
Ground Collision Avoidance System ‘Saves’ First F-16 in Syria - aerocapture
http://aviationweek.com/defense/ground-collision-avoidance-system-saves-first-f-16-syria
======
Animats
The USAF finally went for that? It was first demonstrated in 1998, and has
been used by the Swedish air force for years. Their slogan is "You can't fly
any lower". Here's the 1998 writeup, copied from Aviation Leak:
[http://www.f-16.net/f-16_versions_article8.html](http://www.f-16.net/f-16_versions_article8.html)

The technical paper:
[http://www.icas.org/ICAS_ARCHIVE/ICAS1998/PAPERS/182.PDF](http://www.icas.org/ICAS_ARCHIVE/ICAS1998/PAPERS/182.PDF)

The actions this system takes are drastic. Roll rates to 180 degrees/sec to
get to wings-level, then a 5G pull-up. The pilot's helmet may be banged
against the canopy. It's so drastic because flying 150 feet off the ground in
mountainous terrain is normal procedure for fighters. If the system has to act
to avoid a collision, that action has to be very aggressive.

Here's what it looks like to a pilot:

[https://www.youtube.com/watch?v=aPr2LWctwYQ](https://www.youtube.com/watch?v=aPr2LWctwYQ)

Here, the pilot puts the plane into an insane bank and, as he says, "goes to
sleep" and releases the controls.

~~~
spyder
... and here is a longer video from NASA about their development of collision
avoidance system that can work for regular planes too:
[https://www.youtube.com/watch?v=XWx6-aK8Ick](https://www.youtube.com/watch?v=XWx6-aK8Ick)

~~~
Animats
That's so NASA PR. About 80% of the stuff in that video was not done by NASA.
The F-16 auto-GCAS was a USAF/Swedish Air Force/Lockheed project. The NASA
people are just reusing that technology on a model aircraft.

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WalterBright
Reminds me of a description of air combat where the pursued would dive, and
then pull out at the last possible moment, hoping the pursuer would misjudge
and pull out too late. One pulled out so low he raised dust on the ground.

My father liked to attack ack-ack positions by diving vertically on them, as
the gun crew obviously was reluctant to fire straight up. Of course, you gotta
keep a real close eye on your altitude and airspeed doing that.

~~~
thecopy
There was an incident (among many) between a Swedish figher and the Russian
figher on Swedish territory maybe 20 years ago where the Russian was following
the Swedish fighter. The Swedish planes being more sophisticated then the
Russian fighters, the Swedish pilot went for the sea, straight bown. He pulled
back when he knew his plane would make it, but the Russian figher jet could
not handle the G's, broke and crashed into the sea killing the pilot.

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themodelplumber
This is really interesting. I found a PDF with some neat details and imagery
describing the thinking that goes into Auto GCAS:

[http://www.sfte2013.com/files/78993619.pdf](http://www.sfte2013.com/files/78993619.pdf)

I don't know if it's just coincidental, but a lot of the examples seem to be
concerned with keeping jets from flying into mountains, as opposed to flying
into level ground, which was the first thing that came into mind when I saw
"Ground Collision."

~~~
mik3y
Cool find! The pictures (and one slide) show an Android phone being used on a
"Dryden drone", looks like it might have been a prototyping platform. Would
love to see more detail about this.

Edit: Ah, here's a senior project at CalPoly that was sponsored by NASA and
looks related:
[http://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?articl...](http://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=1199&context=mesp)

~~~
termain
Quite impressive senior project. I know CalPoly aerospace does well with
interacting with the industry and NASA.

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afterburner
"According to the Air Force, 26% of aircraft losses and 75% of all F-16
fatalities are caused by such accidents."

Wow.

~~~
marvin
Keep in mind that jet fighter crashes are often survived by the pilot if he or
she has the time to react and bail out. Many crashes are caused by technical
malfunction or loss of control at altitudes where the pilot has plenty of time
to react.

However, if the pilot is still on board, ground collision at flight speed is
almost universally fatal. Fighter pilots during ground attack or low-level
dogfighting are always pushing the envelope both in aerodynamic/structural
capability and maneuvering wrt. terrain hazards, so ground collision is a very
serious safety hazard. Military pilots have much, much smaller margins of
error than commercial or recreational pilots.

~~~
konstruktor
The article specifically talks about controlled flight into terrain, which, by
definition excludes malfunctions.

~~~
theoh
I think the point being made about malfunctions is that they are less likely
to lead to fatalities than CFIT. This would explain the high percentage of
fatalities caused by CFIT.

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naz
The Stuka had a slightly less sophisticated version of this in 1935:

[http://en.wikipedia.org/wiki/Junkers_Ju_87#Diving_procedure](http://en.wikipedia.org/wiki/Junkers_Ju_87#Diving_procedure)

~~~
cbr
Significantly less, but still impressive for its purpose.

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dankohn1
Can you imagine the testing rigor you would need for this sort of system,
knowing that if you incorrectly engaged or steered the aircraft, you would be
responsible for killing the pilot?

~~~
ccleve
My thought exactly. Warning! Warning! NullPointerException!

No, that's a contract I do not want.

~~~
iLoch
I remember reading somewhere that these guys get all the time they want to
program these systems, and the environment is very relaxed - I suppose for
this very reason.

~~~
curiously
Write one line of code everyday, make sure it's bug free.

