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Thread: Can a VFR GPS substitute for DME

  1. #1

    Can a VFR GPS substitute for DME

    My guess is the answer is no but thought I'd ask.

    What about an IFR certifIABLE GPS?

    Say a KLN-89B that doesn't have an indicator and annunciator installed.

    Cloyd




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  2. #2

    Can a VFR GPS substitute for DME

    No even with an IFR Certifiable GPS if the approach procedure requires a DME
    you need to have one installed.

    Tony
    ----- Original Message -----
    From: "cloyd vanhook" <cloydvanhook@yahoo.com>
    To: "BAC Mail" <bac-mail@beechaeroclub.org>
    Sent: Friday, January 06, 2006 10:30 PM
    Subject: [BAC-Mail] Can a VFR GPS substitute for DME


    > My guess is the answer is no but thought I'd ask.
    >
    > What about an IFR certifIABLE GPS?
    >
    > Say a KLN-89B that doesn't have an indicator and annunciator installed.
    >
    > Cloyd
    >
    >
    >
    >
    > ---------------------------------
    > Yahoo! Photos
    > Ring in the New Year with Photo Calendars. Add photos, events, holidays,
    > whatever.
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  3. #3

    Can a VFR GPS substitute for DME

    Sorry Tony.... I disagree. I dont have a DME and I can do the approach
    with my IFR GPS. The GPS can locate the point either of 2 ways, DME from
    the A/P or the lat/long of the point. On my checkride the examiner made a
    point of indicating it's capability as a DME. We did a DME arc for grins.

    I'm not sure if the VFR GPS can be a DME or not but I think it can.

    BILL


    -----Original Message-----
    From: bac-mail-bounces@beechaeroclub.org
    [mailto:bac-mail-bounces@beechaeroclub.org]On Behalf Of Tony Crowe
    Sent: Friday, January 06, 2006 5:42 PM
    To: cloyd vanhook; BAC Mail
    Subject: Re: [BAC-Mail] Can a VFR GPS substitute for DME


    No even with an IFR Certifiable GPS if the approach procedure requires a DME
    you need to have one installed.

    Tony
    ----- Original Message -----
    From: "cloyd vanhook" <cloydvanhook@yahoo.com>
    To: "BAC Mail" <bac-mail@beechaeroclub.org>
    Sent: Friday, January 06, 2006 10:30 PM
    Subject: [BAC-Mail] Can a VFR GPS substitute for DME


    > My guess is the answer is no but thought I'd ask.
    >
    > What about an IFR certifIABLE GPS?
    >
    > Say a KLN-89B that doesn't have an indicator and annunciator installed.
    >
    > Cloyd
    >
    >
    >
    >
    > ---------------------------------
    > Yahoo! Photos
    > Ring in the New Year with Photo Calendars. Add photos, events, holidays,
    > whatever.
    > _______________________________________________
    > BAC-Mail mailing list
    > BAC-Mail@beechaeroclub.org
    > http://www.beechaeroclub.org/mailman/listinfo/bac-mail
    >

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  4. #4
    gyroj4b at netzero.net
    Guest

    Can a VFR GPS substitute for DME

    I just rechecked my King DVD's. They state it is legal to substitute an ifr certified GPS for a DME. In the senerio they performed an approach using a DME arc.
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  5. #5

    Can a VFR GPS substitute for DME

    In Australia YES. If the GPS is TSO'd then it can be used as a DME for
    Position fixing purposes legally (oxymoron as if you have the GPS you
    know where you are anyhow but thems the regs!). If it is an approach
    certified TSO GPS then it can be used in lieu of DME provided the
    approach plate is annotated that GPS is acceptable. Almost all of our
    approaches are so annotated with very very few exceptions. To be IFR TSO
    certified many, but NOT ALL, GPS require the annunciator etc. When I was
    looking at instruments for my panel upgrade I know for example that the
    Garmin 430 and the like are TSOd without external annunciators and so
    would fulfil the requirement. I have a Garmin 300XL and it needs the
    external stuff to comply. In Australia it is very very very hard to find
    a light aircraft with a DME.

    So my reading from our regulations would be that if it complies with the
    TSO (129 from memory) then yes. If it needs the external CDI to comply
    no.

