Equipment Code

[Lynxman]

So I was discussing this with a friend of mine who just bought a 152 that wants to fly it IFR. He wants to buy a DME for it but doesn't want to spend much money. After looking at prices for used King DME's I told him he might as well buy a used King GPS for a little more. This is when we butted heads, he doesn't want to pay the premium for the GPS which I can understand. So my question is can he buy a VFR GPS and use that as the substitute for DME? My other question is will an out of date IFR GPS not be legal to fly under /A? This is all saying we decide to use the GPS as our DME substitute. I believe and correct me if I'm wrong, is it is ok? The airplane is not filed as a /G where GPS is our primary means of navigating. FAR's also do not state whether the GPS has to be an IFR unit to be substituted for DME. Like I said correct me if I'm wrong because I'd rather be wrong then spew out incorrect info. Thanks

 

[Fearless Tower]

For IFR purposes, a VFR GPS cannot be used as a substitute for DME. You can use it for SA, but if the procedure requires DME then you have to have either an installed DME or IFR certified GPS with CURRENT database.

 

[RipCurl]

To expand on what Fearless Tower posted;

If it's not TSO C129 or TSO C145 compliant, it doesn't count. In other words, it has to be an IFR-approved unit with an approved installation in the aircraft.

Directly from AIM 1-1-19:

VFR and hand-held GPS systems are not authorized for IFR navigation, instrument approaches, or as a primary instrument flight reference. During IFR operations they may be considered only an aid to situational awareness.

Table 1-1-6 in that section of the AIM lists GPS Approval Required/Authorized Use. This table defines, among other things, what types of GPS units are approved for use [SIZE=-1]in lieu of ADF and/or DME. Neither hand held GPSs nor VFR panelmount GPSs are listed under the ADF/DME column, meaning they cannot be used for those functions under IFR operations. As mentioned earlier, they can not in fact be used for ANY function under IFR other than situation awareness. There is also a footnote specifying that the use of an IFR GPS in lieu of ADF/DME requires a current database.

Here's a link to AIM Chapter 1, Section 1; scroll down to section 1-1-19 to see the table I was referring to.

So, tell your buddy to keep filing /A, don't do any approaches specifying DME at the top, and keep gently asking for headings everywhere he goes

Hope that helps.
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[Lynxman]

Awesome thanks for the help guys wish I had more time to just look it up myself.

 

[AC560]

Most IFR GPS's can be used enroute and you can file /G with an expired database provided you verify all enroute points (i.e. lat/lon on GPS versus chart). You can't though use an expired database for an approach. I do believe though cannot find the reference that you can use a GPS in lieu of DME/ADF on an approach which requires one (i.e. VOR/ILS/etc.) with an expired database provided the nav fix location you are replacing is verified. You couldn't though do a GPS approach as example with an expired database.

The Airplane Flight Manual will detail what is/isn't allowed but you can reference page C-2 of the Garmin 430 guide as an example.

As always though 91.13 lurks in the shadows. Also wouldn't take my word on the replacing the ADF/DME on an approach when expired either, I recall reading something somewhere on the topic but can't find the reference.

 

[Lynxman]

Actually a GPS cannot be used for a stand alone ADF approach.

 

[RipCurl]

Most IFR GPS's can be used enroute and you can file /G with an expired database provided you verify all enroute points (i.e. lat/lon on GPS versus chart). You can't though use an expired database for an approach. I do believe though cannot find the reference that you can use a GPS in lieu of DME/ADF on an approach which requires one (i.e. VOR/ILS/etc.) with an expired database provided the nav fix location you are replacing is verified. You couldn't though do a GPS approach as example with an expired database.

There is a lot of confusion out there about this one. I'm not saying you're right or wrong, but I will quote some portions of the AIM relevant to the discussion.

AIM 1-1-19 b3(b)(1)&(3): VFR use of GPS & Database Currency

In many receivers, an up-datable database is used for navigation fixes, airports, and instrument procedures. These databases must be maintained to the current update for IFR operation, but no such requirement exists for VFR use.

When using GPS to navigate relative to a named fix, a current database must be used to properly locate a named waypoint. Without the update, it is the pilot's responsibility to verify the waypoint location referencing to an official current source, such as the Airport/Facility Directory, Sectional Chart, or En Route Chart.

Remember, this is for VFR use of GPS. AIM 1-1-19d & e discuss General Requirements for IFR, and En Route use of GPS under IFR, respectively. Neither of these sections specifically mention database currency. AIM 1-1-19f is Database Currency for IFR operations, but only says the following:

Authorization to fly approaches under IFR using GPS avionics systems requires that: ...All approach procedures to be flown must be retrievable from the current airborne navigation database...

Again, there is no specific mention of database currency for en route operations, only for terminal operations. However, if we look back up to AIM 1-1-19b3 (VFR use of GPS), it does state very clearly:

...databases must be maintained to the current update for IFR operation...

To me that means the database is current or I'm /U, end of story. YMMV.

Also, in my previous post I mentioned to tell your buddy to file /A, I was incorrect. The correct suffix for him (aircraft without a stand alone DME) would be /U, assuming he has Mode C.

Finally, it's worth mentioning that none of this is written in stone. The portion of the AIM dedicated to GPS changes significantly from one year to the next. As they say, always refer to current publications.