My understanding for the UK:
As far as I recall a
STRAIGHT IN approach is something that is instructed by
ATC, and is a way of establishing the aircraft on the final approach track / localiser when it is already within 30 degrees (?) of that track. Perhaps an air traffic controller would confirm or deny this? It is conducted during VMC or IMC, and the step-downs / glideslope etc. must still be followed as per the approach procedure. As one poster has already stated, it's just a way of getting you on to the published final part of the approach without following all the published teardrop / procedure / radar vectored turns because you are already situated in a roughly straight in position.
A
VISUAL approach is an entirely different method where the
pilot requests to continue the approach with visual reference to terrain, foregoing the requirement to adhere to any published IFR tracks & MSAs. From an ATC perspective the pilot need not be in sight of the runway but a reasonable assumption must be made that he is able to continue ultimately to the airport by sole visual reference (or words to that effect). Most responsible airlines however stipulate that approach lighting or the touch down zone must be in sight.
During a visual approach I agree using nav aids, adhering to the published glideslope & meeting minimum altitudes is a reflection of professional airmanship, however I have met pilots who seem to become overwhelmed with the perceived "fun" of a visual approach and abandon many of their instrument and nav aid resources as if they no longer have a use. GPWS aural "GLIDESLOPE, GLIDESLOPE" is the usual tell-tale sign of such cowboys, worsened by their dismissive remark of "disregarding.....visual..."
