CNS 33 HENDO Mess
Thread Starter
CNS 33 HENDO Mess
The Australian Transport Safety Bureau (ATSB) is investigating two separate flight below minimum altitude occurrences 40 km south of Cairns Airport, Queensland. The first involved a Virgin Australia Boeing 737, registered VH-VUT, on 24 October, and the other a Qantas Boeing 737, registered VH-VZA, on 26 October 2022.
In both occurrences, the aircraft were following a standard arrival route (STAR), when they were inadvertently descended below the minimum safe altitude. On each occasion, air traffic control identified the aircraft's descent and alerted their flight crew. The flights in both cases were then completed without further incident.
In both occurrences, the aircraft were following a standard arrival route (STAR), when they were inadvertently descended below the minimum safe altitude. On each occasion, air traffic control identified the aircraft's descent and alerted their flight crew. The flights in both cases were then completed without further incident.
Last edited by PoppaJo; 12th Nov 2022 at 07:10.
It's a pig of an approach with the arc and all the steps, particularly if you don't regularly fly it. Asked to do it in the sim last year as we had a bit of spare time left, we screwed it up and then the check captain in the back also had a go and screwed it up due to a FMS issue.
From the ATC recording, the 737 wasn't the only aircraft having issues with the approach.
From the ATC recording, the 737 wasn't the only aircraft having issues with the approach.
Thread Starter
I recall it was for that whole week however a few hours post the Velocity approach and pre the QF.
What would have happened? Well it’s clear without someone watching VA would have got closer and closer. The report should give some insight into that and the path it was taking.
What would have happened? Well it’s clear without someone watching VA would have got closer and closer. The report should give some insight into that and the path it was taking.
What's going to come out of this, zilch apart for the crews being called in for tea and biscuits and thrown in the dog house for a few weeks due to a ****ty designed approach that should be immediately redesigned and bought into the 21st century. Totally unsuitable in this day and age for a major aerodrome with high terrain around it and such a complicated bloody approach that was probably designed 40 years ago.
What's going to come out of this, zilch apart for the crews being called in for tea and biscuits and thrown in the dog house for a few weeks due to a ****ty designed approach that should be immediately redesigned and bought into the 21st century. Totally unsuitable in this day and age for a major aerodrome with high terrain around it and such a complicated bloody approach that was probably designed 40 years ago.
The coded part of the approach only starts late in the approach so you are relying on a managed descent most of the way down. Not perfect and not always accurate with the altitude constraints ( I am talking Airbus). I'm not sure how difficult it would be to adjust the databases to make the coded part of the approach start earlier. Before RNP approaches were designed for 33 the problem was always getting too high on the approach as you had to start configuring before HENDO which is 22 miles from the airport. A lot of pilots would think they still had time and space to start throwing gear and flap out.
Let’s make sure we are all talking about the same thing here.
IIRC the RNP approaches into CS from the south are AR approaches, only available to VA, JQ and QF due to advanced aircraft FMS upgrades, extra pilot training/checking and recurrency in the sim. There are no ‘bog standard’ older style GNSS/RNAV straight in approaches from the south. The RNP AR’s due to much lower RNP values and the ability to follow multiple curved flight paths (at the lower RNP values) have paths that weave around obstacles such hills and also avoid settlements for NAP. These approaches are constructed from multiple ‘Radius to Fix’ turns (arcs) hence the use of the term ‘arc’. But I believe that the references above to the ‘arc’ from some posters is the DME arc whereby the ‘arc’ is followed around a single DME value, such as the 24 mile arc, to intercept the final approach LOC through a waypoint, in this case HENDO, the whole procedure to the runway following the arc, FAC and step down procedures as you go. If flown manually, or even with basic autopilot functions, in actual IMC these approaches are a **** fight, as many have identified and I agree having done it many times.
But (correct me if I’m wrong) the problem with the VA and QF incidents is that when the crews were programming the FMC with the arrival STAR and the RNP AR approach, they didn’t select HENDO as a STAR transition. If you do not do this then it doesn’t enter the crossing height at HENDO as 6800A, it just calculates the constant descent path between the previous and next waypoints, leaving you too low at HENDO, hence the ATC warnings. This also happened a few times about 10 years ago when this approach was first introduced and my company went to great pains to reinforce the need for the transition selection for the obvious reason of terrain avoidance.
