VFR & IFR GPS

[PilotDerek]

What is the difference between an IFR and VRF certified GPS? Is it just the software? May be a stupid question.

[Earl]

An IFR certified GPS must be panel mounted and assuming the database is updated is authorized for use to perform RNAV/GPS approaches.  I am not sure what a VFR certified GPS is.  As long as you have all available information (ie, current charts, etc.) I assume you can use any GPS for VFR flight.

[BorealOne]

The main certification differences are set out in TSO-C129a.

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/e560cd9c6acf8ba186256dc700717e0f/$FILE/C129a.pdf

I'm guessing that with modern electronics there are ony minor differences in the inherent accuracy, computing power or refresh rates between panel and portable models, but there are some practical pilot observable differences btw an IFR certified and VFR only GPS.

The most obvious to the pilot is the price - an IFR unit is easily 10x the cost of a portable - and of course the fact that the IFR unit has an approach database, not just nav waypoints. Those differences, together with having the GPS nav data visually displayed via a CDI on the panel, just not on the GPS screen are the most obvious. There are also indications re phase of flight (enroute, terminal, approach) that you won't see on a VFR only.

Behind the panel, there are also significant differences and requirements for installation for an IFR certified GPS -- it must be hooked up to a barometric altimeter source (rq'd for RAIM), meet certain frequency reliability and interference tests, etc, etc.

[N601RX]

Assuming the GPS is capable of being IFR certified the difference is the installation.  For VFR you only need to hook up the power wire, ground and antenna coax. Not very complicated or expensive.

To be IFR certified most of the older of the GPS, require an external annunciator, CDI/Glideslope indicator, encoder connection, flight testing and a airplane specific flight manual supplement that must be FAA approved for each plane.  So you basically have a large wiring harness, annuciator, CDI and more paperwork which drives up the price considerably over a VFR install.

[Hank]

IFR units are permantently mounted in the panel within defined ranges of the pilot's view, are hardwired in for ship's power, and have permanently mounted antennas on the outside of the plane, too. The CDI has to have glideslope to use RNAV approaches. Don't know if terrain is required, or if they just have it anyway. Databases are updateable, with the date range displayed to verify that it is current, creating a "need" to log the database update.

Various zoom modes, and in the terminal environment both zoom and CDI deflection automatically change based on distance from the runway.

et¢., et¢., et¢. Anything to drive up ¢o$t, be¢ause $omething defined with 200 rule$ ha$ got to be $afer than $omething who$e rule$ ¢an be handwritten on a $ingle page.

[danb35]

Quote: ehscott

An IFR certified GPS must be panel mounted and assuming the database is updated is authorized for use to perform RNAV/GPS approaches.  I am not sure what a VFR certified GPS is.  As long as you have all available information (ie, current charts, etc.) I assume you can use any GPS for VFR flight.

[danb35]

Quote: Hank

The CDI has to have glideslope to use RNAV approaches.

[Hank]

Without a glideslope, is a GPS approach workable? I thought they don't have step-downs like VOR approaches or timed FAF-MAP distances to know if you made it or not. I also don't have any handy to look at right now, but it seems like it would be hard to do a GPS approach to E. Bumdiddle Airport without a glideslope indicator. Sure, the GPS has a built-in CDI, but it's left-right only, or at least that's all I've ever seen.

[OR75]

I am thinking that the original question was the difference between PANEL MOUNTED GPS.

For handheld, it is easy: they are not approved for anything and you may as well use the cheapest GPS that are sold for cars navigation (these probably won't have an airport database or FAA background). They are approved by the buyer ! I approved by iPad and my old Lowrance handheld !

Between an IFR approved GPS and a VFR approved GPS (both panel mounted) the big difference is the RAIM as already indicated by someone above (details in the respective TSO standards)

The RAIM is a check that the GPS receiver is receiving sufficient satellite signals and working within an error range 

 

  

[danb35]

Quote: Hank

Without a glideslope, is a GPS approach workable? I thought they don't have step-downs like VOR approaches or timed FAF-MAP distances to know if you made it or not. I also don't have any handy to look at right now, but it seems like it would be hard to do a GPS approach to E. Bumdiddle Airport without a glideslope indicator. Sure, the GPS has a built-in CDI, but it's left-right only, or at least that's all I've ever seen.

[carusoam]

DanB,

Kln90b is approach certified, but no Waas...

Database updates are an arm and a leg, or just an arm if you can upload them from an old PC...

Did I miss something?

Best regards,

-a-

 

[danb35]

Quote: carusoam

Kln90b is approach certified, but no Waas...