Causal risk models of air transport - NLR-ATSI

ticket sales (relative to pre-accident)
100
90
80
70
60
50
40
30
20
10
0
-2 -1 0 1 2 3 4 5 6 7 8
Weeks since accident
Figure 8: Estimated changes in new DC-10 bookings on competitive routes after 1989
Sioux City DC-10 crash (relative to pre-crash levels). Source: Barnett et al [1992].
4.2. Who are the users?
According to the Dutch Ministry of Transport, the potential users of a causal risk model are
airlines, air navigation service providers, airport organisations, maintenance and repair
organisations, aircraft manufactures, the central government and the aviation inspectorate.
The projected use is not limited to the Netherlands, so the ‘central government’ could also
mean other national governments, the European Commission, or ICAO. However, when
some of these organisations were asked directly, many doubted whether a causal risk model
could be useful for them. Especially the industry had difficulty to imagine how a causal risk
model could support them in taking daily decisions. The model was nevertheless not
rejected a priori as useless, the opinion was rather that ‘when the causal risk model is ready
we will see what we can do with it’ [De Jong 2006]. In this thesis, we will thus consider
each of the above mentioned organisations as a potential user of a causal risk model.
4.3. Perspectives on aviation safety
This section describes the different perspectives that the stakeholders in the aviation system
may have with respect to aviation safety and how this influences their opinion on the need
to manage and improve safety. A description of the possible role of a causal risk model is
given for every stakeholder based on their needs.
4.3.1. Airlines
For airline management, meeting the minimum safety standards set by the aviation
authorities is a necessary requirement for obtaining an Air Operator Certificate (AOC). In
addition to that, airline management will be aware of the fact that suffering a major
accident may result in significant costs due to decreased ticket sales and may even cause an
airline to go bankrupt, even though most airlines have adequate insurance to meet virtually
all the direct costs arising from an accident (see infobox on the role of insurance).
Especially very small airlines in the holiday charter business are vulnerable in this respect,
because they are often not able to survive the immediate loss of income that is the result of
one of their aircraft being no longer available and of the effect of the crash on public
perception. However, accidents can impact the business of larger airlines as well. Examples
43