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HomeHomeDiscussionsDiscussionsiFly General Di...iFly General Di...Can iFly be used to send altitude info into a transponder?Can iFly be used to send altitude info into a transponder?
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11/17/2012 1:44 PM
 

Background to iFly question (which is below):

We were considering buying installing a mode-C transponder on our little Skyranger.

Discovered to our dismay that it won't operate in mode-C (transmitt altitude information unless it is getting altitude information from an altimeter that is an "encoding altimeter." We're 99% sure our basic steam-gauge altimeter has no such feature.

So my question regarding Ifly is this:
Our iFly 720 I have observed actually gives more accurate altitude readouts than our altimeter.
Can that altitde information be transmitted encoded to our to-be-purchased transponer? If so, how?

Thanks for your time and help.

Alex

P.S., This isn't an iFly question, but maybe someone here knows the answer: If we have a mode-C transponder and don't have an encoding altimeter connected to it it then, if I understand right, operates in a mode (mode-A) that would give position info but not altitude info. Apparently that would not be sufficient to allow operating in class-C airspace, but would it allow using flight following?

 
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11/17/2012 11:20 PM
 

I'm far from an expert, but I would say this would not be a suitable option. The altitude encoder for the mode C broadcasts you pressure altitude, (what your altimeter would read if you set 29.92 in the Kollsman window), ATC RADAR then adjusts that value for the local altimeter setting/barometric pressure and displays that altitude on the ATC screens. The iFly only puts out GPS altutude which is not based on barometric/air pressure at all, and is only coincedentally the same as what your altimeter reads.

P.S. I would say you understand correctly, as long as your planned flight doesn't take you anywhere that requires an operating mode C transponder.

 
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11/18/2012 6:08 AM
 

I believe you need a separate device, commonly referred to as an encoder. This device is independent of the altimeter, although it shares the pitot static system. It is essentially a barometric device which sends an encoded altitude signal to the transponder that enables the Mode C feature. Any radio shop should be able to install and certify an encoder...

Regards,

Ted

 
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11/20/2012 9:42 PM
 

Computer Doc:
Ted "Zenair" is correct. I would recommend the TransCal SSD-120. Execllent value for the price. www.trans-cal.com/ ===Ralph

 
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HomeHomeDiscussionsDiscussionsiFly General Di...iFly General Di...Can iFly be used to send altitude info into a transponder?Can iFly be used to send altitude info into a transponder?