So, yes, the approaches to RWY33CS, no matter how you actually fly them, are pretty ****ty. If flown in basic modes you’ve gotta be aware of where you are and what’s around\underneath you. If flown in more advanced modes then in has to be entered and checked in the FMC, then monitored throughout to ensure correct compliance with the design approach. BUT having said all that, if there’s hills there, then the RNP AR should be constructed/coded correctly to avoid this situation……I agree, code it for 6800A regardless. But (not saying this was actually what happened) all they had to do was push another button and it would have been all good. Not being critical here just factual (I have no first hand knowledge of the actual events or the circumstances leading up to them)…..I’ve had my fair share of stuff ups as well so not throwing stones.
Not sure they would have got closer and closer, the AR’s do recognise a below path situation and will level off to correct it when the next segment path angle comes into the equation. But, like I said don’t know the specifics, if both crews had grossly incorrect QNH set then the aircraft will fly the entire approach at the incorrect altitude (10 hpa high QNH means 300ft low on path
) and all the indications such as crossing heights on your altimeter match the charted heights but you are actually 300 foot lower in space though.
so hope this helps anyone trying to wrap their head around it. But I think we all agree the arrivals could be better designed.
IIRC the RNP approaches into CS from the south are AR approaches, only available to VA, JQ and QF due to advanced aircraft FMS upgrades, extra pilot training/checking and recurrency in the sim. There are no ‘bog standard’ older style GNSS/RNAV straight in approaches from the south. The RNP AR’s due to much lower RNP values and the ability to follow multiple curved flight paths (at the lower RNP values) have paths that weave around obstacles such hills and also avoid settlements for NAP. These approaches are constructed from multiple ‘Radius to Fix’ turns (arcs) hence the use of the term ‘arc’. But I believe that the references above to the ‘arc’ from some posters is the DME arc whereby the ‘arc’ is followed around a single DME value, such as the 24 mile arc, to intercept the final approach LOC through a waypoint, in this case HENDO, the whole procedure to the runway following the arc, FAC and step down procedures as you go. If flown manually, or even with basic autopilot functions, in actual IMC these approaches are a **** fight, as many have identified and I agree having done it many times.
But (correct me if I’m wrong) the problem with the VA and QF incidents is that when the crews were programming the FMC with the arrival STAR and the RNP AR approach, they didn’t select HENDO as a STAR transition. If you do not do this then it doesn’t enter the crossing height at HENDO as 6800A, it just calculates the constant descent path between the previous and next waypoints, leaving you too low at HENDO, hence the ATC warnings. This also happened a few times about 10 years ago when this approach was first introduced and my company went to great pains to reinforce the need for the transition selection for the obvious reason of terrain avoidance.
So, yes, the approaches to RWY33CS, no matter how you actually fly them, are pretty ****ty. If flown in basic modes you’ve gotta be aware of where you are and what’s around\underneath you. If flown in more advanced modes then in has to be entered and checked in the FMC, then monitored throughout to ensure correct compliance with the design approach. BUT having said all that, if there’s hills there, then the RNP AR should be constructed/coded correctly to avoid this situation……I agree, code it for 6800A regardless. But (not saying this was actually what happened) all they had to do was push another button and it would have been all good. Not being critical here just factual (I have no first hand knowledge of the actual events or the circumstances leading up to them)…..I’ve had my fair share of stuff ups as well so not throwing stones.
Not sure they would have got closer and closer, the AR’s do recognise a below path situation and will level off to correct it when the next segment path angle comes into the equation. But, like I said don’t know the specifics, if both crews had grossly incorrect QNH set then the aircraft will fly the entire approach at the incorrect altitude (10 hpa high QNH means 300ft low on path
) and all the indications such as crossing heights on your altimeter match the charted heights but you are actually 300 foot lower in space though.so hope this helps anyone trying to wrap their head around it. But I think we all agree the arrivals could be better designed.
Let’s make sure we are all talking about the same thing here.
IIRC the RNP approaches into CS from the south are AR approaches, only available to VA, JQ and QF due to advanced aircraft FMS upgrades, extra pilot training/checking and recurrency in the sim. There are no ‘bog standard’ older style GNSS/RNAV straight in approaches from the south. The RNP AR’s due to much lower RNP values and the ability to follow multiple curved flight paths (at the lower RNP values) have paths that weave around obstacles such hills and also avoid settlements for NAP. These approaches are constructed from multiple ‘Radius to Fix’ turns (arcs) hence the use of the term ‘arc’. But I believe that the references above to the ‘arc’ from some posters is the DME arc whereby the ‘arc’ is followed around a single DME value, such as the 24 mile arc, to intercept the final approach LOC through a waypoint, in this case HENDO, the whole procedure to the runway following the arc, FAC and step down procedures as you go. If flown manually, or even with basic autopilot functions, in actual IMC these approaches are a **** fight, as many have identified and I agree having done it many times.
