
Planned GPS outages in southern California - eajecov
http://www.avweb.com/avwebflash/news/GPS-Interference-NOTAM-For-Southwest-226365-1.html
======
lb1lf
From the article: "Operators of Embraer Phenom 300 business jets are being
urged to avoid the area entirely. “Due to GPS Interference impacts potentially
affecting Embraer 300 aircraft flight stability controls, FAA recommends EMB
Phenom pilots avoid the … testing area and closely monitor flight control
systems,” the Notam reads."

That is beyond scary; how anyone can defend having critical aircraft control
systems rely on an input which may be turned off at will is beyond me.

Let us at least hope the system fails gracefully and notifies the pilot that
something odd just happened and you will have to do your own flying from this
point on, rather than just going titsup and be done with it.

~~~
jfoutz
I'm pretty sure Iran captured that US drone with GPS spoofing. I have no idea
how you could provide that data in a secure way. But, uh, i can envision some
scenarios where the bad guys would want to remotely take over planes.

Also, i'm not so sure about the graceful failure. Hypothetically, the human
takes over. But if the human hasn't actually flown in months or years the'll
likely be kind of rusty. Now you're throwing them into a complex situation -
the autopilot can handle the simple stuff. Coupling weak skills with difficult
situations seems like a bad idea.

I kinda think autopilots and self driving cars should give a limited clock.
Every, say hour you do it manually buys you a few hours of autopilot. Just to
keep skills relatively fresh.

~~~
drhodes
There's a recent econtalk episode that delves into transferring control from
machine to human. Specifically, regarding the air france disaster:

"The Air France story is a story about a failed handoff, where the automation
onboard an airplane found a relatively minor fault and handed control of the
plane back to the human pilots, too suddenly and ungracefully surprised them.
And they had lost some of their skills flying too much with the automated
systems and lost control of the airplane. Which actually was a perfectly good
airplane about a minute into the crisis. And so they went from tens of
thousands of feet flying through the sky and ended up spiraling into the
ocean, tragically losing all aboard."

[http://www.econtalk.org/archives/2015/11/david_mindell_o.htm...](http://www.econtalk.org/archives/2015/11/david_mindell_o.html)

[https://en.wikipedia.org/wiki/Air_France_Flight_447](https://en.wikipedia.org/wiki/Air_France_Flight_447)

~~~
jfoutz
That tragedy was probably the seed of my concern. Lately i've been thinking a
lot about how automated systems become brittle. The systems don't change,
people forget the dependencies and requirements and in something real time
like an airplane, the feel of the system.

A configuration management system that incorporated spaced repetition would be
cool. Every once in a while, go into an incremental mode where you actually
type in the commands. It has the added bonus of getting new people aware of
the system. Sure, you can always just go read the source and figure it out.
Having the system force some human awareness from time to time would be handy.

~~~
ethbro
Why hand control back to a human when you can do even better?

Have them both handling control at the same time, reconcile the inputs in a
sane manner (or have a master/slave where one is providing phantom inputs).
Added benefit of being able to error check each other.

[https://en.m.wikipedia.org/wiki/Lockstep_(computing)](https://en.m.wikipedia.org/wiki/Lockstep_\(computing\))

~~~
koenigdavidmj
This was exactly the problem in the Airbus crash shown above; reconciling the
inputs is hard. One pilot kept holding one stick back, unbeknownst to the
other. This plane averages them by default, and therefore the plane stalled.
That couldn't happen on a Boeing because the yokes are yokes (inputs on one
are easily visible to both pilots) and physically linked.

(Supposedly the plane is supposed to loudly complain if the inputs diverge.
I'm not sure if this happened.)

~~~
theoh
The Airbus did make the expected warnings ("DUAL INPUT") when the control
inputs conflicted, at least according to this Vanity Fair article:
[http://www.vanityfair.com/news/business/2014/10/air-
france-f...](http://www.vanityfair.com/news/business/2014/10/air-france-
flight-447-crash)

~~~
saint_fiasco
"DUAL INPUT" is only marginally better than "PC LOAD LETTER"

