Definition
An aircraft electrical system configuration in which only one alternator is installed to generate electrical power for the aircraft's electrical systems and to charge the battery. If that single alternator fails, the aircraft has no backup generating source and must operate on battery power alone until the battery is depleted.
Plain English
The airplane has just one device producing electricity in flight. If it quits working, the only electricity left is whatever the battery can supply for a limited time.
Context Anchor
Encountered when discussing aircraft electrical systems, especially during instrument training and planning for electrical failures in flight.
Derivation
“Alternator” comes from “alternate,” referring to electrical current that changes direction back and forth. In an airplane, the alternator is the engine-driven unit that makes electrical power for the aircraft systems and keeps the battery charged.
Why Pilots Care
Alternator failure leaves only battery power, so pilots must reduce electrical load quickly to keep essential instruments running.
Intuition Check
Do not read “single alternator” as “the airplane has only one source of electricity.” It means there is one main alternator; the battery is still part of the electrical system and may power the airplane for a limited time after an alternator failure.
Example Sentence 1
Because the trainer has a single alternator, the instructor emphasised load-shedding procedures in case of an electrical failure during the IFR cross-country.
Example Sentence 2
After a single alternator failure, the pilot shed nonessential loads to preserve battery power for the attitude indicator and nav radios.