Definition
Non-control services provided by ATC to pilots that include traffic information, weather updates, navigational guidance, and other safety-related information. These services help pilots make informed decisions but do not constitute clearances or instructions that must be followed, and they do not relieve the pilot of responsibility for safe flight.
Plain English
Helpful information that controllers pass along to pilots, such as nearby traffic, current weather, or navigation help. It's guidance to support the pilot's decisions, not a command that must be obeyed.
Context Anchor
You encounter this term when reading about what an Air Route Traffic Control Center can provide to aircraft operating in the en route system.
Derivation
Advisory' comes from Latin advisare, 'to give counsel.' 'Assistance' comes from Latin assistere, 'to stand by.' Together they describe services that stand by to offer counsel rather than issue commands -- which is exactly how the FAA uses the phrase.
Why Pilots Care
Gives VFR and IFR pilots extra eyes and information to improve safety without the workload of full ATC clearance compliance.
Intuition Check
Do not read advisory as optional chatter or assistance as guaranteed rescue. In this context, advisory means useful safety information, and assistance means help from air traffic control when it is available and appropriate.
Example Sentence 1
Center provided advisory/assistance services throughout the flight, including traffic calls and a weather update for the destination.
Example Sentence 2
Even without an IFR clearance, the controller offered assistance services including current weather at the destination airport.