Home' RTCA Documents for Review : Addressing Human Factors/Pilot Interface Issues Contents 32
© 2017 RTCA, Inc.
Distinctiveness: Applicants used symbols that were not distinctive and could be
confused with other symbols on the display (e.g., depiction of navigation aids on
Specialized symbology has been developed for specific operations like search and
rescue, specialized takeoff or landing procedures, or envelope protection cueing
without substantiating the choice of symbology, through data, for its intended
“Off-scale” symbology: There have been several certification issues arising from
the depiction of information that falls outside the indicator range shown on the
display because there were no cues telling the pilot where the information was
relative to the depicted range. The following are several examples of portrayal of
information off scale or beyond the viewable area of the display format.
o Heading bugs, target speed bugs, and target altimeter bugs were set to values
that were off the visible portion of the display, particularly tape displays.
o A crew selected a heading on the Flight Guidance Panel (FGP) that was out of
the view of the compass display range when the compass was not set to full
o On Cockpit Displays of Traffic Information (CDTIs), a pilot selected a traffic
target that moved outside the display range and no indication (i.e., a symbol
shape modification) was presented to the flightcrew regarding the location of
o Attitude director indicator (ADI) reference symbols used in traditional
pitch-based attitude displays were not visible when the pitch ladder was
expanded (e.g., takeoff pitch attitude reference line on the pitch ladder). This
occurred with synthetic vision systems that were designed to conformally align
flight path angle, or flight path symbology, over synthetically-generated
terrain imagery on an expanded pitch scale.
o ADI track and heading differences during some flight conditions (e.g
approach crab for crosswind) resulted in the flight path marker moving out of
sight or behind airspeed or altitude tapes, depending on the selected synthetic
vision system (SVS)/enhanced vision system (EVS) field-of-view. A similar
implementation occurred when the FPM (where the aircraft is going versus
where the aircraft is pointed) could no longer be displayed on the HUD
combiner or in the PFD field of regard.
Symbol complexity: Displays with lower resolution were unable to accurately
portray some complex symbols. Symbols were not readable.
Size: Symbology was not readable at the size or scale it was presented. Standby
instruments designed with very small symbology were difficult to read in the
location that they were installed. For example, some applicants proposed
presentations of horizontal situation indicator (HSI) and flight directors in a small
format (e.g., standby instrument) that prevented the pilot from using these
information formats with the appropriate precision.
Depiction of information on a synthetic vision display: Several issues related to
the depiction of symbology have been observed on certification projects.
o A synthetic track display that did not provide symbology cues to the
differences between the track-based view and what the pilot saw out-the-
window along the physical longitudinal axis of the aircraft, particularly in the
Links Archive Guidelines for In Situ Eddy Dissipation Rate Navigation Previous Page Next Page