~~~
schoen
On the other hand, typical Airbus A330 operators probably have a lot better
training about what diagnostic messages mean than typical HP LaserJet
operators do.

~~~
ceejayoz
On the other other hand, two pilots issuing opposite control inputs generally
has a bit more impact than an empty printer tray. Boeing's relatively low-tech
solution of making the two controls physically interlinked seems like a
common-sense solution to a potentially immense issue.

------
matt_wulfeck
Testing against GPS is an interesting challenge. It's technically a critical
public service, so any disruption of it should also be broadcast. Any weapon
therefore must be tested out in the open.

The development of these weapons probably has some influence on the Navy's
decision to bring back celestial navigation[1].

Come to think of it, I don't think I even own a compass.

[1] [http://www.npr.org/2016/02/22/467210492/u-s-navy-brings-
back...](http://www.npr.org/2016/02/22/467210492/u-s-navy-brings-back-
navigation-by-the-stars-for-
officers?utm_source=facebook.com&utm_medium=social&utm_campaign=npr&utm_term=nprnews&utm_content=20160222)

~~~
scoot
_> Come to think of it, I don't think I even own a compass._

If you have an iPhone or (nearly any) Android phone, you have a compass.

~~~
maxerickson
A noisy battery driven compass though. If you are planning for the end of GPS,
it doesn't seem like a great idea to lean on your cell phone.

~~~
derefr
Easier, I think, to just make oneself slightly more autonomous with a solar-
panel USB charger, than to acquire the sheer number of items that the
smartphone phone has replaced. Just the number of physical maps you'd have to
carry in place of one offline navigation app would make one regret the
project.

~~~
adrianpike
Not to sound too crazy prepper, but getting a compass and a couple waterproof
paper maps of the region around me wasn't a huge lift.

------
cryptoz
Useful comments in r/aviation:
[https://www.reddit.com/r/aviation/comments/4msmh7/gps_interf...](https://www.reddit.com/r/aviation/comments/4msmh7/gps_interference_notam_for_southwest_us/)

------
supernova87a
So, here is just a little bit of amateur desk research into some things we
might be able to gather from the information:

The FAA flight advisory provides the coordinates and the nature of the GPS
signal disruption, which is centered near China Lake, and has expanding rings
of area, each of which rises in altitude. For the pilots out there, imagine
the classic upside-down wedding cake shape. Or cone with its point at the
ground.

This would seem to indicate some kind of broadcast or interference from a
source that is located at the ground, propagating line of sight with larger
radii with altitude. Rather than something to do with the satellite itself.

The center of the coordinates are 360822N, 1173846W, which is in a big empty
desert area, just south (SSW of Darwin, California), see here:
[https://www.google.com/maps/place/36%C2%B008'24.0%22N+117%C2...](https://www.google.com/maps/place/36%C2%B008'24.0%22N+117%C2%B038'42.0%22W/@36.1302941,-117.6306855,10664m/data=!3m1!1e3!4m5!3m4!1s0x0:0x0!8m2!3d36.14!4d-117.645)

It could of course be some kind of antenna, or even a flight that is producing
this signal. But there's also an interesting long V-shaped two-legged
testing(?) facility just to the east of these coordinates, which you can see
in the Google Earth image. I might be mistaken about what that facility is,
because aeronautical sectional charts also show a mine in that area, but this
doesn't look like a mine site. Also there are a bunch of vehicles that look
like Humvees on the pad nearby. And there are three antenna looking structures
at the north end of the paved line.

Anyway, it's interesting to speculate about.

~~~
lucb1e
> The center of the coordinates are 360822N, 1173846W

Noob question here: what kind of coordinate system is that? I know the
degrees, minutes, seconds one (51°30', 005°09') and the nowadays more common
decimal degrees (e.g. 51.5,5.15), but not this big number.

Edit: Also, for those who don't like Google Maps because it's slow or just
because it's Google:
[http://www.openstreetmap.org/search?query=36%C2%B008%2724.0%...](http://www.openstreetmap.org/search?query=36%C2%B008%2724.0%22N%20117%C2%B038%2742.0%22W#map=12/36.1400/-117.6450)
or [http://binged.it/24xCR6D](http://binged.it/24xCR6D) (I would use the long
link but I can't link to satellite imagery -- the only thing bing maps is good
at).

~~~
Nadya
It's still Degrees, Minutes, Seconds, but with N/S/E/W postfixed (is usually
prefixed)

36°08'22''N, 117°38'46''W

~~~
lucb1e
Ah okay, thanks!

------
alpb
From Reddit comments at r/aviation
([https://www.reddit.com/r/aviation/comments/4msmh7/gps_interf...](https://www.reddit.com/r/aviation/comments/4msmh7/gps_interference_notam_for_southwest_us/))
it appears like this could affect civilian GPS usages such as geolocation
apps. I wonder if Google Maps or any other GPS apps should be showing a
warning that because those apps can just behave weirdly?

