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I am curious to know a couple of things regarding glide-slope:

  1. How often do ATCs encounter flights capturing false glide-slopes?

  2. What is the response expected from ATCs in such a scenario? In other words, is it the duty of ATC to alert the crew of the possibility of a false glide-slope capture.

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    $\begingroup$ It might be quite rare. Only two results in an NTSB search, and even those aren't really about that. $\endgroup$ Commented May 28, 2022 at 19:55
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    $\begingroup$ Thank you. I have come across this for the first time in the context of PIA 8303. The link is: airlineratings.com/news/… $\endgroup$
    – Quiescent
    Commented May 28, 2022 at 20:22
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    $\begingroup$ On an ils plate there is a table that computes expected altitude at certain distances from a dme ( usually in 1 mile intervals ). Pilots are expected to compare actual altitude with computed one at least 2 times . $\endgroup$
    – cavver
    Commented May 28, 2022 at 21:57
  • $\begingroup$ Agreed. But as in the case of above (PIA 8303) it is a possibility, as was noted in an earlier paper. As this involves landing, not always the crew may have time for re-computation. See: researchgate.net/publication/… $\endgroup$
    – Quiescent
    Commented May 29, 2022 at 4:41
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    $\begingroup$ I realised that my previous comment is wrong , those are specific actions taken by an airline . The incident referred in your link is this : avherald.com/h?article=4641efec/0000&opt=0 . " The revised policy includes a new horizontal landing gate for ILS interception from above; being the earliest of the following: the FAF, 5 DME, 4 NM for VMC operations and 5 NM for IMC operations." $\endgroup$
    – cavver
    Commented May 29, 2022 at 7:46

1 Answer 1

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  1. in 10 years of working at a small airport serving commercial airliners never.
  2. ILS is a pilot interpreted landing aid, ATC has no obligation to follow the plane once established on ILS. ATC has the responsibility to vector the plane to such a position and altitude such that the plane can intercept the localiser and glide slope. At airports doing dependant ILS approaches ( 2 aircraft on 2 parallel runways ) ATC follows the distance between planes, not the altitude/glide slope. If providing radar services the ATC vectors the plane until established on the localiser then it's the crews responsibility to follow the ILS procedure.
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    $\begingroup$ At least in the USA, however, ATC is responsible for vectoring aircraft to intercept the glideslope outside of the GS-capture point at an altitude not above the glideslope itself (nor below the published minimum intercept altitude). JO 7110.65 5–9–1c. $\endgroup$
    – randomhead
    Commented May 28, 2022 at 23:05
  • $\begingroup$ Thank you. Could you please share which country you are referring to? $\endgroup$
    – Quiescent
    Commented May 29, 2022 at 4:43
  • $\begingroup$ I will reword my answer in order to be more clear. $\endgroup$
    – cavver
    Commented May 29, 2022 at 7:21
  • $\begingroup$ Thank you @cavver $\endgroup$
    – Quiescent
    Commented May 29, 2022 at 18:27

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