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represent SESAR improvements1.
Together with significant investment
in capacity by airports, SESAR has
the potential to reduce unaccommodated
demand by up to 40%. However,
these capacity gains will require investment
which goes beyond that currently
reflected in European airports?plans.
Schedule smoothing
This method involves moving
flights to times of the day when
more capacity is available, even if
this might not be the first choice of the
passenger.
The extent of the shift which was
assessed varied between 30 minutes for
some point-to-point flights (mainly business
demand) to three hours for some
short- and medium-haul hub flights.
This mitigation is likely to happen to
some degree anyway, in response
to the trade-off between passenger
demand profile during the day and
making the best use of aircraft, staff
and other resources. However, the
method could be restricted locally by
environmental constraints related to
noise abatement.
The gain with schedule smoothing is
quite small since unaccommodated
demand could be reduced by less than
10%, a figure which is somewhat lower
than may have been considered to
be the case in the past. The limit
nowadays is that in the most congested
case, there are only a few quiet times
when shifted flights can be absorbed.
High-speed train
investment2
The 2030 traffic forecast already
assumed that the European highspeed
train (HST) network will continue
to develop. This mitigation method
assumes that an additional large investment
may be made in extending the
HST network by a further 205 city
pairs, focusing on replacing busy,
short-range airport pairs (more than 10
flights/day and less than 400 km in air
distance). Depending on the HST travel
time, a proportion of air passengers
then shift to HSTs, a hypothesis which
has already proven itself with the introduction
of new HST services, Paris to
Strasbourg to cite but one.
It appears that the HST network has a
limited potential for reducing congestion.
Shifting short-haul flights to HSTs
by extending the HST network from
98 city-pairs to over 300 city-pairs
reduced demand by a further 0.3-0.5
million flights. So it takes three times
the connections to double the reduction.
Given the cost of building HST
lines, this is unlikely to be justifiable in
its own right as a means of reducing
demand.
SESAR improvements and
alternative airports
Combining the two most effective
methods ?i.e. exploiting the
benefits of SESAR while using alternative
airports ?has the potential to
reduce by half the number of unaccommodated
flights, results varying from
45% for the most challenging scenario
to nearly 60% for the most likely one.
Use of larger aircraft
The five methods assessed so far
reduce the level of unaccommodated
demand, which was expressed in
terms of numbers of flights. The approach
1- Best-in-class
airport enhancements
were
extracted from
SESAR Definition
Phase 6 Task
Deliverable TASK
2.3.1 ?Milestone 4
(Document
Number:
DLT-0706-
231-00-06).
2- Mitigation
method
modelled by
STATFOR
Mitigating the challenges ahead
Skyway 50 - Winter 2008 15
proposed by this action is different insofar
as the objective is to meet passenger
demand by using larger aircraft, while
reducing the number of flights through
frequency capping.
This method is consistent with the trend
towards the use of larger aircraft already
apparent in the market.
We assessed the effect of introducing the
use of larger aircraft when a cap of 15, 20
or 30 one-way flights per day was applied
to congested airports. A limit imposed on
traffic growth based exclusively on the
daily flight frequency, regardless of airport
slots availability, could be perceived as
detrimental by the airspace user community.
We therefore limited the traffic growth
between airport pairs to airports considered
to be congested by the 2030 time
horizon. As a result, this solution is of
limited value for the network as a whole.
The following assumptions were made
regarding the increase in aircraft size:
n A conservative step, which considered
that long-haul flights could be
replaced by the version immediately
above the current one within the same
category of aircraft. For instance,
A340-300 (295 seats) are replaced
by A340-600 (300-430 seats). As a
　
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本文鏈接地址：Skyway Magazine Winter 2008(10)