[jdonn]

When I included this suggestion in a recent post the idea (not mine of course) to switch air traffic control to GPS, I got a lot of private positive feedback. It's such a good idea that if I were in congress (hahaha) I would probably make it my first priority to get it done.

Basically the idea is that the current system is very outdated. Planes have to fly very strange paths because they have to stay on areas that radar screens can detect. GPS would allow plans to fly in straight lines because their position at each moment would be far more accurately known.

I don't think I would be exagerating to say the benefits would be astronomical.

- It would save billions (literally) of gallons of fuel a year.
- It would drastically reduce flight times and delays.
- Despite large up-front costs (35 billion + 200,000 per plane), it leads to drastic long term savings (would pay for itself in just 7 years I have read.) The savings are not just in fuel and in reduced delays, but it is estimated that it would cost 30 million a year to maintain the system. The current system costs 150 million a year to maintain.
- It would make flying, admittedly already quite safe, even safer.
- It would triple maximum capacity of airplanes that would fly in an area in the same time. This would even further reduce flight times and delays.
- All the saved fuel would also reduce polution.

I can see really no negatives at all except the up front cost. But is that really enough reason to not get this done? In the end it is all savings anyway. Thoughts? Why is this not brought up more? Are there any advantages (military?) or disadvantages I didn't mention?

[Winstonm]

The negative - and it is impossible to overcome - is that we would all have to give you credit for a good idea.

And that ain't about to happen, Bubba.

Actually, my concern is reliability - it would not be good to spot another plane quickly approaching your plane and here Jenny say, "Recalculating".

[helene_t]

I wonder if there will be a transition time when some airlines use the new system and some the old oneand what problems that would bring about.

That said I think it's a very good idea.

[hrothgar]

Hi Josh

I think that this idea has a lot of merit; however, I'm unsure whether this would have a significant impact on delays.

My impression is that the most important constraint on air travel is the number of landing slots available at airports. If you want to have a significant impact on congestion/delays, you need some way to fix this. It's unclear how switching to a GPS based system would address:

I can certainly see how this type of system would impact fuel consumption and flight times. However, claiming that this would help address variance in flight times doesn't seem that likely.

[jdonn]

hrothgar, on Feb 7 2009, 02:53 PM, said:

My impression is that the most important constraint on air travel is the number of landing slots available at airports.  If you want to have a significant impact on congestion/delays, you need some way to fix this.  It's unclear how switching to a GPS based system would address:

It is entirely plausible that runway and gate congestion is a major cause of delays, or even the most major cause. I tried to look into it a little.

Here is a portion of a transcript from a hearing on the subject of flight delays of the House of Representatives Committee on Transportation and Infrastructure subcommittee on aviation. (Granted this hearing was held in 1995, but it seems to me that other than airport security, nothing is really different now than it was then.)

Quote

The FAA reports that in 1994 74.5 percent of the delays were caused by weather; 19.3 by air traffic volume; 2.3 percent by closed runways or taxiways; 1.6 percent by breakdowns of its computers, radar, or other control equipment; and 2.3 percent caused by other circumstances.

Obviously we can't control the weather, but it seems to me this system would reduce the vast majority of delays that aren't related to weather. And of course if there were a delay in any case, the time could better be made up.

Anyway even if delays didn't change at all (and it seems hard to believe they wouldn't at least improve a little), that is a relatively minor point to me. The biggest reasons I favor this, in order, would be reducing fuel consumption and savings (I anticipate savings would at least partially be passed on to the consumer. Flying right now is VERY expensive). I certainly favor reducing flight times, reducing delays, reducing pollution, heck I bet it would even make us safer (less dependence on foriegn oil, and perhaps improved military operations?), but those are sort of secondary benefits to me.

[jdonn]

helene_t, on Feb 7 2009, 02:52 PM, said:

I wonder if there will be a transition time when some airlines use the new system and some the old oneand what problems that would bring about.

That said I think it's a very good idea.

I anticipate there might need to be a period of time (hopefully just a few hours? but perhaps even a matter of days) where air traffic would need to be grounded. I consider that a small price to pay as long as adequate warning time is given in advance.

Another alternative is perhaps starting up the new system while the old system is still functioning? But I think it is easy to anticipate monstrous logistical difficulties with that (heck, where do you find enough qualified people to operate both systems at once?) so it seems a lot less plausible to me.

Maybe there could be a long term implementation where it's slowly added to existing fleets and there could indeed be some way for the systems to function simultaneously.

Certainly there would be plenty to discuss and plan for.

[hotShot]

I'm pretty sure that they are using GPS already.

The problems are in small little details like.

The shortest route between 2 airports is the same for all plains in all directions. Hurray for the collisions alert....

If a plane is not taking the direct route, it is usually to avoid to fly through restricted areas, the reasons can be military or security (like avoiding nuclear installations).

