Qantas emergency landing
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Originally Posted by Litebulbs
CJ,
Two absolutely excellent posts.
Bulbs
Two absolutely excellent posts.
Bulbs
I'm just trying to plug in some figures, so at least we know what we're talking about.
In this case, a remote-probability ADIRU or AoA sensor failure looks more likely than an equally remote-probability ADIRU or AoA sensor failure PLUS electromagnetic interference from a nearby VLF facility at a negligeable power level.
If you get my drift?
CJ
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Thank you very much for the numbers. The "facility" has been there for many many years, and I have PAXed over it many many times on my way between Perth and the Pilbara. Nary a twitch in the BAE 146.
Elsewhere I've given up on conspiracy theorists. The 9/11 conspiracy inverted triangle relies entirely on the twin towers being "aircraft-proof". So far, no-one has been able to provide specific information about the particular "aircraft-proof" engineering details. That doesn't stop the chatter. The stupid being lead by the wilfully ignorant...
Elsewhere I've given up on conspiracy theorists. The 9/11 conspiracy inverted triangle relies entirely on the twin towers being "aircraft-proof". So far, no-one has been able to provide specific information about the particular "aircraft-proof" engineering details. That doesn't stop the chatter. The stupid being lead by the wilfully ignorant...
Thanks Christian,
Just the laymen's explanation I was hoping for.
It's been commented that aircraft have been passing the facility for years; but we don't know how often the transmissions take place, nor their duration, nor if there might be protocols to avoid them when aircraft are expected. If your figures are of the right order of magnitude, however, further discussion of VLF signal dissipation by Faraday cage and skin effects would seem to be academic.
As for any concentration of transmitter energy by a directional effect, I agree (in the apparent absence of any antenna experts on PPRuNe) that the array would appear to be incapable of anything in the vertical plane. Also, any intentional concentration would presumably be directed horizontally, to increase the power of the ground wave towards a nautical target receiver. Hardly like Fylingdales...
[Re your Concorde HF Tx problem, the autopilot of one of our DC10s suffered something similar for weeks before anything was done about it. Rather annoying, having to remember to disconnect it before transmitting.]
Don't suppose Qantas was working HF?
Chris
Just the laymen's explanation I was hoping for.
It's been commented that aircraft have been passing the facility for years; but we don't know how often the transmissions take place, nor their duration, nor if there might be protocols to avoid them when aircraft are expected. If your figures are of the right order of magnitude, however, further discussion of VLF signal dissipation by Faraday cage and skin effects would seem to be academic.
As for any concentration of transmitter energy by a directional effect, I agree (in the apparent absence of any antenna experts on PPRuNe) that the array would appear to be incapable of anything in the vertical plane. Also, any intentional concentration would presumably be directed horizontally, to increase the power of the ground wave towards a nautical target receiver. Hardly like Fylingdales...
[Re your Concorde HF Tx problem, the autopilot of one of our DC10s suffered something similar for weeks before anything was done about it. Rather annoying, having to remember to disconnect it before transmitting.]
Don't suppose Qantas was working HF?
Chris
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Chris,
I also just noticed that apart from the frequency/wavelength, the whole installation is pretty much like a longwave broadcasting station. Those use much the same transmitter power, between 0.5 MW and 2 MW, mostly. The wavelength is about 10 times less, e.g., BBC longwave operates on 1500 metres.
Now I have no recollection of airliners bouncing all over the sky all over Europe when passing over a longwave transmitter (and there are a fair number).
I think we can lay this one to rest......
I also just noticed that apart from the frequency/wavelength, the whole installation is pretty much like a longwave broadcasting station. Those use much the same transmitter power, between 0.5 MW and 2 MW, mostly. The wavelength is about 10 times less, e.g., BBC longwave operates on 1500 metres.
Now I have no recollection of airliners bouncing all over the sky all over Europe when passing over a longwave transmitter (and there are a fair number).
I think we can lay this one to rest......
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Another Qantas emergency on 26th October?
Anyone hear about another Qantas emergency?
Something along the lines of....
Rumor STARTS
On Sunday 26th October 2008 around 6pm Singapore time a Qantas flight had an emergency landing at Changi(SIN) airport.
Fire trucks were deployed and one of its runways was closed to facilitate this.
Aircraft was towed to gate and SLF departed.
Rumor ENDS
Something along the lines of....
Rumor STARTS
On Sunday 26th October 2008 around 6pm Singapore time a Qantas flight had an emergency landing at Changi(SIN) airport.
