Definition
An ATC procedure or design feature that uses known terrain elevation data to ensure obstacle and terrain clearance for aircraft operating on a given route, approach, or departure. Terrain Based Mitigation allows controllers and procedure designers to apply specific altitudes or routings that keep aircraft safely above surrounding high ground.
Plain English
A way of keeping aircraft safely clear of mountains and high ground by using detailed terrain information when designing routes and assigning altitudes.
Context Anchor
Seen in air traffic control and traffic-flow discussions, especially for busy arrival operations into major airports.
Derivation
Metering comes from the idea of measuring or regulating a flow. In aviation, time-based metering means regulating the flow of aircraft by assigned times.
Why Pilots Care
Pilots must be aware of TBM activity because launches or re-entries can close airspace, create debris hazards, or trigger temporary flight restrictions.
Intuition Check
Tbm is not a cockpit instrument or a physical meter. It is an ATC method for regulating aircraft flow using time.
Example Sentence 1
The minimum vectoring altitude in that sector is set by terrain based mitigation, so ATC cannot clear us lower until we are past the ridge.
Example Sentence 2
A NOTAM advised pilots to avoid the warning area due to falling TBM debris.