Below is a screen grab from the ILS RWY 25R approach chart for HKG/VHHH. What should the plane do after passing SMT radial 084 (or TD D8 NM)?

It doesn't look like immediately turn heading 253 degrees; from an algorithmic point of view does the plane do an RNAV from PLOVE to RIVER, then track SMT radial 253 after RIVER? Or does it start to track SMT 253 right after SMT radial 084?

Also, what does "ITFR" stand for in this graph? The ITFR distance measures from the east and west side of the runway are based on two different ILS localizers, is that correct? Thanks!

VHHH ILS RWY 25R (Source: AD 2-94A, Aeronautical Information Publication, Hong Kong Aeronautical Information Services)

  • $\begingroup$ In answer to your first question, I would read the chart as instructing a course from the Tung Lung IAF to PLOVE, with a lead turn allowed before PLOVE (which might be calculated by an FMS). Regarding your second question, ITFR is the code for the ILS and the DME associated with the ILS. Distances from ITFR refer to the distances from the DME (located at the northeast end of the field ad the end of RWY 25). This is a comment since I don't have any real data on the first question, just speculation. $\endgroup$
    – J W
    Commented Feb 7, 2016 at 3:20
  • $\begingroup$ Jonathan, could you explain what a lead turn is? $\endgroup$
    – user13377
    Commented Feb 7, 2016 at 3:39
  • 1
    $\begingroup$ If Lnafziger's answer (and linked answer) doesn't explain what a lead turn or radial is, you might consider asking that as a new question! From what I can tell, I don't think it has yet been asked here, and I think it would make a good question—something along the lines of "What is a lead turn, and why is it helpful in an instrument approach?" $\endgroup$
    – J W
    Commented Feb 7, 2016 at 19:36

1 Answer 1


SMT RDL 084 is simply a lead radial, so it is there to let you know when to start your turn so that you can intercept the SIU 253 course without overshooting it during the turn.

Just below and to the left of the airport is the box which shows the ILS frequency. It tells us that the DME identifier for this ILS is ITFR, so the distances are provided based on the distance from the DME transmitter associated with the ILS.

  • $\begingroup$ Is the turn required to pass through RIVER then? $\endgroup$
    – user13377
    Commented Feb 7, 2016 at 4:00
  • 4
    $\begingroup$ @siyuanr RIVER is there to define the course, and is not a "fly-over" waypoint, so it would not be required to pass through it. When turning though, you would want to adjust your rate of turn so that you intercept the final course smoothly, and would likely either pass through it or come very close to it (close enough to have "positive course guidance"). $\endgroup$
    – Lnafziger
    Commented Feb 7, 2016 at 4:05

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