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In Jeppesen Approach chart for VABB VOR RWY 32, what does D2.8 (BBB VOR), the MDA is lower at 650ft. when at D3.8 (BBB VOR), the MDA is higher at 780ft.

How to decide which DME should be taken before commencing the approach ?. What parameters should be taken to make the decision to choose DME from VOR (2.8 or 3.8) ?

Also, What does 980ft below 2.8D (BBB VOR) mean in approach profile view?. VABB VOR RWY 32

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    $\begingroup$ The title doesn't seem to match with the content of your question. So what is your question? $\endgroup$ May 15 at 7:43

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The points D1.0, D2.8, D3.8 and D9.5 all refer to DME distances in units of nautical miles. In this case there is only one DME for this approach: the Mumbai VOR/DME (BBB).

You would fly this approach as follows:

  • You cross the VOR/DME at 3800' or above and fly outbound (either on radial 151 or 161, depending on your aircraft approach category) while descending towards 2600'.
  • At a distance of 9.5 NM from the VOR/DME you start the turn and establish yourself on the inbound course of 321° towards the VOR/DME.
  • At a distance of 7.5 NM from the VOR/DME you start a 3.29° descent from the platform altitude of 2600' (this is the CDFA: continuous descent final approach).
  • You must maintain 1330' or above until a distance of 3.8 NM from the VOR (gray area below that segment on the profile view). If you cannot identify1 D3.8, then 1330' is also your MDA (right most box in the minimums section). If you follow a perfect 3.29° descent path, you should also cross D3.8 at exactly 1330' (that is the number directly below the point on the profile view).
  • You must maintain 780' or above until a distance of 2.8 NM from the VOR (gray area below that segment on the profile view). If you cannot identify1 D2.8, then 780' is also your MDA (center box in the minimums section). If you follow a perfect 3.29° descent path, you should cross D2.8 at exactly 980' (that is the number directly below the point on the profile view).
  • After D2.8 you must maintain 650' or above until visual (MDA in the left box in the minimums section).
  • At a distance of 1.0 NM from the VOR/DME you reach the missed approach point (M on the profile view). This is the latest point2 at which a missed approach must be initiated, if not visual.

1 The chart says "DME required", but a suitable RNAV system (e.g. based on GPS) can be used instead. This can lead to a situation where you cannot identify the points D3.8 and D2.8 if the corresponding RNAV points 38VOR and 28VOR (written in square brackets below on the profile view) are not on your flight plan.

2 Note that this happens after reaching the MDA on the CDFA, therefore you would normally execute a go around earlier. Also note that the MDA must be adjusted for height loss when used as a decision altitude (DA) on the CDFA (see note 1 at the bottom of the chart).

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  • $\begingroup$ Ah, this now makes sense with the (1) note at the bottom about VNAV $\endgroup$
    – Jamiec
    May 15 at 8:14
  • $\begingroup$ According to the link you shared (Boldmethod), if 38VOR and 28VOR waypoints are not in the flight plan "and" we don't have DME equipment, then our minimums would be 1330ft. But if we dont have 38VOR and 28VOR in our Flight plan "but" we have DME equipment on board, then our minimums would be 650ft and we have to fly laterally selected and vertically selected (in terms of flying Airbus A320)? Can you also confirm if Laterally managed and vertically selected approach is possible if 38VOR and 28VOR is unavailable ?. $\endgroup$ May 15 at 10:12
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    $\begingroup$ @KrishnaKanth In an A320 you would typically fly any VOR approach in lateral and vertical managed modes. This would either be FINAL APP or FLS (if installed). If you don't have those RNAV points you can still tune the VOR and manually check the DME distances. Otherwise, you'd have to set the higher MDA of 1330' (plus adjustment) as your minimums. See also safetyfirst.airbus.com/… $\endgroup$
    – Bianfable
    May 15 at 10:45
  • $\begingroup$ @Bianfable Can you please explain If the chart says "DME required" and an aircraft does not have DME Equipment but only has GPS receiver, where in the documentation says this approach can be performed using GPS ?. 2. for example, in an A320, "38VOR" waypoint is only available in F-PLN, our technique would be to set our minimums to 650+height adjustment and then when the aircraft crosses 38VOR waypoint, we can switch to vertically selected, why do you say that we can perform lateral and vertical managed beyond "38VOR" ?. $\endgroup$ May 16 at 4:54
  • $\begingroup$ @KrishnaKanth Whether GPS may be used instead of DME probably depends on the specific country policies, in the US AIM 1-2-3. I'm not familiar with Indian regulations. Airbus says "Managed modes are recommended, but selected mode might be useful in case of system or equipment failures" (link above). I don't know what policies your airline has, but I'd use managed modes down to minima (FLS can also be used below minima) and then continue visually. Feel free to ask a new question on how to fly a NPA with an A320. $\endgroup$
    – Bianfable
    May 16 at 6:31

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