Well, for me and most people, safety is assumed as an invariable across all airlines.
How do you judge this invariable yet invisible asset? One can look at their history of incidents/accidents which is defined as the 'autopsy approach', or alternatively, the airline can take more pro-active steps to ensuring a safe(r) environment for its' passengers.
Most large airlines employ great resources to monitoring trends in the way their aircraft are operated via use of equipment that 'flags' transgressions in the normal operating procedure, as well as software that makes the deferral of defects by the hard-pressed engineers, harder to grant.
Consequently these aspects make (IMHO) an airline safer.
These 'tools' are avoided in the Ryanairs of this world as they COST MONEY.
I am not, in any way, questioning the professionalism or integrity of employees of the airlines we are debating, but it is the constant pressure of Cost containment that was the greatest contributor to the demise of ValueJet.
Human error caused by...
- Fatigue
- Time pressure
- Outdated safety systems
..ARE
variables to safety, ask Railtrack.