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Thai Air B777 Melbourne NDB approach

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Thai Air B777 Melbourne NDB approach

Old 8th Feb 2008, 14:16
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Hear, hear Flex.
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Old 8th Feb 2008, 14:36
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Why in the name of the heavens is any international airline aircraft required to carry out an NDB approach into any civilised International Airport?
See post 10 on page 1.
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Old 8th Feb 2008, 22:37
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I hope the ATSB report will address why the runway 09 VOR/DME or RNAV approach was not nominated by ATC. They seem to be very reluctant to use that runway even when a tailwind is present on 27. The approach to 09 is over paddocks and farms so surely noise abatement is not the issue. Also how difficult is it to design an RNAV approach onto runway 16?
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Old 8th Feb 2008, 23:04
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"...my question is why do we not get rid of the whole ndb app. i mean i can see if its used as an aid to other apps but to have an entire app solely based on ndbs?"

"Why in the name of the heavens is any international airline aircraft required to carry out an NDB approach into any civilised International Airport?"

From various points in the report: "In Sept 2007 work commenced on the MEL RY 16 ILS....A NOTAM was issued 4 Oct...advised that the ILS would be unavailable from 8 October to 22 Nov....The crew had received this NOTAM prior to departure from Bangkok...the controller transmitted to the crew 'Descend to 4,000 cleared to runway 16 NDB approach."

The ILS was broke. The wind was 170 @ 25G35

Either fly the NDB or try and put a trip-7 down in 2300 meters on RWY 9-27 (ILS or VOR) with X-wind 25G35, or a VOR to 34 with tailwind 25G35.
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Old 8th Feb 2008, 23:06
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Why in the name of the heavens is any international airline aircraft required to carry out an NDB approach into any civilised International Airport?
I'm not a pilot so I may have this completely wrong - but, it seems to me (having read the report), that the question "why was the crew required to (or chose to) execute a NDB approach" spectacularly misses the real point.

Surely the real issue is "why did the crew fail to execute the NDB approach safely/effectively)" (whether because of error or inadequate training or practice).
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Old 8th Feb 2008, 23:16
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The ILS was broke. The wind was 170 @ 25G35
I can only reiterate what Flex said.

Sure we all know NDBs "should" be capable of being flown. But the fact is they are very rarely flown by these types of crews. MEL is a MAJOR international airport. It is a scandal that if the ILS goes down an international crew has to do a raw-data NDB approach.

Why on earth is there no RNAV approach for 16?

Why on earth isn't the NDB 16 in the FMS database?

Either of these options would have prevented this near-disaster.
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Old 8th Feb 2008, 23:23
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Why on earth is there no RNAV approach for 16?
How many pilots are qualified for RNAV Approaches? A lot of GA pilots are, but most of my airline acquaintances are not!

Figure that one out!
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Old 9th Feb 2008, 00:54
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How many pilots are qualified for RNAV Approaches? A lot of GA pilots are, but most of my airline acquaintances are not!
I have heard Virgin Blue, QF and Emirates pilots doing them, so I assume that there are quite a few.

But even discounting the international drivers who may not be qualified to do them, an GPS NPA RNAV approach in Aus costed $7000 a couple of years ago. Surely the safety benefit to pilots who are qualified to do them (in preference to the "twin" NDB) would outweigh that sort of outlay?
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Old 9th Feb 2008, 02:41
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G'day Gents,

The RW16 ILS was out of service, and NOTAMed, because it was being replaced with a CatII/III facility, so it wasn't just broken.

The RW16 approach is a perfect overlay for the RW16 NDB approach both laterally and vertically. The DME/Altitude scales are the same.

The crew either forgot to engage VNAV or deliberately didn't for some reason and then failed to properly monitor the approach in any case.

I flew the RW16 NDB approach, in a B767, several times during the ILS outage and it worked just fine in LNAV/VNAV.

This sort of thing doesn't only happen in MEL, I was on approach to FRA years ago and had a RW25L VOR approach sprung on me at the last minute, in IMC, due to an ILS failure and had no problem. So, non-precision approaches to major airports do happen from time to time and sometimes due to the prevailing weather conditions are unavoidable.

So the relevant question is not WTF were the MEL airport authorities doing with the ILS, i.e. building a better one, but WTF were the crew doing flying a poorly executed approach in IMC?

Regards,
BH.
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Old 9th Feb 2008, 02:59
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For those of you (QF?) who seem to think flying, in LNAV/VNAV, the ILS from the database when in fact you are flying an NDB approach, I am sure you would find CASA would have a fit if it knew you were doing it. Is it in your company's SOP? Doing such a thing, without a significant amount of local knowledge and extensive analysis of both approaches, is fraught with danger.
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Old 9th Feb 2008, 03:11
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G'day Capn Bloggs,

It is the way we do it and it is CASA approved and what is the problem if you are monitoring the raw data, which is of course a requirement? In fact it's a CASA requirement, as part of our sim programme, to carry out a non-precision approach in exactly this manner.

