Is The FAA’s TIS-B Policy Killing Pilots?

Byssokol

Is The FAA’s TIS-B Policy Killing Pilots?

I hate to use a click-bait headline like that, but the recent news of yet another GA mid-air collision has me angry. Last summer a Cessna 150 and an F-16 collided near Monck’s Corner, South Carolina, killing the pilot and passenger in the Cessna. Two weeks ago a Cessna Caravan and a Piper cub collided in Alaska. Last week another mid-air, this time in Georgia, left three dead. Mid-air collisions are relatively rare but invariably draw the attention and condemnation of the press – something GA definitely does not need.

The recent spate of articles made much of the fact that these accidents occurred at or near “uncontrolled” airports. As pilots we all understand that “uncontrolled” does not mean “out-of-control” or “free-for-all.” The traffic rules and standard practices usually make operation at an uncontrolled airport quite safe. The general public does not understand this. Perhaps more than any other type of accident, mid-air collisions instill a fear of general aviation in the minds of the non-flying electorate. Two pilots failed to maintain visual separation. Two planes were destroyed. Multiple lives were lost. It’s not a pretty picture.

Sadly, many (most?) of these accidents could be avoided with an inexpensive traffic receiver and a comprehensive feed of local traffic. The FAA has the data. ATC radar installations all across the country collect, digitize, and forward a constant stream of real-time traffic. The information is passed to ADS-B ground towers which uplink it as TIS-B (traffic information service – broadcast). This sounds like a potential solution to the problem and it is – if your aircraft is equipped with ADS-B Out. If not, you get either a partial picture (if someone nearby has ADS-B Out) or nothing at all.

This is wrong. It verges on criminal. The FAA’s mandate is aviation safety. The only reason they exist is to make aviation safer. So why don’t they simply broadcast a comprehensive stream of traffic data? Because their current policy is to use TIS-B as a bonus or “carrot” for those who chose to equip with ADS-B Out before the 2020 deadline. This policy may very well be killing pilots, passengers, and bystanders.

I don’t know if any of the pilots involved in the recent mid-airs were using an EFB application, but given how pervasive they have become it is entirely possible. Had any of them been receiving traffic updates it is possible – even likely – that they would have detected and avoided the other aircraft. Yes, they may have been too low to have been receiving ADS-B. Yes, they may have been too low to be visible to any ATC radar. However, in the F-16/C-150 crash, both aircraft were visible to ATC and within 21 nautical miles of an ADS-B ground station making it very likely that they would have had coverage.

The change is apparently not simply a matter of flipping a switch. Originally there was some concern that the amount of data involved in comprehensive traffic broadcast could overwhelm the ADS-B network, compromising safety. According to a source at AOPA, research by an FAA / industry task force debunked this concern. The group reviewed the technical challenges involved and found that uplinking all traffic visible to ATC would not overload the available bandwidth, nor would it place an impossible burden on the towers or the network infrastructure that connects them. The change would require software be revised to provide coverage zones for the towers rather than coverage “pucks” for client aircraft.

If you happen to belong to any of the “alphabet” organizations – AOPA, EAA, NBAA, etc. – please contact their advocacy team and demand that they make opening TIS-B a priority. There is no reason for mid-air collisions to happen in 2016.

Contacts

EAA – Sean Elliott – VP of Advocacy & Safety: Email Now

AOPA – Jim Coon – Senior VP of Government Affairs and Advocacy: Email Now

NBAA – Dick Doubrava – Vice President, Government Affairs: Email Now

NBAA – Christa Fornarotto – Vice President, Government Affairs: Email Now

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5 Comments so far

Dave WatkinsPosted on  9:26 pm - Sep 17, 2016

What kind of coverage can one expect in Canada, I am located at CPU6 near Trenton CYTR, on the north side of Lake Ontario, I fly mostly between Toronto and up as far as Ottawa, thanks Dave.

    ssokolPosted on  12:54 pm - Sep 19, 2016

    Hi Dave,

    The towers can reach between about 100 miles (for low power) and 200 miles (for high power) at higher altitudes. The signals are line-of-sight, so you have to be high enough to “see” a tower from your spot in the sky to receive any data. At Trenton you’re about 65 nm from the nearest tower, so I suspect you would need to be at 4000′ – 5000′ (total guess) to receive tower data.

