Verification of level information

As already known a mode C transponders gives information about the pressure altitude of an aircraft. To use this level indication for vertical separation a controller is obliged to verify this level information as soon as possible after initial contact. To do so you simply compare the reported level of the pilot to the one indicated on your radar screen. Taking into account real life regulations, a discrepancy of 200ft is allowed to exist. Within VATSIM’s simulated environment, a higher offset can be accepted. If the reported level differs significantly from the one indicated on your radar, it is useful to instruct the pilot to turn off his transponder to avoid false conflict alerts. Instead, you have to work with level reports to ensure vertical separation. 

Often wrongly considered as a part of the identification process, a pilot’s level report is completely independent from the procedures shown in the previous chapter.