SIA 422 incident at Mumbai
Only half a speed-brake
You read me wrong, IC. The FMS took the THY all the way down the runway, almost resulting into RNAV autloland. The fact of the aircraft landing on the runway edge was blamed on the THR COORD being wrong (they were). What I mean to say, is RNAV on modern day (Airbus) A/C = precision within 10 m. Sorry for the confusion.
Thread Starter
Join Date: Nov 2012
Location: South of BBB VOR
Posts: 52
Likes: 0
Received 0 Likes
on
0 Posts
Just a question from SLF.
What would the possibility be of the pilots using the wrong input dial for the go around height. ie 3000ft and instead using the heading selector 300 making the aircraft turn.
Is this at all possible or would the auto-land function over ride any manual inputs.
What would the possibility be of the pilots using the wrong input dial for the go around height. ie 3000ft and instead using the heading selector 300 making the aircraft turn.
Is this at all possible or would the auto-land function over ride any manual inputs.
If it was an FMC assisted VOR approach (which I think it must have been), the a/c would be in NAV mode and following the track drawn by the FMC inbound to rwy 09, till the crew had the rwy in sight at which point they would disconnect the A/P and take manual control of the a/c. Highly unlikely that the a/c would be in ‘managed’ mode (A/P engaged w/ HDG/ALT selected) on a VOR approach, that too a few miles from touchdown, but then I may be wrong...?
Join Date: Jun 2000
Location: last time I looked I was still here.
Posts: 4,507
Likes: 0
Received 0 Likes
on
0 Posts
Which brings me back to the point of why the crew would not trust their nav system and leave it engaged until solid confirmation of the visual reference of the target runway. To disconnect early on approach, and make such a significant track change towards a runway for which they must have been very high on profile, seems questionable. At SIA they must have come from another LNAV/VNAV GPS/FMC a/c and so they should have had trust in the basic system. Why the rush, or is there another reason?
Nemo Me Impune Lacessit
Join Date: Jun 2004
Location: Derbyshire, England.
Posts: 4,091
Received 0 Likes
on
0 Posts
Do you mean that the crew were being familiarised with the rwy 09 app (with a deliberate deviation to show them Juhu)?
Definitely not, more a case of using a developing situation to illustrate possible future problems to be avoided and recovering the situation before any risk to flight safety.
FMC aircraft don’t suffer from ‘radial instability’ on VOR approaches.
Is that the way it is for you today misd-agin ? I have no Airbus experience but when we flew the VOR approach to Mumbai it was PF on HSI raw data and PNF on MAP, no such thing as RNAV approach to Mumbai 09. Take my word for it, the radial needle would dither from side to side, the radial would often appear 'bent' and eventually it was the mark one eyeball that brought things to a satisfactory conclusion. As I said in a previous post, I hope all this has long since been sorted out by now.
Join Date: Jan 2006
Location: US
Posts: 2,205
Likes: 0
Received 0 Likes
on
0 Posts
Mateo - no. Not in the automation mode being used. In other automation modes? Yes.
There are mistakes that can be made, like selecting 300 kts and a 250 heading vs 250 kts and a 300 degree heading. That occurred during a low altitude missed approach due to failure of the preceding aircraft to clear the runway. Simple manual flying while the PM fumbled with the automation inputs made it a non issue.
But the track of SIA 422 is not consistent with the mistake you mentioned. And VOR approaches aren’t flown in heading mode. If they were in heading mode, and switched the heading to 105(+/-) the turn would make sense. But there is no altitude setting of 1050 that would explain the mistake you mentioned.
And the missed approach altitude would have been set earlier and changing the heading selector, or changing the altitude selector, would not have changed the automation mode the aircraft was in.
There are mistakes that can be made, like selecting 300 kts and a 250 heading vs 250 kts and a 300 degree heading. That occurred during a low altitude missed approach due to failure of the preceding aircraft to clear the runway. Simple manual flying while the PM fumbled with the automation inputs made it a non issue.
But the track of SIA 422 is not consistent with the mistake you mentioned. And VOR approaches aren’t flown in heading mode. If they were in heading mode, and switched the heading to 105(+/-) the turn would make sense. But there is no altitude setting of 1050 that would explain the mistake you mentioned.
And the missed approach altitude would have been set earlier and changing the heading selector, or changing the altitude selector, would not have changed the automation mode the aircraft was in.
Thread Starter
Join Date: Nov 2012
Location: South of BBB VOR
Posts: 52
Likes: 0
Received 0 Likes
on
0 Posts
"Definitely not, more a case of using a developing situation to illustrate possible future problems to be avoided and recovering the situation before any risk to flight safety."
