ATSB report on very low flying Thai Airways B777 at Melbourne.
Grandpa Aerotart
Old Akro you really don't know what you're talking about in this instance.
A typical FMC in a current model wide, or narrow body, jet CAN get input from VOR or DME but they also get input from dual GPS and VOR/DME input is typically inhibited. With RNP AR they must be inhibited to ensure the required FMS accuracy to fly the approach.
RNP AR does not require WAAS.
Not all FMCs can fly RF (Radius to Fix) legs which is a requirement for RNP AR approaches. The AR btw stands for Authorisation Required...the plates are not published for public consumption.
I very much doubt Thai is RNP AR approved...they MAY be GNSS conversant which is the GPS approach available to GA aircraft. GNSS is a VERY different animal to RNP AR.
An FMC gives you along track distance not slant distance direct to the station like a DME.
That a particular FMC can't do RF legs doesn't mean they can't fly curved tracks - they can.
ANY 777 FMC is perfectly capable of providing vertical guidance, that's what VNAV is, and the aircraft will follow it very well if the auto thrust is working. The LNAV (lateral guidance) and the VNAV is fed to the Computers and presented to the crew and auto pilots via the Flight Director. IT LOOKS JUST LIKE YOU'RE FLYING AN ILS.
When you programme the FMC to fly an approach a bunch of height/speed way points are coded into the legs starting at the RWXX waypoint (50' over the threshold) and back through the FF waypoint, CF waypoint and on back around the DME arc (in this case) and through the IAL transition all the way to TOPD.
In the cae of the 777 if you leave the damn thing alone in LNAV VNAV it will accurately fly the correct profile and decelerate to the required speeds at each constraining waypoint. LITERALLY all you have to do is configure the aircraft and set the MCP ALT (alt window) to each successive altitude constraint until the FAF then to the minima (once you're at least 300' below the missed approach altitude you set that and the aircraft will continue descending to the minima)....extend the flaps when the command bug tells you to and put the wheels down before it gets expensive.
It's EXACTLY like flying an ILS from TOPD...for all intents and purposes. Yes to a higher minima but from an flight instrument interpretation and manipulative stand point an NPA in a modern jet is functionally identical to an ILS.
Now if you insist on not using VNAV and instead use VS (Vertical Speed) or FLCH (Flight Level Change) all bets are off...You better know how to do that pilot sh!t...and you damn well better understand the differences and what happens when the Auto Flight Guidance System goes to 'On Approach' mode.
As an aside RNP AR is a thing of beauty...although not perfect. I'd suggest within 5 years, 10 tops, ILSs will be as rare as NDBs.
A typical FMC in a current model wide, or narrow body, jet CAN get input from VOR or DME but they also get input from dual GPS and VOR/DME input is typically inhibited. With RNP AR they must be inhibited to ensure the required FMS accuracy to fly the approach.
RNP AR does not require WAAS.
Not all FMCs can fly RF (Radius to Fix) legs which is a requirement for RNP AR approaches. The AR btw stands for Authorisation Required...the plates are not published for public consumption.
I very much doubt Thai is RNP AR approved...they MAY be GNSS conversant which is the GPS approach available to GA aircraft. GNSS is a VERY different animal to RNP AR.
An FMC gives you along track distance not slant distance direct to the station like a DME.
That a particular FMC can't do RF legs doesn't mean they can't fly curved tracks - they can.
ANY 777 FMC is perfectly capable of providing vertical guidance, that's what VNAV is, and the aircraft will follow it very well if the auto thrust is working. The LNAV (lateral guidance) and the VNAV is fed to the Computers and presented to the crew and auto pilots via the Flight Director. IT LOOKS JUST LIKE YOU'RE FLYING AN ILS.
When you programme the FMC to fly an approach a bunch of height/speed way points are coded into the legs starting at the RWXX waypoint (50' over the threshold) and back through the FF waypoint, CF waypoint and on back around the DME arc (in this case) and through the IAL transition all the way to TOPD.
