11 miles out @ 530 feet AGL
 

Incident: Eastok A320 at Irkutsk on Feb 28th 2012, ILS malfunction leads to premature descent

Chilling....

Good thing the crew caught the error. I wonder if they were in IMC?

Scarey.Hope they survive their career.

Had an FO who would have landed in an orchard if I hadn't forced her to level out. Stupid is hard to fix sometimes.

not an isolated incident
 

Reminds me of the 2011 AAIB safety review report of an A320 [G-MEDA] doing an approach to Addis in IMC....

A British Mediterranean Airbus A-320 aircraft, registration G-MEDA operating as flight number LAJ 6711 on a flight from Alexandria (Bourg-el-Arab), Egypt, to Addis Abeba, Ethiopia, carried out two approaches using the Addis Abeba VHF Omni-Directional Radio Range beacon (ADS VOR) and associated Distance Measuring Equipment (DME). On the second approach the aircraft crossed over a ridge of high ground in Instrument Meteorological Conditions (IMC) and came within 56 ft of terrain at a location 5 nm to the northeast of the airport. As the aircraft crossed the ridge the crew, alerted a few seconds earlier by a radio altimeter (RA) height callout, carried out a go-around; at the same time the Enhanced Ground Proximity Warning System (EGPWS) generated a ‘TOO LOW TERRAIN’ aural alert
The investigation determined that the antenna of the ADS VOR had suffered water ingress and was not functioning correctly. The correct maintenance procedures for the ADS VOR/DME and its associated monitoring equipment were not followed.
The aircraft received erroneous information from the ADS VOR which was fed to the flight deck VOR display, the Flight Management System (FMS), the navigation displays and the EGPWS computer with its associated Terrain Awareness Display (TAD). A single common position 1
source error thus adversely affected all these apparently independent navigation/situational awareness systems.
The existing certification standards for the aircraft navigation systems were met but were not sufficient to protect against this problem.

Nothing to do with Addis Abebba or similar incident in Alexandria many years ago.

I would really like to know what was the airplane configuration by the time they realised it was a wrong signal. The report says 48 seconds, but that height is too low for such short time from platform height...

The ILS glideslope signal was obviously working bad, because you can never have a false glideslope below nominal glideslope, as far as I know. I have had such event myself at home base and we disconnected immediately. It was VMC, however.

GPWS will not warn you in such a case if you configure, until EGPWS TFC function is triggered at about 500 agl or less.

In IMC and with some fatigue, and at night, I would like to think that I would be aware of the wrong capture, but I cannot be sure until I have such a situation...

48 seconds is a couple of miles or so, which makes the descent point roughly 13 to 14 miles out, 3 deg glide path makes platform height broadly 4000 feet agl 'ish'. Descent from 4000 to 530 feet in 48 secs! I think even I would have noticed a rather high (!) ROD and overspeed conditions.

Would somebody else like to try juggling the numbers and come up with a rational explanation?

So assuming they were at platform of 3-4000' AGL at >11.5d it would take a large ROD to achieve 530'AGL 48seconds after GS* - possibly 2500-3000fpm.

This is similar to the AirInter A320 that hit the mountain on approach to Strasbourg. They were performing a VOR NPA but selected -3300fpm not -3.3°.

It just stresses the importance of checking that the aircraft is descending at a sensible ROD.

As for the comments regarding ILS signal validity (on AvHerald), there is (was) an AIC detailing this. Typically LOC is valid inside 25nm and GP either 10nm or 15nm depending on offset from centreline. Some installations it's more than this due to operational requirements. If you look on a Jepp plate, the vertical profile shows the range the GS signal is valid from - take a look at the ILS for Naples runway 24. You take the LOC from 7000' but the glide is only valid approx 10d - so DON'T arm the approach at BENTO!

A4

You beat me to it Beardy :)

A difference here is that NPAs are normally stabilised (constant speed) and ILSs are decelerated. Go down and slow down ain't pretty when you're hot and high.

Shows the importance for height checks, distance verses height. Not just for the NPA's but as a cross check to the trusty ILS.

I have seen a few strange captures in my time, luckily I was always awake enough to catch it and takeover manually.

One springs to mind in Canada when the signal was being affected by a snow bank (I think) anyway after capture it caused the GS signal to fluctuate up and down... And of course the autopilot followed it, so it was click click and back to manual!

[quote+M2002]because you can never have a false glideslope below nominal glideslope, as far as I know. I have had such event myself at home base [/quote] - err, say again?

Anyone check the Notams?

which is why you should check your position on any approach...and why the outermarker and its published crossing altitude is important (or other similiar fix)

and why RADAR usually says: you are five miles from the outer marker/8 miles from the field, maintain XXXX till established, cleared for ILSXX apch.

So much for autoland :)

Radar?????????????!!! Are you sure it was working? - not much use on this approach! Probably never crossed the OM..

I have a sneaking feeling the ILS was u/s........................not knowing the electric jet I don't know what pitfalls await there.

I faintly remember an event somewhere in Australia I think.
Here to carrier for the G/S was working, but the modulation was U/S.
That will cause the G/S indicator to always stay dead center regardless of where the plane is in the vertical profile.
The autopilot/autoland then did a to steep descend, that would have caused a crash if the crew had not been alert with height versus distance.
To autoland is not really intended for following a signal that never changes. My guess it it tries to reduce power/pitch down until it "sees" a movement on the G/P. If the G/P stays in center, the plane will continue down.

No idea if this is the case in Irkutsk, but its one explanation.

Btw, in the australian incident the G/P U/S was in notam, and the G/P iden't was suppressed from the carrier... Anyone remenbers to listen for that ;-)

Air NZ. APIA. 29 July 2000

http://asasi.org/papers/2002/Air%20N...ope%20Apia.pdf

Quick, somebody copy and paste the METAR!

BOAC;
NOTAMs, especially historical ones, are difficult to track down. The following site is one of the best I've found in checking current and (for terminals I've checked), historical NOTAMs. Keep the URL but replace the last four letters with another ICAO designator.

Metars, TAFs and NOTAMs

Another difficult item to track down is historical weather. "OGIMET" has, so far, been of enormous help: Formulario para peticion de mensajes aeronauticos , METAR/TAF Reports section.

"Celebrating TAWS Saves, but lessons still to be learnt" is a good read on EGPWS.

In addition to the CAA report to which nike refers, Air New Zealand has produced a 3-part video series, ( , , ), on this incident.

Absolutely.

So why do these cross-checks sometimes not occur? Rushed? Distracted? Singularly-focussed on a failed glideslope?...

The larger question is, why don't go-arounds occur when things do not seem quite right or when the approach becomes really unstable? There still seems to be a strong desire to continue an approach when all indications are that a go-around is required. Seen it in the data...why is this so?

PJ2

So 48 sec after GS capture he was at 530ft AGL and 11.5nm from the threshold. If we assume a speed of 160kts and a vertical speed of 800fpm then at GS capture he would have been at 1170ft AGL and 13.7nm from the threshold. I don't know their SOPs obviously but 1200ft at 14 miles would make me decidedly uncomfortable.