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So, looking at TSO C154c and AC 20-165, the difference between SIL 3 and SIL 0 precision is as outlined in the table from the AC:
AC 20-165 Figure 7. Probability of Exceeding the NIC Containment Radius. SIL Value Probability of exceeding the NIC containment radius 3 ≤ 1x10-7 Per Hour or Sample 2 ≤ 1x10-5 Per Hour or Sample 1 ≤ 1x10-3 Per Hour or Sample 0 > 1x10-3 Per Hour or Sample or Unknown And, it would appear that the manufacturer, by changing the transmitted SIL value from "0" to "3" in the software change, is implying that its non-approved GPS position source has demonstrated that level of precision. So it would seem that the basic question is whether or not the position source actually has demonstrated that performance requirement as required by the TSO. |
Has anyone heard anything out of Navworx or FAA lately on status of AD? Any sign of possible resolution or compromise for the 600 EXP units?
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Currently we are waiting on the resolution of the AD on or about December 20th. Based on the final AD, the AD may be rescinded, or the AD may be modified to allow for just previously approved GPS sources. I wouldn't expect to hear any updates from Bill until the first of the year. |
600 EXP units
I too have the exp model. I sent Bill a message on Nov 2nd asking about the exp model since it wasn't mentioned in their letter on their website and received this reply:
"We're working that now in case the EXP stays on the AD , but it shouldn't as it meets the FAA policy and performance requirements for experimental aircraft." Bill Moffitt I didn't really understand the response because the exp met the performance requirements when it was first placed on the AD list by the FAA! |
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Would sure like to see someone state the facts so I can formulate a response to the AD that is based on fact and not hearsay & guesses. Does Navworx have the supporting information that indicates the TSO requirements have been met? Or the the FAA concluding it does not because a specific GPS chipset was not used. The recent midair collisions that have made news in recent weeks could have been avoided with a GPS accurate to hundreds of feet. An accuracy of a few feet would not have provided any more useful information to those that perished. |
Agree that the information is limited at best to be able to respond to the AD. I would like to respond that the ADS 600 Exp unit should be dropped from the AD due to the fact that the FAA accepted the performance of that unit some time ago as per Navworx,and can be installed on an experimental ,But haven't done that yet due to lack of info.
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My Navworx AD Response
I am listing my response here and soliciting ALL to submit a comment on the FAA website.
https://www.regulations.gov/docketBr...=FAA-2016-9226 The National Transportation Safety Board issued a Safety Alert Nov. 15, 2016, to pilots with suggestions on what they can do to reduce their chances of being involved in a midair collision. SEE and AVOID ONLY GOES SO FAR. Two recent mid-air collisions exemplify this point. On July 7, 2015, a Cessna 150 and an F-16 Air Force fighter jet on a training mission collided. An air traffic controller advised the F-16 pilot that the Cessna was a potential traffic conflict. The F-16 pilot was not able to visually acquire the Cessna until it was too late to avoid the collision. The two occupants of the Cessna were KILLED; the F-16 pilot ejected and survived. On Aug. 16, 2015, a North American Rockwell Sabreliner inbound for landing a Cessna 172 that was practicing landings at the same airport collided. The four occupants of the Sabreliner and the sole occupant of the Cessna were KILLED. The Safety Alert highlights the value of traffic avoidance technologies to pilots as an aid to detecting and avoiding other airplanes in flight. The proposed AD is clearly CONTRARY to this NTSB recommendation. AND is contrary to the desires of the FAA to equip most if not all with ADS-B out. AND is contrary to the NSTB 2017-2018 MOST WANTED LIST. The first listed HERE is to INCREASE IMPLEMENTATION OF COLLISION AVIODANCE TECHNOOGY. Many have purchased the Navworx ADS-B transceiver because it was listed by the FAA as a unit approved and eligible for the rebate. The proposed AD mandating removal, months after, makes many VERY unhappy. In addition, the cost to the Navworx owner as listed in the proposed AD is in error. The cost to the owner should not only include a reasonable estimate of the A&P removal cost (4 hours at $80/hour) but should also include the cost of a new ADS-B transceiver and its installation costs. I fly with the Navworx ADS-B transceiver installed. After flying with this equipment for 9 months, it clearly provides me with a very much desired safety margin. I fly in VFR conditions and my experimental aircraft is NOT IFR equipped. FAA?s concern appears to be with the accuracy of the Navworx reported GPS position. I DO NOT, nor do I believe many others need an accuracy of inches or a foot. This is clearly a case where engineers developed a set of specifications and did not use any engineering judgement whatsoever, nor did they consider the multitude variations where the ADS-B out units could be installed. (Certified vs. Experimental, VFR vs. IFR, etc., Light planes vs. those that utilize Class A airspace.) The FAA must reconsider the ramifications of the proposed AD and either cancel it or revise it. If I am forced to disable and remove the Navworx equipment, the probability of me being involved in a mid-air collision has increased many-fold. |
