Could the Americans switch off GPS ?

[Hamma]

Are you saying that during a global GPS outage that planes would be forbidden from landing rather than allow pilots to take control like in the good old days? Seems rather pointless making sure a pilot can land a plane manually during training if that's the case...

I'm pretty sure I've misread something here. Planes fly all the time on cloudy days and always have done even before GPS. Clouds are quite high (I'm not a pilot...) so surely when below the cloud the pilot just looks for the runway and asks over the radio which direction to approach from then aims for it using instruments for altitude and direction etc?

You have completely misunderstood what Buck Turgidson is talking about. You also appear to assume that pilots do not ordinarily land aircraft. In fact that is the opposite of the truth- computers do not ordinarily land aircraft, not even the Airbus.

Buck Turgidson is saying that the approaches in certain wilder parts of North America are no longer predicated on ground-based aids, as they once were. In the days when your pilots of old were making landings they were flying no differently from the way that pilots manually fly approaches now, but the guidance they receive no longer comes from equipment transmitting from the ground, but instead from GNSS.

I'm sure you mean no ill but pilots get pretty fed-up with the certain "belief" that some passengers have that flying a modern aircraft is a question of switching on a computer. You seem to know something about computers. I got an O level in computers at school does that make me an expert in your field?

Autolands are so rare that crews actually practice them and they require more work and a higher level of attentiveness and procedural accuracy than a manual landing.

How about giving a little credit to the professionalism of the people who convey you so safely and cheaply to your destination, rather than repeating this ill-informed and demeaning cliche about our profession?

 

[Buck Turgidson]

ILS, GCA or internal aids could all be used in IMC conditions. Could increase break-off heights unless the aircraft had auto land. Finally, don't understate visual approaches, in many places because of a good weather factor they are the norm & can really shorten the approach for even big aircraft & thereby increase airfield utilization.

Quickest way to get back on the ground - ask any fighter pilot!

I'm quite familiar with a good old fashioned "run and break" but you need to be able to see the ground to do it

 

[nortada]

I'm quite familiar with a good old fashioned "run and break" but you need to be able to see the ground to do it

Too true!

 

[richardbayle]

Too true!

If there is a global conflict on the scale you lot believe is neccessary to 'turn off' GPS who will give a **** where they are? You certainly wont be wandering about sailing or flying or perhaps even driving for pleasure. We will all be hiding under our kitchen tables waiting for the flash!

It really is hilarious to think people are concerned that when two superpowers start talking about lobbing thermonuclear devices around the globe, or an alien life form has invaded earth or some other box office megacatastrophe has occurred you lot are worrying about finding your way to a mooring in the dark after a pleasant days sailing!

Go back to the pub and worry about something realistic for pitys sake!

+1

 

[savageseadog]

Wow, what a load of *******s there is in this thread!

Gps III satellites are not even fitted with selective availability capability so how can you turn on something that is not there?

An act of congress specifically prohibits anyone from 'turning off' gps.

Do people really think that the US military relies solely on GPS to the extent that they would even consider turning it off. It would be a pretty thick military that made a navigation system freely available and then relied on it completely!

The service is under the JOINT control of the National Executive Committee for Space-Based Positioning, Navigation, and Timing and is not solely controlled by the military.

And the biggie ............

If there is a global conflict on the scale you lot believe is neccessary to 'turn off' GPS who will give a **** where they are? You certainly wont be wandering about sailing or flying or perhaps even driving for pleasure. We will all be hiding under our kitchen tables waiting for the flash!

It really is hilarious to think people are concerned that when two superpowers start talking about lobbing thermonuclear devices around the globe, or an alien life form has invaded earth or some other box office megacatastrophe has occurred you lot are worrying about finding your way to a mooring in the dark after a pleasant days sailing!

Go back to the pub and worry about something realistic for pitys sake!

You can be absolutely sure that there will be contingency plans for switching off, degrading or jamming GPS, Glonnass and Galileo however unlikely it is that it will be needed.

 

[nortada]

You can be absolutely sure that there will be contingency plans for switching off, degrading or jamming GPS, Glonnass and Galileo however unlikely it is that it will be needed.

