ADS-B Out rule published 28 May 2010

[Bob Noel]

Its a bit disappointing that there is no anti-spoofing, but I can see how it might be nearly impossible to implement a fool-proof anti-spoofing scheme.

I'm guessing most of the major metro areas are going to have to have radar systems to ensure that there are no spoofed (read hijacked) planes flying around pretending that they are somewhere else.

If there is radar coverage, what's the benefit of ADS-B?

 

[Joe B]

If there is radar coverage, what's the benefit of ADS-B?

A huge percentage of FAA radar sites have two pieces of gear: the primary radar and the "secondary surveilance radar". The SSR is the beacon system that talks to transponders. The FAA's plan is to save themselves a boatload of money by decomissioning about half of the SSR's.

The FAA also claims that they can use ADS-B to reduce separation in the enroute and terminal environments. With the radar-based systems Centers can't let planes at the same altitude get closer than five miles to each other. It's three miles for Approach Controls. These distances are dictated by the resolution of the radar equipment at its maximum range. ADS-B's position information is range-independent and should allow a tighter and uniform set of separation standards throughout the country. In practical terms it'll help with aircraft passing each other and, perhaps, crossing. Large aircraft following each other in trail already are limited by wake separation.

 

[mikea]

If you had any idea how easy it is to jam or spoof a GPS, you wouldn't want one as sole nav source. Seriously.

And the same sort of thing applies to ADS-B. Use the right coding and it's pretty easy to spoof an aircraft.

I do and I totally agree. Jamming is easy and occasionally happens by accident. Not sure about the spoofing though. It is easy to create an imposter GPS signal, but to create say 5 signals, that have the right relative offsets to cause a receiver to make an incorrect solution that will actually cause some sort of damage is pretty advanced. I've not yet seen anything out in the general market that can do that.


I agree the spoofing would be easy. I'm just not sure what the point would be. You could hide whatever you are really doing (hijacking, drug running, visiting the mistress, an extra $100 hamburger), but I'm not sure that it would be a huge risk to air traffic in general.

My guess is there would be no need to do anything with the GPS while the link between the GPS and the transponder is a serial cable. You'd just need to run a 12 line script on a laptop that has a serial port.

 

[John Collins]

My guess is there would be no need to do anything with the GPS while the link between the GPS and the transponder is a serial cable. You'd just need to run a 12 line script on a laptop that has a serial port.

Conceptually true, but the only documented interface is an ARINC 429 with ARINC 743A labels for a position source. This would involve another piece of hardware, a device driver, and a more sophisticated program than a 12 line script on a laptop.

Regardless, spoofed ADSB position reports can be detected in a variety of ways, for example using radar or trilateration or time of arrival of the message at ADSB sites.

 

[Cap'n Jack]

Regardless, spoofed ADSB position reports can be detected in a variety of ways, for example using radar or trilateration or time of arrival of the message at ADSB sites.

Was the spoofing question that of a spoofed location, or a spoof indicating one aircraft was really another one? Your answer clearly covered ways to detect a location spoof.

 

[John Collins]

Was the spoofing question that of a spoofed location, or a spoof indicating one aircraft was really another one? Your answer clearly covered ways to detect a location spoof.

I can understand wanting to be anonymous, but I am not quite sure what the point of a spoof indicating one aircraft was really another one, but this can easily be done in a radar or ADSB environment.

 

[Bob Noel]

Conceptually true, but the only documented interface is an ARINC 429 with ARINC 743A labels for a position source. This would involve another piece of hardware, a device driver, and a more sophisticated program than a 12 line script on a laptop.

Regardless, spoofed ADSB position reports can be detected in a variety of ways, for example using radar or trilateration or time of arrival of the message at ADSB sites.

A real benefit of ADS-B would be situational awareness in the cockpit
without relying on ATC. However, false position reports cannot be
detected by any other aircraft.

When I talk about the lack of ADS-B validation, I'm thinking about
scenarios without radar coverage (after all, if there is sufficient
radar coverage, ADS-B doesn't provide much)

 

[gismo]

There are 406 ELT with GPS built in for 1360.00 right now.

http://www.aircraftspruce.com/catalog/avpages/aircraftspruceelt.php

I can't believe that the cost of adding a GPS to transponder would cause a price point much higher. There is no user interface and all the GPS has to do is give present postion, pretty easy from a software point of view. ( with a GPS chip of course )

It's going to be pretty much all certification cost. You can buy a decent WAAS receiver/antenna in a waterproof case for around $50 from Garmin right now (I have four of them). 3

 

[sba55]

A huge percentage of FAA radar sites have two pieces of gear: the primary radar and the "secondary surveilance radar". The SSR is the beacon system that talks to transponders. The FAA's plan is to save themselves a boatload of money by decomissioning about half of the SSR's.

That answers my question and it's great news. So they're only planning to decommission the SSRs. I was afraid that they were planning to get rid of primary radar as well, which is very ill-advised for lots of reasons...

 

[jtheune]

It's going to be pretty much all certification cost. You can buy a decent WAAS receiver/antenna in a waterproof case for around $50 from Garmin right now (I have four of them). 3

Now I'm not a expert in this area but I would think that the location information for a ELT would have met the certification requirements the same as for a transponder system

 

[gismo]

Now I'm not a expert in this area but I would think that the location information for a ELT would have met the certification requirements the same as for a transponder system

I expect that the certification requirements for ELT position sources are minimal. The consequences of a position error or complete failure on a ADS GPS are far more severe than for an ELT.

 

[John Collins]

I expect that the certification requirements for ELT position sources are minimal. The consequences of a position error or complete failure on a ADS GPS are far more severe than for an ELT.

Lance,

I believe you are correct. An ELT can use a non WAAS GPS source and the only data required is the Lat/Long as can be obtained from the Garmin Aviation protocol. The ADSB position source requires the information in the ARINC 743A protocol and to meet the performance criteria, the only available choice today is a WAAS GPS.

However, I also agree with the posters unstated point that if a GPS can be embedded in an ELT, it can also be embedded in a transponder or an antenna. The functional differences are programming, not primarily hardware, although the hardware has to be fast enough to provide updates of position at a 5 HZ rate.