applicable, above the transition altitude;

2. (b)

   altitudes, for flights below the lowest usable flight level or, where applicable, at or below the transition altitude.