Navworx ADSB...comments to FAA
Here are the comments I posted on the FAA site:
" 1. This Proposed rule will decrease MY Safety!! Without the Navworx ADS600 I will be unable to see other traffic. 2. I rely on my unit to spot VFR traffic and it has already avoided several significant traffic conflicts. Without ADS-B readout in the busy airspace I fly (San Francisco Bay Area) my safety and the safety of my passengers is significantly degraded!!! 3. The estimate of this AD costing only $85 is not based in reality. I have over $8000 of parts and labor invested in my adopting the required ADS-B out requirement and it will cost at least $500 to remove the unit and another $500 to reinstall the Navworx assuming they modify it for free. If I have to buy a new unit that's at least $2500 more. So at a minimum, this Proposed rule will cost me $$1,000 hours and at most $11,500. 4. The proposed rule does not quantify the safety risk of continued operation with the subject hardware. I believe it must be very small, so if the proposed rule must move forward, I would suggest a reasonable period of time to comply with the rule...not "remove the hardware immediately". I would suggest 1 year from AD issue? 5. I suggest that the proposed rule address VFR and IFR use separately. I believe the time to reach compliance for "use only in VFR conditions" should be one year as a minimum and maybe should not even apply to VFR only use!" Bob Cowan RV-7a, 400 +hrs |
800 units effected?????
This AD is supposed to affect only 800 aircraft!!! That's a lot of airplanes! One additional thought to consider is this.... That's 800 units alone... there are untold folks flying with the benefit of just the ADSB IN. So, if each of the 800 affected aircraft is always sending a signal to another 3-5 airplanes in their umbrella of coverage then the much truer number is something like an ADDITIONAL 2400 to 4000 aircraft on top of the 800! I understanding this is speculation. I thought of this after a chat with my hanger neighbor who has just ADSB in. Sometimes he's piggybacked on me so if I'm not ADSB out equipped that's me and another plus an unknown amount more affected. Food for thought.
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I've been trying to get up to speed on the actual argument of this AD and having a ADS600-EXP P/N xxxx 8013 that's specifically named in the AD, I have a horse in this race. Asking all who have this model installed to go back and take a look at the FAA compliance report data on your original install. Looks like page 5 has the meat on it as to accuracy and SIL and SDA which is all the talk of this AD. First of all the report was 100% compliance as per the FAA. But I was interested in just what the accuracy was /is.
Of all the arguments in this AD my ADSB was reporting well within the requirement of TSO that being .05nm or 304 ft called NACp !! it actually was (better than TSO ) under 98.5 feet 100% of the sample both times. 2455 data points on one test and 1780 points on the other it was 100% under the bracket of < 30meters!!!!! ie 100% compliant!! The SIL level was shown as reporting 2455 data points and 1780 points respectively ( on the two test) at < 1x10-7 which is at a level of SIL=3 interesting to note none at lower levels. ie 100% compliant!! The SDA was reported again both test at a level 2 100% of the time ie 100 % compliant!! By Performance Std set in the TSO it appears to me to meets all Performance Standards of the TSO and that are measured by the FAA . So whats this all about concerning the 600 EXP model. I have no info on the other models. I would like to see a plot of others data concerning the questionable parameters but it will take someone smarter that me to plot that out correctly. I will volunteer my data if any takers. Its already public knowledge!! At any rate go back and see what your 600EXP was reporting out at I bet you find it is 100% compliant. |
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That report has no idea what the pedigree of your position source or the SDA of the device actually is.... |
So how or who would be able to measure those values ie SIL and SDA if it's not a measurable value? Assume the horiz boundry numbers are actually the measured performance they are talking about. Then I'm confused on how an installation can demonstrate " MEETS PERFORMANCE" without being TSO d via a pedigree from the mfg.
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Manufacturer.... they would have to ensure their equipment meets TSO... it doesn't have to be certified, but proper tests need to be done to ensure it meets TSO.... and manufacturer pencil-whipping it is a no-no in FAA's eyes.
