There are currently no regulatory requirements for a
non-Instrument Flight Rules (IFR) equipped helicopter, involved in
flight under the Night Visual Flight Rules (NVFR), to be equipped
with a standby attitude indicator (artificial horizon) flight
instrument. Helicopters engaged in single-pilot commercial or
aerial work NVFR operations do not have the same level of system
redundancy as IFR equipped helicopters, to safely cope with
equipment failures and emergency situations.
Attitude Indicators
Loss of the functionality of a normally electrically operated
primary attitude indicator, on a helicopter not equipped with a
standby attitude indicator during flight under the NVFR would
result in limited or partial panel flying by the pilot. Limited or
partial panel flying is defined as flight with key instruments
obliterated or inoperative and external cues absent. Partial panel
flying is very demanding and previous accident investigations
indicate that even highly experienced IFR rated pilots may have
difficulty safely operating a helicopter or aircraft under such
circumstances.
Australian Civil Aviation Safety Authority Civil Aviation Order
(CAO) Part 95.7.3 currently provides specific requirements for
helicopters engaged in charter marine pilot transfers. These
requirements include meeting the requirements of Appendix VIII of
CAO Part 20, section 20.18, 'Instruments Required for Night VFR
Flight in Helicopters Except While Engaged in Agricultural
Operations'. This Appendix includes a requirement for '(1) a
primary attitude indicator and (2) a standby attitude indicator or
turn indicator.'
CAO Part 20, section 20.18, Appendix VII 'Instruments Required for
Instrument Flight Rules Operation in Helicopters (Except Night
VFR)' includes a requirement for a standby attitude indicator for
both one and two pilot operations.
The Helicopter Association of Australia recently drafted a paper
called 'Night Operations Risk Reduction Checklist'. This checklist
is being developed to allow operators to evaluate the risk related
to night operations. The checklist provides an allocation of points
to each item that contributes to the safety of operations (out of a
maximum of ten points per item). The checklist allocates four
points to an operator whose helicopter was fitted with a standby
attitude indicator with an independent power source.
Analysis
Under certain conditions, external visual reference may not be
available while flying a helicopter under the NVFR. These
conditions include operating over remote areas, in moonless or near
moonless conditions, over water, and at times when the celestial
horizon is obscured by cloud.
Spatial disorientation refers to a failure by a pilot to sense
correctly the position, motion, or attitude of the aircraft or of
themselves within the fixed coordinate system provided by the
surface of the earth and its gravitational force. For example, a
pilot's inaccurate perception of their position, attitude, or
motion with respect to the aircraft or their own aircraft relative
to another aircraft, terrain, or other obstacle is considered
spatial disorientation in flight.
When spatial disorientation occurs, pilots are unable to process,
believe, see, or interpret the information on the flight
instruments and they rely upon the erroneous information provided
by their senses. In addition, the risk of spatial disorientation is
high during instrument meteorological conditions (IMC) and night
flying in either visual meteorological conditions (VMC) or
IMC.
Partial panel flying by a pilot inexperienced in IFR flight and
operating in low celestial or artificial lighting conditions,
during flight under the NVFR, may impose a significant safety risk.
The inclusion of a requirement for a standby attitude indicator,
with an independent power source, in the event of the failure of
the primary instrument during flights under the NVFR would mitigate
the risk of the pilot incurring spatial disorientation by providing
him a backup instrument in the case of a primary instrument
failure.
Safety Recommendation
The Australian Transport Safety Bureau recommends that the
Australian Civil Aviation Safety Authority assess the safety
benefits of requiring a standby attitude indicator, with an
independent power source, in all helicopters operating flights
under the NVFR in the Charter and Aerial Work category, excluding
dual pilot training.
Issues raised in the recommendations relate to Civil Aviation
Safety Regulation (CASR) Part 133, which is currently under review.
Therefore, until the review is complete, CASA is unable to provide
the ATSB with any substantial comment.
As part of the consultation process associated with the
development of Civil Aviation Safety Regulation (CASR) Part 133,
CASA consulted with the Helicopter Association of Australia (HAA)
and the general helicopter industry regarding the benefits of a
standby attitude indicator.
On the basis of these consultations, CASA has assessed the safety
benefits of requiring a standby attitude indicator with an
independent power source, and determined that greater emphasis
should be placed on training pilots carrying out NVFR flight. CASA
considers this to be a more effective approach than introducing a
mandatory requirement for the fitment of a secondary attitude
reference instrument. Therefore, CASA has taken steps in CASR Part
133 to strengthen recurrent training and checking and operator
proficiency checks for pilots undertaking NVFR flights in
helicopters engaged in air transport operations. It will also apply
to those engaged in Emergency Medical Service (EMS), Search and
Rescue (SAR) and Marine Pilot Transfer operations as well as any
other aerial work operations that CASA deems appropriate.
The Australian Transport Safety Bureau notes that the Civil
Aviation Safety Authority issued Civil Aviation Advisory
Publication (CAAP) 5.13-2(0) Night Visual Flight Ratings
in December 2006. The CAAP was developed following a number of
accidents involving flight at night under the VFR. The CAAP
addresses typical threats and errors applicable to night flight and
presents possible countermeasures or defences for pilots and
operators conducting NVFR operations. Users are encouraged to
incorporate these into both training and operations.
