Operational demands such as the need for faster turnaround times, reduced aircraft emissions and evolving gate practices create new design considerations for today’s airports – especially for that corridor of activity between the terminal building and the tail limit line of parked aircraft.
The complexity of these demands is exacerbated by new aircraft designs, higher load factors and the expansion of personal electronics into the flying experience.
I believe that these factors force a careful evaluation, or perhaps more accurately, re-evalutation, of gate-related services and utilities.
Cooling parked aircraft
Aircraft at the gate need conditioned air to keep them comfortable for the flying public. And, saving fuel is a key objective. The solution has been to shut down the APU and rely on point-of-use or central system pre-conditioned air products.
Designing for these systems requires the careful evaluation of available gate power or chiller capacity in the central plant. In some cases, the best solution may be combing a point-of-use vapour expansion pcair unit with an existing, but somewhat undersized, central chiller plant. A variety of options are available.
Design evaluations should also take into account changing power demands and heat generation issues within the aircraft. Galley activity, entertainment systems and higher load factors, for example, can impact the conditioned air requirements of the aircraft as can the aircraft model itself. These characteristics should be considered in the design of the cooling capabilities available at the gate.
Powering parked aircraft
The requirements for electrical power too, are changing. Electrical loads and the nature of them have been impacted by ‘next generation’ commercial aircraft, sophisticated shipboard entertainment systems and changes in gate practices, such as cooking at the gate.
Typical 90kVA aircraft draw with power factors of 0.8 are giving way to demands for equipment capable of supplying 90kW, 180kW or more. These changes, in particular the need for kW (rather than kVA) with ground power units supplying 400Hz AC at unity power factors, can have a significant impact on the design of the terminal supply grid and its components – such as breakers and switches.
Increasingly, more 400Hz ground power is required at the gates, sometimes with a heavier-duty support grid, supplied by equipment capable of responding to demand at unity power factors for the duration of the aircraft turn.
Power and conditioned air systems are often designed using a ‘diversity factor’ – an estimate of the average demand that might be placed on the systems.
In a home, for instance, the sum of all the receptacles (each typically rated at 15 amps) will add up to more than the incoming power available to the home itself. This makes sense because it is so improbable that every receptacle will be supplying its rated power simultaneously. A worse case scenario might be that 70% of the receptacles are so employed.
Similar calculations are done when sizing equipment at airports. However, these assumptions must be carefully reviewed against current operational realities.
Higher load factors, compressed turnaround times and larger aircraft all put greater demands on all systems inside the terminal and at the gate interface. Loads are also increased by the influx of banks of aircraft.
At major hub airports, every gate may be occupied by larger, fuller, electronically sophisticated aircraft eight to ten times each day. During these peaks of demand, traditional diversity calculations may prove inadequate.
Gate equipment ‘up time’ and availability
Facilitating the aircraft turn and maximising the customer experience are of paramount importance. Systems like the iOPS apron management capability from JBT are available that connect gate and other equipment, monitor status, detect faults, verify use, and record operations.
This information is invaluable to operations and asset managers within the airport, airline, and service supplier constituencies in providing efficient, cost effective, environmentally friendly aviation services.
Aircraft are changing, aviation practices evolve, and the demands from all aviation sectors continue to increase. These trends mandate that airport planning and design efforts carefully evaluate their impact on the broad family of gate equipment and the infrastructure to support them.