I wouldn't be surprised if they used functional programming and avoiding
object orientated programming.

~~~
PhantomGremlin
Why wouldn't they be using Ada? That's exactly what is was developed for.[1]

Does anybody know if Ada is still in use for writing new applications?

[1]
[https://en.wikipedia.org/wiki/Ada_%28programming_language%29](https://en.wikipedia.org/wiki/Ada_%28programming_language%29)

~~~
ObviousScience
You can take it a step further and use SPARK:

[http://en.wikipedia.org/wiki/SPARK_%28programming_language%2...](http://en.wikipedia.org/wiki/SPARK_%28programming_language%29)

~~~
PhantomGremlin
Excellent. I wasn't aware of SPARK.

It could have been useful for Toyota, rather than the ad-hoc mess they wound
up with controlling their cars.
[https://news.ycombinator.com/item?id=8905718](https://news.ycombinator.com/item?id=8905718)

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derwildemomo
That's great.

Maybe someone here can enlighten me as to why the systems, specifically TCAS
and GPWS in modern civilian planes are only ever used to issue
warnings/recommendations, but never take control? it would have at least
prevented the überlingen mid air collision and probably some other CFIR
incidents in the past years.

I thought about this for a while and couldn't come up with a really good
reason.

~~~
neurotech1
Auto GCAS also used in cases of G-LOC (G-Induced Loss of Consciousness) which
is practically unheard of in a civilian airliner that is able to land safely
afterwards.

Fighter aircraft frequently engage in maneuvers that are seconds away from
hitting the ground (or water) if something goes wrong.

überlingen was a tragic anomaly caused by multiple factors, the pilots knew
they were on a collision course but due to the conflict between TCAS and ATC
they collided. This possibility has been reduced by issuing a TCAS reversal if
the other jet responds differently than expected.

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ricardonunez
This is fascinating stuff. Does anybody know the whole cost of this system? I
only was able to find a pdf and it says that the seed money was $2.5 millions.
If anybody is interested here's the link:
[http://www.nasa.gov/sites/default/files/337112main_Auto-
GCAS...](http://www.nasa.gov/sites/default/files/337112main_Auto-GCAS-NR-
AFPS.pdf)

~~~
boombip
I found this PDF:
[http://www.globalsecurity.org/military/library/budget/fy2015...](http://www.globalsecurity.org/military/library/budget/fy2015/usaf-
peds/0207133f_7_pb_2015.pdf) that says it cost ~2 million to integrate in
2013.

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kator
I just finished the book "Skunk Works: A Personal Memoir of My Years of
Lockheed"

[http://www.amazon.com/Skunk-Works-Personal-Memoir-
Lockheed-e...](http://www.amazon.com/Skunk-Works-Personal-Memoir-Lockheed-
ebook/dp/B00A2DIW3C#)

It was a great book that almost feels like the pre-scrum manifesto applied to
building aircraft.

~~~
nether
All right, this has nothing to do with the Northrop/GD F-16.

~~~
kator
FTA: "Auto GCAS, which was developed by Lockheed Martin’s Skunk Works"

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ForHackernews
"a 5g pull"

Yikes!

~~~
Sharlin
That's a pretty run-of-the-mill acceleration as far as fighter maneuvers go.
Momentary accelerations in excess of 10g are not unheard of and the use of an
ejection seat exposes the pilot to 12g or even more.

~~~
Perdition
Yeah but ejecting is often career ending because of those G's.

~~~
toufka
I was curious how traumatic it can be. Went searching and found this abstract
from a paper[1] studying ejections in the German Air Force from 1981-1997:

"[86 ejections from 56 aircraft had an] overall success [(survival)] rate of
97.6%. Of all 85 participants, 12 (14%) were uninjured, 41 (48.2%) were
slightly injured, and 30 (35.3%) were severely injured. Typical injuries were
those of the spine and lower limbs. The most common severe injury was a
vertebral fracture caused by ejection acceleration. This is followed by lower
limb injuries received during the parachute landing fall."

[1]
[http://www.ncbi.nlm.nih.gov/pubmed/10596782](http://www.ncbi.nlm.nih.gov/pubmed/10596782)

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kingkawn
Why are we bombing Syria?

~~~
rufustherag
Google 'isis' aalong with beheadings, rape, child slavery, sex slaves, burning
people alive, burying people alive etc. Alternatively buy a newspaper from
time to time.

~~~
kingkawn
Funny that you and many others got angry because I asked the question that you
want to no longer have anyone ask.

Is each bomb going to kill ISIS, or might it do more? Then "why are we bombing
syria" never stops being a relevant question to ask, and never one that is
fully answered until the answer becomes that we are not.

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throwaway8898
hmm ... as a pilot and student of WW2 combat, I think this might be ok in
peace-time, but definitely a problem in war time.

\- to avoid radar, you have to fly low - tree-top high \- to save ammo, you
have to shoot near ground-targets \- can the software be fooled in mountainous
terrain? \- what about off-field landings? \- Japan's most effective bombers
were kamikaze, and American pilots also considered ramming other aircraft
after their ammo ran out \- if the software is wrong, does it roll inverted
and pull down at 5G? how do you stop it?

~~~
jjwiseman
From
[http://www.aerotechnews.com/laafb/files/publications/ala_100...](http://www.aerotechnews.com/laafb/files/publications/ala_10082010A20.pdf),
it looks like it's designed to avoid "nuisance activations": “As Nils got down
low, I could see dirt being kicked up off of the desert floor and no nuisance
activations.”

~~~
mjmahone17
1,600 automatic avoidances in 141 hours of flight. Holy crap, that's a lot of
"point it at the ground, hope you don't die". Unless they did something else?

~~~
mattmanser
Surely they just set the ground level to be higher?