As a foursquare/swarm user myself I would be quite pissed off by my OCD if I
cannot check in to places I go haha.

~~~
tomjakubowski
Unless you're on a bridge it should be fine. The article says funkiness starts
at 50 feet above ground level.

~~~
rconti
That cannot be significant. Bridges have ground, and it's also possible to be
above 50 feet above Sea Level while still on the ground. I'm suspicious.

~~~
andyjdavis
From the discussion in this thread it seems likely that the source of the
disruption is something that will be broadcast from ground level. Your
position relative to that transmitter (bearing in mind the curvature of the
earth) will likely matter far more than your elevation relative to the ocean.

If you are on the ground you will presumably be sheltered by intervening
obstacles (building, hills, the earth) while a plane in the air (or anyone
else significantly above ground level) may have line of sight to the source of
whatever is going on.

------
guelo
Interesting that the interference occurs 50' Above Ground Level, not sea
level. I can't even imagine what technology that is that can somehow jam along
the contours of the earth.

~~~
andrewstuart2
If it's ground-based and directional then I can easily see the system having
the highest gain within, say, a 170 degree arc. Point that straight up and
ground-level (and slightly above ground level) wouldn't be affected much.

Useful if you want to avoid disrupting ground travel. It probably gives
significant cloaking benefits too if you can limit effective signal source
discovery to airborne platforms with all the right equipment -- much more
difficult to dig up than something ground-based.

~~~
mysterypie
The FAA has announced that GPS jamming will only affect aircraft above 5000
feet, not above 50 feet that was mistakenly reported.

But I'm still confused by your explanation about how GPS jamming can avoid
affecting areas below 5000 feet.

I can imagine two ways that the jamming could work:

(1) You're jamming the GPS _receiver_. An analogy would be shining a laser
pointer into a photographer's camera. You're overwhelming the receiver so he
can't receive the signal, but you are not actually modifying the original
signal. This seems to fit your explanation.

(2) You're blocking or modifying the actual GPS signal. The analogy here would
be spreading out a huge curtain in the sky at an altitude of 100,000 feet to
block out the sun. Aircraft flying at 50,000 feet won't get any sunlight. But
neither will people on the ground. Your explanation does not seem to work in
this case. You can't block sunlight at 100,000 feet without also blocking it
for people at ground level.

What am I missing here?

~~~
detaro
some ideas:

The jamming sender(s) could be flying as well. If you only send upwards from a
flying plane, you obviously won't jam receivers below it.

and/or the areas where you can receive it below 5000ft are inside restricted
airspace. There is a lot of that around China Lake, but I don't know if they
just can't tell you about issues in there. I'd expect so though, given that
they do all kinds of exercises in there that all would need an extra warning
otherwise. (EDIT: but the sizes/the angle of the cone don't look as they'd
work out for a sender on the ground, unless they added massive safety margins)

Or they are doing something clever with multiple senders, and below 5000 you
can't receive the signals overlapping in such a way that actual jamming
happens. Not sure if that would work in GPS frequency ranges though.

~~~
chipperyman573
>Plane at 5000ft obviously can send signals only forwards/upwards.

Why? Can't you put a sender on the base of a plane?

~~~
detaro
bad wording on my part, meant that if you put a sender that only sends upwards
on a plane at 5000ft, it it obviously won't be received below it. Edited the
comment.

------
tjohns
Interstingly, it looks like this is a semi-regular thing in different parts of
the US:

[https://www.google.com/search?q=FLIGHT+ADVISORY+GPS+Interfer...](https://www.google.com/search?q=FLIGHT+ADVISORY+GPS+Interference+Testing)

Last one looks to have been May 22-23 in Louisiana, with another one from June
1-30 in New Mexico.

~~~
j_s
It's interesting to see HN discover this routine test; the Phenom warning is
boilerplate.

[https://pilotweb.nas.faa.gov/PilotWeb/noticesAction.do?query...](https://pilotweb.nas.faa.gov/PilotWeb/noticesAction.do?queryType=ALLGPS&formatType=DOMESTIC)

The Coast Guard is the middleman for the DoD, obtaining FAA approval for the
tests and coordinating shut down of the tests in emergencies.

[http://navcen.uscg.gov/?pageName=gpsServiceInterruptions](http://navcen.uscg.gov/?pageName=gpsServiceInterruptions)

------
Artlav
I wonder how many of the plane "GPS receivers" can pick up GLONASS as well?

Most consumer units can see both networks these days, however aviation tech is
known to lag a lot in such matters.

