Protecting Missed Approach in NZ

[conflict alert]

All departures/arrivals could end up having standard gaps. RNP and all maneuvers programmed into the FMS will be the norm.

Already in the wind with CAM version 2 Tarq57...enroute will give ETA's at points and there's your gaps...dissappearing very quickly is the art of ATC.

(Must replenish your wine supply one day)

[conflict alert]

Interesting subject though, as an approach controller, on the sector that I work we only protect the missed approach when weather conditions are marginal or below circling for the cateogory of aircraft flying the approach. Having said that, most of our releases of departures are given to the tower as a "Released your sep" on the inbound so the tower won't clear an aircraft for takeoff until they see the inbound or use a "composite" visual sep. Once they have seen the inbound (obviously now VMC) they can instruct the aircraft to enter the circuit (when the MET criteria is there) if for some reason the aircraft goes round or is instructed to go around by ATC for whatever reason.

I'll investigate all the rules and talk to the man in ATS OPS (Airways policy and rules person) and get back.

[Tarq57]

What I find interesting about the current incarnation of the procedure is: why the change?
(That is, why is the wording now "may require an a/c to enter the circuit...")
This has obviously created some uncertainty.
Is it yet another example of the adoption of ICAO standards dumbing us all down, or a genuine attempt to remove the cumbersome ATIS requirement (yay), perhaps as a result of recommendations made concerning that 777 that failed to notice the reduced rwy length at AA a while back?

[haughtney1]

Examples: ATR departing straight ahead, A320 on final, ATR must commence roll before the A320 crosses a 7 mile final. Becomes 5 miles if the ATR is on a side SID.

Wow, what do you guys do when your busy? seven miles? thats a massive spacing!

The whole thing is a bit of a blunt tool, and there is, at times, a lot of wasted airspace. For example, no allowance is made for the fact that a lower performance departure might climb like a rocket. Nor for the fact that, although the speed of approach tested on the sim is 175, most a/c will be 10-30kt slower than that for the last 4 miles of the approach.

So why is this used? isn't it a bit like boxing with one arm tied behind your back?
Surely SSR radar has the required accuracy to provide proper separation inside the terminal area and on approach to make this process look a bit antiquated?
Using Wellington as the example....how often do you get anything bigger than a 767-300 operating on a regular basis? Even at Max landing weight your approach Vref is still only about 140ish knots..which is well below the 175 you quote....
Whats wrong with 180kts till 8 miles...reducing to 160kts till 4 miles etc...? It works bloody well in Europe, and appears to be gaining traction in the USA as well.
No attempt from me to be crtitcal, I'm just trying to understand the thinking behind what appears to be an ill thought-out procedure.

[The Hill]

Whats wrong with 180kts till 8 miles...reducing to 160kts till 4 miles etc...? It works bloody well in Europe, and appears to be gaining traction in the USA as well.

I think that would be a little too fast for some of the turboprops, unfortunatly the SOPs dont allow some of us to descend on the glideslope clean ie gear down, go down policy

[Tarq57]

Wow, what do you guys do when your busy? seven miles? thats a massive spacing!

When busy, in theory we "type match". So the required distance is 4nm. But since there isn't enough room to have a/c pass each other on the threshold taxiways, (thanks for building the taxiways too close together) it usually falls into the "too hard" basket. By the time it's been organized, the situation that made it seem a good idea is often irrelevant.
When really busy, everything just slows right down. The morning and afternoon rush period lasts longer. It's a PITA.

So why is this used? isn't it a bit like boxing with one arm tied behind your back?

Yep. I believe it is referred to as best practice.
But seriously, it works in the worst case scenario, and provides a bit of a buffer. Frequently the space provided by the procedure seems excessive, but TWR staff are not approach rated and have no authority to vary it. (If we were, I believe we could possibly make departure rate increases of the order of 10 maybe 20% on many "below circling" days.)

Surely SSR radar has the required accuracy to provide proper separation inside the terminal area and on approach to make this process look a bit antiquated?

