ILS / DME approaches.

[Rookie50]

.....like 08 at CYTZ, the only ILS there.

Am I authorized without a DME but using an IFR certified GPS for DME info?

[Airmanship Police]

yes

[matrix]

Look for "GNSS in lieu of" in the AIM or CAP GEN

[FenderManDan]

I used to practice that exact approach with cert GPS and ILS with instructor in the rented bird so i guess it is valid

[Rookie50]

Never even landed there before, actually.

It does look like a steep approach to clear ships on the app path.

[photofly]

ILS 08 at CYTZ is RNAV required.

It's not the only ILS there though- the ILS 26 requires OPS SPEC 607.

[switchflicker]

Be careful doing this, especially on a flight test. The DME distance is slant, and the GPS is not. also, the GPS waypoint must be the same spot that the DME transmitter uses. That might me a bit of a trick to determine.

Sw

[photofly]

Be careful doing this, especially on a flight test. The DME distance is slant, and the GPS is not.

The difference between slant distance and ground distance depends on the angle to the waypoint. Anywhere on a 3° glidepath the error is constant at (1-cos3°) = 0.13% - 8 feet error per NM. Not really significant.

But note Per TC AIM COM 3.15.9:
Where ATS requests a position based on a distance from a
DME facility for separation purposes, the pilot should report
GPS distance from the same DME facility, stating the distance
in “miles” and the facility name (e.g. “30 miles from Sumspot
VOR”). This phraseology is used for all RNAV systems.
When reporting DME distance, the pilot includes “DME” in
the report (e.g. “30 DME from Sumspot VOR”). This enables
ATS to allow for the DME slant range.

also, the GPS waypoint must be the same spot that the DME transmitter uses. That might me a bit of a trick to determine.

If using GPS in lieu of DME for a localizer approach, my GPS (a very old one) allows you to select "the localizer" as the navaid from which distance is reported so that the distance matches what a DME would report when tuned to the localizer. Presumably other more modern units solve the issue in a similar way.

[Gear Jerker]

If I'm not mistaken, the approach procedure needs to be indicated as approved for GPS overlay by way of (GNSS) next to the title, and you would need to have the approach loaded and activated in an IFR certified GPS, using a current database, and be in VLoc for the intermediate and final approach segments.

[photofly]

No. You can substitute a GPS for any DME as long as the waypoint is loaded from a database (no typing or dialling the coordinates). No need for the GPS to be in approach mode, or even be approved for approaches at all. (Ref: TC AIM COM 3.15.9)