Definition
Cockpit alerts issued by the Traffic Alert and Collision Avoidance System (TCAS) that direct the pilot to take a specific vertical maneuver — climb, descend, or adjust vertical speed — to avoid a predicted midair collision with another transponder-equipped aircraft. A resolution advisory follows an earlier traffic advisory and is issued when TCAS calculates that the threat aircraft will reach the closest point of approach within roughly 15 to 35 seconds.
Plain English
An automatic cockpit warning that doesn't just tell you another aircraft is close — it tells you exactly what to do (climb, descend, or change your vertical speed) to avoid hitting it. When you get one, you follow it immediately.
Context Anchor
Seen in TCAS operation, especially when nearby traffic becomes a collision threat and the system gives the pilot a specific vertical action to follow.
Derivation
"Resolution" here means "settling or solving a problem" — in this case, solving the conflict between two converging aircraft. "Advisory" comes from "advise," meaning to give guidance. So a resolution advisory is guidance on how to resolve a developing collision threat. Note: although it's called an "advisory," pilots are required to follow it — the name understates how directive it actually is.
Why Pilots Care
Immediate compliance with resolution advisories maintains safe separation and prevents mid-air collisions.
Grounding Statement
A resolution advisory is the point where TCAS goes from warning about nearby traffic to telling the pilot what vertical action to take now.
Intuition Check
Do not read advisory as a casual suggestion here. A resolution advisory is an urgent TCAS command to resolve a traffic conflict; resolution means solving the conflict, not display sharpness.
Example Sentence 1
When the crew received a resolution advisory to descend, the captain disconnected the autopilot and immediately followed the commanded vertical speed.
Example Sentence 2
The crew responded to the resolution advisory by reducing climb rate as instructed.