GPS = DME

Tom-D

Tom-D

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Tom-D
Where is it stated that a GPS is considered equal to the DME for approaches.

IFR rules not my strong suit.
 
Tom-D said:
Where is it stated that a GPS is considered equal to the DME for approaches.

IFR rules not my strong suit.
Click to expand...

Open this https://www.faa.gov/air_traffic/publications/media/AIM.pdf

hit "ctrl" and "f" type in "substitute" and surfing through the search.

a. Discussion. This paragraph sets forth policy, while providing operational and airworthiness guidance regarding the suitability and use of RNAV systems when operating on, or transitioning to, conventional, non−RNAV routes and procedures within the U.S. National Airspace System (NAS): 1. Use of a suitable RNAV system as a Substitute Means of Navigation when a Very−High Frequency (VHF) Omni−directional Range (VOR), Distance Measuring Equipment (DME), Tactical Air Navigation (TACAN), VOR/TACAN (VORTAC), VOR/DME, Non−directional Beacon (NDB), or compass locator facility including locator outer marker and locator middle marker is out−of−service (that is, the navigation aid (NAVAID) information is not available); an aircraft is not equipped with an Automatic Direction Finder (ADF) or DME; or the installed ADF or DME on an aircraft is not operational. For example, if equipped with a suitable RNAV system, a pilot may hold over an out−of− service NDB. 2. Use of a suitable RNAV system as an Alternate Means of Navigation when a VOR, DME, VORTAC, VOR/DME, TACAN, NDB, or compass locator facility including locator outer marker and locator middle marker is operational and the respective aircraft is equipped with operational navigation equipment that is compatible with conventional navaids. For example, if equipped with a suitable RNAV system, a pilot may fly a procedure or route based on operational VOR using that RNAV system without monitoring the VOR. NOTE− 1. Additional information and associated requirements are available in Advisory Circular 90-108 titled “Use of Suitable RNAV Systems on Conventional Routes and Procedures.” 2. Good planning and knowledge of your RNAV system are critical for safe and successful operations. 3. Pilots planning to use their RNAV system as a substitute means of navigation guidance in lieu of an out−of−service NAVAID may need to advise ATC of this intent and capability. 4. The navigation database should be current for the duration of the flight. If the AIRAC cycle will change during flight, operators and pilots should establish procedures to ensure the accuracy of navigation data, including suitability of navigation facilities used to define the routes and procedures for flight. To facilitate validating database currency, the FAA has developed procedures for publishing the amendment date that instrument approach procedures were last revised. The amendment date follows the amendment number, e.g., Amdt 4 14Jan10. Currency of graphic departure procedures and STARs may be ascertained by the numerical designation in the procedure title. If an amended chart is published for the procedure, or the procedure amendment date shown on the chart is on or after the expiration date of the database, the operator must not use the database to conduct the operation. b. Types of RNAV Systems that Qualify as a Suitable RNAV System. When installed in accordance with appropriate airworthiness installation requirements and operated in accordance with applicable operational guidance (e.g., aircraft flight manual and Advisory Circular material), the 12/10/15 AIM Performance−Based Navigation (PBN) and Area Navigation (RNAV) 1−2−7 following systems qualify as a suitable RNAV system: 1. An RNAV system with TSO−C129/ −C145/−C146 equipment, installed in accordance with AC 20−138, Airworthiness Approval of Global Positioning System (GPS) Navigation Equipment for Use as a VFR and IFR Supplemental Navigation System, or AC 20−130A, Airworthiness Approval of Navigation or Flight Management Systems Integrating Multiple Navigation Sensors, and authorized for instrument flight rules (IFR) en route and terminal operations (including those systems previously qualified for “GPS in lieu of ADF or DME” operations), or 2. An RNAV system with DME/DME/IRU inputs that is compliant with the equipment provisions of AC 90−100A, U.S. Terminal and En Route Area Navigation (RNAV) Operations, for RNAV routes. A table of compliant equipment is available at the following website: http://www.faa.gov/about/office_org/ headquarters_offices/avs/offices/afs/afs400/afs47 0/policy_guidance/ NOTE− Approved RNAV systems using DME/DME/IRU, without GPS/WAAS position input, may only be used as a substitute means of navigation when specifically authorized by a Notice to Airmen (NOTAM) or other FAA guidance for a specific procedure. The NOTAM or other FAA guidance authorizing the use of DME/DME/IRU systems will also identify any required DME facilities based on an FAA assessment of the DME navigation infrastructure. c. Uses of Suitable RNAV Systems. Subject to the operating requirements, operators may use a suitable RNAV system in the following ways. 1. Determine aircraft position relative to, or distance from a VOR (see NOTE 6 below), TACAN, NDB, compass locator, DME fix; or a named fix defined by a VOR radial, TACAN course, NDB bearing, or compass locator bearing intersecting a VOR or localizer course. 2. Navigate to or from a VOR, TACAN, NDB, or compass locator. 3. Hold over a VOR, TACAN, NDB, compass locator, or DME fix. 4. Fly an arc based upon DME. NOTE− 1. The allowances described in this section apply even when a facility is identified as required on a procedure (for example, “Note ADF required”). 2. These operations do not include lateral navigation on localizer−based courses (including localizer back−course guidance) without reference to raw localizer data. 3. Unless otherwise specified, a suitable RNAV system cannot be used for navigation on procedures that are identified as not authorized (“NA”) without exception by a NOTAM. For example, an operator may not use a RNAV system to navigate on a procedure affected by an expired or unsatisfactory flight inspection, or a procedure that is based upon a recently decommissioned NAVAID. 4. Pilots may not substitute for the NAVAID (for example, a VOR or NDB) providing lateral guidance for the final approach segment. This restriction does not refer to instrument approach procedures with “or GPS” in the title when using GPS or WAAS. These allowances do not apply to procedures that are identified as not authorized (NA) without exception by a NOTAM, as other conditions may still exist and result in a procedure not being available. For example, these allowances do not apply to a procedure associated with an expired or unsatisfactory flight inspection, or is based upon a recently decommissioned NAVAID. 5. Use of a suitable RNAV system as a means to navigate on the final approach segment of an instrument approach procedure based on a VOR, TACAN or NDB signal, is allowable. The underlying NAVAID must be operational and the NAVAID monitored for final segment course alignment. 6. For the purpose of paragraph c, “VOR” includes VOR, VOR/DME, and VORTAC facilities and “compass locator” includes locator outer marker and locator middle marker.
 
