Originally Posted by
Meikleour
IMPRECISE ACCURACY
This thread has shown some clear differences in attitude to routine ops. The OP outlined the scenario of a FLEX departure and a subsequent small rise in actual OAT used initially. Many of the posters have outlined the inherent "buffers" which are already used in the calculation ( esp. Villas ) Since the common use of EFBs for calculations it seems that many people get hung up on spurious accuracy which these will show. By that I mean : How accurate is the loadsheet really - assumed weights plus look at the amount of hand luggage regularly carried. How accurate is the fuel on board actually - sure the gauges read to 10 kgs but what is their accuracy levels really.? How accurate has the runway line-up been done - did you definately not cut the corner on line up to get away quickly? On hot days - how much warmer is the air above the runway versus the ATIS value used? Is the wind component accurate ( sure it is factored but what if zero wind was used)
The buffers are build into the software for good reason - do not assume that implied extra accuracy is there just because the EFB is used and if minor changes produce critical situations then perhaps FLEX is inappropriate?
Computing 101: accurate data in - accurate data out.
less than accurate data in - dubious result out
In more succinct terms - measuring with a micrometer and cutting with an axe.