There is no impending Mode S requirement unless you plan to be flying above 18,000'. There is a lot of confusion on the subject. Mode-S even with extended squitter doesn't really provide enough bandwidth for all the information the FAA is going to want on ADS-B OUT and you will be better served by using a UAT to transmit your GPS position data rather than using Mode-S and transmitting that via radar returns. Sandia Aerospace has a nice write-up on this issue at <http://www.sandia.aero/?q=system/files/Why+Mode+C.pdf>. The write up is their answer for why they just introduced a new Mode C transponder rather than selling Mode S.
Bottom line here is that with the UATs, the transponder becomes redundant equipment, although The FAA will continue to require transponders. However, the data they would like you to broadcast via Mode S with extended squitter will be completely redundant if you have a UAT installed in the plane, which will be your ADS-B Out transmitter. Admittedly, their information provided goes along with their sales data for their new STX-165 Mode C transponder with integral encoder. Had this been available when I was building my Cub 2 years ago, that's what would be mounted in it. Much less expensive and more compact than any other transponder/encoder set up on the market. Right now the ADS-B equipment is just starting to make it to the market place and there are going to be a lot of changes, improvements and price reductions coming up over the next few years. I wouldn't buy a transponder in anticipation of using it for ADS-B out when a much less costly alternative is likely to exist in the very near future. However, I wouldn't let this keep me from buying an ADS-B weather receiver or a dual channel ADS-B weather and traffic receiver. -Jeff Scott Los Alamos, NM > ----- Original Message ----- > From: Mark Langford > Sent: 12/31/12 09:29 AM > To: KRnet > Subject: KR> Mode S transponders? > > Quick question. I've spent a few minutes searching the web, but didn't come > up with a definitive answer on the requirement date for Mode S transponders, > especially as it pertains to Experimentals. I did find reference to aircraft > having mode A or C installed being allowed to retain them indefinitely until > they were irreparable (see link below). Just wondering, what's the latest > ruling on this, and where do we appear to be headed? I'm building a new panel > for the KR2, and need to know if I should cut a hole for my current Terra > TR-250, or put a 2.25" hole in it for the advent of a new Mode S? [I realize > the Mode S is a good thing when considering ADSB-out]. The link I'm referring > to is at > http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2011/InFO11018.pdf > , although it is dated. As luck would have it, my transponder was > manufactured before 1990, which may be relevant to the link above. I'm > considering a cover plate that would allow me to go either way, but I'd > rather just do it once. Anybody know which way the Mode S winds are blowing > now? > > Thanks, > > Mark Langford > ML at N56ML.com > website at http://www.N56ML.com > -------------------------------------------------------- > > _______________________________________ > Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. > To UNsubscribe from KRnet, send a message to [email protected] > please see other KRnet info at http://www.krnet.org/info.html
