Annunciators — Your Early Warning System

Since about 1980, aircraft have enjoyed certain changes that allow pilots to fly more safely. Aircraft systems now warn pilots of problems promptly, instead of allowing the problem to intensify to the point that it identifies itself. When your life depends on how quickly you find a problem, this sort of change can make a big difference.

Annunciator systems were added to most small GA aircraft in the mid-1980s. In automobiles, they call these little gadgets “idiot lights,” since if you manage your car by them, you are likely to see significant damage to the car shortly after seeing illumination of the light. While the annunciators in aircraft are similar, what we do before we fly takes the idiot out of the idiot light.

PREFLIGHT — This is your big chance to find problems before you take off. Your walkaround checklist is designed to have you look at all the systems that could challenge the safety of your flight. The preflight checklist is your first line of defense in flight safety.

ANNUNCIATORS — As the name implies, when a problem comes up, the annunciator announces it, or brings it to your attention. The majority of systems announce a problem by the illumination of a light on the annunciator panel, which has a legend printed on it identifying the system that light monitors. If the OIL PRESS lamp comes on, you should check your oil level as well as the pressure gauge to look for a problem. While sensor failure or breakdown does occur, these annunciator systems are designed to bring a potential problem to your attention in time for you to take action and prevent a catastrophic failure.

RESPONSE — When flying, it is best to assume the worst about any problem that an annunciator may indicate. IMMEDIATELY CHECK THE PARAMETER THAT IS IN ALARM. If the parameter is not where it should be, follow your emergency procedures in your POH. If the procedures call for you to land the plane, do it.

SECOND-GUESSING — Some people second-guess the annunciators in their airplanes … and rightly so. With improper maintenance, the annunciator system will become little more than your own personal, airborne ‘boy who cried wolf’ — they will be unreliable and indicate an alarm at the wrong time. However, if you have properly maintained the sensors, why not believe them? While the lights are never providing good news, the news is usually more useful than the silence that comes after the engine stops due to a lack of oil pressure or fuel.

Annunciators serve an important function. Most pilots don’t scan their engine instruments as often as they should and annunciators supplement that scan by monitoring the various parameters regardless of whether a pilot is checking them or not. Of course, this can be both good and bad:

  • If a pilot allows his or her scan to deteriorate by depending on the annunciator to warn of impending doom, than the pilot/annunciator system is not working to its fullest potential.
  • On the other hand, with the additional monitoring provided by an annunciator, a relaxed scan of the engine instruments becomes more forgiving. With an annunciator, an overloaded pilot, working alone in a busy cockpit and in poor conditions, can concentrate more energy on flying the airplane and not busting any ATC course or altitude requirements.

BOTTOM LINE: Are annunciators the do-all of aviation? Unfortunately, no. However, if your airplane is equipped with these little wonders, they can help to make you more productive in the cockpit while making your flight safer by acting as a ‘second set of eyes’ and warning you of problems before those problems become self-evident.