In the cae of the 777 if you leave the damn thing alone in LNAV VNAV it will accurately fly the correct profile and decelerate to the required speeds at each constraining waypoint. LITERALLY all you have to do is configure the aircraft and set the MCP ALT (alt window) to each successive altitude constraint until the FAF then to the minima (once you're at least 300' below the missed approach altitude you set that and the aircraft will continue descending to the minima)....extend the flaps when the command bug tells you to and put the wheels down before it gets expensive.
It's EXACTLY like flying an ILS from TOPD...for all intents and purposes. Yes to a higher minima but from an flight instrument interpretation and manipulative stand point an NPA in a modern jet is functionally identical to an ILS.
Now if you insist on not using VNAV and instead use VS (Vertical Speed) or FLCH (Flight Level Change) all bets are off...You better know how to do that pilot sh!t...and you damn well better understand the differences and what happens when the Auto Flight Guidance System goes to 'On Approach' mode.
As an aside RNP AR is a thing of beauty...although not perfect. I'd suggest within 5 years, 10 tops, ILSs will be as rare as NDBs.
Last edited by Chimbu chuckles; 27th Feb 2013 at 09:41.
Catering for the lowest denominator?
I lament the death of the slide rule and loss of skill with 7 figure log tables. I miss drafting tables with cane cored scales, an assortment of sharpened clutch pencils. I am dismayed by ABS, stability control and even synchromesh in cars - all of which degraded the skill and enjoyment of driving.
But there are 2 choices and I vote to not be left behind.
Old Akro you really don't know what you're talking about in this instance.
The thing that I don't understand (and I thought admitted to) is whether the FMC gives vertical guidance for non-precision RNP approaches. You've explained that. Thanks.
Grandpa Aerotart
VNAV gives accurate vertical guidance for NDB, VOR, GNSS, RNP AR. The tolerances vary.
Doesn't matter whether you're flying an NDB, VOR, GNSS, ILS or RNP AR in a modern jet...keep the needles centred and you arrive safely at the minima.
Doesn't matter whether you're flying an NDB, VOR, GNSS, ILS or RNP AR in a modern jet...keep the needles centred and you arrive safely at the minima.
Last edited by Chimbu chuckles; 27th Feb 2013 at 10:08.
keep the needles centred and you arrive safely at the minima
You just have to know what the needles are telling you!
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All this going around in circles by way of explanation seems to ignore one key point.
A crew of a supposedly premium international carrier were unable to interpret information presented to them such that they screwed the pooch in a fairly unsafe fashion.
I am utterly astounded after reading the report for the 4th time that they managed to get themselves into the position they did.
It's not as if ATC at MEL is hard to understand, neither is the coding for the approach (I looked at it last night in our FMC), there are no traps for the unwary.
Thinking even more deeply into it, if I was feeling more of a Luddite than usual (no comments please CC) and I'd decided I was going to use FLCH to get to platform altitude...then a basic understanding of ALT followed by VNAV being armed would have me flying the prescribed vertical profile...even then...V/S at about 700-800fpm on that approach would keep me easily within limits.
Is it really that hard?
A crew of a supposedly premium international carrier were unable to interpret information presented to them such that they screwed the pooch in a fairly unsafe fashion.
I am utterly astounded after reading the report for the 4th time that they managed to get themselves into the position they did.
It's not as if ATC at MEL is hard to understand, neither is the coding for the approach (I looked at it last night in our FMC), there are no traps for the unwary.
Thinking even more deeply into it, if I was feeling more of a Luddite than usual (no comments please CC) and I'd decided I was going to use FLCH to get to platform altitude...then a basic understanding of ALT followed by VNAV being armed would have me flying the prescribed vertical profile...even then...V/S at about 700-800fpm on that approach would keep me easily within limits.
Is it really that hard?
Last edited by haughtney1; 27th Feb 2013 at 10:24.
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The important question is not whether or not a competent pilot should be able to fly the approach without an ILS, the question is whether an ILS would reduce the chances of someone crashing in Footscray etc. one day... and if it would, whether reducing that chance is worth the cost of an ILS.
