‘Commercial Air Transportation’ means the transportation by air of passengers, cargo or mail for remuneration or hire. (See IEM 1.1, Commercial Air Transportation.)
‘Continuous Maximum Icing’ (see ‘Icing Atmospheric Conditions’)
*‘Crewmember’ means a person assigned to perform duty in an aircraft during flight time.
‘Critical Altitude’ (piston engines) means the maximum attitude at which, in standard atmosphere, it is possible to maintain, at a specified rotational speed without ram, a specified power or a specified manifold pressure. Unless otherwise stated, the critical altitude is the maximum altitude at which it is possible to maintain, without ram, at the maximum continuous rotational speed, one of the following:–
a.  
The maximum continuous power, in the case of engines for which this power rating is the same at sea level and at the rated altitude.

b.  
The maximum continuous rated manifold pressure, in the case of engines the maximum continuous power of which, is governed by a constant manifold pressure.

*‘Critical Engine’ means the engine whose failure would most adversely affect the performance or handling qualities of an aircraft.
‘Critical Part.’ Where the failure analysis shows that a part must achieve and maintain a particularly high level of integrity if Hazardous Effects are not to occur at a rate in excess of Extremely Remote then such a part shall be identified as a Critical Part.
‘Decision Height’, with respect to the operation of aircraft, means the wheel height above the runway elevation by which a go-around must be initiated unless adequate visual reference has been established and the aircraft position and approach path have been visually assessed as satisfactory to continue the approach and landing in safety.