The minimum radar spacing is 3nm. Shaving it by .5nm won't make a huge difference.

Using Wellington as the example....how often do you get anything bigger than a 767-300 operating on a regular basis? Even at Max landing weight your approach Vref is still only about 140ish knots..which is well below the 175 you quote....
Whats wrong with 180kts till 8 miles...reducing to 160kts till 4 miles etc...? It works bloody well in Europe, and appears to be gaining traction in the USA as well.

Generally the largest sched a/c is a 757 (maybe 3-7X a week.) The bread and butter is 737/A320, lots of DH8's/ATR72/B190, a fair few C208 and light twins.(PA31 etc.) 767+ usually only run through WN if diverting. The arrival of a 777 or 747 etc is rare, maybe a once or twice a year event. (Perhaps needless to say, the poor C208 etc is at the bottom of the food chain when it's like this, and I've seen one of them wait well over an hour for a departure gap at times.)
Partly the reason this seems antiquated is that the wx around here is unusually changeable, can get quite windy, windshear and turbulence is likely, and terrain to the north prevents radar vectoring below 3000'. The procedure is tailored to the worst case scenario, and in that scenario (overshoot likely due wx, preceding climbing poorly due turb, preferred approach airspeed higher rather than lower due w/s) you absolutely would not want to shave it. That it is excessive in a situation of light wind but cloud below the circling minima, where everyone is performing normally, is an unfortunate consequence. I guess alternative and more expeditious procedures are just too hard to dream up and implement. I don't know,but I imagine that such a procedure would have to be nightmarishly complicated to satisfy the regulators' requirement. So in fair weather we have to guard against an event that happens maybe once a fortnight, using procedures that are designed against the worst case scenario. Sad, innit?

[conflict alert]

Controller instuctions according to our Bible - the Manual of Air Traffic Control - with regard to protection of the missed approach.


306 PROTECTION OF THE MISSED APPROACH

Separation shall be applied between an IFR flight on missed approach and other aircraft in accordance with the applicable airspace rules. An aircraft that is unable to establish visual reference by the MAPt is required to carry out the published missed approach procedure. Aircraft may need to carry out a missed approach for other reasons.

When conditions are at or above the published circling minima for an arriving aircraft’s approach category and the type of approach, the missed approach may be protected by instructing the pilot to circle visually within the aerodrome traffic circuit by day or night, except that:

• circling instructions shall not be issued where circling is not authorized for the aircraft approach category or type of approach; and

• circling instructions shall not be issued to category D aircraft; and

• for approach category C aircraft, the known or reported MET conditions shall be equal to, or better than, ceiling 2000 ft and visibility 8 km or the circling minima for the aircraft approach category and the type of approach, whichever is the higher.

Where a higher criteria or other conditions apply, this shall be documented in LUO’s

Note: For all aerodromes:
The pilot may decline circling at any stage during the approach if it is considered unsafe. In this circumstance, separation must be established by the quickest means practicable and essential traffic information given if applicable. Confirmation of ability to circle should be established earlier rather than later.

A controller shall not use this procedure when:

• MET conditions such as fluctuating cloud base, severe turbulence or strong cross winds are reported to an aircraft or broadcast on the ATIS; or

• It is known or suspected that the pilot is unfamiliar with the aerodrome; or

• The pilot advises approach or aerodrome control at any time that they are unable to carry out this procedure.

Phraseology examples:

1) When ATC initiates the procedure:

“FOR SEPARATION, CONTINUE (type) APPROACH. WHEN VISUAL (circuit joining instructions) RUNWAY (number). REMAIN IN THE CIRCUIT [(level details)]. TRAFFIC IS (details)”

2) When a pilot unexpectedly initiates a missed approach and MET conditions are suitable for visual circling:

“FOR SEPARATION, REMAIN IN THE CIRCUIT, RUNWAY (runway), [(circuit joining instructions)] [(level details)]. TRAFFIC IS(DETAILS)”.

Note: the pilot may refuse circling. See previous Note.


