Definition
A function of the Traffic Flow Management System (TFMS) that predicts, based on filed flight plans and active flights, when the projected traffic count for a sector or airport will exceed its Monitor Alert Parameter (MAP) for one or more 15-minute intervals. The alert prompts traffic managers to consider actions such as rerouting, metering, or ground delays to keep demand within capacity.
Plain English
A computer-generated heads-up to traffic managers that too many aircraft are about to be in the same airspace or arriving at the same airport at the same time, so something needs to be done to spread the traffic out.
Context Anchor
Pilots usually do not see an MA directly. They may hear the result as an air traffic controller asking them to check altitude, climb, or confirm their position.
Derivation
Monitor comes from the Latin monere, meaning to warn or remind. The system is continuously watching projected traffic and warns managers before the airspace gets overloaded.
Why Pilots Care
Prevents controller overload that could compromise separation standards and flight safety.
Intuition Check
Monitor Alert does not mean the pilot should switch to a frequency and simply listen. In this FAA use, it is a controller-side warning generated by air traffic control automation.
Example Sentence 1
A Monitor Alert for the arrival sector prompted the traffic management unit to issue miles-in-trail restrictions for inbound flights.
Example Sentence 2
When the MA triggered, the controller began metering departures to keep sector loading within limits.