You could also fly the approach in Hdg Select and V/S, but that is a higher workload than using LNAV/VNAV and you always have the option of changing modes if the map is inaccurate or going around if it really gets pear shaped.

Regards,
BH.
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Old 9th Feb 2008, 04:17
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You can build a suitable LNAV track or use an overlay approach that is the same. As pointed out earlier, you can't construct a VNAV profile, it MUST be supplied in the FMC database and you must be trained and authorised to do VNAV approaches.

We (can) use LNAV for non-precision approaches, with raw data monitoring, which means you can concentrate on getting the descent profile accurate without having to keep adjusting the heading using HDG SEL. We use VS for the descent path, having calculated and cross checked suitable step downs for each DME mile, interpolating between supplied hard altitudes on the chart, if required.

So I am not sure I agree with Flex and his rant about 'big' airlines having to fly non-precision approaches. They are a fact of life in many parts of the world and you can fly them safely in a big aeroplane if you are trained, practised and you fly a constant descent from the right point to the right minima. They are more challenging than an ILS and the risk factor is higher, but for once I agree with 411A, that's what you get paid to do, so learn how to do it.

RYR-738-Jockey
it certainly looks like they had briefed for a VNAV approach because of the 50' addition to MDA.
Not sure why you would come to that conclusion. Many airlines are authorised by their authority to add 50' to published MDA on a non-precision approach in order to fly it as a CDA and not to bust MDA in event of a go around. Indeed this reason is mentioned in the report as to why they did this. Nothing to do with VNAV being used.


From the report
The database did not contain the runway 16 NDB approach. The copilot reported that he entered into the FMCs the final approach fix waypoint at 6 DME with an altitude constraint of 2,100 ft above mean sea level (AMSL). Other segment minimum safe altitude constraints associated with the NDB approach were not entered into the FMCs.
So unless they can enter VNAV approaches in manually, they were not following correct procedure.

The F/O put 2,100ft in at 6D, whereas the procedure crossing altitude at that point should have been 2,250ft according to the chart (LIDO, which I am not overly familiar with).

They started descent from 4,000ft at 9.9dme instead of the published 11.5dme, that is 1.6nm later than published, so probably somewhere in the region of 170ft high on profile at that point. They were not fully configured for landing at that point either.

They descended at an average of 1500fpm, and recorded 1808fpm at 8.5dme. When they descended out of cloud all three of them were 'looking out' and the PF was not concentrating on 'looking in'. They got to 513ft above terrain level with 2 EGPWS cautions. The F/O then disconnected and climbed, then flew level before following the PAPIs, stating they were fully stabilised by 500' ARTE.


So to speculate;

I would say

1. They were not adequately briefed for this non-precision approach.

2. I suspect they did not follow correct procedures and constructed an (incorrect) VNAV descent path for the final approach. Nobody cross checked the FMC entries adequately.

3. The increased workload lead to a rushed approach. The aircraft was not configured for landing before starting the final descent from 4000' and the descent point was missed.

4. Neither (or infact none of the three) pilots recognised the high workload and dealt with the overload that the F/O found himself in (when he missed the descent point and was unsure of their clearance to fly the approach) and when he conducted the final approach contrary to the briefing he had given (he used LVL CHG and not VNAV).

5. An high rate of descent after missing the descent point further increased the workload and lead to less than optimum aircraft handling and ultimately a descent well below procedure safe altitude when the EGPWS cautions occured.

6. Situational awareness had broken down and there seemed to have been little active monitoring and assertive communication from the captain, who should have had the spare capacity and could have just said 'Go around' and corrected the situation.

These are just my thoughts though.....

PP
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Old 9th Feb 2008, 06:32
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We still have NDB'S on our 757's but none on the 76's.

As was mentioned there are no NDB approaches in the database, cleared for one, however we are certified to use an overlay of, for example an ILS approach (no glideslope) to the same runway and LNAV / VNAV down to, either a 'derived decision altitude' of MDA + 50 feet or, as noted on the chart, in some cases MDA itself as your DA or decision altitude.

There is no better method to fly a NPA, stabilized, almost as good as an ILS.
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Old 9th Feb 2008, 08:39
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Just poor airmanship

I see it once in a while beeing an instructor in the sim, crews start the descent late, are using an idle descent mode (level change, as the thai guys did) to chase the path, and do not have any gate to stop the massive rate of descent. Furthermore they are not using the vertical profile displays to avoid coming low. Just a nice example of THREE pilots who lost their situational awareness completely.....
Non prec approaches are nowadays as easy as ILSes! It just needs a little bit of preparation and maximum use of the modern instrumentation we have nowadays...
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Old 9th Feb 2008, 10:42
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As QANTAS parked one on the golf course at Don Muang a few years back, perhaps Thai thought they'd return the favour!



ADFs are usually an option. My company's Airbus all have twin ADF fits.

