AppendixAppendix
Appendix 4Allowable Probabilities
The following probabilities may be used for environmental conditions and operational factors (not caused by aeroplane failures) in quantitative safety analyses: Environmental Factors
| Condition | Model or other Justification | Probability |
|---|---|---|
| CS-25 Appendix C icing conditions | 1 | |
| CS-25 Appendix O icing conditions | 10-2 per flight hour | |
| Icing conditions beyond certified conditions (considered as ‘Severe icing’) | No accepted standard data | |
| Head wind >25 kt during takeoff and landing | AC 120-28 CS-AWO | 10-2 per flight |
| Tail wind >10 kt during takeoff and landing | AC 120-28 CS-AWO | 10-2 per flight |
| Cross wind >20 kt during takeoff and landing | AC 120-28 CS-AWO | 10-2 per flight |
| Limit design gust and turbulence | CS 25.341 (Under review by Structures Harmonisation Working Group) | 10-5 per flight hour |
| Air temperature < -70°C | No accepted standard data |
Aeroplane Configurations
| Configuration | Model or other Justification | Probability |
|---|---|---|
| Centre of gravity | Standard industry practice | Uniform over approved range |
| Landing and Takeoff Weights/Masses | Standard industry practice | Uniform over approved range |
Flight Conditions
| Condition | Model or other Justification | Probability |
|---|---|---|
| Flight condition requiring Stall Warning | Assumption | 10-2 per flight |
| Flight condition resulting in a Stall | Assumption | 10-5 per flight |
| Excessiveness of VMO/MMO | Assumption | 10-2 per flight |
| Flight condition greater than or equal to 1.5 g | No accepted standard data | |
| Flight condition less than or equal to 0 g | No accepted standard data |
Mission Dependencies
| Event | Model or other Justification | Probability |
|---|---|---|
| Any rejected take-off | No accepted standard data | |
| High energy rejected take-off | No accepted standard data | |
| Need to jettison fuel | No accepted standard data | |
| Go-around | No accepted standard data |
Other Events
| Event | Model or other Justification | Probability |
|---|---|---|
| Fire in a lavatory not caused by aeroplane failures | No accepted standard data | |
| Fire in a cargo compartment not caused by aeroplane failures | No accepted standard data |
Notes:
1.If “No accepted standard data” appears in the above tables, the applicant must provide a justified value if a probability less than 1 is to be used in the analysis.
2.The probabilities quoted in this Appendix have been found to be appropriate for use in the context of a quantitative safety analysis performed to demonstrate compliance with CS 25.1309. They may not always be appropriate for use in the context of other requirements.
[Amdt 25/24]
APPENDIX · Appendix 4 — CS-25 · ED Decision 2020/001/R · CS-25 Easy Access Rules · EAR revision 26 Jan 2023