NZ60 Erronious ILS Incident, Apia Samoa

[FlexibleResponse]

Can you trust the ILS G/S?
(The purpose of G/S "check heights")

A rather chilling video on the subject:

http://www.youtube.com/watch?v=GelRBhJ4gmI

[Capn Bloggs]

Interesting that there wasn't a "GS Check Height" on the chart (no outer marker due to the water under the approach). There is a LOC profile on the bottom of the plan view but was there a DME-GS check in the SOPs (granted the ILS DME was sus in this case)?

At one of our airports, the service provider wants to get rid of the markers. Cost too much. Replace them with DME-GS checks. Perhaps this is not a good idea. As happened to this crew, under high workload (falsely caused by the premature capture of the glideslope and subsequent stuffing down of the nose to follow the (false) glideslope), a crew could miss the GS check if it's based on DME. Done it myself. A marker beeping and flashing at you is much more likely to get your attention.

Congrats to this kiwi crew who were put in the ultimate gotcha situation, realised it and survived.:ok:

[bookworm]

At one of our airports, the service provider wants to get rid of the markers. Cost too much. Replace them with DME-GS checks. Perhaps this is not a good idea. As happened to this crew, under high workload (falsely caused by the premature capture of the glideslope and subsequent stuffing down of the nose to follow the (false) glideslope), a crew could miss the GS check if it's based on DME. Done it myself. A marker beeping and flashing at you is much more likely to get your attention.

I think you're ignoring a key point made in the video (part 2). A single GS check close to intercept point is not sufficient to determine if the aircraft is following an erroneous glideslope. The autopilot may pitch the aircraft down and establish an approximate rate of descent, and then make adjustments to that rate of descent based on the glideslope deviation. If there is no indicated deviation because the glideslope is erroneous, it makes no correction.

With a single OM, the altitude may be approximately correct, even with an erroneous glideslope. But the crew may never live to check the altitude at the MM. With a DME, altitude cross-checks can occur periodically along the glidepath, e.g. every mile.

[Capn Bloggs]

Bookworm, point taken. I'm just saying having a marker with it's obvious visual and audio indications will be a big help/prompt to actually do a GS altitude check especially if under high workload. If you are on altitude at the OM and the ROD is normal, chances are things are OK. Still this crew probably thought things were OK anyway being on slope, with an ident and no flags...

[uniuniunium]

Perhaps a software change to allow VNAV path indications to be displayed and crosschecked side by side with G/S indications (I'm thinking along the lines of Boeing's RNP/ANP display), or a FMC "G/S VNAV DISCREP" message to bolster charted altitude checks would be helpful in these situations. It's pretty scary to think that a single antenna failure would result in such indications, especially at unmonitored installations.

Cheers,
-Lee

[theamrad]

Just an addition - concerning DME height checks etc, the NTSB (in written submission/letter) didn't think the crews actions were quite as praise-worthy as the incident report's authors did. More or less stating that they should have spotted 'things' earlier.

[AerocatS2A]

Well, if the crews actions were trully praise worthy then we would've heard nothing about it because the error would have been picked up so early that the whole incident would be a non issue. So of course, the crew didn't do particularly well for a period of time. The good stuff happens from the point they finally realise that something is wrong. I suspect the two reports are simply focussing on different aspects of the incident.

[pakeha-boy]

Quote........So of course, the crew didn't do particularly well for a period of time. ....

Aero....little harsh dont you think:confused: ....have you ever flown an ILS where things may not have looked "right"....personally,I applaud the crew for the CRM....it seemed to me that they realized something was wrong...the problem is not always obvious,they had time,altitude and the foresight to discuss the issue at hand ....rather than able along and do nothing.

Take a look at AA @,Cali incident,[email protected] little or no crew discussion....look at the consequences:ugh:

The crew should be applauded.... not for anything else but for doing their job,the way thay were trained to do it .....it,s when you dont do what you train for or know it,are when issues occur...