    You might post this on the forum (support.openflightsolutions.com) and see if any Canadian pilots care to share their experiences.

    Thanks,

    Steve

Capt. Al Blakely CD (ret’d)Posted on  3:47 am - Sep 20, 2016

Hi Steve:

You are absolutely correct in saying that it is boardering on criminal to not provide flight safety technology to General Aviation. It shoul be broadcast to anyone with an ads-b in capability. In Canada, NavCan has absolutely no intention of allowing the GA community to connect to their new Areon satellite system. This is against their mandate of providing air traffic services to clients in Canada, wether they be the airlines or not. The technology is there, why not use it. It is criminal not to make it available. NavCan is a not for profit company and they must recoup their costs. The majority of us understand this. We have to pay for everything in aviation anyway (that’s why we pay a yearly fee). So to not make it available, for free or any reasonable cost is truly too bad. So much for them preaching flight safety, when a big part of that will never be made available.

JPCPosted on  9:58 pm - Oct 17, 2016

Hi Steve,

Good post. Why no blanket data coverage without ADS-b out? Or, said another way, why require ADS-b out to get TIS-B data for the area around me?

The answer is more nuanced than is obvious at first glance. First of all, we can all agree the TIS-B service is critical and valuable to every GA plane in the air. However, while the FAA bureaucracy has done a poor job of explaining why they don’t support it, without ADS-b out to trigger it, there is more than a carrot-to-comply at work here.

In a word it is bandwidth. The amount of data the 978 channel can reliably send is fairly large, but not unlimited. In a congested area there is a real concern blanket transmitting all traffic data *for the entire reception area* will quickly overload the system. The key point is the entire reception area. Rural areas nearby metro area can depend on their data from metro transmitters.

For you network techies, consider the risk of network saturation in a busy UDP only network, with one collision domain (think hub in the 1990’s). Remember all airliners plus GA ADS-b out sends a traffic update once per second, into one or both bands.

For non techies consider this scenario: The San Francisco Bay Area is extremely congested. Just north, still using many of the same (978) TIS-B ground transmitters, quickly transitions to rural and fairly devoid of traffic (compared to the metro SF area). When I fly north, out of the bay area, I get traffic and other weather/tactical data for my route of flight. This “extra” data is only sent for my use, for the 30 minutes or so I am transitioning north out of the area. The rest of the twenty-three and a half hours in the day my “extra” data is not clogging the band.

Almost certainly this additional data is of relevance me, and maybe only a couple of other airplanes, at that moment. The vast majority don’t need it. If TIS-B was to blanket transmit without knowing who was listening (via ADS-b out) the data relevant to a few, will be blasted to everyone. So the plane near San Jose, landing, will be receiving data useful only to planes in a hundred mile (or more!) circle. Quickly we will run out of bandwidth. As it stands now many networking experts have warned for years the Los Angeles basin (for example) will saturate on good weather weekends with all the GA traffic, and note this is with the bandwidth savings ADS-b-Out provides!

I have no doubt some genius in the public relations department at the FAA seized on the carrot angle to push us all to do what suits them. That said the question of bandwidth is no doubt the key driver for the network architects; unfortunately, the lack of transparency in the FAA is preventing this valid argument from the network architects trickling down to pilots, who are smart enough to understand and perhaps help steer the conversation.

Finally, I would like to point out architecting this sort of a wireless network is very-very-complex to stay inside the limits of the *chosen technology*. As such I think we should all treat this like an ever changing beta-test (can’t trust, give feedback-loudly!) until 2020. I also want to encourage this sort of discussion to achieve a consensus of understanding that will allow folks like Steve, and all the avionics manufacturers, to begin to steer the deployment and architectural choices more effectively.

P.S.: for any ham radio operators that have used APRS, clearly the FAA lifted the entire architecture wholesale from us inventive hams! Which explains why such poor privacy and encryption is implemented; hams are not allowed privacy or encryption, and the FAA has yet to figure out they should do so for ADS-b. Ham operators that have used APRS are in a good position to explain what we have learned about bandwidth utilization after decades of experimenting: for more information contact your local ham and ask them about it!

John P.Posted on  11:17 pm - Nov 28, 2016

Hams got the technology from the same place aviation did, namely addressable cable TV boxes from as far back as the ’80’s!!

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