306.1 ARRIVING AIRCRAFT REQUESTING A MISSED APPROACH

When a request for a missed approach is received from an arriving aircraft that is not experiencing an emergency, the aircraft may, for separation purposes, be instructed to:

• continue the approach down to a level which is separated from other aircraft prior to permitting the missed approach to be carried out; or

• carry out a visual circuit, provided that the conditions specified above are met.

All copy right of course.

[murdoch_disliker]

So, after reading all this; when we are on the instrument approach should we preset the published MAP alt OR the circuit alt in the alt preselect window of the autopilot?? Which is the most correct philosophically?? Maybe nit-picking but important for standardisation.
Ta

[conflict alert]

I for one won't even begin to get involved with what you should set within your flight deck etc, that's your choice. What I can tell you is that when the circling conditions are equal to or better than that required for your aircraft cat, then the expectation is that you will get visual and as an approach controller I will NOT protect the missed approach and as a Tower controller, in the event of an overshoot, I would be instructing you to enter the circuit.

So if I were in your shoes, after establishing that conditions are suitable for circling then probably setting the circuit alt would be more appropriate coz that what ATC is going to tell you to do!

When circling conditions are below the criteria for your aircraft type as an approach controller I WILL protect the missed approach and as a Tower controller my only expectation in the event of an overshoot or not going visual at the DA or MAPt is that you will execute the missed approach procedure.

So if I were in your shoes, after establishing that conditions are NOT suitable for circling then setting the Missed Approach alt would be more appropriate.

When conditions are above circling for your aircraft cat but you don't want to circle you should advise ATC that that is your intention as early as possible so that in this case they can protect the missed approach. This is covered in someways by the blurb on some airport ATIS's that ask you to advise ATC if not able to circle.

So if I were in your shoes, after establishing that conditions are suitable for circling but you don't want to in the event that you overshoot, (and advising ATC of this!) then setting the Missed Approach alt would be more appropriate!

Now that you know what our expectations are, you should be able to decide what to select on your altitude preselect yourself. It will just depend on the wx conds at the time of your approach.

Clear as mud!!

[dejapoo]

Dragging up an old one for a kiwi 🥝 determination? 185 KIAS missed approach speed restriction off the ILS is for the climb gradient? How do you effectively manage this at higher weights? Thanks for any local knowledge.

[Tarq57]

The 185 limit is so an a/c on a miss doesn't catch a departure ahead.
If there's doubt you'll make the required gradient at or below that speed, ask the approach controller for an exemption prior to commencing the approach.

[missy]

Originally Posted by Tarq57

The 185 limit is so an a/c on a miss doesn't catch a departure ahead.
If there's doubt you'll make the required gradient at or below that speed, ask the approach controller for an exemption prior to commencing the approach.

185K limit in the missed, fascinating. Is this a NZ thing?

[NZScion]

Originally Posted by missy

185K limit in the missed, fascinating. Is this a NZ thing?

It’s published on the approach charts for some aerodromes in NZ. From memory, AA and WN have 185kt missed approach speed limits. CH has 210kts.

[missy]

Thanks. It's the first I have ever heard of such a restriction. I haven't been on Pprune as longer as this tread. It makes sense to me, surprised it's not an ICAO / PBN based thing vs a local thing.

[Tarq57]

Originally Posted by missy

Thanks. It's the first I have ever heard of such a restriction. I haven't been on Pprune as longer as this tread. It makes sense to me, surprised it's not an ICAO / PBN based thing vs a local thing.

I think possibly that's likely to be because the NZCAA requires a protection in place for an unexpected missed approach. In many (perhaps most) other jurisdictions a miss will result in ATC quickly coming up with something to prevent a collision. Here, we have to have something in place in advance.

[missy]

I think possibly that's likely to be because the NZCAA requires a protection in place for an unexpected missed approach. In many (perhaps most) other jurisdictions a miss will result in ATC quickly coming up with something to prevent a collision. Here, we have to have something in place in advance.

Bravo to NZCAA. 185K would've helped in some of the missed approaches I have seen, either as a participant or a spectator.