3 Numerical values
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Statutory Documents - IMO Publications and Documents - International Codes - HSC Code - International Code of Safety for High Speed Craft, 1994 – Resolution MSC.36(63) - Annex - International Code of Safety for High Speed Craft, 1994 - 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 should 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 should 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 1

Effect Criteria Not To Be Exceeded     Comments
  Type of Load Value    
LEVEL 1 Minor Effect Maximum acceleration measured horizontally 0.20 g 0.08 g and 0.20 g/s: Elderly person will keep balance when holding
Moderate degregradtion of safety     0.15 g and 0.20 g\s: Mean person will keep balance when holding
      0.15 g and 0.20 g\s: Sitting person will start holding
LEVEL 2 Major Effect Maximum acceleration measured horizontally 0.35 g 0.25 g and 2.0 g/s: Maximum load for mean person keeping balance when holding
Significant degredation of safety     0.45 and 10 g/s: Mean person falls out of seat when not wearing seat belts
LEVEL 3 Hazardous Effect Collision design condition calculated Ref. 4.3.3   Risk of injury to passengers , safe emergency operation after collison
Major Degredation of safety Maximum structural design load, based on vertical acceleration at centre of gravity Ref. 4.3.3 1.0 g: Degredation of passenger safety
LEVEL 4 Catastrophic Effect       Loss of craft or and fatalities
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 life
F.A.R Probability (reference only) Probable Probable Probable Improbable Improbable Extremely Improbable
  Probable Probable Probable Improbable Improbable Extremely Improbable
JAR-25 Probabiity Frequent Frequent Reasonably Probable Remote Exteremely Remote Improbable
Category of Effect Minor Minor Minor Major Hazardous Catastrophic
1, The United States Federal Aviation Regulations 2,European Joint Airworthiness regulations          
Parent topic: Annex 3 - Use of Probability Concept
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