New technology for Colorado

Everskyward

Everskyward

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Everskyward
http://www.aopa.org/advocacy/articles/2009/090924wam.html?WT.mc_id=090925epilot&WT.mc_sect=gan

A new surveillance system introduced in Colorado allows air traffic controllers to track aircraft in areas not covered by radar.
The new system, called Wide-Area Multilateration (WAM), requires no new equipment for aircraft and uses a network of relatively small sensors on the ground to pinpoint the location of aircraft in remote, mountainous regions. The sensors send out signals that are received and sent back by aircraft transponders.
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They've been talking about this for a while and it's now in operation. We'll see how well it works.
 
I'm thinkin' that the system isn't a big step in terms of technology. The method is already used to locate cellphones. As long as the data flow can be handled it should work reasonably well.
 
Clark1961 said:
I'm thinkin' that the system isn't a big step in terms of technology. The method is already used to locate cellphones. As long as the data flow can be handled it should work reasonably well.
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It should be much more accurate than traditional surviellience radar since it isn't dependent on the rotation of the interrogator antenna and is independent of the transponder turn around time. If ADSB wasn't coming along, it would make sense to replace all existing radar systems with this approach. A similar system is in use at many large airports to monitor aircraft position on the ground.
 
I'm pretty sure it will work technically, which is what everyone here addressed. I'm more interested in how well it will work in eliminating delays. :)
 
Well I can assure you that it won't cause me any delays.:D Izzat good enough?
 
Everskyward said:
I'm pretty sure it will work technically, which is what everyone here addressed. I'm more interested in how well it will work in eliminating delays. :)
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The goal is not eliminating delays, the goal is

"pinpoint the location of aircraft in remote, mountainous regions."
 
That reminds me of a short clip in the front of IFR magazine this month... an idea I'd actually thought of several times but didn't think it was technically feasible. I guess it is:

YOU CAN'T HEAR THE TRAFFIC COMING, BUT YOUR AIRPLANE JUST MIGHT

Ron Barret-Gonzalez, associate professor of aerospace engineering at the University of Kansas (KU), and graduate students have completed ground testing on an acoustic vector sensing system for detecting airborne traffic. In those tests, it tracked vehicles that ranged in size "from a full-size helicopter to a model plane, with accuracy of within less than one meter." That accuracy held true at a distance of more than six miles (10 km), according to KU. This technology has been used in underwater applications for years. The team hopes the final system will provide "pilots with accurate alerts" and "urge evasive maneuvers," and cost less than $10,000.
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DC uses a similar system of acoustic sensors on the roofs of buildings to determine where shots are fired. It's been used in at least one prominent case to prove that someone did fire first before the police returned fire, and has been shown to provide quicker and more accurate response than call-in reports alone.
 
TMetzinger said:
DC uses a similar system of acoustic sensors on the roofs of buildings to determine where shots are fired. It's been used in at least one prominent case to prove that someone did fire first before the police returned fire, and has been shown to provide quicker and more accurate response than call-in reports alone.
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You're right, Tim, it's an acoustic vectoring system. I found more info on the University's project: http://www.engr.ku.edu/news/2009-08-19/alert-system-perfected-ku-researchers-may-have-pre

Not sure how they'll adapt that to an aircraft, but I hope they can!
 
TangoWhiskey said:
You're right, Tim, it's an acoustic vectoring system. I found more info on the University's project: http://www.engr.ku.edu/news/2009-08-19/alert-system-perfected-ku-researchers-may-have-pre

Not sure how they'll adapt that to an aircraft, but I hope they can!
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Given the amount of local noise including the engine, prop, and relative wind, I'm having a hard time seeing how this could work well on an airplane. And while unlike TAS, it does work without the bogeys having any required equipment it's accuracy, especially in range, is likely to be pretty bad. And the price is projected to be about the same as active TAS.
 
midlifeflyer said:
Huh? :confused:
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That was a non-serious sideways comment on the wording of your post which could be interpreted to mean the location was known accurately because the "system" put the plane there. Yes it's a stretch and was totally in jest.
 
gismo said:
Given the amount of local noise including the engine, prop, and relative wind, I'm having a hard time seeing how this could work well on an airplane. And while unlike TAS, it does work without the bogeys having any required equipment it's accuracy, especially in range, is likely to be pretty bad. And the price is projected to be about the same as active TAS.
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Yes but superposition still applies, if you have a detector with enough dynamic range the bogey noise signature has the same amplitude regardless of any signal generated at the receiver. The wind noise is of completely different character so its probably "easy" to subtract and the receiver is generating the local propeller noise which gives you an edge in filtering it. I am just speculating but its similar to a problem I have encountered (sampling an EKG during an MRI acquisition).

