

Airplanes Can Now Take Off and Land With GPS. Will Flights Be Faster? - hoag
http://mashable.com/2012/02/07/faa-gps/

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zdouglas
A machinist I knew for an airline told me a story about how the avionics in
plains in the late 80's could land autonomously in fair weather. The problem
wasn't that the systems weren't smart enough, but that the tarmacs weren't
robust enough to handle 'perfect' performance every time. After thousands of
planes touched down within feet of each other, the pavement would crack and
the systems couldn't be configured to inject variability to compensate.

~~~
jdietrich
There's a very similar problem in maritime navigation. Ships used to steer
their course along shipping lanes by hand, but now they're automatically
steered by GPS. Everyone is crowded right into the middle of the lane, greatly
increasing the likelihood of collisions. After a fatal accident caused by this
issue[1], the British Coastguard specifically instruct ships not to follow the
exact line of the shipping lanes in the English channel.

[1]
[http://www.maib.gov.uk/cms_resources/SB_%202_2001_%20Ash_and...](http://www.maib.gov.uk/cms_resources/SB_%202_2001_%20Ash_and_Dutch_Aquamarin.pdf)

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brndnhy
Great news, though the headline is kind of weird.

GPS-only RNAV STARs (Standard Terminal Arrival Routes) have been in use for
some time.

The "next gen" technologies referred to in the article involve a lot more than
just GPS improvements (such as WAAS and publishing more RNAV GPS approaches
annually). They include new ground radar for automated taxi operations, a
replacement of traditional transponder-based aircraft separation, redesigning
ATIS and weather reporting, and an overall push to standardize all ATC data --
ultimately getting more real-time data into cockpit avionics.

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hoag
It's about freaking time. I remember back in May 2009 I was on a UA flight
from HNL-SFO and if I'm not mistaken, they were testing SFO's GPS approach
system: IIRC, we descended from cruising altitude to wheels down in about 10
minutes. Awesome.

~~~
nekojima
That's quite a common time (10-13 minutes) from cruising altitude to landing
at most airports in East Asia. America has other issues that interfere with
more sensible landing procedures that need to be addressed, but are unlike to
be.

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DrJokepu
This is very interesting, if you have a few minutes, can you please explain
briefly why this is the case to someone who doesn't know much about aviation?

~~~
nekojima
From what I understand, its mostly due to the landing approaches being more
straight forward, the lack of stacking of planes to land (less circling) and
timing between planes is usually slightly longer than in the US.

An extra ten or twenty seconds between planes taking off and landing can have
a large impact over the course of a day. In the US the majority of flight
delays are in the late-afternoon and into the evening because of the knock-on
effect of delays (at that airport or others) and the lack of spare capacity
within the timings to adjust the scheduling of takeoffs and landings.

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bprater
Today, it seems like the bulk of the pilot's job is to get the plane in the
air and then get it back on the ground. In 10 years, are we going to be at the
point where a pilot's job is completely redundant? (Or maybe a fleet of planes
is handled by a small group of "ground" pilots?)

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joshwa
Go read the AF 447 accident report and you'll see why humans are both the
weakest link and still completely necessary. Sensors fail.

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CamperBob
Correction: _crappy, inadequately-redundant_ sensors fail.

~~~
chronomex
Everything fails, if given enough chances to do so.

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kijin
Just curious: What happens if some dude in a truck drives around an airport
with an illegal GPS jammer? These things are everywhere:
<http://www.economist.com/node/18304246>

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gibybo
Couldn't someone do the same thing with existing radio navigation tech? I
suspect they just track the source of the signal down and arrest them.

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deserted
Hasn't the FAA seen Die Hard 2?

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DanielBMarkham
This works great until some foreign power takes out several of our GPS birds
or a CME fries some important stuff, then what? We give up IMC aviation? Can't
go back to ILS -- I hear they're taking those out. NDBs? Gone. LORAN? Are
those even in existence any more? Can the big airports supplement with WAAS
units enough for some kind of commercial aviation to continue? Is that
possible?

I love GPS, and I'm for using it more and more, but I have a philosophical
problem with putting all of our eggs in one basket. Just like the military's
reliance on stealth, this is really cool stuff -- until it stops working. Then
you're worse off than before.

Maybe I'm just old cranky guy today.

~~~
jdietrich
GLONASS (and eventually Galileo and Compass) have put us in something of a
cold war situation. All the superpowers will have full GNSS systems in
operation by 2020. Crucially, Galileo is effectively the "non-aligned" GNSS
system, with diverse investment from outside Europe.

If we start shooting at satellites, there'll be much scarier things to worry
about than how aviators will plot a course for landing. For better or worse,
satellite warfare is the new Mutually Assured Destruction.

~~~
DanielBMarkham
Thank you. Okay, I'll buy the MAD analogy, although we were very lucky that
MAD worked. No guarantee it's going to work in a multi-party situation. But
fine.

Sill, where's the dual technology system? When I got my IFR ticket, I shot an
NDB and an ILS _plus_ I had to know about GPS approaches (they weren't
certified then). If I couldn't shoot an ILS at an airport, maybe I could pull
off an NDB at my alternate. If your GPS broke you could use the NDBs to get a
fix, your pitot freezes over you use pitch and power, your vacuum gyro fails
you have an electric backup, etc. There was always a mix of methods. The
beauty of the system was that you never depended on just one thing.

Is that gone now? It's all GPS or nothing? A solar flare takes out our GPS
capability, and simply because "there'll be much scarier things to worry
about" that means we're not as hosed?

Thanks again for the information. Just trying to sort out in my head what
risks are being taken.