I don't think I follow you parabellum, "developing situation..." meaning what?
"I have no Airbus experience but when we flew the VOR approach to Mumbai it was PF on HSI raw data and PNF on MAP, no such thing as RNAV approach to Mumbai 09. Take my word for it, the radial needle would dither from side to side, the radial would often appear 'bent' and eventually it was the mark one eyeball that brought things to a satisfactory conclusion. As I said in a previous post, I hope all this has long since been sorted out by now."
You said you have flown into Mumbai on both the B767 and B747, and I am assuming that they were both FMC equipped. What was the rwy 09 VOR app like? I assume it was FMC assisted...? Also, could you please elaborate on the 'bent radial'. I am pretty sure all this has been sorted out now, but it would be nice if pilots regularly flying into Mumbai were to give an overview of the current situation.
I don't think I follow you parabellum, "developing situation..." meaning what?
"I have no Airbus experience but when we flew the VOR approach to Mumbai it was PF on HSI raw data and PNF on MAP, no such thing as RNAV approach to Mumbai 09. Take my word for it, the radial needle would dither from side to side, the radial would often appear 'bent' and eventually it was the mark one eyeball that brought things to a satisfactory conclusion. As I said in a previous post, I hope all this has long since been sorted out by now."
You said you have flown into Mumbai on both the B767 and B747, and I am assuming that they were both FMC equipped. What was the rwy 09 VOR app like? I assume it was FMC assisted...? Also, could you please elaborate on the 'bent radial'. I am pretty sure all this has been sorted out now, but it would be nice if pilots regularly flying into Mumbai were to give an overview of the current situation.
Last edited by India Charlie; 9th Dec 2017 at 08:31. Reason: Typo
Thread Starter
Join Date: Nov 2012
Location: South of BBB VOR
Posts: 52
Likes: 0
Received 0 Likes
on
0 Posts
“Which brings me back to the point of why the crew would not trust their nav system and leave it engaged until solid confirmation of the visual reference of the target runway. To disconnect early on approach, and make such a significant track change towards a runway”
RAT 5, Perhaps they were (over) confident that they could hand fly the approach. What other reason to disconnect automatics...?
RAT 5, Perhaps they were (over) confident that they could hand fly the approach. What other reason to disconnect automatics...?
Join Date: Jun 2000
Location: last time I looked I was still here.
Posts: 4,507
Likes: 0
Received 0 Likes
on
0 Posts
Perhaps, indeed, but why would you if you can't see the target on an NPA? Confident that they needed to reposition the a/c off their current erroneous track to the target runway they had visual. Ouch. I still suspect there were 2 heads outside and no-one inside monitoring all the clues that confirmed the error.
They were skilful in bailing out of the first approach, but, as is often said, the skilful pilots uses their skills to avoid......etc
They were skilful in bailing out of the first approach, but, as is often said, the skilful pilots uses their skills to avoid......etc
Nemo Me Impune Lacessit
Join Date: Jun 2004
Location: Derbyshire, England.
Posts: 4,091
Received 0 Likes
on
0 Posts
I don't think I follow you parabellum, "developing situation..." meaning what?
Several VORs world wide have had a sector notamed as possible fluctuations and if you fly the needles you will be changing heading to compensate, such sectors were usually nominated as unreliable and cautionary notes would be on the Jep. chart. Going back now to 2001, SOP for a VOR approach was PF on HSI and PNF on map and could be flown auto pilot and auto throttle engaged. Blindly following the 'purple worm' was not considered accurate enough, map shift caused by updating could occur. As previously said, hopefully all those problems have been overcome, one way or another, by now, even in India.
If it was an FMC assisted VOR approach (which I think it must have been), the a/c would be in NAV mode and following the track drawn by the FMC inbound to rwy 09, till the crew had the rwy in sight at which point they would disconnect the A/P and take manual control of the a/c. Highly unlikely that the a/c would be in ‘managed’ mode (A/P engaged w/ HDG/ALT selected) on a VOR approach, that too a few miles from touchdown, but then I may be wrong...?
Of course, if it was being flown as an FLS, it makes the deviation even harder to understand.
Thread Starter
Join Date: Nov 2012
Location: South of BBB VOR
Posts: 52
Likes: 0
Received 0 Likes
on
0 Posts
An interesting article “Safely Flying Non-Precision Instrument Approaches” in the The Airbus Safety Magazine: http://www.aircraft.airbus.com/compa...ocID%5D=231887
Thread Starter
Join Date: Nov 2012
Location: South of BBB VOR
Posts: 52
Likes: 0
Received 0 Likes
on
0 Posts
I’m sorry I did not clarify that.
