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GDP trends and their effect on the individual’s propensity to fly;
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Timescales for the introduction of another transport mode between two city pairs (e.g. the high speed train between Brussels and Paris) which could significantly reduce the number of flights between the two points;
Note: Whilst determining the timescales for the introduction of a new transport mode may be relatively simple, the same cannot necessarily be said when it comes to determining the effect of the alternative transport mode. In the case of high-speed trains, the total travel time gained/lost by the HST when compared to air travel is a significant factor.
Examples of ‘triggering events’ which are more difficult to predict include –
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political developments across Europe in 1989/1990 (which, for example, started a new tourist trend between Russia and northern Greece);
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the 1991 Gulf war (which affected traffic density)
.
the wars in South-East Europe in the early 1990s (which affected the geographic distribution of traffic as a consequence of closing large tracts of airspace in the area.)
In closing, it is opportune to add that undertaking a ‘raw demand’ analysis such as depicted in Figure 4 – 5, is also useful for such futuristic projects.
4.3.2 DETERMINING THE PREDOMINANT & SECONDARY RUNWAY(S) IN USE
By and large, the predominant and secondary runway(s) in use are usually easier to identify (e.g. either because environmental requirements or weather phenomena dictate runway use). The importance of identifying which runway(s) is used more than another will be seen in the following Chapter, the predominant Terminal Routes invariably take precedence over minor routes.
Whilst ‘predominant runway in use’ is a relative term (as is ‘major traffic flow’), a predominant runway is one that is used most of the time. Usually stated as a percentage e.g. 80% (which equals 292 days a year), it may be said that RWY20 is used 80% of the time, and RWY02 20% of the time. At multiple-runway airports, this ‘predominance’ may be distributed among several runways e.g. e.g. RWY20 is used 80% of the time by arriving aircraft, and RWY 18 is used 90% of the time by departing aircraft.
4.3.3 CONSTRAINTS, MITIGATION AND ENABLERS
As stated in Part C, Chapter 3, the Critical Review provides an occasion to identify constraints in the Reference Scenario, and possible mitigation measures and associated enablers. This said, however, constraints are also identified once the conceptual design phase starts (see next Chapter, Chapter 5).
Whilst Table 4-1 depicts enablers as being the means whereby constraints can be overcome, enablers are also what make it possible to realise design objectives. In either case, the viability and correct identification of enablers is to be most effectively found in a partnership between technical/engineering expertise (e.g. PANS-OPS specialist), air traffic controllers and pilots.
Because of the increasing use of RNAV in ECAC terminal airspace (and therefore the increasing ‘visibility’ of navigation), Attachment C.4-1 provides an overview of Navigation as an enabler in the context of RNAV.
Similarly, because of the importance of the ATC system to the design, Attachment C.4-2 is provided, entitled Understanding the ATC System: Constraint or Enabler.
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