Menu Sign In Contact FAQ
Banner
Welcome to our forums

GPS IAP design in different countries

zuutroy wrote:

Are you expected to fly it unless told otherwise, and if you are cleared for the approach without the need for the hold, how do you get the GNS to skip it and go from ERTUN to FAF?

IIRC you go to FRD17, press direct twice (or something like that) to activate the leg from ERTUN to FRD17.

LDZA LDVA, Croatia

The sequence looks correct and the inclusion of the racetrack is addressed in a footnote on p 92 of the Garmin 400W Series Pilot’s Guide & Reference, Garmin part number 190-00356-00 (rev. K) (pdf link):

“NOTE: Upon activating an RNAV GPS approach,
you are given the option to skip any non-required
holding patterns during the initial transitions of
the approach. In a GPS approach, you will not be
given the option and you must manually reselect
waypoint sequencing."

zuutroy wrote:

Are you expected to fly [the racetrack] unless told otherwise…

No according to the operational practices established in ICAO PANS OPS. See vol I (Flight Procedures) ch 2 (Terminal Arrival Altitude) paras 2.2.4 to 2.2.6:

2.2.4 Entry to procedure
An aircraft established within a TAA area may enter the associated approach procedure at the IAF without conducting a
procedure turn provided the angle of turn at the IAF does not exceed 110°. In most cases, the design of the TAA will
not require a turn in excess of 110° unless the aircraft is located close to the intermediate segment or is transitioning
from one TAA to another. In such cases, the aircraft may be manoeuvred with the TAA to establish the aircraft on a
track prior to arrival at the IAF that does not require a procedure turn (see Figure II-1-2-6).
Note. — The maximum 110° requirement ensures that the segment length of the approach procedure is adequate to
provide turn anticipation and to permit interception of the following segment at the maximum airspeed permitted for
the procedure.

2.2.5 Reversal procedures
Where entry cannot be made to the procedure with a turn at the IAF less than 110°, a reversal procedure shall be flown

2.2.6 Holding
A racetrack holding procedure will normally be located at an IAF or the IF. When one or more of the initial segments
are not provided, the holding pattern will normally be located to facilitate entry to the procedure (see Figure II-1-2-7).

See also thread France: straight-in IFR joins prohibited (a VFR circuit is mandatory?) if tower is unmanned.

Operational practice in US is a little different. See thread Procedure turn not required and the US AIM (link) para 5-4-5 (d)(4) et seq.

London, United Kingdom

Is it the correct sequence for the RNAV 17 appch? When loading the approach the 430 would normally ask the user to select the transition, which in this case would be ERTUN, URITI or DINVI as the IAF. That would then be the first waypoint in the loaded approach procedure.

Last Edited by NeilC at 15 May 18:58
NeilC
EGPT, LMML

NeilC wrote:

Is it the correct sequence for the RNAV 17 appch? When loading the approach the 430 would normally ask the user to select the transition, which in this case would be ERTUN, URITI or DINVI as the IAF. That would then be the first waypoint in the loaded approach procedure.

I loaded it with ERTUN selected as the IAF and that was what it did. From the other fixes it didn’t sequence the hold. Maybe just an Xplane glitch. I downloaded the newest Navdata from Navigraph today so I’ll try it again tomorrow.

EIMH, Ireland

NeilC wrote:

Is it the correct sequence for the RNAV 17 appch?

The sequence corresponds to the selection of ERTUN as the IAF with a course reversal (racetrack) and ERTUN has been passed. The label “hold” in the waypoints column is a contraction of the US term “hold−in−lieu−of−PT” and it is to be interpreted as a racetrack. If the approach is selected while the aircraft is located outside the capture region of ERTUN then a course reversal will included by default, otherwise the user is asked whether one is wanted.

London, United Kingdom

The IAF should continue to be shown on the waypoint sequence after it is passed – at least, it does on my boxes, both GNS and GTN. In post 29 above, you should still see ERTUN immediately under the approach name (which appears to be wrong). Old sim nav data probably

NeilC
EGPT, LMML

Yes ERTUN should be on the first line instead of the incorrectly labelled and formatted approach name. The flight mode annunciation is incorrect as well and the magenta subscript ‘glosses’ FA and MA are missing from the listed waypoints. The sequence is otherwise correct. Clearly room for improvement in X-Plane or whatever was used.

The nav data is probably fine. The 170M desired track values for the intermediate and final approach segments differ from the values on the published approach chart, which uses magnetic declination for the year 2015, but correspond to declination appropriate for the period from mid 2019 to mid 2024 (WMM but should be the same as IGRF used by Garmin). Explained in FAA InFO 12009 (link):

Unlike IFPs, RNAV systems are not constrained by charting conventions.
Rather, many of these systems will rely on their navigational database for
magnetic variation or will calculate it dynamically based on aircraft position. For this reason, it is possible
that the magnetic variation applied by the RNAV system will be marginally different than the magnetic
variation used by the procedure designer when the IFP chart was created, or last updated. Thus, the
magnetic course displayed by the RNAV system for a particular IFP leg may also slightly vary from the
magnetic course charted on the IFP plate.

London, United Kingdom

This company is doing some GPS IAP design in the Czech Republic. Interesting reading.

Administrator
Shoreham EGKA, United Kingdom
48 Posts
Sign in to add your message

Back to Top