Fire trucks were deployed and one of its runways was closed to facilitate this.
Aircraft was towed to gate and SLF departed.
Rumor ENDS
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FFS....
Facts: Aircraft blew a tyre during departure FRA. No indications of any other damage. Upon arrival it turned out that a gear sensor had been taken out by the tyre, so crew got GEAR UNSAFE message when selecting Dunlops down. They went around, ran the C/L from the QRH, came back and landed safely. No drama. End of facts.
Like it's never, ever, happened before to any other airline or aircraft....
Nothing to see here.
Facts: Aircraft blew a tyre during departure FRA. No indications of any other damage. Upon arrival it turned out that a gear sensor had been taken out by the tyre, so crew got GEAR UNSAFE message when selecting Dunlops down. They went around, ran the C/L from the QRH, came back and landed safely. No drama. End of facts.
Like it's never, ever, happened before to any other airline or aircraft....
Nothing to see here.
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Hi
I also just noticed that apart from the frequency/wavelength, the whole installation is pretty much like a longwave broadcasting station. I love this forum and thanks for this.
========================================
Arnold
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Arnold
The Reverend
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The LA to SYD flight is a new low.
Quote from Arnold123:
I also just noticed that apart from the frequency/wavelength, the whole installation is pretty much like a longwave broadcasting station.
[Unquote]
Welcome! Yes, they're an endangered species over here, unfortunately. The old BBC transmitter at Droitwich that Christian refers to, currently broadcasting Radio4LW on 198 kHz (used to be on 200kHz, until rationalised to a multiple of 3 by some convention), is a valuable nav-aid for all sorts of purposes. Powerful and reliable for off-airways flying in Britain, and – if you have a suitable receiver – a good way of finding north (as well as monitoring the Test-Match) when you are travelling in the south of France... No doubt fishermen 500 miles off shore still use it for navigation if their GPS goes on the blink, as well as for receiving the shipping weather-forecasts.
All analogue broadcasting is being phased out in the UK in the next few years, and shutting down Droitwich will save the BBC, admittedly, a great deal of money. But it'll be a sad day, particularly for those of us who are still fascinated by long-distance radio transmissions.
The Droitwich antenna array masts go up to about 700ft agl, but – as far as I know – there are still no special flying restrictions. As Christian says, aircraft are not generally known to suffer RFI effects in their vicinity, even at low level.
I also just noticed that apart from the frequency/wavelength, the whole installation is pretty much like a longwave broadcasting station.
[Unquote]
Welcome! Yes, they're an endangered species over here, unfortunately. The old BBC transmitter at Droitwich that Christian refers to, currently broadcasting Radio4LW on 198 kHz (used to be on 200kHz, until rationalised to a multiple of 3 by some convention), is a valuable nav-aid for all sorts of purposes. Powerful and reliable for off-airways flying in Britain, and – if you have a suitable receiver – a good way of finding north (as well as monitoring the Test-Match) when you are travelling in the south of France... No doubt fishermen 500 miles off shore still use it for navigation if their GPS goes on the blink, as well as for receiving the shipping weather-forecasts.
All analogue broadcasting is being phased out in the UK in the next few years, and shutting down Droitwich will save the BBC, admittedly, a great deal of money. But it'll be a sad day, particularly for those of us who are still fascinated by long-distance radio transmissions.
The Droitwich antenna array masts go up to about 700ft agl, but – as far as I know – there are still no special flying restrictions. As Christian says, aircraft are not generally known to suffer RFI effects in their vicinity, even at low level.
Last edited by Chris Scott; 29th Oct 2008 at 13:13.
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reply to chris
Thanks for that CJ, I think you (and I ) have done it to death.
The point is, even in the remotest chance that the tx had anything to do with this incident (I'll do a nude run down any main street you can name if it is proven) it would still be a fault with the aircraft/component by way of shielding, bonding or filtering.Aircraft are bombarded by a multitude of RF signals from within and out and are built with that in mind.
Over and out.
The point is, even in the remotest chance that the tx had anything to do with this incident (I'll do a nude run down any main street you can name if it is proven) it would still be a fault with the aircraft/component by way of shielding, bonding or filtering.Aircraft are bombarded by a multitude of RF signals from within and out and are built with that in mind.
Over and out.
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The LA to SYD flight is a new low.
The reliability of new generation weather radar antennae is outstanding. I used to have to replace faulty ones every second month. Now I hardly ever hear of a failure... but it's still not what one would call "newsworthy".
