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ATM Occurrences
Occurrences are defined as accidents, serious incidents and incidents. The most common types of ATM related
occurrence are: Unauthorised Airspace Penetration (UAP), Aircraft Deviation from ATC Clearance (CLR), Separa‑
tion Minima Infringements, Runway Incursions (RI) and Inadequate Aircraft Separation (IS). Occurrences can be
classified under more than one category, for example a CLR could lead to an SMI. The numbers of these over
the period examined are shown in Figure 42, along with the severity classification applied using the Risk Analy‑
sis Tool (RAT) methodology. The severity classes are Serious Incidents (A), Major Incidents (B), Significant (C), No
Safety Effect (E), and Not Determined (D).
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Figure 42:
Number of ATM-related occurrences by occurrence category and severity grade
in EASA MS FIRs, 2010 – 2014
0
5 000
10 000
15 000
20 000
25 000
UAP
CLR
SMI
RI
IS
Number of Occurrences
A
B
C
E
D
Not classi ed