    -Allan Palmer
    Anaesthetist, Brisbane, Australia


    > -----Original Message-----
    > From: bac-mail-bounces@beechaeroclub.org
    > [mailto:bac-mail-bounces@beechaeroclub.org] On Behalf Of cloyd vanhook
    > Sent: Saturday, January 07, 2006 8:30 AM
    > To: BAC Mail
    > Subject: [BAC-Mail] Can a VFR GPS substitute for DME
    >
    > My guess is the answer is no but thought I'd ask.
    >
    > What about an IFR certifIABLE GPS?
    >
    > Say a KLN-89B that doesn't have an indicator and
    > annunciator installed.
    >
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  6. #6

    Can a VFR GPS substitute for DME

    With all due respect, you guys seem to be missing the distinction between an
    IFR-certified- GPS and an IFR- certifiable one. If you go out and buy a
    KLN-89B (or a Garmin GNS 530, or a high-end Honeywell flight management
    system costing more than any three of our planes) and slam it in your panel,
    you can't legally use it as an IFR navigation source (except to enhance
    situational awareness) unless and until the installation is signed off to be
    in conformity with the requirements of AC-20-138A:
    http://www.airweb.faa.gov/Regulatory...visoryCircular
    .nsf/0/8a2ae2491c85226f86256e35004c638b/$FILE/AC20-138A.pdf . In addition
    to the external switch and indicator installation requirements, your radio
    shop has to go through a whole routine with flight checks, flight manual
    supplements, and 337s to file and get approved at the local FSDO. And of
    course, only the IFR GPS's are eligible for such approval in the first
    place. I have a student who is in exactly that situation.



    Additional fun factoid: Once certified, it can substitute for a DME for any
    purpose except for declaring an alternate. If you declare an alternate
    airport that only has approaches that require a DME, you have to have a real
    DME aboard and in working order - the GPS won't do. Once you get there, you
    can use the GPS for the approach, it's the getting there that's the legal
    issue.



    Craig MacCallum

    Sierra N525SB

    Montclair, NJ



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  7. #7

    Can a VFR GPS substitute for DME

    An IFR certifed approach GPS (Class A) is legal in lieu of DME, but my
    understanding is there are the following requirements:

    -For DME ARCs the DME location must have a fix in the GPS
    database
    -For DME based fixes in approaches the individual fixes must
    have fixes in the GPS database
    -GPS distance from the DME navaid is _not_ usable for a
    DME based fix

    The reason for the difference is several fold, but real.

    At no point is a non-IFR GPS or even a Class B (enroute) GPS legal for
    primary use in any function in a GPS approach. A GPS can only be used
    to fly GPS approaches (including approaches that say "or GPS") - but GPS
    can be used to determine fixes/waypoints/intersections in non-GPS
    approaches _if_ the fix has a GPS point specified and in the database.
    So for instance it _is_ legal to fly a VOR approach requiring DME using
    a VOR and a GPS to identify the DME fies. The "or GPS" would mean it's
    legal to fly the approach without the VOR at all.., again, only with a
    IFR approach certified installation.

    IFR certification of a GPS meets several requirements for integrity (ie:
    RAIM) and display and accuracy and depends on the equipment. All GPS
    Type A installations under TSO 129a (pretty much all GA IFR certfied GPS
    installations are under this standard) are required to have a CDI
    display meeting the requirements for indictation accuracy of enroute
    versus approach mode - but not all installations require an annunciator,
    for instance Garmin 420/430 and 530 installations don't require an
    annunciator because the unit itself has the required inputs and
    acceptable indications, but Garmin 300 and 155 installations do...

    Also - when a GPS based approach is the approach to be used at the
    primary airport and an alternate is required that alternate must be
    served by a non-GPS based approach _and_ all non-GPS equipment required
    for that approach must be available. Ie: you can use a GPS for an "VOR
    or GPS" approach requiring DME if the DME points have GPS fixes - but if
    your alternate requires DME you must have DME, if it requires ADF you
    must have ADF. The idea is that there can be systemwide failures of GPS
    due to equipment failures, satellite availability, activation of
    selective availability, etc. This rule changes somewhat with VNAV/RNP
    based approach minima and WAAS certified equipment.

    Note the IFR certified GPS installations genernally have a specific or
    generic supplement to the POH/AFM, this will be referenced by the 337
    and/or STC to do the installation - that supplement may have additional
    limitations...and of course the individual installation must be
    certified, the 337 filed, etc.