The challenge I think would be what technology to use for the microphone.

Having said that if I were a VC, I wouldn't find the idea, its dumb.
 
What do folks think of ADS-B, or rather, what do you think of retiring primary radar as a cost savings to fund it?

I for one, still derive some measure of security from the fact that with a handheld walkie-talkie, I could receive enough instruction to execute a PAR, or ASR approach after every other light bulb had gone out.

I also am assuming that if all the vintage ARTCC computers conked out at once that there would still be some security in green lima beans on scopes being sheparded around with shrimp boats.

Is this un-necessary nostalgia?
 
twdeckard said:
What do folks think of ADS-B, or rather, what do you think of retiring primary radar as a cost savings to fund it?

I for one, still derive some measure of security from the fact that with a handheld walkie-talkie, I could receive enough instruction to execute a PAR, or ASR approach after every other light bulb had gone out.

I also am assuming that if all the vintage ARTCC computers conked out at once that there would still be some security in green lima beans on scopes being sheparded around with shrimp boats.

Is this un-necessary nostalgia?
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Out west that skin paint can be mighty tough to find. Since that's the case I see little advantage to keeping primary radar around. Maybe keep it to watch the Bravo and Charlie airspaces (so we can get a waiver when the transponder quits) but that's about it.
 
gismo said:
That was a non-serious sideways comment on the wording of your post which could be interpreted to mean the location was known accurately because the "system" put the plane there. Yes it's a stretch and was totally in jest.
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Ah. "Locating" as is putting it there v. "locating" as in finding it there. Very subtle. :smilewinkgrin:
 
twdeckard said:
Yes but superposition still applies, if you have a detector with enough dynamic range the bogey noise signature has the same amplitude regardless of any signal generated at the receiver. The wind noise is of completely different character so its probably "easy" to subtract and the receiver is generating the local propeller noise which gives you an edge in filtering it. I am just speculating but its similar to a problem I have encountered (sampling an EKG during an MRI acquisition).

The challenge I think would be what technology to use for the microphone.

Having said that if I were a VC, I wouldn't find the idea, its dumb.
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While I agree that acoustic signals including noise are additive (assuming as you said that there's enough dynamic range in the transducer) but wind noise is random and very broad spectrum and thus might be very difficult to subtract. And the sound from the airplane's own engine is likely to have the same signature as one from a distant airplane making them rather hard to separate. Also since the sound from an aircraft 3 miles away will be something like 30-50 dB lower than the sound from the local one the local noise needs to be attenuated by another 3-10 dB which is likely to be very tough to accomplish with any consistency. Might not be impossible but definitely not easy.
 
Clark1961 said:
Out west that skin paint can be mighty tough to find. Since that's the case I see little advantage to keeping primary radar around. Maybe keep it to watch the Bravo and Charlie airspaces (so we can get a waiver when the transponder quits) but that's about it.
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I'm gonna be rather surprised if all primary radar except for the TRACONS went away since that would mean any airplane that didn't want to be seen would just have to turn off their transponder.
 
Just to turn the thread back to the original discussion about WAM. I was one of the volunteer pilots who flew around the WAM service area at 1K AGL last winter for certification testing. We had a differential GPS on board to record our flight path and that was compared to the recorded radar track of Denver Center's radar. The test flight lasted several hours and I came away impressed with WAM's capability. The motivation for installing the system was that Hayden Apt. had lots of traffic but low approach flow (one in one out). During the winter they had significant delays. The airport authority talked the Colorado Aeronautical Board into funding the WAM system (design and installation). Ownership of the WAM system passed to the FAA when it was certified. The system allows 5 mile in trail separation to all traffic because the controller sees all aircraft including the aircraft on the airport surface. How this will translate to increased traffic flow in real weather will soon be known. My guess is the delays of the past few years will go away.