So what I glean from this is :
you must have a IFR certified GPS to use the system. as a DME
 
Tom-D said:
That's OK I got it.
Click to expand...

Yep,

1. An RNAV system with TSO−C129/ −C145/−C146 equipment...

Installed as an IFR navigator. Believe it or not there are VFR Only installation instructions for these in the STC package. I doubt that option is used much lol.

 
Last edited:
Tom-D said:
So what I glean from this is :
you must have a IFR certified GPS to use the system. as a DME
Click to expand...
Yes. All IFR GPS primary navigation (as opposed to unofficial but helpful situational awareness) use requires an IFR certified GPS
 
Tom-D said:
Where is it stated that a GPS is considered equal to the DME for approaches.

IFR rules not my strong suit.
Click to expand...

AC 90-108. My reading of this advisory circular is that the substituted fix has to be in the nav database. (some instructors disagree, they claim you can do addition.) All named fixes on a VOR approach that requires DME are, of course in the database. All ILS that have DME are in the database. For example IJAC is in the database. ICNO is not. And, the RNAV navigator has to be IFR certified and so installed.
 
Tom-D said:
So what I glean from this is :
you must have a IFR certified GPS to use the system. as a DME
Click to expand...
And depending on the AFM supplement you must either have a current DB or have verified the location accuracy of any waypoints you're referencing for distance.
 
I just had to look this one up. Seems that the GPS need only be En-route certified to substitute for DME. (Don't need approach or WAAS)

If the GPS is en-route only, would it have LOCs and/or ILSs in the database?
 
rolivi said:
I just had to look this one up. Seems that the GPS need only be En-route certified to substitute for DME. (Don't need approach or WAAS)

If the GPS is en-route only, would it have LOCs and/or ILSs in the data base?
Click to expand...
Typically, yes. Most if not all (certainly all in current production) IFR GPSs have provision for approach data which in the case of an enroute only IFR GPS is for monitoring and situational use only. In addition, virtually all of the enroute only status is the result of installation limitations rather than a design limitation of the box itself.
 
In the AIM. (Don't remember the section.) During my recent IR oral, the examiner made me find it. Took a while. I already knew that GPS could be substituted for DME, but he wanted me to prove it.
 
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