This part of ISO 1151 is intended to define the concepts and terms used in flight dynamics studies to specify aircraft flight conditions and envelopes. lt is necessary, for this purpose, to give definitions specifying the terms: mission, controls, geometric configuration, Situation of the Systems, state of’ the aircraft, environment, etc. These concepts are necessary for safety analyses, for qualification purposes, and they apply to the analysis of operational, experimental or simulated flights, taking into account potential failures and likely environmental conditions. The following International Standards are necessary as reference documents for application of this part of ISO 1151: ISO 2533, Standard atmosphere. ISO 5878, Reference atmospheres for aerospace use.