On Sat, 14 Oct 2006 15:34:12 +0200, Mxsmanic
wrote:

Emily writes:

Can't he just read the regulations? He's obviously got access to
internet.
...
(b) Operate an aircraft that is equipped with an anticollision light
system, unless it has lighted anticollision lights. However, the
anticollision lights need not be lighted when the pilot-in-command
determines that, because of operating conditions, it would be in the
interest of safety to turn the lights off.

Nothing in this quoted section mentions engines, so it doesn't answer
my question.

Yes it does. In the excerpt here, "Operate" means running the engines.
That means all conditions, day or night, except for the exclusion.
That's also mentioned in section 3 of the AIM, "Airport Operations."
In that section, they mention the risk from jet/prop blast. I've read
other FAA articles that discuss the risk of propeller accidents, which
might be prevented with lighted anti-collision lights. A spinning
propeller may not be immediately evident to someone walking across the
ramp. Walking into a propeller can not only cause serious injury or
death, but even worse, may require an expensive engine teardown to
inspect for damage. Any measure that helps prevent that can only be a
good thing.

RK Henry