An exothermic nuclear explosion would make the GPS satellites eyes water but still don't think it will happen - pain is greater than the gain.

Worry about it? Never, just a point to debate.

 

[Malabar]

The Russians have beaten Europe in the race to provide the alternative GMDSS (Glonass) China and India also have systems coming on line fast. Don't start me off on Galilleo . Precise timing is arguably as important as precise positioning. AIS for one thing depends on satnav timing. Fortunately E Loran - rugged and terrestial based- also has a precise timing component.

 

[lustyd]

You have completely misunderstood what Buck Turgidson is talking about. You also appear to assume that pilots do not ordinarily land aircraft. In fact that is the opposite of the truth- computers do not ordinarily land aircraft, not even the Airbus.

Buck Turgidson is saying that the approaches in certain wilder parts of North America are no longer predicated on ground-based aids, as they once were. In the days when your pilots of old were making landings they were flying no differently from the way that pilots manually fly approaches now, but the guidance they receive no longer comes from equipment transmitting from the ground, but instead from GNSS.

I'm sure you mean no ill but pilots get pretty fed-up with the certain "belief" that some passengers have that flying a modern aircraft is a question of switching on a computer. You seem to know something about computers. I got an O level in computers at school does that make me an expert in your field?

Autolands are so rare that crews actually practice them and they require more work and a higher level of attentiveness and procedural accuracy than a manual landing.

How about giving a little credit to the professionalism of the people who convey you so safely and cheaply to your destination, rather than repeating this ill-informed and demeaning cliche about our profession?

Um no. I was actually confused at his saying that pilots would not be allowed to land planes any more. There was no double meaning to my post, I literally meant what I wrote!

 

[toad_oftoadhall]

Wow, what a load of *******s there is in this thread!

Gps III satellites are not even fitted with selective availability capability so how can you turn on something that is not there?

An act of congress specifically prohibits anyone from 'turning off' gps.

Do people really think that the US military relies solely on GPS to the extent that they would even consider turning it off. It would be a pretty thick military that made a navigation system freely available and then relied on it completely!

The service is under the JOINT control of the National Executive Committee for Space-Based Positioning, Navigation, and Timing and is not solely controlled by the military.

And the biggie ............

If there is a global conflict on the scale you lot believe is neccessary to 'turn off' GPS who will give a **** where they are? You certainly wont be wandering about sailing or flying or perhaps even driving for pleasure. We will all be hiding under our kitchen tables waiting for the flash!

It really is hilarious to think people are concerned that when two superpowers start talking about lobbing thermonuclear devices around the globe, or an alien life form has invaded earth or some other box office megacatastrophe has occurred you lot are worrying about finding your way to a mooring in the dark after a pleasant days sailing!

Go back to the pub and worry about something realistic for pitys sake!

And the crowd go wild. Wonderful post, thanks.

I've always chuckled at the idea that there really are people who are genuinely fearing for nuclear Armageddon/alien attack causing GPS to be disabled. Yet, their ONLY concern about a global disaster is that in the post apocalyptic aftermath they won't be able to go on holiday in a small boat with a needlessly accurate method of getting a position!

I suppose they're some logic to it. In the post nuclear wasteland it would be a good plan to sail round to Cornwall or Norfolk where a few mutations will pass as normal.

 

[Beadle]

Not that can be timed accurately.... atomic clocks are great.... but are on the network, with therefore unreliable certainty over latency.... only any use if they are local... and too many aren't, so would cause an avalanche of outages that would eventually take everything down... very few telcos for example now have their own clocks, so all bandwidth (inc telehouses with core traffic switching) would probably fall over fairly quickly.

Well I must say that I'm incredibly disappointed to learn that multi-billion pound (and dollar) telcos will rely entirely and totally on a single timing source from atomic clocks in satellites belonging to another country and vulnerable to a whole range of unpredictable mishaps without having a reliable back-up that will allow their networks to continue to generate the millions of pounds a day that they stand to lose.