I was flying over Aspen today and watched the current system (non WAM) create some small delays on a slow day. An outbound jet was pulling the gear up as I passed over the airport. The next departure called the tower and was told he would be delayed until the arrival of an inbound. The inbound jet couldn't start the approach until the outbound appears on center's scope. All of this takes more time than you think. I got several photos and was headed east before the inbound jet landed, got off the runway and the waiting departure got his departure clearance.

Technology has certainly changed the way we operate in the mountains. Thirty years ago we thought it was daring to head for Rifle Apt. when it had a 3000' ceiling. Today with a properly equipped aircraft (RNP less than 1.0) and an authorized aircrew you can drop down to 300' AGL to have a look for the Rifle airport. All of this can be done while in radar contact. I wish someone had thought up WAM before the ADS/B system got started. The WAM system promises to provide a good level of service in the mountains without the significant cost of ADS/B.
 
Watertown airport in Wisconsin used to have a (TLS) Transponder Landing System for experimental purposes. It worked on the same principle but provided a feedback loop into a radio signal that your airborne receiver intrepreted as localizer feathers. If the ground based system computed you were left of course it adjusted its unidirectional signal so your airplane displayed left-of-course on the CDI. The system assigned you a transponder code and (obviously) could only provide guidance to one person at a time.

I had an instructor/mentor who was very enamoured with it becuase after I hemstitched several bad passes at it we could land and fetch a printout of my course on the approaches. Who knows, perhaps it was not the advent of GPS that doomed it but rather some engineers confusion at the unexplained sinusoidal signals in the triangulation algorithms ...

Todd
 
Walt said:
How this will translate to increased traffic flow in real weather will soon be known. My guess is the delays of the past few years will go away.
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Thanks for the insight, Walt. Since we (not just me personally but also the company I work for) do a lot of flights to these airports it will help a lot if many of these delays are at least shortened.

Walt said:
I was flying over Aspen today and watched the current system (non WAM) create some small delays on a slow day. An outbound jet was pulling the gear up as I passed over the airport. The next departure called the tower and was told he would be delayed until the arrival of an inbound. The inbound jet couldn't start the approach until the outbound appears on center's scope. All of this takes more time than you think. I got several photos and was headed east before the inbound jet landed, got off the runway and the waiting departure got his departure clearance.
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I think part of the problem at Aspen is that it's one way in and out. Is there enough separation between the approach and departure courses even if they had the new system? Telluride would be in the same situation.
 
You are right Aspen is always going to be a problem because it is a one way in, opposite direction out airstrip. WAM might help a little but not like the improvement in traffic flow they got in Rifle and Hayden.

A WAM constellation is being discussed for Southwest Colorado. It might be large enough to include Gunnison, Telluride and Durango. If current WAM constellations meet expectations you might see this happen in a few years.
 
Everskyward said:
Thanks for the insight, Walt. Since we (not just me personally but also the company I work for) do a lot of flights to these airports it will help a lot if many of these delays are at least shortened.

I think part of the problem at Aspen is that it's one way in and out. Is there enough separation between the approach and departure courses even if they had the new system? Telluride would be in the same situation.
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Without looking at the topology, it seems plausible that an aircraft departing Aspen could be vectored far enough out of the way of an incoming aircraft to allow both to have IFR separation at a fairly low altitude compared to the current system and I'm thinking the incoming aircraft might also benefit from vectors to final at a lower altitude than available now. That said, I thought there was a radar site on a nearby mountain that already provided coverage in the Aspen basin, am I remembering wrong?
 
gismo said:
Without looking at the topology, it seems plausible that an aircraft departing Aspen could be vectored far enough out of the way of an incoming aircraft to allow both to have IFR separation at a fairly low altitude compared to the current system and I'm thinking the incoming aircraft might also benefit from vectors to final at a lower altitude than available now. That said, I thought there was a radar site on a nearby mountain that already provided coverage in the Aspen basin, am I remembering wrong?
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You are right, there is radar at Aspen but I'm not sure how low it goes. Then in thinking about it, there is another problem. The missed approach procedure follows the same route as the normal departure procedure. Plus, I'm not really convinced that there is enough room in the valley for two airplanes which can't see each other, especially close in to the airport. As it is now when they are doing visual approaches and departures it feels a little bit like a game of "chicken".

As far as vectors to final at a lower altitude goes, the runway itself is aligned with some pretty high terrain as it is. If you are doing it visually you can drop down a little but that sometimes upsets the TAWS. If you slide the final further over to where the missed approach course is in order to be able to drop down lower there is there is no way to make the turn out of the valley.

http://naco.faa.gov/d-tpp/0910/05889LDE.PDF
http://naco.faa.gov/d-tpp/0910/05889LINDZ.PDF
 
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Everskyward said:
You are right, there is radar at Aspen but I'm not sure how low it goes. Then in thinking about it, there is another problem. The missed approach procedure follows the same route as the normal departure procedure. Plus, I'm not really convinced that there is enough room in the valley for two airplanes which can't see each other, especially close in to the airport. As it is now when they are doing visual approaches and departures it feels a little bit like a game of "chicken".

As far as vectors to final at a lower altitude goes, the runway itself is aligned with some pretty high terrain as it is. If you are doing it visually you can drop down a little but that sometimes upsets the TAWS. If you slide the final further over to where the missed approach course is in order to be able to drop down lower there is there is no way to make the turn out of the valley.

http://naco.faa.gov/d-tpp/0910/05889LDE.PDF
http://naco.faa.gov/d-tpp/0910/05889LINDZ.PDF
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AZE is where I experienced my first real mountain flying in the form of a mountain flying course there. It was a long time ago so my recollections are a bit hazy but I was thinking that visually it was acceptable to fly down the valley (roughly following the reverse of the departure procedure) and join the straight in final just south of the last ridge/peak. It seems to me that this would put you on final well before the MAP in the approach procedure and thus in plenty of time to make the right turn to exit back the way you came in. Prior to GPS it would have been difficult to fabricate an instrument approach along those lines but it seems like it would be a piece of cake now and would eliminate the long steep descent of the present procedure.
 
gismo said:
I was thinking that visually it was acceptable to fly down the valley (roughly following the reverse of the departure procedure) and join the straight in final just south of the last ridge/peak. It seems to me that this would put you on final well before the MAP in the approach procedure and thus in plenty of time to make the right turn to exit back the way you came in. Prior to GPS it would have been difficult to fabricate an instrument approach along those lines but it seems like it would be a piece of cake now and would eliminate the long steep descent of the present procedure.
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I think part of the problem is that in order to meet the standard missed approach climb gradient the MAP needs to be at that altitude. This is technically a circling approach since that final is so steep. Plus if someone was doing the approach over there by the departure course that would preclude having any departures... I would think anyway. Isn't that what we were originally talking about, having simultaneous arrivals and departures because of better radar coverage? There are some special approaches into KASE with lower minimums but I don't have copies of them so I can't say for sure what they are.
 
Everskyward said:
I think part of the problem is that in order to meet the standard missed approach climb gradient the MAP needs to be at that altitude. This is technically a circling approach since that final is so steep. Plus if someone was doing the approach over there by the departure course that would preclude having any departures... I would think anyway. Isn't that what we were originally talking about, having simultaneous arrivals and departures because of better radar coverage? There are some special approaches into KASE with lower minimums but I don't have copies of them so I can't say for sure what they are.
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I didn't mean to imply that putting a dogleg in the approach would allow lower mins, I agree that those are limited by the climb gradient issue. I was just thinking they could set it up so it didn't require a 6 degree slope to fly it. As to the simultaneous incoming and outgoing, I think that no matter what the approach path, the departure path will conflict with the missed approach procedure and the only thing that WAM could offer WRT that would be the ability to initiate an approach a tiny bit sooner after a departure.
 
TMetzinger said:
DC uses a similar system of acoustic sensors on the roofs of buildings to determine where shots are fired. It's been used in at least one prominent case to prove that someone did fire first before the police returned fire, and has been shown to provide quicker and more accurate response than call-in reports alone.
Click to expand...
I know at least KOAK uses such a system to correlate noise signatures of aircraft to ATC clearances. To wit: an aircraft is cleared for departure, a ground based sensor detects a noise exceeding the maximum db...violation recorded, notice with time stamp sent.
 
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