But (correct me if I’m wrong) the problem with the VA and QF incidents is that when the crews were programming the FMC with the arrival STAR and the RNP AR approach, they didn’t select HENDO as a STAR transition. If you do not do this then it doesn’t enter the crossing height at HENDO as 6800A, it just calculates the constant descent path between the previous and next waypoints, leaving you too low at HENDO, hence the ATC warnings. This also happened a few times about 10 years ago when this approach was first introduced and my company went to great pains to reinforce the need for the transition selection for the obvious reason of terrain avoidance.
So, yes, the approaches to RWY33CS, no matter how you actually fly them, are pretty ****ty. If flown in basic modes you’ve gotta be aware of where you are and what’s around\underneath you. If flown in more advanced modes then in has to be entered and checked in the FMC, then monitored throughout to ensure correct compliance with the design approach. BUT having said all that, if there’s hills there, then the RNP AR should be constructed/coded correctly to avoid this situation……I agree, code it for 6800A regardless. But (not saying this was actually what happened) all they had to do was push another button and it would have been all good. Not being critical here just factual (I have no first hand knowledge of the actual events or the circumstances leading up to them)…..I’ve had my fair share of stuff ups as well so not throwing stones.
Not sure they would have got closer and closer, the AR’s do recognise a below path situation and will level off to correct it when the next segment path angle comes into the equation. But, like I said don’t know the specifics, if both crews had grossly incorrect QNH set then the aircraft will fly the entire approach at the incorrect altitude (10 hpa high QNH means 300ft low on path) and all the indications such as crossing heights on your altimeter match the charted heights but you are actually 300 foot lower in space though.
so hope this helps anyone trying to wrap their head around it. But I think we all agree the arrivals could be better designed.
IIRC the RNP approaches into CS from the south are AR approaches, only available to VA, JQ and QF due to advanced aircraft FMS upgrades, extra pilot training/checking and recurrency in the sim. There are no ‘bog standard’ older style GNSS/RNAV straight in approaches from the south. The RNP AR’s due to much lower RNP values and the ability to follow multiple curved flight paths (at the lower RNP values) have paths that weave around obstacles such hills and also avoid settlements for NAP. These approaches are constructed from multiple ‘Radius to Fix’ turns (arcs) hence the use of the term ‘arc’. But I believe that the references above to the ‘arc’ from some posters is the DME arc whereby the ‘arc’ is followed around a single DME value, such as the 24 mile arc, to intercept the final approach LOC through a waypoint, in this case HENDO, the whole procedure to the runway following the arc, FAC and step down procedures as you go. If flown manually, or even with basic autopilot functions, in actual IMC these approaches are a **** fight, as many have identified and I agree having done it many times.
But (correct me if I’m wrong) the problem with the VA and QF incidents is that when the crews were programming the FMC with the arrival STAR and the RNP AR approach, they didn’t select HENDO as a STAR transition. If you do not do this then it doesn’t enter the crossing height at HENDO as 6800A, it just calculates the constant descent path between the previous and next waypoints, leaving you too low at HENDO, hence the ATC warnings. This also happened a few times about 10 years ago when this approach was first introduced and my company went to great pains to reinforce the need for the transition selection for the obvious reason of terrain avoidance.
So, yes, the approaches to RWY33CS, no matter how you actually fly them, are pretty ****ty. If flown in basic modes you’ve gotta be aware of where you are and what’s around\underneath you. If flown in more advanced modes then in has to be entered and checked in the FMC, then monitored throughout to ensure correct compliance with the design approach. BUT having said all that, if there’s hills there, then the RNP AR should be constructed/coded correctly to avoid this situation……I agree, code it for 6800A regardless. But (not saying this was actually what happened) all they had to do was push another button and it would have been all good. Not being critical here just factual (I have no first hand knowledge of the actual events or the circumstances leading up to them)…..I’ve had my fair share of stuff ups as well so not throwing stones.
