GPS Jammers

[harvyk]

Just read on nonews this story...

Internet jammer can be bought for $55, can bring down plane, say experts | News.com.au

My personal belief is that this story is total BS, as whilst yes quite a few planes use GPS, they also use alternate navigation systems (IRS \ INS) to navigate, and thus a loss of GPS would not cause a major problem.

Any of our pilot friends care to comment? Am I right in thinking the majority of planes could lose access to the GPS signel and yet still be ok?

 

[markis10]

Not BS when you are located near the antenna in a car for the GPS, different story for an aircraft. plenty of backup systems regardless, DME, NDB etc. Oh, and there are star shots when you are really in trouble!

 

[harvyk]

Obviously where your using only GPS, such as in a car, then yes... But me thinks that a would be terrorist will be very disappointed when they try to take down a plane using one...

 

[Aussie_flyer]

Yes it seems BS. If the GPS signal is lost, there are other ways to navigate, first is the IRS which a lot of aircraft use as the primary and only system (GPS wasn't always around obviously). If the aircraft is over or near to land then there are the radio signals like VOR and NDB. There is also radar navigation by air traffic control if within radar area, and then of course good old VISUAL REFERENCE and the stars....

 

[markis10]

Considering the terrorist is inside a faraday cage and the GPS antennas are in different positions outside that cage, he/she has no chance.

Might stop those from using their notebook GPS's because they are bored cough cough

 

[markis10]

Yes it seems BS. If the GPS signal is lost, there are other ways to navigate, first is the IRS which a lot of aircraft use as the primary and only system (GPS wasn't always around obviously). If the aircraft is over or near to land then there are the radio signals like VOR and NDB. There is also radar navigation by air traffic control if within radar area, and then of course good old VISUAL REFERENCE and the stars....

The last airliner in Australia to use IRS as its primary navigation was the Ansett 767-200s, since then airliners have used GPS as part of the Air Data Inertial Reference System for navigation which uses multiple sensors including the pitot system as well as radio navigation aids to present an accurate position indication to the pilots, a cobination of dead reckoning, terristial and satellite based technologies. The space shuttle still uses IRS, for obvious reasons, the lat and long of each airport gate was displayed so that pilots could give the system a starting point that was accurate when IRS was the primary navigation aid.

 

[Aussie_flyer]

The last airliner in Australia to use IRS as its primary navigation was the Ansett 767-200s, since then airliners have used GPS as part of the Air Data Inertial Reference System for navigation which uses multiple sensors including the pitot system as well as radio navigation aids to present an accurate position indication to the pilots, a cobination of dead reckoning, terristial and satellite based technologies. The space shuttle still uses IRS, for obvious reasons, the lat and long of each airport gate was displayed so that pilots could give the system a starting point that was accurate when IRS was the primary navigation aid.

Thanks for the info markis10. I miss Ansett 762s! Anyway, should the GPS signal be lost mid-flight would the IRS part of ADIRS still be able to keep the current position up to date, even if out of range of land based navaids?

 

[markis10]

Thanks for the info markis10. I miss Ansett 762s! Anyway, should the GPS signal be lost mid-flight would the IRS part of ADIRS still be able to keep the current position up to date, even if out of range of land based navaids?

Yes the aircrafts position would still be displayed however at an increasing error rate/tolerance, given that it would be based on essentially dead reckoning, bit like some GPS's when you are in a tunnel.

Pilots get an error message and the system provides an estimation of the tolerance they have to now work with as shown in the picture for an A330, GPS loss on an RNP approach is an automatic abort.

 

[medhead]

I read the headline for this on iphone and recalled reading something about GPS jammers being used to bring down the various cruise missles. That made me think that the reporter had probably not done their research very well and had made a jump from cruise missle to aircraft. Now that I'm on a computer and reading the article i see a clear reference to military operations. I dare say that this is where these devices would be most useful, there is no one on a cruise missle doing star sightings

Experts say it's only a matter of time until terrorists in the United States catch on and use them to disrupt GPS reception on aeroplanes or in military operations.

The risk may be low for aeroplanes, which use ground-based radars for guidance and have a back-up navigation system that does not depend on satellites


But GPS jamming could nonetheless cause confusion in the coughpit as pilots have to switch to back up navigation systems. And maritime shipments that rely on GPS coordinates for finding port locations could face problems as well.

I also note that the article clearly states that it is a low risk. (I'd lead towards very, very, very low risk)

The maritime disruption is a good idea, but I'm not sure how effective it would be, imagine the situation - "Our GPS is stuffed, we're in the middle of the ocean and that bearded passenger we picked up at the last port is carrying around a small black box." :shock:

Surely the holes (windows) are too big in an aircraft fuselage for it to be an effective faraday cage?

 

[markis10]

The maritime disruption is a good idea, but I'm not sure how effective it would be, imagine the situation - "Our GPS is stuffed, we're in the middle of the ocean and that bearded passenger we picked up at the last port is carrying around a small black box." :shock:

Surely the holes (windows) are too big in an aircraft fuselage for it to be an effective faraday cage?

GPS antennas are usually mounted on the highest part of the superstructure or radio mast above radars etc, with their receive elements facing to the sky, not to where the pax are, the little black box would in fact need a very large power supply to have an EIRP that would cause interference let alone take out a GPS receiver, and usually like aircraft there are more than one receiver/antenna being used.

As for the windows negating the faraday cage, a faraday cage is not a solid object but can be a mesh, its in fact the faraday cage that is formed by the fuselage that provides the pax inside with protection from a lightning strike.

 

[v8Statesman]

Considering the terrorist is inside a faraday cage and the GPS antennas are in different positions outside that cage, he/she has no chance.

Might stop those from using their notebook GPS's because they are bored cough cough


View attachment 678

BNE-CBR??? or vv???

Maps

 

[markis10]

DRW-SYD three weeks ago on the 2.30PM

 

[jb747]

....and there are star shots when you are really in trouble!

Jeez, how old are you?

Loss of GPS would be little more than a comment over the coffee. Navigation accuracy is perfectly acceptable with INS/FMS system.

For what it's worth, only 3 of the QF 767s have GPS incorporated into the nav systems. And when it first arrived, the 747-400 didn't have it either.

 

[markis10]

Jeez, how old are you?

Long enough to know why the RAAF HS748's had a bubble window 2 down on the port side, and they were introduced the year after I was born .

 

[jb747]

Not that old then. The RAAF 748....I've got hours in them, from the RAN Observers course. No GPS there either.

 

[medhead]

GPS antennas are usually mounted on the highest part of the superstructure or radio mast above radars etc, with their receive elements facing to the sky, not to where the pax are, the little black box would in fact need a very large power supply to have an EIRP that would cause interference let alone take out a GPS receiver, and usually like aircraft there are more than one receiver/antenna being used.

I was thinking more aboutfreight maritime operations, which often will also take a couple of pax and running that supertanker aground is going to be much worst in terms of outrage than a passenger ship. Evidence Exxon Valdez, which constantly gets mentioned, versus all the passenger ferry sinkings that no one remembers.
I should have been more clear.

The other point that makes attacking ships in this way kinda pointless is that we have known how to do longitude for a little while now . But of course all the ship wrecks along the great ocean road highlight the difficulty of old navigation, in ships.

As for the windows negating the faraday cage, a faraday cage is not a solid object but can be a mesh, its in fact the faraday cage that is formed by the fuselage that provides the pax inside with protection from a lightning strike.

A dare say that lightning is vastly different to RF waves. The key requirement for a faraday cage to work is that the openings have to be smaller that the wavelength of whatever they are blocking. The openings in mesh are that small. The windows in a fuselage are not that small.