View Full Version : GPS disruption

Timmy Tomkins
1st Nov 2020, 15:23
Fortune magazine reporting concerns over GPS disruption over the Med and other places in the Middle East


Has anyone experienced this? Possibly Vlad being naughty, as it seems to originate in Syria

tubby linton
1st Nov 2020, 15:34
I believe one operator had an aircraft that had a gpws event because of a map shift caused by gps interference moved their computed position from the coast into the middle of a mountain range.
Airbus have produced the following briefing note-

1st Nov 2020, 16:31
I have seen this several times. The first I recall was in the cruise near Pula during the problems in the Balkans circa 1993. The track/groundspeed suddenly increased illogically and the position went to the Azores then it failed. It came back of it's own accord about 50nm later.

The second occasion was landing in Cairo around 2015. At that time they only had LLZ approach available so being lazy we elected to fly an RNAV. Around 1500' one GPS failed quickly followed by the other with 'UNABLE RNP' warning. Thankfully we were able to continue to land visually. I recall it happened two or three times before the fleet got the message... It was probably coming from a military facility nearby who did not want to invite GPS guided cruise missiles.

Much more recently every trip to the Gulf (from London) has had disturbance or complete loss of GPS in south-eastern Turkey over their Syria/Iraq border. On a couple of trips to DXB both GPS went off and never came back until after landing in DXB. I would suspect the Turks are protecting their interests!

1st Nov 2020, 17:39
Yep, two or three times over the last few years, north eastern med or over eastern Turkey..and it happened to several of my colleagues as well.

The symptoms I saw weren't quite as dramatic as those seen by magplug, If I remember correctly the first clue (Boeing) was usually the ND displaying "inertial", then several seconds/minute or so later the "Unable RNP" msg coming up..and all resolved quite simply by ensuring DME/DME updating was available...

Not a big deal if going back to north west europe because you'd usually get valid GPS updating back once you were out of the area but if you were going the other way and it happened shortly before descent into one of the nearby airports who were offering RNP approaches it meant a quick replan/rebrief.

1st Nov 2020, 19:26
From Cyprus eastward and descending into Beirut is nearly always the case. Is it Syria, Vlad or whoever? On Boeings itís not that much of a problem especially if briefed according to notams (at least company notams).

Pugilistic Animus
1st Nov 2020, 19:28
Selective availability? I thought that policy was discontinued.

kungfu panda
1st Nov 2020, 19:50
Areas of the middle East are being protected. It's happening all of the time. Presumably the concern is Iranian or Iranian backed militia firing against US allies.

Easy Street
1st Nov 2020, 19:56
Selective availability? I thought that policy was discontinued.

This is probably not the US trying to degrade precision; itís much more likely to be certain regional actors protecting themselves using GPS jammers like this (https://www.armyrecognition.com/russia_russian_missile_system_vehicle_uk/r-330zh_zhitel_jamming_cellular_satellite_communication_statio n_technical_data_sheet_pictures_video.amp.html) which are an effective defence against commercially-available drones. Because the signal:noise ratio of GPS is so low, one jammer can disrupt civil GPS reception across a wide area. Military grade receivers use encryption, multiple frequencies and wider bandwidth to reduce susceptibility to jamming.

1st Nov 2020, 21:21
Nearly always the case near Cyprus or Tel Aviv. It's a fact of life there; you cannot rely on GPS reception. Sometimes it works, most times it doesn't.
Back to the old DME-DME updates.

ATC Watcher
2nd Nov 2020, 10:15
Yes , we all have a tendency to forget that GPS belongs to the US military, it is still used for military operations, and it is extremely easy to jam ( very low output signal) ,
For those of you flying in airports in mountainous areas , remember that not only you lose RNP but also EGPWS . Not a good combination ..

2nd Nov 2020, 15:40
Even potentially worse is deliberate GPS spoofing. One demo of it on a boat moored in an Italian hrbour had the boat proceeding at 900knots south east to Libya, 60 metres UNDERNEATH Italy! There was an article on the subject some time back in the IEEE Spectrum magazine. I did read somewhere that some US Navy captains are making their officers refresh their classical navigation techniques with sun and star sights....

ATC Watcher
2nd Nov 2020, 16:37
While jamming is today for everybody ( jammers for sale as low as 150 USD on internet ) spoofing is more complex and far more expensive and normally done by a State ,e.g. the Russian military. You find it today commonly around military exercises and conflict areas. e.g. Syria, Libya , Baltic. Black sea .etc.. Brings back the old question of what civilian commercial traffic is doing flying close or over those areas but this is another subject.

2nd Nov 2020, 17:39
ATC #10,
EGPWS is more likely to be available depending on aircraft configuration and alternate navigation inputs.
If not then the basic GPWS should remain active with Rad Alt input; again depending on aircraft systems and switching.

2nd Nov 2020, 21:08
There was a good article on the topic here (https://www.linkedin.com/pulse/gps-jamming-biggest-aviation-threat-2018-dean-constantinidis/) I saw recently.

3rd Nov 2020, 00:57
From Cyprus eastward and descending into Beirut is nearly always the case. Is it Syria, Vlad or whoever? On Boeings it’s not that much of a problem especially if briefed according to notams (at least company notams).
Had it pretty much every time into Cyprus over the last two years. We get GPS Fault (1+2) which comes and goes. Also we get ADS-B Out Fault, though perhaps that is to do with the GPS source failing, or maybe the ADS-B Frequency is similar to that of GPS and is jammed in the same jamming range, though I'd expect the former to be true.

