When considering any new GSE for any airport operation, it is prudent to look at all cost factors for the considered equipment, beyond the mere purchase cost. For a toilet service unit, this includes man-power requirements, operational up-time (reliability), speed of operation and – if with a vacuum system – the beneficial impact on aircraft maintenance: When properly cleaned by high airflow with regular intervals, aircraft piping systems are simply less susceptible to blockages than if only serviced by gravity-operated systems.