    But at no point is your VFR GPS legal as the sole means to identify the
    DME distance or fixes...
    -=-
    Mark





    -----Original Message-----
    From: bac-mail-bounces@beechaeroclub.org
    [mailto:bac-mail-bounces@beechaeroclub.org] On Behalf Of
    gyroj4b@netzero.net
    Sent: Friday, January 06, 2006 6:57 PM
    To: heybruck@bellsouth.net
    Cc: bac-mail@beechaeroclub.org; cloydvanhook@yahoo.com
    Subject: RE: [BAC-Mail] Can a VFR GPS substitute for DME

    I just rechecked my King DVD's. They state it is legal to substitute an
    ifr certified GPS for a DME. In the senerio they performed an approach
    using a DME arc.
    _______________________________________________
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  8. #8

    Can a VFR GPS substitute for DME

    I've had a couple of requests for the specific references so I thought
    I'd share them with everyone, plus one correction.

    A DME fix does not have to be a named fixed in the database - using the
    DME facility in the database as the active waypoint is acceptable _or_ a
    Named fix int the database can be used. Additioally if a DME facility
    is not in the database and the DME fix is an unnamed waypoint you can
    use a Named DME fix on the same course from the same DME facility to
    establish the distance for the unnamed fix. This is less and less of an
    issue as databases become more complete and as approaches get updated
    with named fixes.

    There's a good overview article at
    http://www.avionicswest.com/myviewpoint/gpsuse.htm
    <http://www.avionicswest.com/myviewpoint/gpsuse.htm> .

    The primary official reference is section 1-1-19 of Chapter 1 of the AIM
    - it has exhaustive detail on the requirements...
    http://www.faa.gov/ATpubs/AIM/Chap1/aim0101.html#1-1-19
    <http://www.faa.gov/ATpubs/AIM/Chap1/aim0101.html#1-1-19> .

    In particular here's the allowed uses of a GPS in place of ADF or DME (
    - the ground based facility does _not_ have to be operational to do
    these:

    (a) Operations allowed:

    (1) Determining the aircraft position over a DME fix. GPS
    satisfies the 14 CFR Section 91.205(e) requirement for DME at and above
    24,000 feet mean sea level (MSL) (FL 240).

    (2) Flying a DME arc.

    (3) Navigating to/from an NDB/compass locator.

    (4) Determining the aircraft position over an NDB/compass
    locator.

    (5) Determining the aircraft position over a fix defined by an
    NDB/compass locator bearing crossing a VOR/LOC course.

    (6) Holding over an NDB/compass locator.

    And the basic restrictions thereof:

    (b) Restrictions

    (1) GPS avionics approved for terminal IFR operations may be
    used in lieu of ADF and/or DME. Included in this approval are both
    stand-alone and multi-sensor systems actively employing GPS as a sensor.
    This equipment must be installed in accordance with appropriate
    airworthiness installation requirements and the provisions of the
    applicable FAA approved AFM, AFM supplement, or pilot's guide must be
    met. The required integrity for these operations must be provided by at
    least en route RAIM, or an equivalent method; i.e., Wide Area
    Augmentation System (WAAS).

    (2) For air carriers and operators for compensation or hire,
    Principal Operations Inspector (POI) and operations specification
    approval is required for any use of GPS.

    (3) Waypoints, fixes, intersections, and facility locations to
    be used for these operations must be retrieved from the GPS airborne
    database. The database must be current. If the required positions cannot
    be retrieved from the airborne database, the substitution of GPS for ADF
    and/or DME is not authorized.

    (4) The aircraft GPS system must be operated within the
    guidelines contained in the AFM, AFM supplement, or pilot's guide.

    (5) The Course Deviation Indicator (CDI) must be set to terminal
    sensitivity (normally 1 or 1 1/4 NM) when tracking GPS course guidance
    in the terminal area. This is to ensure that small deviations from
    course are displayed to the pilot in order to keep the aircraft within
    the smaller terminal protected areas.

    (6) Charted requirements for ADF and/or DME can be met using the
    GPS system, except for use as the principal instrument approach
    navigation source.

    (7) Procedures must be established for use in the event that GPS
    integrity outages are predicted or occur (RAIM annunciation). In these
    situations, the flight must rely on other approved equipment; this may
    require the aircraft to be equipped with operational NDB and/or DME
    receivers. Otherwise, the flight must be rerouted, delayed, canceled or
    conducted VFR.

    ( For TSO-C129/129A users, any required alternate airport must
    still have an approved instrument approach procedure other than GPS that
    is anticipated to be operational and available at the estimated time of
    arrival, and which the aircraft is equipped to fly. If the non-GPS
    approaches on which the pilot must rely require DME or ADF, the aircraft
    must be equipped with DME or ADF avionics as appropriate.