~~~
walrus01
fun fact: most consumer grade GPS stuff can pick up GLONASS, particularly the
RF baseband chips found in all modern smartphones, because about 5 years ago
Russia threatened to put a 250% import duty on all imported smartphones that
didn't function with GLONASS. Therefore companies like Qualcomm which develop
the RF chips in a smartphone were required by their customers (such as LG) to
include GLONASS.

~~~
rconti
Do you know if it's supported in software; say iOS or Android?

~~~
Piskvorrr
On Android, check
[https://play.google.com/store/apps/details?id=com.chartcross...](https://play.google.com/store/apps/details?id=com.chartcross.gpstest&hl=cs)
\- it will actually show you _which_ satellites from the constellation are
_whose_ : I can see US, Russian and Chinese units. On a higher level, it's
integrated into the location provider - the apps don't need to care, they just
get a location fix, regardless of the technology used.

------
lutorm
How does the FAA think this is going to work after 2020 when air traffic
control will run off of ADS-B positional telemetry from aircraft. It seems a
GPS shutdown like this would basically shut down IFR flying and airport
terminal control since ATC has no other way of knowing the position of
airplanes.

~~~
mschuster91
> It seems a GPS shutdown like this would basically shut down IFR flying and
> airport terminal control since ATC has no other way of knowing the position
> of airplanes.

I highly doubt that good old-fashioned radar will be shut down. It has to be,
anyway, for all the planes either that don't have the equipment for IFR, and
the pilots which are not certified for IFR, only for VFR.

~~~
lutorm
By 2020 _any_ airplane that flies in controlled airspace is required to be
equipped with ADS-B out. This applies to VFR as well as IFR flights.

Of course, VFR flights can continue flying VFR if GPS shuts down, but IFR
flights wouldn't have that option.

------
disposeofnick9
Why on earth does the military-industrial complex need to spend money on a
duplicate, irrelevant technology? I worked at Trimble Nav in the radio group,
and the POTUS has the ability to increase selective available (SA) to an
enormous number (which can be defeated by differential/kinematic corrections,
but was set to 0 by executive order under Clinton) or disable the unencrypted
channel entirely for a particular region or the entire planet (which includes
space). WTF!

~~~
jhayward
Satellites designed after May 2000 no longer have SA capability.

~~~
disposeofnick9
because it's pointless and since areas can be and have been turned off for
non-military receivers.

~~~
jhayward
No, it has never been turned off since it first went to full availability [1].

[1] [http://www.gps.gov/support/faq/#off](http://www.gps.gov/support/faq/#off)

------
brc
I know someone who was at sea when their GPS stopped working. They found out
later a nuclear sub had come into port around the same time. Seems like it
wasn't a coincidence as gps outages are rare.

~~~
yompers888
Where was this?

~~~
hammock
He could tell you, but his GPS was down.

------
gaius
If you are in the UK [http://stakeholders.ofcom.org.uk/spectrum/gps-jamming-
exerci...](http://stakeholders.ofcom.org.uk/spectrum/gps-jamming-exercises/)

------
jackgavigan
GPS jamming is old hat.

A lot of weapons testing takes place at China Lake (where the disruption will
originate from), including missiles and guided bombs that use combination GPS
and inertial guidance systems.

They're probably testing various weapons systems' ability to continue to
function in the face of GPS jamming.

------
nameless912
I, for one, cannot _believe_ that GPS doesn't have a pre-prod environment. I
guess they just don't grok dev ops like us young hip developers.

No but seriously, the fact that we don't have a backup for when GPS inevitably
shits the bed sometime in the future is a fundamental existential threat to
mankind. We should probably do something about that.

~~~
Artlav
The existing backup is the Russian GLONASS system, which many consumer chips
support since the start of this decade or so, and there are two more
constellations being deployed, by ESA and China.

I'm not sure how you can test such things not in the production environment.
The early development was done with the transmitters on airplanes, but i would
guess that the jammability can't really be tested that way.

~~~
paulgerhardt
GPS uses a certain frequency. Use the high side band for prod, the low side
band for staging. Simple :)

~~~
hamiltonkibbe
The nice thing about PRN codes is that you can just use a different set of
gold codes in the same band, as long as they have low enough cross-correlation

------
sandworm101
Um .. why do they need a weapon to "disrupt" GPS? It's their birds. They can
turn it on/off selectively whenever and wherever they deem necessary. Or is
this meant as a test of something to disrupt the Russian/Chinese systems?

