Conditions of direct and indirect competition Direct competition Analysing the level of dependence of European airports on particular airlines (under the Herfindahl Hirschman – HHI concentration index, which reaches a value of completely handled by a single airline), it emerged that Malpensa airport is the European airport with the lowest level of dependence on a single airline (leading the HH index in terms of ASK – Available Seat Kilometres), while in terms of seats placed second behind Venice.