Thai Air B777 Melbourne NDB approach
 

"On 4 November 2007, a Boeing Company 7772D7 aircraft, registered HS-TJW, was being operated on a scheduled passenger service from Bangkok, Thailand, to Melbourne, Vic, with 17 crew and 277 passengers on board. During a non-directional beacon (NDB) non-precision approach to runway 16 at Melbourne Airport, the aircraft descended below the segment minimum safe altitude at 6.8 distance measuring equipment (DME, a measure in nautical miles). Soon after, the crew received two enhanced ground proximity warning system (EGPWS) cautions. The crew then levelled the aircraft and conducted a visual approach and landing on runway 16.
The investigation is continuing."

Full report here...

http://www.atsb.gov.au/publications/...727_prelim.PDF

I was led to believe that modern a/c like the 777 and some of the newer generation airbus's do not have ADFs on them....

all Boeings do I think but the new gen Airbusses (Airbi.??) dont. Caused a few dramas the few months the ILS was out Im told...

all the latest Airbus i flew, had a single ADF on them, so still able to fly ndb approaches.

Not to MEL 16!! It requires 2 ADF.

nope it does not .
in the old days it was a twin locator approach, not anymore.

one adf
 

Why do airlines/manufacturere penny pinch on the relatively small extra cost of a second ADF. There are may instances of incidents/accidents caused by the lack of a second one. The USAF 737 fatal at Dubrovnik being just one. Trying a twin locator (ADF) approach with only one is iffy to say the least.
Or am I just behind the times?

The Jepp chart now states DME and both NDBs required even though its now an NDB rather than a Twin Locator.... Now, whether that means both need to be monitored simultaneously or not is another question..

No go-around ?

There wouldn't be any NDBs in Australia today (and for quite some years now), saving tens of millions of dollars a year in maintenance and upkeep, if some nameless person in Canberra hadn't screwed up royally when writing the GPS specs of the J model Herc.

But that's another story...

Non precision approaches in big aeroplanes are seen to be so incredibly dangerous by some airline managements that they forbid their aircrews from practising them on the line. (Not just NDBs, but VORs and LLZRs as well.) Total exposure to NPAs is once every six months in the sim - unless a line pilot has to do one for real on the line because a precision approach is not available.

I don't know if Thai follow this... shall we say rather remarkable practice. However, when aircrew who aren't allowed to practise have to do an NPA in anger, their management wonders why they sometimes get it wrong.

Join Ryanair, and you will likely shoot a NPA every or every other day. All flown in VNAV now though so no massive rates of descent in V/S, which is where the danger lies.

They are not dangerous if you are well trained, diligent and practise regularly.

Hello everyone, first time post!
NPA are normal ops on charter flights, I fly either A330 and A321 both equipped with two ADF extremely usefull for landing in places like Boavista, Capoverde or Banjul, Ghambia. If you are trained its fun tough! :}

If they did indeed use VNAV and it flew them low there'd better be some flack-jackets issued for the database boys in Jepp...

On that point (and never trusting Bill Gates oops I mean computers in general) it is interesting that two profile points, 8DME and 7DME, are not printed on the approach chart. How on earth is a crew supposed to easily monitor the VNAV (or do it themselves) if the chart hasn't got the complete profile on it? The two that are not there cover the height the aircraft got to when the EGPWS went off. "Thanks for nothing, system." Really nice pic of the runway though...

Firstly: most current 777's have 2 ADF's fitted. However the next bunch of 300ER's at CX will NOT come with ADF's

Second: I'm pretty sure the 16 Twin Loc app in MEL is not in the Honeywell FMC database. You can build the legs if you want to and use L Nav ( monitoring the raw data for tracking ) BUT you cannot use Vnav for the arrival. Only Data base approaches can use V Nav for guidance. ( ILS's VOR/DME GPS etc all ok, there are no NDB approaches at all in a Boeing FMC )

...but in this instance you can select the ILS - and use it as an overlay. LNAV VNAV should then work, with appropriate raw data and profile height checks.

I dont see why the honeywell FMC cant be as flexible as the smiths FMC.

Smiths you can just build rwy extension and waypoint on waypoint, plug some altitudes in and watch LNAV VNAV fly it for you.

