Regarding UAT certification
Let me see if I can help clarify the UAT certification issue
FCC approval means that the radio transmits at the right frequency, at the right power, and doesn’t spew energy into other parts of the spectrum.
FAA endorsement of the FCC approval means that the FAA agrees it transmits at the right frequency and at the right power.
This of course has absolutely nothing to do with operational approval of an ADS-B system. ADS-B is a part of the larger change in the airspace system towards satellite based navigation - in fact, it is the principal Air Traffic Management tool for the next few decades. As such we should be thoughtful about how we interact with it - for our own safety and for the safety of those around us.
An approved airborne ADS-B transmitter has two components - a high integrity position source and a radio that sends information from that position source (along with other elements) to the Air Traffic Control (ATC) system. The ATC system uses that information, integrated with other data sources (radar when its available for instance), to determine safe separation, provide flight following and other ATC services, and furnish highly accurate fixes to Search and Rescue teams should that be necessary. The position source requirements are essentially the same for all aircraft types. This makes sense since we all share the same airspace.
If an aircraft ADS-B system is not meeting the integrity and accuracy requirements that have been defined for valid operation, it will tell the ground system (since there are integrity and validity flags in the message) and the ground system will reject the aircraft as an air traffic target - in fact any info on the aircraft is filtered out and never even gets to the ATC system.
In an environment where the ATC system is relying on this self reporting, being rejected is not good for you or for anybody flying in your immediate vicinity. In areas where there is radar coverage, they will pick you up anyway - no harm no foul. However, ADS-B will cover more of the airspace system than the current radar system - and the radar system is gradually going away. In this case you are invisible if your ADS-B system is not meeting standards. This is why the FAA is requiring that almost everybody (basically if you need a transponder today you need ADS-B tomorrow) equips with a compliant system.
In return for equipage, the FAA is providing free services back to the aircraft via ADS-B “in” - basically traffic and flight information services such as graphical weather. The ADS-B ground system today is sending the Flight Information (including weather) to anybody with a compatible receiver, and they are sending traffic to anybody who sends an ADS-B signal - valid or not. This will change shortly and they will be filtering the
traffic message and power modulating the Flight Info message.
For experimental category aircraft the certification process for ADS-B systems will most likely follow the model of other “for credit” equipment having a safety impact on surrounding aircraft. The easiest way to get sign off will be to use TSO equipment. Equipment that meets the minimum standards does not have to carry a TSO but you will have to show that the minimum performance is met - and a manufacturer saying that his unit is good enough is not going to cut it - unless he has a TSO unit and can demonstrate that the non TSO product is identical.
So - in summary. An ADS-B radio that meets FCC standards but not operational standards, and which has an unapproved position source, can be used to trigger a traffic broadcast from the FAA until such time as they close that loophole. The traffic picture you get will assume that your GPS position is actually correct, so good luck with that.
For further questions regarding ADS-B, check out
ADS-B FAQs
I would think seriously before committing this amount of money to something that has apparently limited utility.
