Definition
FLOWSIM is an FAA traffic flow management tool used by air traffic specialists to model and rehearse changes to the flow of aircraft through the National Airspace System before those changes are applied in the real world. It allows planners to test how proposed reroutes, ground delay programs, miles-in-trail restrictions, or other traffic management initiatives would affect demand at airports and sectors, so the most effective option can be selected.
Plain English
A computer simulation that air traffic planners use to try out different ways of managing aircraft traffic before deciding which approach to actually use.
Context Anchor
Seen in FAA acronym lists and traffic flow management discussions, especially when planning for weather, congestion, or heavy traffic periods.
Derivation
A blend of 'flow' (the movement of traffic through the airspace system) and 'sim' (short for simulation). The name simply describes what the tool does: it simulates traffic flow.
Why Pilots Care
When a flight is delayed by a ground delay program or assigned a reroute, that decision was often tested in a tool like FLOWSIM first. Knowing this helps pilots understand that traffic management actions are planned, modeled choices rather than arbitrary changes.
Intuition Check
FLOWSIM is not a flight simulator for practicing aircraft control. It is a planning simulation for the movement of many aircraft through the airspace system.
Example Sentence 1
Before issuing the reroute, the traffic management unit ran the proposal through FLOWSIM to see how it would affect arrival demand at the destination airport.
Example Sentence 2
FLOWSIM results helped the team decide which departure fixes needed extra spacing during morning rush.