Not sure they would have got closer and closer, the AR’s do recognise a below path situation and will level off to correct it when the next segment path angle comes into the equation. But, like I said don’t know the specifics, if both crews had grossly incorrect QNH set then the aircraft will fly the entire approach at the incorrect altitude (10 hpa high QNH means 300ft low on path
) and all the indications such as crossing heights on your altimeter match the charted heights but you are actually 300 foot lower in space though.so hope this helps anyone trying to wrap their head around it. But I think we all agree the arrivals could be better designed.
What is going on in the training departments here?As trainers move on and are replaced with the new breed,this sort of training information,to use the HENDO transition when selecting this approach is essential.RW 32 at CNS is not used that often,so it needs to be part of the on going SIM program so people are reminded of the problem.
What is going on in the training departments here?As trainers move on and are replaced with the new breed,this sort of training information,to use the HENDO transition when selecting this approach is essential.RW 32 at CNS is not used that often,so it needs to be part of the on going SIM program so people are reminded of the problem.
If they put every approach that doesn’t get used very often but could potentially be problematic, into every sim, there’d never be time for anything else.
2 events from 2 different airlines doesn’t spell out problems with training departments to me. It spells out bad design, or, just bad luck. How many times in the past has this occurred?
If they put every approach that doesn’t get used very often but could potentially be problematic, into every sim, there’d never be time for anything else.
If they put every approach that doesn’t get used very often but could potentially be problematic, into every sim, there’d never be time for anything else.
Note I said LESS time, not NO time on RTO's & engine failures, but realistically if these were visited once every two years it should be enough. More aircraft have probably crashed due to mismanaged approaches than mismanaged systems failures.
However, if we stopped wasting valuable sim time on familiar stuff (long-winded briefings, engine starts, taxying, SIDs & STARS at home base, ILS approaches etc) and reduced the amount of time spent on things we should be able to handle (rejected take-offs or engine failures), maybe we could devote more time to the tricky things more likely to be encountered. Some of the recurrent training and check matrixes I have seen seem to be there to give an impression all eventualities are being covered, without consideration for probabilities and relative risk. Often run from the pilots' home airport or over a familiar route. Pointless box ticking.
Note I said LESS time, not NO time on RTO's & engine failures, but realistically if these were visited once every two years it should be enough. More aircraft have probably crashed due to mismanaged approaches than mismanaged systems failures.
Note I said LESS time, not NO time on RTO's & engine failures, but realistically if these were visited once every two years it should be enough. More aircraft have probably crashed due to mismanaged approaches than mismanaged systems failures.
However, if we stopped wasting valuable sim time on familiar stuff (long-winded briefings, engine starts, taxying, SIDs & STARS at home base, ILS approaches etc) and reduced the amount of time spent on things we should be able to handle (rejected take-offs or engine failures), maybe we could devote more time to the tricky things more likely to be encountered. Some of the recurrent training and check matrixes I have seen seem to be there to give an impression all eventualities are being covered, without consideration for probabilities and relative risk. Often run from the pilots' home airport or over a familiar route. Pointless box ticking.
Note I said LESS time, not NO time on RTO's & engine failures, but realistically if these were visited once every two years it should be enough. More aircraft have probably crashed due to mismanaged approaches than mismanaged systems failures.
Note I said LESS time, not NO time on RTO's & engine failures, but realistically if these were visited once every two years it should be enough. More aircraft have probably crashed due to mismanaged approaches than mismanaged systems failures.
What is going on in the training departments here?As trainers move on and are replaced with the new breed,this sort of training information,to use the HENDO transition when selecting this approach is essential.RW 32 at CNS is not used that often,so it needs to be part of the on going SIM program so people are reminded of the problem.
Also the prior rnp selection issues at CNS were on the other rwy iirc
looking at the star charts compared to others we're used to for AR stuff, the CNS charts seem to be presented differently and HENDO on the RNP chart is a little subtle, as a transition, compared to others.
That's where I'd be looking at for contributing factors.
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I have to agree with NIE above but add the following. Having been involved with Managed (Airbus) VOR/DME, NDB, GPS, RNP and RNP AR since inception, it is absolutely imperative that the coding of the FMS is checked intimately against the AIP of the country. In the early days there were massive errors in the coding resulting in the aircraft in auto flight descending abruptly, or not descending or levelling off during the approach. RNP AR has improved database coding , but there are still occasional errors. An airline is required to have a form of database checking, however it is certainly in the Airbus SOP that the PIlots are required to check the database coding against the chart before commencing the approach and ensuring it complies with the ATC Clearance and the charted approach. In my experience pilots often accept the FMS database as correct without checking. “After all the aircraft flew it OK last month”.