Decisions are in concept either based on personal experience or on process data, as Operational or Optimal decisions. Operational decisions are based on heuristic data of outcome, while Optimal decisions are based on variations and performance measurements.
In addition to human factors variations, there are multiple other variations affecting safety of flying. Some of these are short runways, high altitude, unpredictable weather, difficult terrain or combinations of all, and including adding human performance variations.
|If just getting there was the point, nothing has to change.|
A perfect accident free record is not necessarily guarantee of an accident free future, or that the operation is managing safety. What heuristic data is telling us, is that operational parameters for a safe flight were greater than the optimal performance parameters of the aircraft. This can simply be illustrated with the process of a pilot's first solo flight. The aircraft is built to perform to far more restrictive parameters than the parameters for a pilot's first flight. Applied operational outcome data does not hold water in today's new generation of SMS, QA and SPC. A landing is only as perfect as the process behind the approach.
|The old windsock displays results, but does not give upwind data.|
Optimal decisions are based on aircraft performance parameters and takes into account performance parameters of approach speed, approach slope, approach stability, threshold crossing speed, touchdown speed, touchdown distance and rollout distance. When runways, altitude, weather and terrain are in favor of aircraft performance capability, it is not necessary that the aircraft meets critical performance parameters for a safe landing.
A decisions based solely on heuristic data does in itself allow for optimal performance parameters to be ignored.