But would you really fly an approach that you've "built" down to minimums and be the first one to see if it works? Or doesn't. :ugh:

I dunno about the legality of that, Blueloo! VNAV below the MSA using an different approach to that being flown? Duck heads, over.

Does the 777 have the "Green Arc" showing descent point like the 757/767? I use that in VS a lot. (Yes, I know I'm a danger to myself and humanity in general for using vert speed. I fully expect the police to be at my door anytime now...:rolleyes: )

Descending below the min alt. for a given segment on a NPA can be done by anyone not paying attention. Certain individuals go below G/S without a peep from the other seat, too. TC

Even if, as they were, joining the V-Nav (FMC calculated glidepath) from above the initial MCP Alt window should have had 4000' until 12D when 3000' would have been entered until 9D and so on.

The FMC should be an aid, with the MCP Alt window still protecting the the crew from the "embarrassment" of FMC mistakes..

"But would you really fly an approach that you've "built" down to minimums and be the first one to see if it works? Or doesn't. "

Most probably not would be my answer at this stage.

- my thoughts - if no non-precision approach - or overlay as appropriate is in the database why could you not build an LNAV track to replicate the approach. Your choices - a blank map and raw data - in a big boeing using HDG SEL and VS. Or build an LNAV track - let it fly LNAV monitoring raw data - you now have a display for situational awareness, and you shouldnt have to fiddle with the HDG knob every few seconds when the wind changes, or you havent got the HDG/drift quite right....



Capn Bloggs:
Remember you still must monitor raw data. The approach must be flown ie Alt constraints etc as per the NDB chart - (or company requirements) - all VNAV and LNAV are doing is reducing the workload, to allow you to monitor and manage the approach - an ILS overlay which has the same exact lateral tracking should be fine (the melbourne ILS overflys BOL and ROC) - and as ILSs tend to fly 3 degree approaches then VNAV should be appropriate.


Woodpecker:
"Passed the Cb, we were cleared present position direct to the VOR"

I must have missed something in the cleareance - or was it "cleared to the VOR to resume the STAR"?

I am not familiar with the area you are talking about - the terrain ATC or otherwise.

If you are cleared direct - surely you are no longer on the STAR. Which presumably means the Atl constraints are no longer valid. So you need minimum safe altitudes from somewhere.....the original STAR constraints may not protect you if you are off track - they may in fact be higher.

Bluetoo,

The basic point is, under V-Nav and L-Nav, should you rely on waypoint altitude protection or should the MCP Alt window reflect the minimum altitude that you can descend at you present position?

Forget the Daros 1A, have a look at the Melbourne plate (URL link), should the MCP Alt have been set to the locator height or to 4000 (until 12D)?

Which is the safe option, and which is SOP?

Airmanship suggests 4000' is safe, SOP's (in my airline) suggest the locator height.

Must be some confusion here - my apologies - thought you were talking about the STAR and direct tracking on the STAR- not the Approach itself. Approach constraint would be different entirely, and I agree the in the Melbourne case 4000' is the minimum until BOL ( I am using the jepp chart).

Our SOP, once "established", is to set the MDA. Then allow either the VNAV or use VS/FPA to follow the briefed or charted profile down. We don't wind in each limiting step because it increases workload to the point of distracting the crew, especially where there are many steps.

Re setting limiting steps on a STAR, if you did do this, then you couldn't set your actual level cleared-to by ATC. This would lead to the possibility of missing your assigned (as opposed to STAR-limit) level.

Indeed so, Capt.
Many new crew use the automation so much they can't see the forest for the trees and, if crew can't keep a mental picture of what they are doing, they don't belong in the pointy end in the first place.
Are NDB approaches 'interesting', in some circumstances, especially with a large heavy jet?
Of course they are, but that is precisely why we are paid the big bucks.
Can't stand the heat, stay out of the kitchen.:rolleyes:

Isn't this a non-event?

"The crew then levelled the aircraft and conducted a visual approach and landing on runway 16."

Xsbank, have you had a look at the profile on the full report?