Company NOTAMS mention it. Cyprus still assigns GPS RNAV arrival prodecures and I just request the (mostly) identical conventional STARS. You always get visual flying outbound so the final approach is fine and the GPS faults tend to finish below 15,000ft. I figured it was either Syria or Northern Cyprus to blame.

It's definitely worse flying to LCA rather than PFO and seems worst over the centre of the island.

3rd Nov 2020, 08:07
Well, its definitely still prevalent when flying around the Iraq/Syria/Turkey borders - had it (GPS loss) both ways in roughly the same areas, when flying that way a few weeks ago.

3rd Nov 2020, 10:36
. Brings back the old question of what civilian commercial traffic is doing flying close or over those areas but this is another subject.

Well FWIW the jamming I mentioned upthread happened (twice to me) on a track that ran from very roughly overhead Paphos northwestwards going "feet dry" well west of Antalya... how close do you define as close and how big an area do you suggest needs avoiding?

ATC Watcher
3rd Nov 2020, 12:17
Very good question, which for answering it we have to go into politics, and I am not sure how the Mods here will react .
I can try but before I do that I want to say that I am not pro one side or another, just sating the bare facts.

I take the area and flight path you described as an example . : Paphos Northwest ,,then you go into ERCAN airspace right ? well this airspace is the result on the Turkish invasion of North Cyprus in 1974 and is not recognized by the neighbors . for ICAO this is still Nicosia FIR., and for the Cypriots , and the Greeks, it is illegal occupied airspace by the Turkish air force. Flying in there , as most airlines do to fly direct to and from Larnaca , already puts you into the grey zone.
The latest military tensions between Turkey and Greece , the full stage war in Syria are making this whole area a conflict area. If you add Israeli and Russian fighters flying around fully armed flying above the Mediterranean, you will see that defining which area to avoid there becomes either very difficult or extremely clear. .
The lessons of MH 17 and Ukraine 752 should not be forgotten too easily.
.Jamming is one thing , Spoofing is far more dangerous as it could divert you to fly inside a real conflict area and you can easily become a misidentified target as you are not supposed to be there.
During the Iran-Iraq war , civil cargo lights delivering weapons to Iran were spoofed into Russian airspace to be intercepted or even shot down ( an Argentinian CL44 from Paphos to Teheran was shot down like this in 1981 over Armenia) by just imitating a VOR signal at a much higher power output than the real one .That was pre-GPS times but same results. .

4th Nov 2020, 08:19
I think many of us have negotiated "Chaos Corner" a few times over the years..:bored:

As for GPS spoofing...much talked about but how demonstrably effective is GPS spoofing at actually significantly changing an aircraft's flight path when that aircraft concerned has a nav suite that only using GPS as one of several navigational sources?

Flying Clog
4th Nov 2020, 10:04
Correct wiggy. It's not rocket surgery. We just get on with it.

8th Nov 2020, 07:09
Itís a daily way of life along the whole Eastern part of Turkey, especially near the Syrian Border.

Fuel Crossfeed
8th Nov 2020, 20:44
A frequent occurrence for the A380 around Turkey & Iraq border. Could sometimes get a locked out MMR, even though GPS primary comes back, there was no ECAM for the locked MMR. GPS would have to be reset by engineer on the ground if any GPS jamming occurred.

8th Nov 2020, 21:22
Standard Tech Log entry on certain flights from the middle east overflying Iran, Iraq, Syria etc.
"GPS Interference ".
"BITE check satis" is the usual reply. 😁

8th Nov 2020, 22:56
GPS spoofing at actually significantly changing an aircraft's flight path when The previous operator had records to show the position drift was vulgar enough to trigger EGPWS warnings on approach or take the A/C outside its RNAV arrival protected area. Significant flight path alternation followed, not to mention the paperwork needed to sort it out.

Not exactly what you asked but painful beyond acceptable already. Especially the fake EGPWS have serious consequences, no need to mention.

Max Angle
9th Nov 2020, 09:39
Several crews at our outfit have had spurious EGPWS warnings low down during approach and departure from LCA. We are allowed to turn off the enhanced function below 1000ft under certain conditions for the approach but are supposed to leave it on for take-off. Unfortunately (certainly on the Airbus) it is not possible to deselect GPS from the EGPWS in the same way you can take it out of the FMGS position calculation which is what we do as we hit that airspace.

16th Nov 2020, 15:44

As I am boating every summer around Pula, I can confirm that this area has issues with GPS signal, and is not related only to Balkan war time. There are even warnings on some nautical guidebooks about it - and it still happens. I can only confirm that the area has large military installations and big radars are visible on the far tip of peninsula (in former Yugoslavia, nearby Brioni islands were Tito`s summer residence and the place is still used as Croatian government VIP area). Interesting, my mobile phone is not affected, when I pass by - probably becouse mobile phones are using triangulation too. The same goes for Airbuses etc. Dropout of GPS signal alone should not cause position shift, as position is calculated using different sources, adding different influence to final position calculation. See your FCOM.

17th Nov 2020, 08:41
Are other satellite navigation systems (Galileo etc) similarly affected ?

17th Nov 2020, 15:44
A crude jamming system would affect them all equally.
Spoofing multiple systems to the same false location would be much more difficult.