Warning Switch Cluster Gulfstream 550

Warning Switch Cluster Gulfstream 550


An alarm sounds in a potentially dangerous scenario, what do you do?

Studies estimate that our days are interrupted by alarms, ringing phones, message alerts, visual and audible alerts 100-1000 times every day, so much so that we often no longer react at all when an alarm sounds. Welcome to the concept of, “alarm fatigue”.

A common definition in medical training circles would be, “alarm fatigue is sensory overload when clinicians are exposed to an excessive number of alarms, which can result in desensitisation. Patient deaths have been attributed to alarm fatigue.” Change “clinicians” to “pilots” and “patient” to “passenger” and the risk interpretation is clear.

The growing trend toward alarm fatigue is a significant risk to safety. In order to make improvements, we must first recognise the risk, understand its consequences and engage in safe, open discussion towards proactive strategies to reduce the impact.

We certainly suffer alarm fatigue in aviation. A simple online search of “airplane accidents with alarm related factors” provides several examples such as the Eastern 401, Air France 447, and Helios Airways 522. In one study published by James Bliss of Old Dominion University most alarm-related events, 58%, or 158 included alarms that signaled danger accurately. The next highest category was false alarms, which accounted for 28% (76) of the alarm-related events. Thirteen percent (35) of the events were categorised as those involving missed alarms, and 1% (4) involved alarm-related events that did not fit neatly into the other categories (confusing or ambiguous alarm signals).

When more than one quarter of events according to data from the ASRS database involve false alarms, crew members can become lulled into cancelling alarms without significant investigation. This complacency is referred to as “alarm disregard”. If we disregard what triggered alarms because we are so accustomed to cancelling them, we cannot reasonably expect to reliably catch the times when safety demands proper investigation of an alarm cause.

Another type of alarm fatigue and resultant complacency is “alarm neglect”. This occurrence is when the crew member is so fatigued by repeated and/or false alarms that they do not even cancel the alert. This can be witnessed by crew members who don’t appear to even hear the aural alarms anymore, in fact in these instances, crew allows alarms to repeat without cancelling or investigation.

Alarm neglect doesn’t have to manifest on the master warning or master caution levels. Often a minor flight management system (FMS) message (on some aircraft) triggers an amber “MSG” symbol to appear somewhere on the electronic primary flight display of the pilots. It will remain until the FMS messages are cleared or acknowledged from the scratchpad. The crewmember who fails to investigate and clear the scratchpad on the FMS keeps the amber MSG displayed and therefore receives zero warning if subsequent triggers cause new FMS messages. The overall issue is a very common occurrence on some avionics platforms.

Solutions that could be explored as retrofit in existing cockpits (and incorporated in future avionics) could include:

  • Aural alarms that state the system affected by the alert with voice readouts similar to an EGPWS or TCAS alert. System alerts could use a different voice than flight navigation and traffic alerts. Subtle differences between alerts is all that is required to achieve discrete recognition.
  • Visual alarms that are more effective in escalating fashion depending on the nature of the alarm. For example, a Hydraulic Low Pressure CAS message on an aircraft could also result in the backlighting of the hydraulic panel switches intensifying above other systems. The backlighting surrounding system panels could change colour to match the alarm intensity. For example, an amber hydraulic CAS message results in an amber box illuminated on an overhead hydraulic switch panel.
  • Manufacturer efforts to reduce false alarms and nuisance messages to reduce alarm fatigue in crew members.
  • Education and training efforts can be expanded in the immediate term to reduce alarm fatigue. Efforts can begin in initial pilot training and be incorporate throughout curricula up through to the airline transport level. This effort should be spearheaded by regulatory authorities and embraced by the training industry.

The purpose of my article is not to lay blame on any one source for alarm fatigue and inaction but to explore which methods we could employ to reduce alarm fatigue. With modern displays, haptics, and design philosophy it is time for our industry to begin expecting and demanding productive solutions to reduce alarm fatigue in our cockpits. What do you think?