What are minimum vectoring altitudes?
Minimum vectoring altitudes (MVAs) are the lowest altitudes a controller can assign when vectoring aircraft off published routes. They guarantee at least 1,000 feet of terrain and obstacle clearance (2,000 feet in mountainous areas). Every sector of controlled airspace has an MVA chart that divides the area into irregular polygons, each with its own minimum altitude.
Why they exist
Published routes (SIDs, STARs, airways) have their own built-in terrain clearance. The altitudes on those procedures are carefully designed so that an aircraft following the route will clear all terrain and obstacles along the way.
But when a controller takes an aircraft off a published route - "turn right heading 270" - that terrain protection disappears. The aircraft is now going somewhere the procedure designers didn't plan for. MVAs fill that gap. They tell the controller: in this chunk of airspace, don't go below this altitude.
How MVA charts work
An MVA chart looks like a jigsaw puzzle laid over the airspace. Each piece has a number - the minimum altitude in hundreds of feet. One sector might show 30 (3,000 feet), the adjacent one 45 (4,500 feet), and a mountainous sector nearby might show 90 (9,000 feet).
The boundaries follow terrain features, not neat geometric shapes. A valley might have a lower MVA than the ridgeline next to it. Controllers memorize these for their sectors.
MVAs vs MEAs
MVA and MEA (Minimum En-Route Altitude) are different things:
- MEA applies along a published airway. It guarantees terrain clearance AND adequate navigation signal reception along that specific route.
- MVA applies to a geographic area regardless of route. It only guarantees terrain clearance.
MVAs are often lower than MEAs because they don't need to account for navigation signal coverage. This is why a controller vectoring you off an airway can sometimes descend you below the MEA - as long as you're above the MVA for that sector.
Real-world examples
Denver's airspace is a good illustration. East of the airport, the terrain is flat plains and MVAs might be 8,000 or 9,000 feet. West of the airport, the Rocky Mountains push MVAs up to 14,000 or 16,000 feet. A controller can't just descend a westbound departure to 10,000 feet without checking which MVA sector the aircraft will be in.
In contrast, Houston or Miami sit on flat terrain. MVAs are low everywhere, and terrain is rarely a factor.
Controller responsibility
This is entirely on the controller. Pilots following vectors trust that ATC is keeping them above terrain. If a controller descends an aircraft below the MVA, there is no cockpit alert to save them (EGPWS/TAWS might catch it, but that's the last line of defense, not a plan).
Controllers must know their MVAs cold. When they issue a descent, they mentally check: where is this aircraft going, and what's the MVA there?
In radarcontrol.io
There are no MVA restrictions currently in the sim. You can descend aircraft to any altitude without terrain warnings or violations. This means you won't encounter the real-world constraint of needing to keep aircraft above specific altitudes in specific areas.
Real controllers must always respect MVAs when issuing vectors. In mountainous airspaces like Denver or Salt Lake City, MVAs are a constant factor in every descent clearance. The sim doesn't model this, so descents that would be impossible in the real world due to terrain work fine here.
Related: What is a flight level? | What is a SID and STAR? | What are airways? | How does ATC separation work? | What is an ILS approach?
Guides: Command reference | Arrivals guide
Play Denver Center - manage traffic in airspace where MVAs would matter most.