And it's no use these days saying that a failure to fly an accurate NPA is down to pilot proficiency and we all managed it safely in the old days. Things have progressed and safety is more of an issue, hence the tendancy for ILSs. My company is allowed to do fully managed NPAs providing we have GPS primary. It takes away all the risk, the approach is not much different to an ILS - and it is very safe.
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Old 9th Feb 2008, 10:52
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Capn Bloggs
For those of you (QF?) who seem to think flying, in LNAV/VNAV, the ILS from the database when in fact you are flying an NDB approach, I am sure you would find CASA would have a fit if it knew you were doing it
Bullethead
It is the way we do it and it is CASA approved
Oh dear Capn Bloggs Do keep up!
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Old 9th Feb 2008, 11:56
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737Only,
Furthermore they are not using the vertical profile displays to avoid coming low
What vertical profile display?

Fathom,
Oh dear Capn Bloggs Do keep up!
Keep up with what? I don't know of any rule that says I can load an ILS into the FMS and then fly a NDB just because I looks like it's the same approach...
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Old 9th Feb 2008, 13:08
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Captn Bloggs

you can construct a lateral profile to follow using LNAV IF you monitor raw data. So, if you drew an inbound course to the NDB as promulgated on your approach chart this would be permitted (as long as it complies with company SOPs). If that inbound course to the NDB was exactly the same as the ILS inbound course what would the difference be if you just selected the ILS in the FMC and followed the lateral portion using LNAV? That is what posters are saying. Remember, the lateral navigation is being done on the raw data display, you are merely using the LNAV capability to keep the raw data tracking correct. If it shows an error, then you MUST follow the raw data info and use another mode, HDG SEL or G/A.

The VNAV portion of that approach is what stands out to me as being inappropriate. As I stated earlier, in my company you are NOT allowed to construct the VNAV profile, it MUST be in the FMC database and thus the profile is generated when you select the approach in question. Perhaps the incident demonstrates why my company do not allow the vertical profile to be constructed and flown in VNAV (the input error that was not noticed by any of the pilots) and then they never used it anyway, selecting a high rate of descent in LVL CHG due to being above profile and unstable!

I think it all comes down to the approach not being planned well enough with a clear enough picture of how it was going to be flown.

As an aside, we've all heard an approach brief where a pilot rattles through the detail on the plate, but neglects to say HOW he is going to fly the approach, what modes will be used, when he will configure the a/c and what cross checks he will be requiring from the NHP to ensure compliance with the step downs/ profile. This is more critical when flying a non-precision approach and 'getting down and dirty' at the platform and being fully configured to start the final descent at the correct point is the safest way to conduct this sort of approach IMHO. I have seen many trying to fly an NDB approach like an ILS, keeping the speed inappropriately high and leaving the config until late and invariably the approach is untidy as the workload goes up exponentially and you don't have the luxury of LOC/GS to reduce the workload to free up grey cells.....the bit that usually goes wrong? The descent profile. With some 'pink string' or a beam bar display the lateral portion is visually easier to monitor. The vertical profile needs concentration and use of some brain power to maintain a stabilised path as you need to constantly keep checking crossing altitudes and speeds. This is where VNAV approaches can help to free up capacity, in effect making the approach more like an ILS, but you need to make sure that the VNAV profile is correct before you start as there is no raw data backup, just you and your colleague....

PP
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Old 9th Feb 2008, 13:32
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hawker750 . . . if you re-read the report carefully you would have known that the airplane was equipped with dual ADFs, and according to the report the airplane was delivered new from the factory just the previous month. So it's highly likely that both ADFs were in working order.

permFO . . .the event occured in daylight hours, shortly after 1 o'clock PM.
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Old 9th Feb 2008, 17:12
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Pilot Pete.

I must say, excellent analysis of what should be SOP on any non precision approach; i.e be fully configured with all checks completed latest 2 miles before start of the chart "glidepath", and most importantly, raw data monitoring of lateral and vertical profile by the PM. The profile is invariably printed on the chart. How difficult is it for PM to sing out the required ht against DME range and for the PF to adjust accordingly? The ND "profile guide" is a good crosscheck, if the coded approach has not been modified (again another SOP). Some glides are steepish, others (e.g SHJ) are shallow,but all close enough to a standard 3 degree glide; any such anomalies well covered in company airfield brief.

However, having said all this, it is often easier said than done, especially with regard to the "fully configured" bit, when ATC vectors you in tight, there is a tailwind, or finger trouble with MCP selections, all resulting in not being at the correct platform ht for VNAV PTH descent (talking Boeing 744 here); mode goes to VNAV ALT(thats if if you remembered to reselect VNAV from whatever you were using before- VS or FLCH) and then you're scrambling. I like to practice VNAV PTH descents whenever possible (nice clear days!), as we don't get to do too many non precision approaches in our operation, but I have to admit that in an IMC environment,(and sim checks!) I will take LNAV (raw data monitored) and VS (raw DME/chart ht back up) any day. Too many gremlins lurking in VNAV. As for FLCH on finals, don't think so somehow!

Last edited by Phantom Driver; 9th Feb 2008 at 17:19. Reason: clarification
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