Definition
An evasive maneuver issued by ATC during simultaneous close parallel PRM approaches in which the pilot turns away from the adjacent approach course and descends to avoid a deviating aircraft on the parallel approach. It is used only when terrain, obstacles, or traffic make a climbing breakout unsafe, and is flown immediately on instruction without question.
Plain English
If a nearby aircraft on the parallel runway strays toward you, the controller may tell you to turn away and go down to get clear of it. That turn-and-descend escape is called a descending breakout.
Context Anchor
Heard on final approach during closely spaced parallel instrument approaches monitored by Precision Runway Monitor controllers.
Derivation
Breakout means stepping out of the approach you were flying. Descending tells you which direction the escape goes. The pairing exists because most breakouts climb, so the descending version is named to make sure pilots don't reflexively pull up.
Why Pilots Care
Provides immediate lateral and vertical separation to prevent a mid-air collision during close parallel approaches.
Intuition Check
Do not confuse breakout here with breaking out of the clouds and seeing the runway. In this context, breakout means an urgent controller-directed escape from the approach path; descending means that escape includes going lower.
Example Sentence 1
During the PRM approach briefing, the captain reviewed the descending breakout procedure in case ATC issued one before they reached minimums.
Example Sentence 2
The pilot turned 45 degrees left and descended to the published altitude as directed during the descending breakout.