No-Transgression Zone (NTZ)

No-Transgression Zone (NTZ)

File:Parallel ILS approaches.png

Parallel Approaches (Source: FAA AIM)

In aviation, a No Transgression Zone (NTZ) is a 2,000-foot wide airspace corridor situated equidistant between the extended runway centerlines or final approach courses during simultaneous independent parallel approaches, where aircraft penetration requires controller intervention to maneuver any threatened aircraft.

Purpose

The NTZ is designed to ensure safe separation between aircraft conducting simultaneous independent parallel approaches to runways that are closely spaced.

Location

The NTZ is located centrally between the extended runway centerlines or final approach courses.

Dimensions

The NTZ has a minimum width of 2,000 feet (610 meters).

Monitoring

Air traffic controllers monitor the NTZ using radar to ensure that aircraft do not penetrate it.

Controller Intervention

If an aircraft is observed entering the NTZ, the controller will issue instructions to the aircraft on the adjacent approach to maneuver and avoid the transgression.

Pilot Responsibility

While the primary responsibility for navigation on the final approach course rests with the pilot, control instructions and information are issued only to ensure separation between aircraft and to prevent aircraft from penetrating the NTZ.

Simultaneous Independent Approaches

The NTZ is a key element of simultaneous independent approaches to parallel runways, which allow for increased airport capacity.

Precision Runway Monitor (PRM) System

The PRM system provides air traffic controllers with the tools to monitor the NTZ during PRM approaches with precision, high update rate, secondary surveillance data.

Phraseology

If an aircraft enters the no transgression zone (NTZ), the controller will breakout the threatened aircraft on the adjacent approach using the phraseology "(aircraft call sign) TURN (left/right) IMMEDIATELY, HEADING (degrees), CLIMB/ DESCEND AND MAINTAIN (altitude)".

References

• FAA
• SKYbrary