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3 Answers

False GlideSlope

Asked by: 4472 views Commercial Pilot, FAA Regulations, Flight Instructor, General Aviation, Instrument Rating

Is it better to intercept GS from above instead of at intercept altitude? Any advantage or disadvantage?(The dpe in my school wants us to intercept at higher altitude but if so wont we get caught with False GS? According to the dpe the book is wrong the False GS is higher than 9 degrees.  )

3 Answers



  1. KDS on Nov 13, 2017

    I suspect John Collins will come along with a much better answer, but I’ll throw in my two-cents for now.

    I’ve never in my life heard anyone advise capturing the glide slope from above. As reported, that statement from the DPE is so abnormal as to make me believe something was lost in communication and he doesn’t really mean that.

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  2. Mark Kolber on Nov 15, 2017

    I agree with KDS that something may have gotten lost in the translation.

    If what the DPE said was that you may intercept the glideslope at a higher altitude than the charted intercept, that would be correct, so long as you were within the glideslope’s service volume – 10 miles for an ILS glideslope. That 3 degree glideslope continues all the way out (within the service volume) so intercept before the FAF/charted GSI will of course be higher.

    “At a higher altitude” is not the same as “from above” as that term is generally used.

    If John does not expand on this, read his comment in the recent “ILS approach height” thread. It answers your question as well.

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  3. william0203usa on Dec 03, 2017

    Intercepting the glide from above is a very very common procedure in other parts of the world (not in the US though). Airbus even has the procedure listed in the normal ops SOP (see below). It is an easy and trivial “procedure” , just need to watch out with tailwinds. With a little situational awarness you can tell you are not on the feared 6 and 9 degree fake glideslopes. At the FAF doing a quick altitude check on the chart will clearly show you are on the right path.
    However, the threat is real if pilots are not situational aware on the glide. Read the 747 accident
    http://avherald.com/h?article=4a38d07d/0000&opt=0

    Airbus from above procedure on the A320 family.
    GLIDE INTERCEPTION FROM ABOVE The following procedure should only be applied when established on the localizer. The flight crew must react without delay to meet the stabilization criteria. In order to get the best rate of descent when cleared by ATC and below the limiting speeds, the flight crew should lower the landing gear and select flaps as required (at least CONF 2 should be selected to ensure that the aircraft speed will not increase).  If above the glideslope: APPR mode ………………………………………………………………………………ARM / CHECK ARMED FCU ALTITUDE…………………………………………………………………..SET ABOVE A/C ALTITUDE V/S MODE……………………………………………………………………………………………………….SELECT ‐ Select V/S 1 500 ft/min initially. V/S in excess of 2 000 ft/min will result in the speed increasing towards VFE. ‐ When reaching VFE, the AP maintains VFE and reduces the V/S without MODE REVERSION.

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