Definition
A protected airspace corridor located between two final approach courses for closely spaced parallel runways during simultaneous independent approaches. If an aircraft penetrates the no transgression zone (NTZ), air traffic control immediately issues breakout instructions to the aircraft on the adjacent approach to maintain separation.
Plain English
A buffer strip of airspace running down the middle between two parallel runway approaches. Aircraft are not allowed to cross into it, and if one does, controllers immediately turn the nearby aircraft away to keep them apart.
Context Anchor
Seen on airport traffic pattern diagrams and briefings for airports with parallel runways.
Derivation
‘Transgression’ comes from the Latin ‘transgredi,’ meaning ‘to step across.’ The name describes the zone literally: a strip of airspace that aircraft must not step across.
Why Pilots Care
Maintaining separation from this zone prevents loss of required lateral spacing and reduces collision risk during simultaneous approaches.
Analogy
Think of it like the painted buffer between two lanes of traffic. Each lane has its own path, and the buffer is there so vehicles do not drift into each other’s space.
Intuition Check
“Transgression” does not mean a moral mistake here. It means crossing into an area that must be kept clear for safe parallel runway operations.
Example Sentence 1
During the simultaneous ILS approaches to runways 28L and 28R, the controller monitored both aircraft to ensure neither entered the no transgression zone between the final approach courses.
Example Sentence 2
Controllers issue corrections if an aircraft begins to drift toward the no transgression zone between the two runways.