If you can refer me to where it says that, I will stand corrected.
Here's a portion of the Letter I googled on the newsgroups. I didn't pull it from my Summit CD, so I can vouch for the exact authenticity, but it does match in content the letter that I have duplicated many times:
November 07, 1984
Mr. Joseph P. Carr
Dear Mr. Carr:
This is in response to your letter asking questions about
instrument flight time.
First, you ask for an
interpretation of Section 61.51(c)(4) of
the Federal Aviation Regulations (FAR) regarding the
logging of
instrument flight time. You ask whether, for instance, a
flight
over the ocean on a moonless night without a discernible horizon
could be logged as actual
instrument flight time.
Second, you ask for an
interpretation of Section 61.57(e)(2) of
the FAR, noting that Advisory Circular 61-65A, Certification:
Pilots and
Flight Instructors, seems to contain advice contrary
to your understanding of the rule. [answer not included in this post]
As you know, Section 61.51(c)(4) provides rules for the
logging
of
instrument flight time which may be used to meet the
requirements of a certificate or rating, or to meet the recent
flight experience requirements of Part 61. That section
provides, in part, that a pilot may log as
instrument flight time
only that
time during which he or she operates the aircraft
solely by reference to instruments, under actual (
instrument
meteorological conditions (i.m.c.)) or simulated
instrument
flight conditions. "Simulated"
instrument conditions occur when
the pilot's vision outside of the aircraft is intentionally
restricted, such as by a hood or goggles. "Actual"
instrument
flight conditions occur when some outside conditions make it
necessary for the pilot to use the aircraft instruments in order
to maintain adequate control over the aircraft. Typically, these
conditions involve adverse weather conditions.
To answer your first question, actual
instrument conditions may
occur in the case you described, a moonless night over the ocean
with no discernible horizon, if use of the instruments is
necessary to maintain adequate control over the aircraft.
The determination as to whether
flight by reference to instruments is
necessary is somewhat subjective, and based in part on the sound
judgement of the pilot.
Note that, under Section 61.51(b)(3),
the pilot must log the conditions of the
flight. The log should
include the reasons for determining that the
flight was under
actual
instrument conditions in case the pilot later would be
called on to prove that the actual
instrument flight time logged
was legitimate.