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Source Integrity Level (SIL) indicates the probability of the reported horizontal position exceeding the containment radius defined by the NIC on a per sample or per hour basis, as defined in TSO-C166b and TSO-C154c. System Design Assurance (SDA) indicates the probability of an aircraft malfunction causing false or misleading information to be transmitted, as defined in TSO-C166b and TSO-C154c. I think the above are actually calculations based on some measurements rather than a measured value, after all they are just probabilities. :) |
FAA Emergency order suspends -012, -013
Just in directly from the FAA
Interesting - doesn't mention the -EXP units - which if I understand correctly contain the same GPS hardware as the -012 and -013 units. |
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Thanks - I was trying to figure out how to do that!
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FAA logo
Press Release For Immediate Release Date: November 22, 2016 Contact: Lynn Lunsford Phone: (817) 222-4455 Email: lynn.lunsford@faa.gov You are subscribed to News updates for the Federal Aviation Administration. A new Press Release is now available. We've included a copy of the release in this email. FORT WORTH, Texas – The U.S. Department of Transportation’s Federal Aviation Administration today issued an emergency order suspending the authorization NavWorx Inc. uses to manufacture certain Automatic Dependent Surveillance-Broadcast (ADS-B) navigation units. Such units, when properly manufactured and operated, help to improve the safety and efficiency of aircraft operations. The authorization, known as a Technical Standard Order Authorization (TSOA), enables suppliers to produce components for use on aircraft after proving that each component meets FAA standards. Federal regulations set forth FAA’s authority to inspect suppliers’ quality systems, facilities, technical data, and products to determine whether they meet safety standards. These regulations also provide that FAA may witness any tests necessary to determine a product’s compliance. The suspension order was issued after NavWorx declined on repeated occasions to allow FAA personnel to conduct the required inspections. The suspension is immediate and will remain in effect until NavWorx consents to the inspections and demonstrates compliance with FAA standards. The FAA is concerned that two versions of the company’s ADS600-B units, carrying part numbers 200-0012 and 200-0013, may contain an internal Global Positioning System (GPS) chip that does not meet the FAA’s minimum performance standards for transmitting an aircraft’s accurate location. On June 29, the FAA requested to inspect NavWorx’s facility to determine the specific GPS unit and software installed in part numbers 200-0012 and 200-0013, and if the units are marked correctly. NavWorx informed the inspector that he would not be allowed inside the company’s facility. During subsequent correspondence, NavWorx agreed to allow an Aug. 31 inspection but then denied access when FAA inspectors arrived. NavWorx later agreed to allow inspectors into the facility on Nov. 21 but they were again denied access. Due to the company’s unwillingness to comply with these requirements, the FAA has determined that NavWorx’s continued use of its FAA authorization is contrary to the interests of safety in air commerce. During the suspension, NavWorx may not mark or otherwise indicate that its ADS600-B units meet FAA standards. |
Tinfoil hat time?
A buddy of mine tells me that his EXP unit stopped receiving traffic and weather today after about 5 minutes of use in flight. It has been working fine all summer long.
I don't believe that the ADSB protocol includes any information about the manufacturer of the equipment sending a signal. He did not send for one of the compliance reports so I don't see any way they can remotely detect what kind of UAT he has in his airplane. Can anyone confirm this? Don |
There is no way to know what transmitting device you are using when outside the plane.
Additionally, weather is broadcast to everyone all the time, even if there are no planes around. They can't shut off weather to one plane even if they wanted to. They can kind of shut of traffic, but not "all" of it unless they shut off traffic to all planes. |
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Now, traffic (ADS-R and TIS-B) is only up-linked if the ground station knows about you. The ground station builds a "puck" of aircraft around you. However, even without this, you can see traffic sent to other ADS-B clients in your area. Again, the way that portables work and show some traffic even though they don't have OUT. If two planes with ADS-B out fly next to one another, the ground station doesn't send two sets of other aircraft out, it knows that when it sends it out once, each plane can see it. Here's a good page from the FAA on how it all works: https://www.faa.gov/nextgen/equipadsb/ins_and_outs/ Quote:
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And now back to the real story:
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erich |
Very disappointing
I was a very early adopter. Paid $$$. I hope Bill has a plan. Time to let them in Bill!
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I'm guessing this would be coming from the manufacturing side of the FAA. It's entirely possible Navworx doesn't want to to"let them in" as this would be a waste of time until the issues with the engineering side are resolved.
