Disadvantages
Loading bridges restrict aircraft parking to spots immediately adjacent to the terminal. Thus, airports still use mobile staircases to facilitate boarding at hardstands (remote parking positions).
Loading bridges may pose hazards to aircraft if handled improperly. If the bridge is not retracted fully prior to departure, it may contact protruding parts of the taxiing aircraft (e.g. a pitot tube), requiring repair and delays. Furthermore, during cold weather, the loading bridge may become frozen to the aircraft. In this case, when the jet bridge retracts, it could damage the aircraft if that area has not been properly de-iced.
Loading bridges usually cost more to use than remote stands, so many low cost carriers (e.g., Ryanair, Easyjet and AirAsia) prefer not to use them.
When regional jets are used, jet bridges have another disadvantage, since they only allow one aircraft to park at the gate at a time. Several airlines have removed jet bridges at regional jet gates at airports such as Atlanta which are short on gates. When boarding on the ramp, airlines can fit two or more regional jets per gate. In many other airports like Beijing Capital Airport and Paris Charles De Gaulle Airport, a gate for large aircraft can be used to accomendate two smaller aircraft like Boeing 737s or Airbus A320s.
Read more about this topic: Jet Bridge