In airplane it is turn radius+reaction time, with a
helicopter it is stopping distance+reaction time. Since the
slowest airplanes, J3 or Helio Courier can fly at less than
50 mph and a helicopter height/velocity envelope may limit
minimum flight speed for a low-altitude helicopter. In very
low visibility, there may be little contrast so seeing will
be difficult. Also, unless the helicopter is flown at low
altitude, below 500 feet, the flight will be very much by
instruments, making an observer useful. Just like driving
in fog, it isn't hard to do with a 1/4-1/2 mile vis., but
when less than 100 yards it gets hard to follow the tail
lights in front or avoid the headlights coming at you.

Airplanes, VFR minimum is 1 statute mile, helicopter is see
and avoid. Since I have used 7 of my 9 lives, my minimums
are higher.


--
James H. Macklin
ATP,CFI,A&P

"Peter Duniho" wrote in
message ...
| "Jim Macklin" wrote
in message
| news:0kmkf.11519$QW2.182@dukeread08...
| VFR for a helicopter is enough visibility to stop before
you
| hit something.
|
| The same is true for an airplane. The difference being
that a) helicopters
| are able to fly at arbitrarily low airspeeds, and b)
helicopters can
| actually be brought to a stop mid-air.
|
| No one is saying that helicopters can fly in any weather,
least of all me.
| But that's not what this thread is about. The question is
simply whether
| helicopters can fly in lower visibility than airplanes,
and clearly the
| answer is yes.
|
|