Abstract: Methods and systems for functional monitoring of a reservation system. A specific architecture, which reproduces a system of monitored terminals, includes gauges connected in a specific manner to take into account rules already set between the terminals. The architecture is produced in order to monitor a specific part of the system of terminals as requested by the user. New indicators are defined with specific rules and calculated with corresponding formulae based on the existing indicators. For example, a rule can be a request for receiving an indication of when a specific level of occupied seats in a plane is reached in order to allow the flight to occur. The answer to the request refers to a specific calculation based on current data coming from a real situation of checking the number of occupied seats on a regular basis.