This was a classic example of a "sim session"....in reality,roadblocks thrown up,.....recognition,decision and actions.....

This is a great example of self disclosure,where the example can be used as a training aid for others,as it has done.....and if the video is close to being correct/real ..a great example to the young fellas about problem solving and real life situatons....how bad can that be.....:ok: PB

[AerocatS2A]

I don't disagree with you PB.

There's good and bad stuff that happened. Depending on where you put the emphasis of your report, or opinion, reflects on how the crew's performance looks.

And no, I haven't flown an ILS where things don't look right. Mainly because we don't have those high tech approaches around this part of Aus and so I do very very few of them. I have to make do with those dodgy NDB thingos and if I'm lucky, a VOR. So I'm not really overly qualified to comment on the specifics of what happened.

[Graybeard]

Hand flying that approach would have undoubtedly revealed the GS failure much sooner, as you would expect to see deviation upon tuning to the ILS. If not then, you would expect to chase the beam at least a little bit.

There are a lot of presumptions made in autoland design, and one of them is that you won't have shoddy maintenance of the ILS. Autoland design basically assumes a Cat III quality ILS.

GB

[pakeha-boy]

Aero....mate no worries....have done a few NDB/VOR/LORAN thingo,s out back myself...and it is those thingo,s that make the pilot....the ILS is payday and requires a no different attitude than any other....stay within the parameters and the app is successful...obvious I know

Did an ILS into Victoria Canada late one, ****ty night......very late....pushing to get in...Airport @mins...cleared for the ILS on vector ......they had changed Rwys on our arrival and hadnt switched the localizer around(same ILS freq feeds both runways)........intercepted on a 15 mile final..... and thats when the fun started....used the NDB (OM) to maintain track the localizer......finally asked the controller if the ILS was protected,any problems...it was then they confessed....go-around vectors....for another app.....

My point....sometimes red flags dont always need instant rections....there is time to discuss and situations like these,and it tellS how well a crew does and reacts....and eventually the outcome....nothing is written in stone..

GB....DITTO

[FlexibleResponse]

The message is getting around the aviation community. Youtube now shows 11,911 views and counting...!

[FlexibleResponse]

Saskatoon,
A very thoughtful and professional observation!
Give back to the pilot community and preservation of life is job No 1.
I am also a great admirer of those who add to knowledge-base that keeps us all alive.
Cheers!

Youtube views now 12,154.

Tell all your friends and make this video a classic.

[Brian Abraham]

Kudos should be given to the airline as well for the way they handled the issue. None of the knee jerk so often seen (shoot the guilty b******ds) which is what all too often makes people less than forth coming in owning up to indiscretions.

[chimbu warrior]

Of greater concern is that as recently as 18 months ago (last time I was there) the ILS check height/DME distance at Apia is still not correct. I forget the magnitude of the error (more than half a mile as I recall), but ATC are totally dismissive of any complaint about it.

If you operate there, particularly at night, be VERY cautious, as ATC are worse than useless. I once went there at night and all the ground staff were "half-cut". When I queried them they revealed that there had been a "session" in the tower prior to arrival, and they couldn't wait to get rid of us so that the party could continue!

[habagat1]

Dear Flex,

Thank you very much for SHARING this Info,..:ok: ..Everything is POSSIBLE and can happen even on the most Modern and Advanced Technology we'ved got.. Back to Basics is really is our Solution.


Safe and Happy FLYING man:D


Habagat1

[FlexibleResponse]

Thank you Habagat, my pleasure to pass on the information, but the thanks should go to the Kiwi airline and their aviation authority.

Chimbu, just in case you are measuring the Height check with a baro altimeter (and what the hell else can you use!), don't forget to make a correction for non-standard temperature. A baro altimeter only can measure pressure. The relationship of pressure to height is only an accurate depiction of reality when operating at standard temperatures and pressures.

In a tropical area, the baro altimeter will ALWAYS read in the order of 125 feet too low at the check point (equivalent to about 0.4 DME), due to the temperature being about ISA+15 deg.