Non Transgression Zone

[Jetpipe.]

In the context of independent parallel approaches, NTZ is a corridor of airspace of defined dimensions located centrally between the two extended runway centerlines and between the NOZ (Normal Operating Zones), where a penetration by an aircraft requires a controller intervention to maneuver any threatened aircraft on an adjacent approach.

The minimum NTZ width is 610m.

NOZ extends from the Runway threshold to the point aircraft are established.


My question is now, where is that NTZ width defined from?

My first thought was the most obvious, from the extended centerlines.. but then, if one aircraft was established half deflection right or left depending on runway that would put them in the NTZ but that is not correct as they are established in the NOZ
Then I thought that is says NTZ is located centrally between the two extended runway centerlines. That means it doesnt need to be defined by those.. So my logic says that these 610m are defined from half scale deflection to the Right from the Left Runway and halv scale deflection to the Left from the Right Runway, and it starts from a point were vertical separation no longer can be 1000ft between the two R.

I anxiously await your responses :)

[de facto]

Maybe you should move this to the ATC forum.

[hvogt]

The NTZ is laterally limited by the adjacent normal operating zones. NOZs and NTZ do not overlap.

The wording "located centrally between the two extended runway centre lines" is a bit misleading. The NTZ is between the centre lines, but it is not limited by them.

In other words, the width of the NTZ is defined by the width of the NOZs (see 1.2.2.1.3 of PANS-OPS Volume I, Part III, Section 2).

[Siera]

1check limitations (A320)

2 check QRH minimum req for CAT 2.

It will be enough for you

[FlightPathOBN]

NTZ. An NTZ is established and depicted on the FMA as a
protected zone 2,000 feet wide, equidistant between parallel
runway centerlines, beginning from the point where adjacent
inbound aircraft first lose 1,000 feet of vertical separation,
and extends to 0.5 NM beyond the farthest departure end of runway
(DER), or the point where a combined 45 degrees divergence
occurs, whichever is farthest. The beginning of the NTZ for the
final segment should begin at the most distant precision final
approach fix (PFAF)

NOZ. An NOZ is established so that the NOZ for each close
parallel runway is not less than 700 feet wide on each side of
the approach course at any point. For the offset localizer case,
an NOZ is established so that the NOZ for each close parallel
runway is not less than 500 feet wide on each side of the
approach course at any point. The width of the NOZ is equal on
each side of the final approach course centerline, and the
half-width is defined by the distance from the nearest edge of
the NTZ to the final approach course centerline. The length of
the NOZ equals the length of the NTZ. Each parallel runway
provides a NOZ for the final and missed approach segments that
equal the length of the NTZ

Reference: FAA 8260.39A

[Jetpipe.]

So if my math is correct the total minimum distance from centerline to centerline has to be 2500ft (760m) .

Half NOZ (250ft) + NTZ (2000ft) + Half NOZ (250ft)?
Anybody can confirm this number?


Maybe you should move this to the ATC forum.

Pilots shall know these numbers defacto! :)

[aterpster]

Jetpipe:

Pilots shall know these numbers defacto!

Why? It is information for ATC to determine when a transgression is happening. And, the controller doesn't know the values; rather it is all rather precisely presented to him or her on a final monitor radar video map.

[Jetpipe.]

Aterpster

Ok i admit, maybe ''shall'' was a strong word in the sentence. No knowledge is compulsory what so ever but you can never say you know enough either...
Knowledge is like a safety bubble-shield, the more you know the stronger the shield. In my opinion as ATC is there to help us pilots so are these numbers, in a way that when understanding the method used i.e. for the construction of parallel runways you also put a tiny bit to reenforce your knowledge-shield. Safety is increased when pilots understand the margins of NOZ and NTZ, not because they know the numbers by heart but because they understand the context in them. I recall my fellow classmates from my ATP course saying numerous times '' ..and why do we have to know that? Our job is to fly, not to be an aeronautical engineer!!''

In conclusion, the only bad thing with knowledge is that it grows you old! :(

[ATCast]

From PANS-ATM (ICAO doc 4444):

a no-transgression zone (NTZ) of at least 610 (2000 ft) wide is established equidistant between extended runway centre lines and is depicted on the radar displayFurthermore it states that the distance between the runway centre lines shall not be less than 1035 meters subject to requirements on the surveillance equipment. The worse the surveillance performance, the larger the minimum distance between the centre lines.

I guess the math is correct but you forgot to add some margin for the (in)accuracy of the radar.

ATCast

[KRUSTY 34]

Some time ago I had a "nice" experience with the NTZ. PRM's RWY's 16L/R at Sydney.

Coming in from the North onto 16L with wicked 65kt croswind from the west. 30 mile final so plenty of time to let the A/P adjust. FAF, and centreline nailed with judicious amounts of drift laid off. Over to Tower and cleared for the approach. Within 500', wind drops to 30kts. Slight drift to the right of centreline as A/P slow to correct. From monitor, "Krusty 123, right of centerline and diverging". Heading mode imediately selected, hand moves to heading selector, heading bug place 15 degrees left of centreline. Total deviation to the right,1 dot! I am not BS'ing you, ONE DOT!! "Krusty 123 BREAKOUT ALERT! Climb, heading, YADDA YADDA! You have got to be Sh!tting me!

Aircraft on 16R as observed by TCAS approx 1-2 miles ahead, and nearly a thousand feet below. IMHO NTZ protocals on that day appeared to be more about the controller either covering his arse, or perhaps proving a point!

Love your work. Incoming expected.:suspect:

[ATCast]

I measured the distance between the centre lines of 16R/L of SYD on Google maps; the distance is 1035 meters, the minimum allowable distance for independent approaches. This means there is not much margin for deviation from the localizer, more than 210 meters will get you in trouble, not taking into account radar inaccuracies.

When the crosswind suddenly drops by 30 kts, soon you'll be moving towards the NTZ with 30 kts. That means that within 15 seconds you're well into the NTZ.

The surprising part is that YOU as infringing aircraft were vectored off. According to the ICAO PANS-ATM, the other aircraft should be instructed to climb / turn away from the infringing aircraft. I am not sure what the rationale behind this rule is but I guess the idea is that the infringing aircraft is not capable of following a localizer, so he might not be capable of following any instructions at all.

[Jetpipe.]

Krusty,

If you dont mind me asking, what type of aircraft was it you were flying and what cloudbase did you have at the approach? It cant have been low if the winds were as strong as you say.. Did you have visual contact with the runway? Why not fly manual (company policy?) as you probably expect winds dropping and backing (Ups! I think its veering at the southern hemisphere :ooh: ) at lower level.. :)

ATCast,

Interesting followup comment.. Maybe it should be ATC discretion which aircraft should receive instructions in case of transgression, but totally understandable why it is as it is today!! :)

[AviatorGNamaste]

Kindly explain regarding NTZ
"where a penetration by an aircraft requires a controller intervention to maneuver any threatened aircraft on an adjacent approach."