Not sure what they would inspect, since the manufacturing must surely be shut down pending resolution of the AD. John Allen |
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Interesting there hasn't been a peep from navworx regarding this whole thing. The letter on their web page states to check back for weekly updates... and this thing broke open a month ago. If you call them, it goes to the mailbox.
I did go flying this evening and was interested to see if my navworx 600 EXP was receiving. There's an earlier post here someplace that theirs quit working 5 minutes into the flight. I can report that mine did not quit working. However there was a king air, a bonanza and another RV that made position reports with each of them being less than 10 miles from me, (I'm set for 25nm and +- 2500 feet). I was looking for them on the ifly and no joy. The king air did show up on my Zaon XRX. Each was at a different time but all were within about 10 minutes of each other. The entire time there was other traffic showing up on my screen. Is this something the FAA is doing with navworx units or is there another answer? |
Beta
I, like many other members here, read just about anything that pops up on the topic of ADS-B. Taking all I have seen personally and also read about... leaves me feeling that all of this is really still in the BETA stage. Traffic that does not show up, compliance reports that fail or just show no data...
Approved or not approved GPS receivers and so forth. I never saw such a push to have the general public adopt a technology so far before a mandated calendar date... and at considerable expense. It illustrates the power of the airlines and influence of big money. Navworx should have released an immediate press release, if they have an adequate explanation. I don't think we will see the demise of radar sites anytime in the next thirty years. TCAS-II works well presently, as I don't recall hearing of many airliners being hit by light planes. I do suspect we will see more drone incursions... particularly after major gifting holidays. I have made good use of the weather products coming from the ground stations on UAT frequency. But that is about all I see so far that is a tangible safety enhancement. Chime in if you think I am way off base. Cheers. Nick |
Effective 11/22/2016 FAA Suspends Approval of Certain NavWorx ADS-B Units.
The reason stated was that the FAA was denied access to the property to inspect the facility 3 times. The issue is over internal GPS installed in -B units with part numbers 0012 and 0013. The latest company statement is posted on their web site. They are awaiting the outcome of the AD which will be resolved around December 20. |
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The FAA indicates the approved GPS sensors for the Navworx certified unit is the Aspen Avionics Accord Technologies NexGen Mini. Accord Tech site indicates they have a second one Maxi and a new one labeled Micro. Appears that the Mini is the only one Navworx has TSO to use. Also interesting to note, Mini appears to be the same one used in the Trig TT3x, also certified for use in Dynon and Bendix King units. Not that this means anything just interesting info I found in looking at some of this. FYI
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I do not know what is going on with FAA and NavWorx.
It would appear to be a peeing contest at local level. I was talking with local FBO owner thus week, FAA inspectors show up and wanted to inspect his shop. When asked what they were looking for they would not say. He denied them access and they left. He then called an FAA attorney about the incident and was told have them call me next time. I do believe, rarely, but sometimes, the FAA does have a local loose canon, new guys trying to make a mark. |
Not sure I'm worried.... about NavWorx
I'm not jumping off the cliff yet ... I've had my Navworx ADS600B since 2012 and I've always found them very quick to reply to any questions I've had. I noticed today on the site that Bill had updated that there is an approved upgrade if the AD goes into effect. So I'll wait and see what happens... but 800+ pilots will be much less safe in high-traffic areas without units we've come to rely on.
ON SOAPBOX: However, I've always been curious about the "certified GPS" issue.. I asked the FAA at Oshkosh several years ago about the requirement.. since our current GPS units are very very accurate...and got no good answer. Back then only the big guys offered 'WAAS cerified GPSs' that could be used. I suspect my trusty old 430 is accurate to less than the width of my RV6 .. which should be good enough for traffic separation etc. I really hope that the controllers don't direct anyone closer to me than that.. yet there is this mandate for EXPENSIVE GPS upgrades or new receivers...to what benefit? There must be a middle ground. We've got to support the smaller vendors ...even during challenges .. Navworx made ADS-B cost effective while the big guys wanted 2-5x the amount. The same holds true for our 'glass' cockpits .. without GRT, Dynon or Advanced there would be no low cost option for the experimental population. I for one have called my Representative .. who happens to be a big-time pilot and a primary sponsor of the 3rd class medical bill... everyone should do the same. Without a proliferation of lower cost avionics, flying will become much too expensive for regular people. OFF SOAPBOX: Sorry about that! Regards, DWS |
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