Basics in aviation safety

Question 1

safetycan be compromised by failures in the following domains

Answer 1

1. Design
2. Materials and components
3. Production
4. Personnel in operations
5. Maintenance, repair and overhaul (MRO)
6. authorities, unsufficient regulations

Question 2

Definition Airworthiness

Answer 2

• FAA: An aircraft is considered to be airworthy when it is in conformity with its type design and in a condition for safe operation
• an A/C is airworthyif the probability of an incident or accident as a result of malfunction, power or handling is on an acceptable level. The acceptable level is defined by the authorities
• The only metric to be used for airworthiness can be obtained by tracing and analyzing air incidents and accidents. In addition, the authorities use the lessons learned from the accidents to adapt und update certification regulations.

Question 3

Fault, Failure Mode, Failure Effect:

Answer 3

• Fault: An undesired anomaly in an item or system
• Failure Mode: the way in which a fault/failure occurs in an item/system.
• Failure Effect: the consequences of a failure mode on function, status oroperation of an item/system

Question 4

Acceptable level of risk

Answer 4

Plot: safety effect - probability
Table: T1 F5/6

Question 5

Altitude definitions
Pressure altitude
Density altitude

Answer 5

• Pressure altitude: Altitude which corresponds to a certain pressure p of the ISA atmosphere (with ps= 101325 Pa) Consequence: if current weather conditions show no difference to the standard pressure curve, in other words QNH = 101325 Pa then Hgeo= Hpressure
• Density altitude: Altitude which corresponds to a certain density of the ISA atmosphere

Example 1: Consider a cold day (ISA-10 K)and standard pressure (QNH =101325 Pa). In this case, we can conclude: HGEO= Hpressure> Hdensity

Example 2: Consider a hot day (ISA+15 K)and a lower pressure than the standard ISA pressure (QNH =101000 Pa). In this case, we can conclude: HGEO< Hpressure< Hdensity