I’m not familiar with the new FLS function on the A350. My “knowledge base” comes from the A320. I am however familiar with the IAN approach feature on the B737.
I’m not familiar with the new FLS function on the A350. My “knowledge base” comes from the A320. I am however familiar with the IAN approach feature on the B737.
Join Date: Aug 2000
Posts: 1,501
Likes: 0
Received 0 Likes
on
0 Posts
Definitely not, more a case of using a developing situation to illustrate possible future problems to be avoided and recovering the situation before any risk to flight safety.
Is that the way it is for you today misd-agin ? I have no Airbus experience but when we flew the VOR approach to Mumbai it was PF on HSI raw data and PNF on MAP, no such thing as RNAV approach to Mumbai 09. Take my word for it, the radial needle would dither from side to side, the radial would often appear 'bent' and eventually it was the mark one eyeball that brought things to a satisfactory conclusion. As I said in a previous post, I hope all this has long since been sorted out by now.
Is that the way it is for you today misd-agin ? I have no Airbus experience but when we flew the VOR approach to Mumbai it was PF on HSI raw data and PNF on MAP, no such thing as RNAV approach to Mumbai 09. Take my word for it, the radial needle would dither from side to side, the radial would often appear 'bent' and eventually it was the mark one eyeball that brought things to a satisfactory conclusion. As I said in a previous post, I hope all this has long since been sorted out by now.
This flight looks like they were doing a normal non prec approach, got visual with Juhu, disconnected and turned towards Juhu, discovered their mistake and did a go around. Not that hard to understand that this can happen.
LNAV/VNAV is a Boeing term...and their version of these approaches (at least in the 747-400) is far inferior to the FLS used in the 380 and 350.
Basically, in those aircraft the system produces a synthetic ILS, which is flown and displayed, exactly as per an ILS. It does have to be part of the FMC suite of approaches, but I see nothing on the approach plate that would preclude it from being there.
Basically, in those aircraft the system produces a synthetic ILS, which is flown and displayed, exactly as per an ILS. It does have to be part of the FMC suite of approaches, but I see nothing on the approach plate that would preclude it from being there.
Join Date: Jun 2001
Location: Rockytop, Tennessee, USA
Posts: 5,898
Likes: 0
Received 1 Like
on
1 Post
It wouldn't be the first time Airbus has reinvented something done by Boeing years ago.
Airbus has this new fangled 'Soft Go-Around' technology where the motors throttle back on the go-around to give 2000 fpm climb instead of blasting up at TOGA power. Wow. Where have we seen that before?
Boeings have had that 'feature' since the 757 hit the streets in 1981.
Dynasty and other carriers have pranged a lot of 'buses over the years on those TOGA go-arounds.
Airbus has this new fangled 'Soft Go-Around' technology where the motors throttle back on the go-around to give 2000 fpm climb instead of blasting up at TOGA power. Wow. Where have we seen that before?
Boeings have had that 'feature' since the 757 hit the streets in 1981.
Dynasty and other carriers have pranged a lot of 'buses over the years on those TOGA go-arounds.
Airbus has this new fangled 'Soft Go-Around' technology where the motors throttle back on the go-around to give 2000 fpm climb instead of blasting up at TOGA power. Wow. Where have we seen that before?
Dynasty and other carriers have pranged a lot of 'buses over the years on those TOGA go-arounds.
On the other hand though, Boeing auto thrust behaviour seems to have been an issue of late.
Both makers have their good features, as well as plenty of others that make you wonder what they were thinking.
Join Date: Jun 2001
Location: Rockytop, Tennessee, USA
Posts: 5,898
Likes: 0
Received 1 Like
on
1 Post
I don't think TOGA has actually had anything to do with it. The issue was that the autopilot disconnect behaviour in the 300/310 was different once you were in approach mode.
On the other hand though, Boeing auto thrust behaviour seems to have been an issue of late.
Both makers have their good features, as well as plenty of others that make you wonder what they were thinking.
On the other hand though, Boeing auto thrust behaviour seems to have been an issue of late.
Both makers have their good features, as well as plenty of others that make you wonder what they were thinking.
I sheepishly admit to having a couple of Airbus ratings from years ago.
Join Date: Aug 2000
Posts: 1,501
Likes: 0
Received 0 Likes
on
0 Posts
Back to the topic:
Whatever you call it, I’m pretty sure they didn’t fly this approach coupled to the VOR. Even if they did, it would not explain this turn towards Juhu.
This is an easy mistake to do and they did correct their mistake as they should do.
Whatever you call it, I’m pretty sure they didn’t fly this approach coupled to the VOR. Even if they did, it would not explain this turn towards Juhu.
This is an easy mistake to do and they did correct their mistake as they should do.