Are you serious?? TURN IT OFF and FIX IT! This industry is dangerous enough as it is without known and accepted traps like this. Rediculous.

As this thread is still going i thought i would dig a little in the FR24 archives.

It's quite likely the 747 lining up for departure is causing the GS distortion.
So you can't just "fix it", you need to adjust ATC procedures.

(I'm not sure about different antenna types though i believe there are types that are less prone to distortion)

See the following pictures looking at the 20th October at 22:13 UTC

https://cimg5.ibsrv.net/gimg/pprune....624015ec49.png
https://cimg4.ibsrv.net/gimg/pprune....1ea34f5587.png

1) Move the holding point before the U-turn, and introduce "Line up behind" [ICAO standard since long ago].

I was actually about to say a bit in defence of the crew, but seeing the graph by wiedehofp, now I am glad I did not.

This is not an inherent problem with the GS equipment at VHHH. It is due to departing aircraft on the ground proceeding into the ILS Critical Area and interfering with the GS signal.

Clearly well-known to the authorities, since they have carefully painted an ILS HOLD line on taxiway K, abeam the GS antenna (see top image, post #43, and the airport diagram). And not uncommon at other airports.

If the ceiling is below 800' and/or visibility is below 2 miles, and an aircraft is on the ILS inside the OM, ATC should not permit an aircraft (or other vehicles) to pass that hold line. because it is well-known that that can make the GS reception unreliable.

However, on this day, the weather was well above those requirements, and ATC was not required to protect the GS signal.

Therefore it is up to landing crews, well-informed by charts, NOTAMs, and ATC verbal warnings that the GS could be unreliable as departing aircraft interrupt it periodically in good weather, to use common sense and not be automation-dependent. Use the ILS for guidance if you wish, but be prepared for a honking great 747F to pass in front of the antenna and foul up the GS signal. Be ready to hit the VS HOLD button, or cancel the A/P altogether and hand-fly the rest of the approach manually and visually.

Use common sense ? since when common sense is used as a mitigating factor for a deficiency in aviation ? The only valid reason I see to do that is to increase capacity , i.e. money/greed.
If as you said , this only applies in good weather, then say " G/S unserviceable "during that period. You protect yourself as ATC and it is clear for all crews. Because if as ManaAdaSystem prediction above do materialize one day , the guys that authorized this will most likely end up somewhere very unpleasant. .

Indeed, if the instructions above are too hard to follow, then maybe flying isn't for you and you should consider another career choice.

It's not that bloody difficult snowflakes.

We have holding points right in the beam and I've never had a duck-dive on final. Something cockeyed here...

have to agree with you on this one Bloggs...something not right

Does the fluctuation, in anyone's opinion, explain what we see on the profile as recorded on FR24? I experienced some G/S fluctuations at SVO for the very same reason of GP antenna shielding, but the overall effect was very different.

The second approach, just starting the final descent

https://cimg5.ibsrv.net/gimg/pprune....973133b109.png


Same position but on the first approach. Already well below profile, -2000 fpm and keeps descending

https://cimg6.ibsrv.net/gimg/pprune....acbe12550d.png

First approach, 5 miles out: 400 ft AFE and still -2000 fpm

https://cimg3.ibsrv.net/gimg/pprune....3790d5ce7d.png

And the correction is … creepy.


https://cimg7.ibsrv.net/gimg/pprune....28fb6ca142.jpg

It can't be "fixed" if it is a taxiing airplane blocking the GS transmitter during good weather conditions.

GS fluctuating.
 

It's called reading the notes. If we have to hope an airline pilot will read the notes, then this profession is no longer a profession.
https://cimg6.ibsrv.net/gimg/pprune....79d209b765.jpg

5. If you still choose to fly the ILS WHILE ON THE A/P you have accepted the risk.

Glide slope blanking by aircraft taking the runway is common. As is LOC fluctuations as a plane clears the runway. This isn't new.

Are those sink rates and altitudes correct? 2,600 FPM at 1350'? 1,900 FPM at 525'? Who's minded the store?

If the ILS signal, or autopilot, gets twitchy it's taken out of the loop ASAP.

During my career my company required we fly the ILS, if the runway had one. We often didn't couple. Hand flying works quite nicely, or at least it used to. And, there are no other approaches to 7R unless you are RNP AR qualified.

It just needs more cooperation between Ground and Approach. Sit them next to each other.

GLS would solve the issue..

Maybe it's time to match operations to reality (i.e., that a standard approach is on the ILS with the AP, and anything else is a quasi emergency) and protect the GS critical area no matter what the weather is.

So there's a note that legally transfers responsibility... what's the flight crew supposed to do with that info, hand fly the approach? I think that ship has sailed.

Did anyone look out of the window?

That's a nice feature.

apparently not

I really hope that you are joking.

About 50/50

If only that comment was in the notes! ;)

Jepp has put the note about the LOC being useable in The Notes section, but not the note/Caution about the GS interference. Not desirable.

Look at Post #57. The note is prominent and in the plan view.

When I was flying airliners, an instructor saw me focusing too much on the outside and he told me to follow FD down to 50 feet.
This was in Asia !!!!

When crew is informed about GS unreliability they needed to have a plan to mitigate the threat. Close monitoring of GS with ILS DME and when required disengaging the GS and selecting appropriate VS, planning a LOC only approach or switching to visual approach are part of the options. From available evidence it appears the threat was not assessed in it's entirety and suitable threat mitigation was not planned. Surely action based on GPWS cannot be a safe option. The CVR read out should reveal the crew thought process if any. Since the issue is recurring event I hope the airline quickly addresses the issue and circulates the information and procedures to manage the threat.

True vilas, and very systematic. Only half of the story though, the less important one. It is not right they did not have a workable plan to a known hazard, what's wrong is how the situation was allowed to unfold.

The A/C left 1700 ft 2 NM before the G/S intercept point and dived with 2700 fpm. Eventually becoming stabilized with -2000 fpm' for 40 seconds until approx 400 ft AGL. Then an adjustment was made reducing to -300 fpm for another 40 seconds, still descending to surface.

Apart from the preparation, assessment and mitigation that śhould have been in place, a completely different toolbox of skills was not present to stop the developing situation. If the report and corrective actions are only limited to what you describe - stage 1 - of what happened, it would be a very sad state of affairs. A missed opportunity as well, let's wait and see.

I hadn't seen this. No approach has such high descent segment and that itself is an indicator that something is wrong and immediately it should have been stopped. Shudder to think if GPWS was U/S.

LOL... All these excuses, always excuses. No one is flying the aircraft anymore and using their common sense... If I'm flying an aircraft at 1700' AGL and the machine decides on its own to leave that altitude 2.0 nm before the G/S intercept point and starts a 2700 feet per minute descent then it's time for some "real" pilot thinking and action… Like I said before... Click, click... Autopilot "OFF" fly manually!

Too many idiots flying aircrafts these days.

I wouldn't call them idiots, they're only inept and incapable.
Idiots, and i am staying politically correct because privately i use more stringent terms, are the regulators giving them a licence and airline managers giving them a seat.

I'll go along with that!:ok: