Author Topic: Mode-S ADS-B  (Read 49514 times)

Offline BMT

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Mode-S ADS-B
« on: October 10, 2008, 01:29:16 PM »
How will Mode-S help ATC??

BMT



Offline pgarside

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Re: Mode-S ADS-B
« Reply #1 on: October 10, 2008, 03:48:14 PM »
Mode S tansponders offer everything that Mode C transponders are capable of with the addition of offering ACAS II.  Thus, it doesnt necessarily give the controler any extra information to work with, but could help eliminate mid-air collisions.

Many G1000 equiped airplanes now come with Mode S.  On the multifunction display I can see up to I believe 8 airplanes within about 5 miles.  It gives a good idea of what direction the plane is traveling as well as altitude in relation to my airplane.

Offline goowe

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Re: Mode-S ADS-B
« Reply #2 on: October 11, 2008, 12:12:31 AM »
I don't know much about this technology, but I do have a picture from the ADS-B panel in the planes our school flies...

http://www.facebook.com/photo.php?pid=30103766&l=17e00&id=1411492282

This was taken in a C172 on approach to 7L at KDAB (Daytona Beach Intl) with two airplanes (the triangles) in front of us and a whole bunch on the ground. A few minutes earlier you could see all of the aircraft (four or five!) on final in front of us... it was very neat to watch the controller vector traffic from the airplane's ADS-B display...

Offline pgarside

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Re: Mode-S ADS-B
« Reply #3 on: October 11, 2008, 12:27:27 AM »
The only thing is that there shouldnt be any planes on the ground being displayed.  The system works by basically 'stealing' the information from a radar facility.  Therefore, it would not be able to pick up any planes on the ground as they would not be visible to the radar facility.  I believe it is rated to work above 500 AGL, even though radar would pick up airplanes below that. 

Very cool though to see the planes lined up for final, I have never seen that from the airplane before.

Offline goowe

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Re: Mode-S ADS-B
« Reply #4 on: October 15, 2008, 04:50:32 PM »
"ADS-B uses satellite navigation and datalink to enable an aircraft to broadcast its identification, position, altitude, velocity, and intent to every other aircraft in the vicinity as well as to the ground tracking system. This broadcast information may be received and processed by other aircraft or ground systems for use in improved situational awareness..."
Commercial Aviation Safety, Fourth Edition

I don't think the ADS-B steals any information :-\

I know we've been taxiing on the ground before, with the ADS-B display zoomed in and you can see all other aircraft currently squawking on the ground.

Offline skyguard81

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Re: Mode-S ADS-B
« Reply #5 on: October 29, 2008, 06:27:15 AM »
Those Aircrafts equiped with mode S or TCAS have a touchdown relay so the transponder stop transmiting after landing and it would be invisible on radar screens

Offline KSYR-pjr

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Re: Mode-S ADS-B
« Reply #6 on: October 29, 2008, 07:30:39 AM »
Those Aircrafts equiped with mode S or TCAS have a touchdown relay so the transponder stop transmiting after landing and it would be invisible on radar screens

The "ground mode" on a mode S transponder can also be enabled via a speed limit.   My Garmin GTX330 modes S transponder is one such unit where the speed limit of ground mode is set at (IIRC) 40kts.  When the aircraft accelerates across 40kts the transponder automatically switches to full on and when it decelerates across 40kts it automatically switches to ground mode.

One question I have, though, is if this ground mode does appear on the ground radar that some airports have.  I never investigated that but I should.

edit: Changed a strange typo to its real-world counterpart and then took a drink of coffee to remove the cobwebs
« Last Edit: October 29, 2008, 08:44:31 AM by KSYR-pjr »

Offline MathFox

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Re: Mode-S ADS-B
« Reply #7 on: October 29, 2008, 07:56:38 AM »
One question I have, though, is if this ground mode does appear on the ground radar that some airports have.  I never investigated that but I should.

I have found some "operational guidance" in for EHAM in the AIS: http://www.ais-netherlands.nl/aim/080911-081023/eAIP/html/eAIP/EH-AD-2.EHAM-en-GB.html#ssid-1109062702246 (URL valid as long as it lasts)
Quote
Schiphol Airport is equipped with a mode S surface movement system. Aircraft operators should ensure that the mode S transponders are able to operate when the aircraft is on the ground according to ICAO specifications (Annex 10, volume IV, 3.1.2.8.5.3 and 3.1.2.10.3.10).
[...]
Activation of the mode S transponder means selecting AUTO mode, ON, XPNDR, or the equivalent according to specific installation. Selection of the STAND-BY mode will NOT activate the mode S transponder. Depending on the hardware configuration, selecting ON could overrule the required suppression of SSR replies and mode S all-call replies when the transponder is on the ground.

To ensure that the performance of systems based on SSR frequencies (including airborne TCAS units and SSR radars) is not compromised; TCAS should not be selected before receiving the clearance to line up. For arriving aircraft, TCAS should be deselected as soon as possible after vacating the runway.

Offline KSYR-pjr

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Re: Mode-S ADS-B
« Reply #8 on: October 29, 2008, 08:46:08 AM »
Thanks for that.  It seems from that text that in the Garmin transponder's case that this ground mode may indeed be contradictory to an airport's need to have the unit remain on while on while taxiing.

Offline Jason

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Re: Mode-S ADS-B
« Reply #9 on: October 29, 2008, 12:16:43 PM »
Thanks for that.  It seems from that text that in the Garmin transponder's case that this ground mode may indeed be contradictory to an airport's need to have the unit remain on while on while taxiing.

It's my understanding that you have to squawk mode C at those airports advertising the use of ASDE-X on the ATIS, or as charted on the airport diagram.  I'm fairly confident that the ground mode doesn't transmit any signal(s)...simply a squat-switch controlled standby function.

Best,
Jason

Offline KSYR-pjr

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Re: Mode-S ADS-B
« Reply #10 on: October 29, 2008, 12:24:45 PM »
It's my understanding that you have to squawk mode C at those airports advertising the use of ASDE-X on the ATIS, or as charted on the airport diagram.  I'm fairly confident that the ground mode doesn't transmit any signal(s)...

Very good.  Thanks.

simply a squat-switch controlled standby function.

Or a speed controlled stand-by function.  :-)

Offline Unbeliever

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Re: Mode-S ADS-B
« Reply #11 on: November 01, 2008, 08:38:06 PM »
Thanks for that.  It seems from that text that in the Garmin transponder's case that this ground mode may indeed be contradictory to an airport's need to have the unit remain on while on while taxiing.

But you can always hit the "ALT" button and turn it back on, manually. 

--Carlos V.

Offline BMT

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Re: Mode-S ADS-B
« Reply #12 on: December 26, 2008, 06:44:58 PM »
FAA begins to roll out air traffic control system

By Gautham Nagesh gnagesh@govexec.com November 24, 2008
After years of development and testing, the Federal Aviation Administration announced on Monday that it plans to begin deploying a nationwide air traffic control system that tracks aircraft by satellite rather than radar.
Urged by an executive order issued by President Bush last week, the switch from testing to roll out of the new technology marks the first step in the agency's ambitious program to overhaul the nation's air traffic control system. FAA claims the Automatic Dependent Surveillance-Broadcast system reduces the risk of mid-air collisions and weather-related accidents by giving pilots in the sky access to the same satellite and weather information that air traffic controllers view from their seats in towers.
"The next generation of air travel has arrived," said FAA acting Administrator Robert Sturgell in a release sent out on Monday. "ADS-B is the backbone of future air traffic control."

"Today's decision is the green light for nationwide deployment of ADS-B," said FAA spokesman Paul Takemoto. "This is the first step in making NextGen a reality."

FAA plans to deploy all ground stations by 2013. By then, the agency will provide satellite coverage in all areas where radar exists -- and in some places where no coverage is available, including the Gulf of Mexico and Alaska, Takemoto said.

http://www.govexec.com/dailyfed/1108/112408n1.htm

Offline sykocus

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Re: Mode-S ADS-B
« Reply #13 on: February 01, 2009, 02:19:47 AM »
How will Mode-S help ATC??

BMT

I've read that some facilities in the UK have secondary radar that interrogates mode-s.  Things like the assigned altitude entered into by the autopilot, magnetic heading and indicated airspeed can be displayed in the data tag. Neat stuff, but nothing you can't live without.

Offline captray

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Re: Mode-S ADS-B
« Reply #14 on: February 28, 2009, 12:37:17 PM »
Ok all that sounds good but I am here to tell you that it is a matter of installation. Whether or not the Mode S is on. In the G4 that I fly, with Mode S, the nutcrackers (squat switch) has nothing to do with the transponder. It's selected by the pilot only. This was also true in a Hawker that I flew that had Mode S.

Offline pacallen

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Re: Mode-S ADS-B
« Reply #15 on: March 09, 2009, 12:15:58 AM »
The only thing is that there shouldnt be any planes on the ground being displayed.  The system works by basically 'stealing' the information from a radar facility.  Therefore, it would not be able to pick up any planes on the ground as they would not be visible to the radar facility.  I believe it is rated to work above 500 AGL, even though radar would pick up airplanes below that. 

Very cool though to see the planes lined up for final, I have never seen that from the airplane before.

As long as the plane is being picked up by a radar facility, the ADS broadcast will transmit the locations of transponder equipped planes squawking alt, regardless if they are on the ground or not. Most of the time, however, they aren't picked up because they are below radar coverage.

ADS-B and Mode S transponders are fantastic (though its coverage is a bit spotty further away from radar facilities, especially down low)! It's almost unnerving how much traffic goes unnoticed during normal VFR flight!

Offline Casper87

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Re: Mode-S ADS-B
« Reply #16 on: March 18, 2009, 04:27:38 PM »
How will Mode-S help ATC??

BMT

I've read that some facilities in the UK have secondary radar that interrogates mode-s.  Things like the assigned altitude entered into by the autopilot, magnetic heading and indicated airspeed can be displayed in the data tag. Neat stuff, but nothing you can't live without.

Correct. Only LTC have it at the moment, as far as I know. Mode S will give all sorts of info including displaying the callsign of the aircraft independant of SSR code/callsign conversion, as long as the Mode S is set up correctly.
To be fair, more level busts have been prevented thanks to the SFL being displayed to the controllers.

C