3 Numerical values
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Statutory Documents - IMO Publications and Documents - International Codes - HSC 2000 Code - International Code of Safety for High-Speed Craft, 2000 – Resolution MSC.97(73) - Annex 3 - Use of probability concept - 3 Numerical values

3 Numerical values

 Where numerical probabilities are used in assessing compliance with requirements using the terms similar to those given above, the following approximate values may be used as guidelines to assist in providing a common point of reference. The probabilities quoted shall be on an hourly or per-journey basis, depending on which is more appropriate to the assessment in question.

Frequent More than 10-3
Reasonably probable 10-3 to 10-5
Remote 10-5 to 10-7
Extremely remote 10-7 to 10-9
Extremely improbable Whilst no approximate numerical probability is given for this, the figures used shall be substantially less than 10-9

Note:

Different occurrences may have different acceptable probabilities, according to the severity of their consequences (see table 2).

Table 2 Severity of consequences

SAFETY LEVEL 1 1 1 2 3 4
EFFECT ON CRAFT AND OCCUPANTS Normal Nuisance Operating limitations Emergency procedures; significant reduction in safety margins; difficult for crew to cope with adverse conditions; passenger injuries. Large reduction in safety margins; crew over-burden because of workload or environmental conditions; serious injury to a small number of occupants. Deaths, usually with loss of craft
F.A.R. 1 PROBABILITY (reference only) <— — — — PROBABLE — — — — —> < — — IMPROBABLE — — > EXTREMELY
<— — — — — — >
IMPROBABLE
JAR —25 2 PROBABILITY <— — — — PROBABLE — — — — —> < — — IMPROBABLE — — > EXTREMELY
<— — — — — — >
IMPROBABLE
<— — FREQUENT— — > REASONABLY
<— — — >
PROBABLE 		<— REMOTE —> EXTREMELY
<— — — >
REMOTE 		 
  10-0 10-1 10-2   10-3 10-4 10-5 10-6 10-7 10-8 10-9    
CATEGORY OF EFFECT <— — — — —MINOR — — — — —> <— MAJOR —> <—HAZARDOUS—> <—CATASTROPHIC—>
 
1United States Federal Aviation Regulations.
2European Joint Airworthiness Regulations.
Parent topic: Annex 3 - Use of probability concept
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