 

[Phoenix of Hamble]

Well I must say that I'm incredibly disappointed to learn that multi-billion pound (and dollar) telcos will rely entirely and totally on a single timing source from atomic clocks in satellites belonging to another country and vulnerable to a whole range of unpredictable mishaps without having a reliable back-up that will allow their networks to continue to generate the millions of pounds a day that they stand to lose.

You'll also be disappointed to discover that Google's entire (in house developed) NoSQL equivalent, upon which a lot of their infrastructure now runs is entirely synched by GPS too then.......

Its not as clear cut as people would like to make out.... there is now so much interdependency between the big players on the network, that only a few having major problems could cause a significant effect on many others.... its OK saying that switches can handle poor clocks... but not when it gets to core switching between different AS environments, when speeds and volumes, and hence timing become a much bigger issue.... and a lot of the big players are not only massive content and service providers, but also key parts of the core switching network...

So, yes, a few global telcos do still maintain their own timing services, but a lot of mid tier telcos and service providers don't.... and they are just as critical to a balanced service nowadays.

 

[Beadle]

I didn't say that switches can handle bad clocks.

And timing problems have always been a big issue - in a past life I used to take on problems on synchronous networks using BT Kilostream and Megastream.

Even in those very early days there were multiple sources of timing - all to the 1 in 10 to the awful lot (can't remember the number).

It isn't so much the accuracy I was referring to, it is the diversity of having a number of independent sources so that if one or two fail there are enough left to maintain synch.

I don't really see why an atomic clock in a satellite is somehow better than one in a controlled environment on earth.

 

[Phoenix of Hamble]

I don't really see why an atomic clock in a satellite is somehow better than one in a controlled environment on earth.

It isn't. But the reality is that there aren't enough locations that can take a signal from a timing clock in a terrestrial location with certainty over latency, whereas many locations have a simple GPS receiver. Google, as above, found this out when development distributed data processing systems failed due to timing issues, and hence moved to GPS and solved their problems.

 

[boomerangben]

As a fully qualified instrument rated pilot flying an all weather aircraft, I am not permitted to use GPS as an approach aid and as far as I know there are no airports in the UK that have approved GPS approaches. GPS is a great aid to navigation but it is not a prerequisite for being able to land in poor weather.

 

[boomerangben]

Just checked and there are GNSS approaches at some of the London airports but they won't get you as close to the ground as land based nav aids. Give me an ILS any day.

 

[elton]

Doesn't anybody still rely upon MSF time?

 

[Beadle]

I suspect this is an issue that has cropped up since I moved away from technical stuff - my experience was 1980s when giga bits and terra bits were something to dream about, at least over long distance networks.

Lots of the stuff I worked on was still routed on copper pairs

Our biggest issue used to be earthing problems causing noise - I guess that's something optical stuff doesn't suffer from

Interesting chat

Brought back old times

Cheers

 

[Buck Turgidson]

Just checked and there are GNSS approaches at some of the London airports but they won't get you as close to the ground as land based nav aids. Give me an ILS any day.

Take a look at slide 15: http://www.transportstyrelsen.se/Global/Luftfart/Flygplatser/LPV_Implementation_in_UK.pdf

and AMC3 CAT.OP.MPA.110 Aerodrome operating minima:

Table 3: System minima
Facility
Lowest DH/MDH (ft)
ILS/MLS/GLS
200
GNSS/SBAS (LPV)
200
GNSS (LNAV)
250
GNSS/Baro-VNAV (LNAV/ VNAV)
250

LPV can have the same minima as a CAT I ILS.

But this is aviation stuff not nautical so I'll leave it there.

 

[Uricanejack]

They would need some serious justification to ground the world's commercial airline fleet and dock the world's merchant navy...

Niether of these would happen. They just would have to go back to previous systems which they still have as backup.
GPS is just one aid to navigation. The pros do not rely on GPS alone.
Would they? for a good reson. War? its their system
They don't want the bad guys to use their system to home in on their boy's.

If they do it will be only in the conflict area.
I'm not worried. I will just use my back ups.

 

[Sybarite]

Nasa have just indicated that there is intense electromagnetic activity related to a "hole" in the sun's corona. They anticipate problems with GPS signals and G4 reception over the next two months.


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