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[Varche]

I am surprised no one has commented or about gps jamming on planes.

[STEMO]

I am surprised no one has commented or about gps jamming on planes.

Someone just has 

[Marks DTM Calib]

It wasn't jamming, it was spoofing 

[Doctor Gollum]

Flying to India there's no reliable GPS after Turkey.

Which highlights the unintended consequence of Airbus fitting a GPS based auto descend system to the A350 that descends the aircraft automatically following a decompression...

A very real possibility of hitting the mountains.

[Viral_Jim]

A very real possibility of hitting the mountains.

My understanding is this only kicks in if no pilot intervention post decompression.

It also drops the aircraft to the greater of 10,000 ft or Minimum Enroute Altitude, which is route-based and set prior to departure, so barring a system failure, or an incorrect route being set (seems unlikely as significant deviations from route would trigger alerts) then the plane won't drop itself low enough to interface with the scenery. 

I'm sure LC will be along in a minute to offer further commentary 

[Doctor Gollum]

The 350 does it automatically and they have to tell it not to. We have to allow them time to make contact because the descent itself isn't indicative that they're flying.

Everything else we operate has to be manually descended so you have to wait ~80 seconds before checking the flight crew are ok if nothing happens fairly quickly.

[Marks DTM Calib]

Flying to India there's no reliable GPS after Turkey.

Which highlights the unintended consequence of Airbus fitting a GPS based auto descend system to the A350 that descends the aircraft automatically following a decompression...

A very real possibility of hitting the mountains.

That makes no sense, the GPS GNSS constellation covers the entire globe, as does Galileo, Glonass, BeiDou etc.

In fact, pretty much every receiver on the planet needs to see a few GPS satellites in order to achieve positioning on the other constellations.

[LC0112G]

I don't approve of GPS for anything critical. Far too easy to spoof the civil variant, and jam the military equivalent. You can also derive altitude from GPS, and some aircraft systems are starting to use it as input to the flight manegment system - i.e. effectively the autopilot. There are reports over on PPrune of pilots getting 'terrain avoidance' instructions whilst happily bimbling along at 37,000 feet. What exactly are you going to bump into at FL370?

An alarming number of systems also get their time signals from GPS. If GPS stuffs up (either accidentally or through spoofing/jamming) then all types of systems fall over, and an airborne reset is often either not possible or advised against.

The specific problem in this case appears to be known but being kept quiet for whatever reasons. The aircraft spent about 10 minutes extra airborne (not hours) but the ADSB output indicated a good GPS signal throughout. Something obviously happened to the onboard systems which caused the pilots to think the GPS was unreliable, forcing them onto backup systems. Unfortunatly, Plovdiv is a sh1thole (yes I've been there - Mil8/24 base) and most of the other NAVAIDS there were already off line, so AIUI their choices were a Military PAR (Precision Approach Radar - effectively a talk down, left a bit, right a bit, up a bit, down a bit) or a visual approach. The jet in question is civil regisered, but operated on behalf of the Belgian Military so I've no idea what the pilots are allowed to do.

Interestingly, the main Bulgarian fighter base (Graf Ignatievo) is about 10 miles north of Plovdiv. I'd be surprised if the Bulgarian military don't know exactly what happened, and that's why they are trying to shut down the story.

[LC0112G]

Flying to India there's no reliable GPS after Turkey.

Which highlights the unintended consequence of Airbus fitting a GPS based auto descend system to the A350 that descends the aircraft automatically following a decompression...

A very real possibility of hitting the mountains.

That makes no sense, the GPS GNSS constellation covers the entire globe, as does Galileo, Glonass, BeiDou etc.

In fact, pretty much every receiver on the planet needs to see a few GPS satellites in order to achieve positioning on the other constellations.

There are lots of systems, mostly military, designed to either jam or spoof GPS. The main reason is that many drone and missile systems have been developed for attacking targets using GPS to navigate. If you can spoof or jam the GPS signals over an area then you can stop those drones/missiles finding their targets.

The UK CAA regularly publish NOTAMS about GPS jamming even in UK airspace - usually related to NATO exercises in the North Sea or north of Scotland. There is a big exercise happenig later this month so GPS jamming NOTAMS should appear shortly.

[Marks DTM Calib]

Jamming is not such an issue as it is easy to detect, the spoofing is more of an issue, we are starting to see spoofing used in car theft now

[LC0112G]

Jamming is not such an issue as it is easy to detect, the spoofing is more of an issue, we are starting to see spoofing used in car theft now

It is an issue in aviation - many of the newer approach procedures (called RNAV) rely on GPS, and the problem is that if the GPS signal is interrupted/spoofed anywhere along the route then the onboard systems' GPS is considered unreliable, and a RNAV approach cannot be performed. The systems cannot be reset in flight.

As DG says, GPS is routinely 'unreliable' over most of the middle east (Israel, Afghanistan, Iran, Iraq), and with Russian and Ukrainian airspace being off limits to western airliners there aren't many eastbound from Europe long haul flights which aren't affected.

[Doctor Gollum]

Going east, we either thread the needle across the top of Persia or over the UAE.

If something serious happens there's a very real chance that the aircraft won't be returning home.