[matmat]

jdonn, on Feb 7 2009, 03:12 PM, said:

Quote

The FAA reports that in 1994 74.5 percent of the delays were caused by weather; 19.3 by air traffic volume; 2.3 percent by closed runways or taxiways; 1.6 percent by breakdowns of its computers, radar, or other control equipment; and 2.3 percent caused by other circumstances.

I am wondering whether "air traffic volume" doesn't include runway and gate congestion, which, imo, is different than "closed runways or taxiways"



edit --
also, weather is kind of a distraction here, but if you think about it, a lot of the weather related delays are known ahead of time and can be predicted, so travelers are less likely to be caught by surprise by them. I mean, if you're in the middle of january in Chicago and you know there is a snowstorm moving in, you know to expect ohare/midway to be closed.

Noone really expects the airlines to fix the weather related delays (though it would be nice) and it seems like numbers like these try to shield the real causes by making them appear minimal.


another edit --
are these percentages the time or the number of delays?

[jdonn]

Hotshot, I'm fairly certain that your entire post was assumptions rather than facts, and that in fact each of your assumptions is wrong. There is nothing like 5 minuts of googling before you start jumping to incorrect conclusions.

hotShot, on Feb 7 2009, 03:29 PM, said:

I'm pretty sure that they are using GPS already.

Please show me where GPS is mentioned. Or you can just read the first sentence of this, which is also a great summary of the entire topic.
(Oddly enough, it points to delays as the number 1 reason for this entire system being explored. It's still not my number one reason!)

Quote

The shortest route between 2 airports is the same for all plains in all directions. Hurray for the collisions alert....

Lol. They all fly the same paths now! (proven by the same link that disproves your next point.) In fact the amount of pathways airplanes would be using would increase dramatically, reducing the amount of planes using identical pathways.
Just imagine that all planes are flying over a chess board. With the current system they can only stay on the lines that seperate squares but they can't fly over squares directly. In the new system they would be able to fly anywhere over the board at all.

Quote

If a plane is not taking the direct route, it is usually to avoid to fly through restricted areas, the reasons can be military or security (like avoiding nuclear installations).

Easily disproven by this. Start watching just a little before halfway.

[hotShot]

jdonn, on Feb 7 2009, 10:54 PM, said:

Hotshot, I'm fairly certain that your entire post was assumptions rather than facts, and that in fact each of your assumptions is wrong. There is nothing like 5 minuts of googling before you start jumping to incorrect conclusions.

hotShot, on Feb 7 2009, 03:29 PM, said:

I'm pretty sure that they are using GPS already.

Please show me where GPS is mentioned. Or you can just read the first sentence of this, which is also a great summary of the entire topic.
(Oddly enough, it points to delays as the number 1 reason for this entire system being explored. It's still not my number one reason!)

Take a look at:
Swiss ministry of air traffic (sorry the English link is not working)

Quote

Die Auswertung der GPS-Daten des Airbus 320 der Swiss, welcher am 8. August 2005 die künftige Route des Instrumentenlandesystems (ILS) auf die Südpiste 34 des Flughafens Basel-Mülhausen abflog, zeigen, dass das Flugzeug im Endanflug genau den vorberechneten Kurs einhielt. Die Daten aus dem Flugzeug bestätigen die Radaraufzeichnung der französischen Behörden. ...

It basically says that the GPS log from a plane in Basel in 2005, proved that it was on course. So "they" use GPS. Probably I don't mean the same people that you meant, but I'm still sure that the planes navigation uses/utilizes GPS.

If navigation and flight control both use GPS, you create a single point of failiure: The GPS system. The military authorities can distort the GPS system and I won't be surprised if one day some terrorist hacker could do that too.

[jdonn]

Ok sorry I guess? I thought when you said "they" are using GPS you meant the same "they" that I had been talking about, USA. I am certainly aware the technology exists, though I had no idea if any countries were using it already and if so which ones.

[WarrenL]

Rather than rampant speculation, there are pilot forums like this one for anyone interested in facts.

[barmar]

Delays presumably refers to departures and arrivals that are later than the published schedules, and the schedules already take the circuitous paths into account, so changing the paths is not likely to make a big difference in arrival delays. It will likely reduce the flight time, though.

[jtfanclub]

Military planes use GPS for steering.

Civillian planes do not.

The reason for the latter was originally because the military was afraid people would hijack or steal planes, set the GPS coordinates for the World Trade Center, turn on the autopilot, and parachute out. It's very easy to get exact GPS coordinates for a building (you can find them on the Internet). Trying to hit a building with a plane via dead reckoning is almost impossible. Obviously, this didn't stop the 9/11 terrorists, because they were willing to die in blowing up the WTC, but that's a lot tougher to stop.

There are other mechanisms in the civillian GPS signal to prevent it from being used for autopilots (especially with ICBMs).