And why southern california? Alaska, the pacific... northern Canada ... there
are lots of lower-traffic areas. We aren't getting the full story.

------
chockablock
According to the NOTAM [1], this extends to SF Bay area as well, even near
ground level.

Tests may be repeated on June 7, 9, 21, 23, 28, and 30, between 9:30a-3:30p.

[1]
[https://www.faasafety.gov/files/notices/2016/Jun/CHLK_16-08_...](https://www.faasafety.gov/files/notices/2016/Jun/CHLK_16-08_GPS_Flight_Advisory.pdf)

------
gene-h
I have a hunch that some people are going to have difficulty withdrawing cash
from ATMs[0] tomorrow. Although, perhaps they are being overly cautious here.

[0] [https://www.newscientist.com/article/dn20202-gps-chaos-
how-a...](https://www.newscientist.com/article/dn20202-gps-chaos-how-a-30-box-
can-jam-your-life/)

------
Animats
I wonder what this will do to ground-based GPS users. Aviation doesn't really
need GPS; aircraft have multiple other systems. But phones, cell towers, and
other devices have no other position input. Car navigation systems may become
lost. We now get to see which GPS units have enough smarts to detect
inconsistent data.

------
emblem21
Satellite warfare adaptability simulation?

------
cbanek
Take that Vandenberg AFB. Surprised they didn't use the Nevada test site.

------
Raphmedia
Something like that could wreck havoc in a world where all cars are self
driving... !

~~~
PhasmaFelis
Self-driving cars use GPS for route guidance; moment-to-moment driving
decisions are supported by built-in all-around sensors. The worst that might
happen in a GPS outage is that all the affected cars might safely and
carefully pull over/become gridlock.

~~~
bennettfeely
> the affected cars might safely and carefully pull over/become gridlock.

As a best case scenario I'd still file that under "wrecking havoc"

~~~
PhasmaFelis
That's the _worst_ case scenario. Best case is that the cars are smart enough
to fall back to navigating by road signs and stored maps, and there's no real
interruption apart from maybe a warning light on the dash. It's not even
_that_ improbable; it's not uncommon to lose GPS signal in e.g. deep valleys,
so any fully autonomous self-driving car would want to have some kind of fall-
back scenario.

~~~
Piskvorrr
Deep valleys, such as Manhattan offers ;) In other words, this is one of the
most often encountered scenarios, and for momentary dropouts, even consumer-
level navigation apps have dead reckoning algorithms (I was surprised by this
when my smartphone kept the "you are here" dot moving inside a tunnel, fairly
precisely)

------
KateBone
I'm definitely crossing off the Embraer Phenom 300 from my shopping list of
personal jets !

Seriously though, who thought this was a good, or safe, idea?

~~~
colejohnson66
Most likely the military because they need to test something... A GPS jammer
perhaps?

~~~
davesque
You'd think they could test it in a less populated area.

~~~
chipperyman573
Maybe population was a part of it. There are so many things they could be
doing/testing we can't really make any assumptions other than that some
government organization is doing something.

------
awqrre
Does that have anything to do with voters suppression for today's election?

~~~
function_seven
I struggle to see how aviation GPS jamming would impact voter turnout.

~~~
awqrre
Aviation schedules are already very unreliable (75% on-time?)... I would
assume that this could only make it worst.

~~~
function_seven
Sorry, I guess I should clarify. _Who_ would be behind this plan, and what
votes would they be looking to suppress?

~~~
awqrre
I don't know, I just thought that it was really odd that they decided to
experiment with this on election day where an important election is being
held...

------
shapiro44
Coincidence? Is this meant to disrupt the California primary? Voters getting
lost on way to voting stations without reliable GPS. There are a lot of first
time voters.

~~~
_kst_
The article says it affects "GPS signals down to 50 feet AGL". (I believe
that's Above Ground Level.) So it shouldn't affect surface navigation.

~~~
excalibur
Does anyone have a good explanation for how that's possible? Aren't the same
GPS signals used regardless of elevation? Coming from a satellite, wouldn't
they have to traverse the area where they're supposedly "jammed" before they
can make it to ground level?

~~~
roywiggins
Jamming doesn't block the signal, it shouts over the signal. So, if your
receiver can't hear the jammer, it will be unaffected, even if receivers
between you and the satellite can hear the jammer.

~~~
gherkin0
IIRC, there exist things for GPS called "null steering antennas" that allow a
receiver point a "null" at a jamming source to block it. I believe they're
considered controlled munitions by the US government.