Today's Australian Daily Telegraph article on this referred back to the Airbus incident, claiming that it suddenly dropped 2000 meters (even after the DFDR data had been released to the public). According to this particular newspaper, Qantas is now responsible for manufacturer faults. Huh?
Also reported was the fact that the aircraft arrived four hours late... which is probably about six hours sooner than it would if it had turned back to LAX.
The crew showed some initiative, but it's not like it's never been done before.
The expression "flying blind" has been bandied about.... as if the pilots could lose their way, flying in cloud
Maybe they haven't heard of IRS, GPS, Satcom weather reports, TCAS....Another slow news day....
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Although manual control was resumed after "a few seconds", it seems that upon encountering the sudden uncommanded pitch down the PIC's instant first (and natural) response was to pull back on the stick - all the way back... which the aircraft ignored! This may be the "airbus way" but it would be a very unnerving experience for any pilot.
Further to ChristianJ's calculations, actually radiating 1MW at 19.8kHz is pretty difficult. Antenna efficiencies are going to be low, especially as the highest tower is of the order of 0.025 wavelengths. This means a very low feed impedance and doubtless a high reactance, so the losses in the matching will be pretty enormous. To actually radiate 1MW will probably need something of the order of 50MW of RF out of the transmitter. Not impossible, but you need your own power station!
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Originally Posted by awqward
This may be the "airbus way" but it would be a very unnerving experience for any pilot
Helpless feeling ... What's coming next ???
For sure that crew was only relieved once on the ground, and maybe not so keen to go back in their once beloved 330 ... ?
Originally Posted by Yamagata ken
The 9/11 conspiracy inverted triangle relies entirely on the twin towers being "aircraft-proof"
Electro Magnetic Interference
I think the possibility of EMI being involved in this (and/or other incidents) is being too easily dismissed by some. (And NO, I am not saying that I'm sure this is the case here!)
Though the math is no doubt correct (I'm definitely not qualified to question it) on the posts relating to propagation, I think there is some confusion between carrier frequencies and RF energy itself. For instance ELF (extra low frequency) is tricky stuff and as I'm sure some ppruners are aware it can be used it as a weapon. The principal is the same as an EMP burst, as ELF can generate high intensity EM field and unfortunately any "electronics" can be susceptible -- especially gyro-based computer components. Previous comments about higher frequency RF are in principal correct, but there is also reason to discount the notion that whatever transmitter(s) may be involved, they would be directed at the surface, as opposed to the ionosphere.
Lots of sources of interesting info out there, but for many, this might be an interesting start: High Frequency Active Auroral Research Program - Wikipedia, the free encyclopedia
Grizz
Though the math is no doubt correct (I'm definitely not qualified to question it) on the posts relating to propagation, I think there is some confusion between carrier frequencies and RF energy itself. For instance ELF (extra low frequency) is tricky stuff and as I'm sure some ppruners are aware it can be used it as a weapon. The principal is the same as an EMP burst, as ELF can generate high intensity EM field and unfortunately any "electronics" can be susceptible -- especially gyro-based computer components. Previous comments about higher frequency RF are in principal correct, but there is also reason to discount the notion that whatever transmitter(s) may be involved, they would be directed at the surface, as opposed to the ionosphere.
Lots of sources of interesting info out there, but for many, this might be an interesting start: High Frequency Active Auroral Research Program - Wikipedia, the free encyclopedia
Grizz
"Naval base transmissions may have led to Qantas jet plunge"
From the Melbourne 'Age' newspaper - Naval base signals may have led to Qantas jet plunge | theage.com.au
Naval base transmissions may have led to Qantas jet plunge
Kerryn Macaulay, of the Air Transport Safety Bureau, said yesterday it was considered unlikely that a low frequency transmission from the Harold E. Holt transmitter near Exmouth could have caused the problem but that possibility was still being investigated.
She said it was also possible that an electronic device being used by a passenger might have interfered with the aircraft's computer system.
Ms Macaulay said examination of information from the aircraft's flight data recorder indicated that at the time the aircraft's autopilot was disconnected.
- Brendan Nicholson
- November 14, 2008 - 10:46AM
Kerryn Macaulay, of the Air Transport Safety Bureau, said yesterday it was considered unlikely that a low frequency transmission from the Harold E. Holt transmitter near Exmouth could have caused the problem but that possibility was still being investigated.
She said it was also possible that an electronic device being used by a passenger might have interfered with the aircraft's computer system.
Ms Macaulay said examination of information from the aircraft's flight data recorder indicated that at the time the aircraft's autopilot was disconnected.