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Bloggs we do have control of international airlines. The US & the EU ban unsafe operators from their airspace. Australia is too busy kowtowing & PC. They pick on easy targets that can't defend themselves.
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ANZ has RNP-AR capability, someone was asking about international airlines prior.
RNP-AR is available to DA's around 300 ft AGL to multiple destinations and those charts wont show up in the Jepps because they are operator specific, only Brissy and Melbourne are available on the general subscription. For QF we can get these approaches to CNS, TSV, ISA, OOL, HBA, ASP, AYE, DRW, ZNE, KTA, BME, PHE, KGI, PHE, ADL, name an airport and a procedure can be built to get to ILS plus about 50-100ft DA's depending on terrain, with no ground based aid augmentation. I don't fully believe ILS will be gone in 10 years because of the risk with a GPS shutdown, but it is the way of the future.
RNP-AR is available to DA's around 300 ft AGL to multiple destinations and those charts wont show up in the Jepps because they are operator specific, only Brissy and Melbourne are available on the general subscription. For QF we can get these approaches to CNS, TSV, ISA, OOL, HBA, ASP, AYE, DRW, ZNE, KTA, BME, PHE, KGI, PHE, ADL, name an airport and a procedure can be built to get to ILS plus about 50-100ft DA's depending on terrain, with no ground based aid augmentation. I don't fully believe ILS will be gone in 10 years because of the risk with a GPS shutdown, but it is the way of the future.
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Just one more clarification Arko, since RNAV approaches there ain't no "precision" or "non-precision" approaches any more. RNAV approaches vary in their precision so that terminology is gone. In Sydney QF have been operating commercial RNAV approaches to autoland (called GLS which is GBAS assisted GNSS updated RNAV). RNP-AR approaches vary in their precision depending on the RNP figure used (a tighter RNP gives a lower minima). VOR and NDB approaches flown in LNAV/VNAV are just as precise as RNP-AR approaches (if they are coded to the RWY threshold). In fact, in QF the approach aid doesn't even have to be working.
Last edited by Derfred; 27th Feb 2013 at 15:05.
About the incident- anyone could have done what the Thai crew did. Australian jet crews over the years have nearly landed on roads, botched go-rounds, taken off at night without lights, nearly ran wing tanks dry, nearly hit hills in the hold, descended below altitude restrictions. Anything else? I prefer to look at this incident as a learning exercise.
With respect to pilot standards, we are not taught these days to excel, we are taught to be average. Very few colleagues I fly with practice hands on flying, let alone manual thrust. Very few will also continue the approaches if visual early just to see where the minima really is and what you would be looking at ( always fun at Cooly and Maroochy.........sorry Goldy and Sunny). This is part of our culture nowadays. The sim is treated as checking tool. Not a training device. Schedules are crammed. Rosters make you want to do the minimum amount of work required. Sops do not contain words like "Captain's discretion"or "common sense". And if anything goes astray, JUST see what a JUST culture will do for you.
About the approach type debate- RNP will quite happily fly you into the ground even with VNAV engaged if you miss set the QNH.
With respect to pilot standards, we are not taught these days to excel, we are taught to be average. Very few colleagues I fly with practice hands on flying, let alone manual thrust. Very few will also continue the approaches if visual early just to see where the minima really is and what you would be looking at ( always fun at Cooly and Maroochy.........sorry Goldy and Sunny). This is part of our culture nowadays. The sim is treated as checking tool. Not a training device. Schedules are crammed. Rosters make you want to do the minimum amount of work required. Sops do not contain words like "Captain's discretion"or "common sense". And if anything goes astray, JUST see what a JUST culture will do for you.
About the approach type debate- RNP will quite happily fly you into the ground even with VNAV engaged if you miss set the QNH.
Grandpa Aerotart
Fathom an ILS will 'fly you into the ground with the needles centred' too -it's called auto land
Honestly, between the FMC, FD, FMA and RADALT it's really not rocket science.
Clark y agree completely - that doesn't make it any less a training and standards issue.
What in that report gives anyone the impression that THAT crew on THAT day would have done better self positioning for the ILS?
Honestly, between the FMC, FD, FMA and RADALT it's really not rocket science.
Clark y agree completely - that doesn't make it any less a training and standards issue.
What in that report gives anyone the impression that THAT crew on THAT day would have done better self positioning for the ILS?
self positioning for the ILS?
While Thai bashing gets people thinking more about commonsense DME v height as a double check on profile management, you would be unpleasantly surprised at the astonished looks of dismay sometimes seen when in the simulator both CDU's are failed and the crew are asked to find their way procedurely to the airport ILS from 50 miles out, hand flying raw data and no radar vectors.
But it is just this sort of handling practice that keeps the pilot sharp rather than lazy in his old age. But then again, does he need to be sharp when the automatics are so reliable nowadays?
The counter argument of course being that that sort of combination of events would never happen in real life. Like the double engine failure at low level that Sully had with his A320 ditching in the river.
Or the Garuda double engine failure in a 63,000 thunderstorm coupled with a total electrical failure when his APU failed to start because of a long stuffed battery and of course the all flaps up ditching that was the result. Of course that could never happen, either. But it did.
Last edited by Centaurus; 27th Feb 2013 at 23:48.
I did not see anything in the ATSB report about the efficacy or otherwise of the ground based warning system that Airservices must surely have in place when aircraft get too low and provides a warning to the Approach controller.
Surely the flight was already low when the pilot contacted the TWR?
I am sure Dick Smith and others in the past have mentioned that the ATC system has warnings like this.
I will have to enquire with my controller acquaintances??
Surely the flight was already low when the pilot contacted the TWR?
I am sure Dick Smith and others in the past have mentioned that the ATC system has warnings like this.
I will have to enquire with my controller acquaintances??
I pretty sure I'm correct about DME feeding the FMS - how else does it know the track miles to run? The INS needs updating. It can come from GNSS or DME. I'm guessing the FMS uses DME as default.
The FMC builds a profile from the end of the runway with fixes at certain points based on a 3 degree slope. It's all done in the computer with no external reference.
I always do a 3x check from the end of the runway anyway to ensure we don't have a Air NZ scenario again. (Type 'A Free Lesson' into YouTube if you don't know what I'm talking about)
Last edited by neville_nobody; 28th Feb 2013 at 22:01.
To all those who state that an ILS on 34 would fix all the problems regarding foreign carriers and NPAs, 16R in Sydney has an ILS but it's out for maintenance for nearly a month. Guess what approach had to be flown to get into Syd? As an aside did Emirates end up landing after curfew with a screaming southerly?
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you would be unpleasantly surprised at the astonished looks of dismay sometimes seen when in the simulator both CDU's are failed and the crew are asked to find their way procedurely to the airport ILS from 50 miles out, hand flying raw data and no radar vectors.
The issue with this incident however, isn't the lack of stick and rudder skills, but the lack of awareness of engaged autoflight modes and the inability to use and monitor them correctly.
It doesn't matter whether its out for an hour what matters is that professional flight crew can operate the aircraft in the environment that they are presented with. Having an ILS on 34 in Melbourne (and that would also have to include 05 AD 11DN 30HB 14R LT) might make it easier but it won't make it safer if the person at the controls does not have a good knowledge of how his/her aircraft works. I flew an approach into Sydney yesterday that gave me all the appearances of an ILS with an LDEV and a VDEV indication and FD's that were centered. I would have been in for a nasty shock however if I thought that it was going to autoland as well.
Modern FMC's, autopilots and glass cockpits were also supposed to take away the risk of an NPA but all we have is a different set of problems. If you want to eliminate the risk then 16R shouldn't be used at all while the ILS is U/S. That would also imply that if an ILS was installed on 34 then the airport would be unavailable if it required maintenance and the only runway that could be used was 34.
Modern FMC's, autopilots and glass cockpits were also supposed to take away the risk of an NPA but all we have is a different set of problems. If you want to eliminate the risk then 16R shouldn't be used at all while the ILS is U/S. That would also imply that if an ILS was installed on 34 then the airport would be unavailable if it required maintenance and the only runway that could be used was 34.