    Some people noted that an AFM supplment must be provided but that is not
    quite true. Note the verbage says AFM, AFM supplement, or pilot's
    guide. Many GPS just use the Pilots Guide now - but an AFM supplement
    will generally be required for anything that interfaces with the
    aircraft control systems, like an Autopilot. In any event the item must
    be "approved" which means the AFM supplement or Pilots Guide should be
    attached to the Form 337 as supporting documentation.


    Immediately following in the AIM are _extensive_ details on the
    requirements and procedures for each application - I won't repeat them
    here except a note on DME arcs - the AIM requires that use of a GPS to
    fly a DME ARC must have the fix for the DME navaid as the currently
    active waypoint. This generally means a single GPS cannot be used to
    fly a DME ARC _and_ a GPS overlay at the same time - this will require
    two GPS or GPS+DME or GPS+VOR. An example would be flying a "VOR or
    GPS" approach with a DME ARC - you would need a 2nd GPS, DME or VOR.
    -=-
    Mark


    -----Original Message-----
    From: Mark Gooderum
    Sent: Sunday, January 08, 2006 10:43 PM
    To: 'gyroj4b@netzero.net'; heybruck@bellsouth.net
    Cc: bac-mail@beechaeroclub.org; cloydvanhook@yahoo.com
    Subject: RE: [BAC-Mail] Can a VFR GPS substitute for DME

    An IFR certifed approach GPS (Class A) is legal in lieu of DME, but my
    understanding is there are the following requirements:

    -For DME ARCs the DME location must have a fix in the GPS
    database
    -For DME based fixes in approaches the individual fixes must
    have fixes in the GPS database
    -GPS distance from the DME navaid is _not_ usable for a
    DME based fix

    The reason for the difference is several fold, but real.

    At no point is a non-IFR GPS or even a Class B (enroute) GPS legal for
    primary use in any function in a GPS approach. A GPS can only be used
    to fly GPS approaches (including approaches that say "or GPS") - but GPS
    can be used to determine fixes/waypoints/intersections in non-GPS
    approaches _if_ the fix has a GPS point specified and in the database.
    So for instance it _is_ legal to fly a VOR approach requiring DME using
    a VOR and a GPS to identify the DME fies. The "or GPS" would mean it's
    legal to fly the approach without the VOR at all.., again, only with a
    IFR approach certified installation.

    IFR certification of a GPS meets several requirements for integrity (ie:
    RAIM) and display and accuracy and depends on the equipment. All GPS
    Type A installations under TSO 129a (pretty much all GA IFR certfied GPS
    installations are under this standard) are required to have a CDI
    display meeting the requirements for indictation accuracy of enroute
    versus approach mode - but not all installations require an annunciator,
    for instance Garmin 420/430 and 530 installations don't require an
    annunciator because the unit itself has the required inputs and
    acceptable indications, but Garmin 300 and 155 installations do...

    Also - when a GPS based approach is the approach to be used at the
    primary airport and an alternate is required that alternate must be
    served by a non-GPS based approach _and_ all non-GPS equipment required
    for that approach must be available. Ie: you can use a GPS for an "VOR
    or GPS" approach requiring DME if the DME points have GPS fixes - but if
    your alternate requires DME you must have DME, if it requires ADF you
    must have ADF. The idea is that there can be systemwide failures of GPS
    due to equipment failures, satellite availability, activation of
    selective availability, etc. This rule changes somewhat with VNAV/RNP
    based approach minima and WAAS certified equipment.

    Note the IFR certified GPS installations genernally have a specific or
    generic supplement to the POH/AFM, this will be referenced by the 337
    and/or STC to do the installation - that supplement may have additional
    limitations...and of course the individual installation must be
    certified, the 337 filed, etc.

    But at no point is your VFR GPS legal as the sole means to identify the
    DME distance or fixes...
    -=-
    Mark





    -----Original Message-----
    From: bac-mail-bounces@beechaeroclub.org
    [mailto:bac-mail-bounces@beechaeroclub.org] On Behalf Of
    gyroj4b@netzero.net
    Sent: Friday, January 06, 2006 6:57 PM
    To: heybruck@bellsouth.net
    Cc: bac-mail@beechaeroclub.org; cloydvanhook@yahoo.com
    Subject: RE: [BAC-Mail] Can a VFR GPS substitute for DME

    I just rechecked my King DVD's. They state it is legal to substitute an
    ifr certified GPS for a DME. In the senerio they performed an approach
    using a DME arc.
    _______________________________________________
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    BAC-Mail@beechaeroclub.org
    http://www.beechaeroclub.org/mailman/listinfo/bac-mail

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  9. #9
    mark at jumpweb.com
    Guest

    Can a VFR GPS substitute for DME

    RE: [BAC-Mail] Can a VFR GPS substitute for DMEThese are all good and correct points.

