What you are saying is true. The problem is when you are not aligned
with the correct direction, either because you are being vectored, lost
or some other reason. When you are being vectored (or intercepting from
a PT), how do you tell whether you have blasted through the course, or
still heading towards it?? By the time you figure it out using the
left/right interpretation, you will have gone several miles out. It is
trivial with the heading interpretation. Another example is cross
radials. Some fixes on approaches are defined by a VOR cross radial. How
do you know whether you have passed that fix or still heading towards
it? Again, this is trivial with the heading interpretation, but
significantly more difficult with the left/right interpretation. I can
give you many more examples. However, I do agree with you that
left/right works when you are more or less aligned with the course. But
the important point is that it work ONLY in that situation. The other
technique works in ANY situation.





Jose wrote in
m:

The CDI tells you which heading to turn to if you dial in the correct
OBS. Which do you think is more useful command: turn left, or turn
to a heading of xxx?

If I'm already pointing more or less in the right direction, "turn
left" is more useful. If not, the actual heading is.

When on an approach, I'm pointing more or less in the direction I want
to go, and I use the CDI to make small corrections to keep on the
flight path I want. So long as these corrections remain small, and I
remain more or less on the localizer, all I need is "a little more
left". The command "turn to heading xxx" requires me to figure out
how to get to xxx. "turn a little left" does not.

Jose