AT THE GATE
By Grant Smith, PG
Creating adaptable terminal gates is key to the future of
airports. Airlines and airports are being driven to increase
efficiency and profitability, which results in fuller planes, shorter
turnaround times, tighter gate space, and many ground support
vehicles for onboard services accessing the aircraft at once.
Gates must provide more access than ever before. At the
same time, more people are moving through airports faster,
so coordinating gate functions with the arrival and departure
of people is critical for smooth airport operations.
The gate area functions are behind the scenes to the traveling
public — things that happen on the ground around the
aircraft — but they can have a tremendous passenger impact
on every flight. Aircraft layout, passenger boarding bridges,
preconditioned air, ground power, fueling and ground service
equipment operations — all these things must be considered
when evaluating whether to build a new terminal or renovate
an older one.
Aircraft Layout
Aircraft layout is both an art and a science. The layout must
maximize flexibility to accommodate a range of aircraft while
minimizing the space required for each gate, allowing the
largest number of gates at the terminal. Computer programs
can help determine aircraft parking positions, but the work
doesn’t stop there. Experienced engineers and planners are
adept at recognizing nuances in aircraft layouts that computers
can’t detect. For example, a computer layout tool won’t
necessarily identify that fueling pits or access doors may be too
close together for service vehicles to safely maneuver around
aircraft. Determining the optimum aircraft layout is more than
a life-size jigsaw puzzle.
Passenger Boarding Bridges
The passenger boarding bridge (PBB) is one of the most critical
components contributing to a gate’s flexibility. Considerable
differences exist in aircraft layout for regional jets versus
narrow-body aircraft when using a PBB. Regional jets are lower
to the ground and typically must be farther from the terminal
than narrow-body aircraft, allowing them to meet the required
maximum slope for boarding or deplaning passengers. The PBB
maneuverability and stowage must also be considered, along
with the configuration of any associated fixed walkways and
their support column locations.
When deciding between a new PBB and an existing unit, it
is critical to focus on maximum flexibility at the gate. Costs
for new PBBs that accommodate many aircraft types can be
considerably higher as well, and that can influence decisions
during the aircraft layout phase for both new and modified
terminals. However, the benefit of future flexibility may be
worth the additional cost in this ever-changing business.
Preconditioned Air Systems
Preconditioned air (PCA) systems are the most economically
and environmentally advantageous means to providing
in-cabin air while an aircraft is parked. But these systems must
be properly sized to accommodate the varying sizes of aircraft
and the maximum ambient temperature for the location. Often
there is a “builder’s grade” approach to sizing PCA systems —
planning for the averages. The load factors for PCA systems
are based on the aircraft size and number of passengers. When
selecting a PCA system, airport engineers must consider the
potential minimum and maximum sizes of aircraft, as well as
the cooling losses that occur while service doors are open
during the aircraft turn. For example, if the gate is to service
737 aircraft, there is a big difference in the cooling needs of
a 737-400 (approximately 145 passengers) and those of a
737-800 (up to 189 passengers).
Ground Power
Ground power (400 hertz) is required to run the aircraft’s
systems while it is parked at the gate when the engine is off.
Auxiliary power units (APUs) are usually part of the aircraft
system and can provide power during a turn. However, airlines
are increasingly reducing APU use to save expensive jet fuel
and reduce environmental emissions. Ground power — cleaner
