# Transponder & Encoding Alt ?

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#### planecrazzzy

##### Well-Known Member
Hey Guys,
I'm in the middle of class "B" airspace..(Mpls/StPaul)....So in order to fly out of a local airport I would need a Transponder & Encoding Alt...
This is for an experimental aircraft....Kolb Firestar II , I have a 12volt battery....

#### Rhino

##### Well-Known Member
Another way mode S can lessen pilot workload and improve interaction with ATC is that it allows them to 'see' your aircraft type and judge your general capabilities without asking. I.e., they will automatically have a general idea of your ability to respond to requests for speed and/or altitude changes, etc. For Instance, they won't bother asking a C-172 if they can increase speed to 250 knots. While this decreased interaction and increased ability will often be transparent to the pilot, the potential advantages are obvious.

Then there's the down side. You may hear some pilots refer to mode S as mode 'snitch'. If you accidentally overfly the edge of a restricted airspace somewhere, they'll know exactly who you are (no landing and hiding in the bushes). To me, just the traffic awareness ability far outweighs any potential downside except maybe the prohibitive cost, but costs are falling nicely, so we'll see. I'm a long way from deciding my panel setup anyway.

#### Rhino

##### Well-Known Member
Interesting news. The FAA now seems to be steering away from support for some traffic awareness technologies that they previously advocated. They are going to end Mode S TIS support at 23 tracons. Not a good sign, especially for those early adopters that bought such technology at the urgings of the FAA.

http://www.aopa.org/whatsnew/newsitems/2005/050714tis.html

#### Dieselfume

##### Well-Known Member
I was at an FAA seminar thing a little while back. I believe it was either a person from Seattle Center or Seatac Approach that said something to the effect of
"it works great, when it's working. It only seems to be working half the time..." (Mode S)

Basically they said it was quite helpful, but the system wasn't reliable so they were reluctant to encourage people to buy it.