Home' RTCA Documents for Review : Addressing Human Factors/Pilot Interface Issues Contents 40
© 2017 RTCA, Inc.
Some electronic display systems show status of installed databases on the system
initiation page at power up and require pilot acknowledgement to continue the
ALERTING, ANNUNCIATIONS, AND SYSTEM STATUS INDICATIONS
Alerts and annunciations are used to attract the pilot’s attention and inform the pilot to
changes in the status or condition of aircraft systems and environment. To accomplish this,
alerts may be presented using different senses (for example, visual, aural, haptic) or cues
and they can take many forms (e.g., display messages, prompts, aural tones, stick shakers,
etc.). Note that the term “alert” is used generically here to cover both normal and non-
A comprehensive flight deck alerting system considers all system functions or
malfunctions that require pilot notification and/or time criticality of pilot response. An
outgrowth of the increased complexity of systems on modern aircraft is the management
of warnings, cautions, advisories and notifications on the flight deck. For aircraft with non-
integrated, federated systems, feedback of aircraft status or malfunctions was straight
forward to implement. As aircraft systems have become more integrated, both the
complexity and prioritization of the alerting design needs to be addressed. The challenge
becomes how to best present aircraft status in a way that can be easily understood and
addressed by the flightcrew, supporting timely awareness and recovery procedures.
Degradation of Sensor Sources
Timely alerting and annunciation that indicate a degradation, or loss of redundancy in
sensor status are particularly important if the aircraft is in a phase of flight where time
critical action may be required by the flightcrew, such as on final approach. The earlier this
information is obtained by the system monitors and presented to the flightcrew, the earlier
that a mitigation means can be applied by the flightcrew for a stable recovery.
Specific Certification Issues
System effects, requiring crew action, were not annunciated. Examples include the
o Unannunciated degradation of GPS or other navigation inputs to the FMS has
resulted in decreased fidelity of displayed ownship position on a moving map.
o GPS failures that did not indicate degradation (for example decreased fidelity
of the raw lateral and vertical guidance deviations driving the flight director)
during area navigation (RNAV) approaches.
o Delayed annunciations, such as degradation of satellite-based augmentation
system (SBAS), until the aircraft had reached the critical phase of approach.
The display system did not convey the information to the flightcrew in a timely
o No means to annunciate to the flightcrew that the aircraft had entered an area
that could cause magnetic heading anomalies. These areas may be close to the
magnetic poles of the planet or when arriving and departing from oil rigs or
ships. As a result, the crew had no awareness of the compass system's degraded
capability to operate in area of compass unreliability. For example, an aircraft
transitioning to an area of compass unreliability would not have any change in
indications of unreliable MAG heading data.
Links Archive Guidelines for In Situ Eddy Dissipation Rate Navigation Previous Page Next Page