One thing notorious for RWY16 is the undulating terrain associated with steep gullies around the 6-4nm final. This may set off an alert if not in the appropriate config. A few years ago I have had a terrain alert on a clear day with a slighly higher descent than normal with flaps 1 (airbus) selected.

Sure, the outcome was a non-event but history is rife with RT misheard followed by CFIT. Here is one example:

http://aviation-safety.net/database/...?id=19890219-0

In this ymml case, overhearing the cloud level elsewhere was 1700 when in fact it was 1000 @ymml. Presumably @1700 the crew must have wondered when they would break out.

I think the EGPWS was a tidge late wrt the initial deviation from the minimums but a timeline would help. Certainly the corrective action upon the second warning was welcome.

I would count this as an EGPWS 'save'. A valuable piece of equipment to say the least.

The 737 NG's (7,8 and 900's) do NOT have any NDB's on them, yet with the FMS's installed, we still shoot the NDB approaches (in the sim, never done one real time yet)

I think NDB approaches are in the emergency section, aren't they? :)

K

This incident has nothing to do with a vnav approach. The crew flew over the ndb, set the minima and then pushed LVL CHG or, for the Airbus minded, the equivalent of selecting open descent. A basic error but not a non-event. Certainly airline procedures will need to be addressed as the crew response to an EGPWS warning at night would probably not be considered ideal.

Oh well, if they didn't do what they briefed they were going to do...

A jet decending below MDA is a non-event?

They didn't just get below profile they busted an MDA step. I also gather they were in cloud. It's an NDB approach, but it's a straight in runway aligned one with no reversal procedure. Coupled to LNAV it's basically a localiser approch from an altitude management point of view.
Also, why not use a FPA descent? at the top of the profile (11.5DME) set -3.0 degrees dialing in check heights along the way and let Mr. Boeing do the rest.

They didn't start descending at the appropriate point, the FO hit Level Change to get down, and it certainly looks like they had briefed for a VNAV approach because of the 50' addition to MDA. Anyway, at 6,8 D they were a 1000' low on profile triggering GPWS. NDB or not....totally irrelevant, the point is the crew started descending in a non-standard mode and did nothing when passing through the VNAV path/CDA profile.
On a side-note, the crew responded correctly to the GPWS. Levelling and continuing visually is accceptable on GPWS caution.

XSBANK - NOT a not event. The outcome was good (ie no CFIT), but they the aircraft was not going where it was supposed to go. (Lucky they were in VMC)

"On a side-note, the crew responded correctly to the GPWS. Levelling and continuing visually is accceptable on GPWS caution. "

I think this is acceptable in day VMC but this occurred at night time. Also there is a high probability that the crew's SA was not good. The only reason to ignore an EGPWS warning is if you are aware of the terrain and you can see it. I don't think that was the case in this incident.

b777 ndb app at melbourne
 

my goodness still doin an ndb app. 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?man its out of date and out of taste

How can anyone cock up a twin locator or ndb approach?

Especially into 16 at Mel which is as simple as they come!

Strewth!...didn't we all learn this in a link trainer when we were kids?

Gotta wonder about the standards here, guys!! :sad::sad:

How utterly disgraceful!

How utterly third world!

How utterly primitive!

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

For God's sake, aren't the passengers taxed enough on their tickets and the airlines on landing charges to expect 21st friggin' century technology approaches at destination?

Even your piece of crap shopping trolley car has a reliable GPS these days...

Shame Australia! Shame and again Shame!

I am embarrassed to be Australian. Does anybody remember that Australia was involved with the invention of the Microwave Landing System for example?

I've seen much better service as most of the poor third-world destinations in Asia.

I say shoot the bastards collecting the money at Melbourne Airport for their miserable failure and incompetence in maintaining a safe aviation facility at a minimum acceptable standard that might be expected by a reasonable man for the operation of International RPT!

There is no way this particular twin locator will be removed. Qantas Longhaul is obsessed with twin locator approaches and no doubt will pay for this one to remain in service.

Oh wait a minute - I hear the quote - "its not qantas - its the casa matrix!"

(Which is in laymans terms "I am to lazy to change it - or spend money and install new technology and equipment into our ageing fleets")

BIG difference between a CAUTION and a WARNING. ;)

Flex, I gotta agree with you there...