    If you're shopping when quoting avionics GPS installs make sure you request a quote for an "IFR certified" installation. If you're buying look at the 337s for the aircraft - if there isn't one for the GPS install that covers IFR certification then the installation is _not_ IFR legal, even if it was performed to IFR standards - the 337 must be filed and approved _and_ the referenced AFM supplement and/or Pilots Guides _must_ be in the POH/AFM to be legal. As a side note the complete _current_ AFM for the Muskeeteers are available from Raytheon Docs for about $75 _including_ the binder and dividers - fill in the information with your aircraft's model and serial number info and include a current Weight and Balance and copies of all the supplements in your real POH and that AFM is now a legal POH for your aircraft - nice to have at home for flight planning and/or to have a spare if it gets dropped, misplaced or lost, or to replace one that is excessively beat up...

    My experience quoting an install of a Garmin GNC300XL TSO was there was an almost $2000 delta between a non-IFR certified and IFR certified install (not counting another $700 or so for a used OBS head I had to add as I only had 1 and it wouldn't interface to the 300, my primary NAV/COM is a Narco Mk12D+ so a mismatch on the resolver integration). As noted below there is a lot of extra paper work _and_ testing including a flight test for an IFR certified installation. Also check on the shop's bonding/insurance - for instance my insurance does not cover flight tests performed by repair stations but does cover flight tests performed by an A&P - but a IFR GPS install will almost always be performed by a repair station.

    The annunciator alone is $600-$800 new - and as noted by others the Garmin 400/420/430/530 series don't require annunciators - so the cost is lower and the delta from a 300 to a 420 is less than you might think due to that savings (although it was still substantial through 12/31 due to the special garmin was running on reconditioned 300 units they had gotten as trade in on an earlier 420/430 upgrade deal, post 1/1 the delta is probably less than $2000 on the real installed price, but with the deal last month is was more like $3000 so I went with the 300).

    But do shop around and have some flexibility - I wanted a new audio panel at the same time as the GPS/COM and needed a 2nd CDI - but I was flexible on what audio panel and CDI I would take and also encouraged alternative quotes for functionally similar units (420, Apollo 55, etc) - so I found a shop with a used Garmin 340 and a compatible used CDI and negotiated a deal that netted out over $1000 less than the next cheapest quote and about $1500 under the median quote.

    The AIM has the best information on IFR operations but TSO 139a and AC 20-138A and AC-20-130 are available online and worth a reading for education if nothing else...
    --
    Mark


    ----- Original Message -----
    From: Craig MacCallum
    To: bac-mail@beechaeroclub.org ; cloydvanhook@yahoo.com
    Sent: Saturday, January 07, 2006 7:40 AM
    Subject: RE: [BAC-Mail] Can a VFR GPS substitute for DME


    With all due respect, you guys seem to be missing the distinction between an
    IFR-certified- GPS and an IFR- certifiable one. If you go out and buy a
    KLN-89B (or a Garmin GNS 530, or a high-end Honeywell flight management
    system costing more than any three of our planes) and slam it in your panel,
    you can't legally use it as an IFR navigation source (except to enhance
    situational awareness) unless and until the installation is signed off to be
    in conformity with the requirements of AC-20-138A:
    http://www.airweb.faa.gov/Regulatory...visoryCircular
    .nsf/0/8a2ae2491c85226f86256e35004c638b/$FILE/AC20-138A.pdf . In addition
    to the external switch and indicator installation requirements, your radio
    shop has to go through a whole routine with flight checks, flight manual
    supplements, and 337s to file and get approved at the local FSDO. And of
    course, only the IFR GPS's are eligible for such approval in the first
    place. I have a student who is in exactly that situation.



    Additional fun factoid: Once certified, it can substitute for a DME for any
    purpose except for declaring an alternate. If you declare an alternate
    airport that only has approaches that require a DME, you have to have a real
    DME aboard and in working order - the GPS won't do. Once you get there, you
    can use the GPS for the approach, it's the getting there that's the legal
    issue.



    Craig MacCallum

    Sierra N525SB

    Montclair, NJ



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