Aeronautical Information Manual (AIM), page 572

Index   571 -- Page 572 -- 573

f. The RFM also identifies other specific limita-
tions associated with IFR flight. Typically, these
limitations include, but are not limited to:

1. Minimum equipment required for IFR flight

(in some cases, for both single pilot and two pilot


2. Vmini (minimum speed - IFR).
The manufacturer may also recommend a minimum IFR
airspeed during instrument approach.
3. Vnei (never exceed speed - IFR).

4. Maximum approach angle.
5. Weight and center of gravity limits.
6. Aircraft configuration limitations (such as
aircraft door positions and external loads).

7. Aircraft system limitations (generators,
inverters, etc.).
8. System testing requirements (many avionics
and AFCS/AP/FD systems incorporate a self-test

9. Pilot action requirements (such as the pilot
must have his/her hands and feet on the controls
during certain operations, such as during instrument
approach below certain altitudes).
g. It is very important that pilots be familiar with
the IFR requirements for their particular helicopter.
Within the same make, model and series of helicopter,
variations in the installed avionics may change the
required equipment or the level of augmentation for

a particular operation.

h. During flight operations, pilots must be aware
of the mode of operation of the augmentation
systems, and the control logic and functions
employed. For example, during an ILS approach
using a particular system in the three-cue mode
(lateral, vertical and collective cues), the flight

director collective cue responds to glideslope
deviation, while the horizontal bar of the "cross-
pointer" responds to airspeed deviations. The same
system, while flying an ILS in the two-cue mode,

provides for the horizontal bar to respond to

glideslope deviations. This concern is particularly

significant when operating using two pilots. Pilots
should have an established set of procedures and
responsibilities for the control of flight director/auto-
pilot modes for the various phases of flight. Not only
does a full understanding of the system modes
provide for a higher degree of accuracy in control of
the helicopter, it is the basis for crew identification of
a faulty system.
i. Relief from the prohibition to takeoff with any
inoperative instruments or equipment may be
provided through a Minimum Equipment List (see
14 CFR Section 91.213 and 14 CFR Section 135.179,
Inoperative Instruments and Equipment). In many
cases, a helicopter configured for single pilot IFR
may depart IFR with certain equipment inoperative,
provided a crew of two pilots is used. Pilots are
cautioned to ensure the pilot-in-command and
second-in-command meet the requirements of
14 CFR Section 61.58, Pilot-in-Command Profi-
ciency Check: Operation of Aircraft Requiring More
Than One Pilot Flight Crewmember, and 14 CFR
Section 61.55, Second-in-Command Qualifications,
or 14 CFR Part 135, Operating Requirements:
Commuter and On-Demand Operations, Subpart E,
Flight Crewmember Requirements, and Subpart G,
Crewmember Testing Requirements, as appropriate.

j. Experience has shown that modern AFCS/AP/

FD equipment installed in IFR helicopters can, in
some cases, be very complex. This complexity
requires the pilot(s) to obtain and maintain a high
level of knowledge of system operation, limitations,
failure indications and reversionary modes. In some
cases, this may only be reliably accomplished
through formal training.

10-1-2 Helicopter IFR Operations

Page 572 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   571 -- Page 572 -- 573