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Why is KOAK's alternate minimum higher than standard?

  • According to TERPS (FAA Order 8260.3C) section 3-4, alternate minimum for PA is the higher of PA minimum or standard alternate minimum(600'-2).

  • KOAK ILS 12 minimum is 200'-1/2. Standard alternate minimum is higher than that PA minimum. Thus, alternate minimum should be 600'-2(standard). But actually, alternate minimum for KOAK ILS 12 is 1400'-3(for CAT D aircraft).

I'd like to know how alternate minimum to be determined.

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    $\begingroup$ Hi. Welcome to Aviation.SE. People volunteer and spend their own time helping others on this site. It is normally expected that you will put at least as much effort into creating a good question as people will spend in answering it. As it stands, it is unclear what you are asking and your question will probably be closed as such. Please edit your question to include the relevant detail and highlight exactly what you are not sure about. $\endgroup$ – Simon May 21 '17 at 6:52
  • $\begingroup$ I'm not sure how much detail you want, but see 3.4 in the FAA's TERPS. They calculate the minimums as usual (considering terrain, obstacles, weather etc.), and if the resulting numbers are higher than a set of standard reference numbers, alternate minimums are required. It's often difficult to find out more about one specific airport or approach because the calculations are complex. $\endgroup$ – Pondlife May 21 '17 at 14:43
  • $\begingroup$ It is unclear what you are asking by this question. I understand that you are wondering why KOAK's alternate minimums are high, presumable because you recognize that none of the airport's approaches are authorized for use for alternate planning. Why they are not authorized may be answerable. But what aspect of determining alternate minima are you asking about? $\endgroup$ – J Walters May 21 '17 at 22:08
  • $\begingroup$ So let's discuss about KOAK's alternate minimums as a example. According to FAA Order 8260.3C Section 3-4, alternate minimum for PA is the higher of PA minimum or standard alternate minimum(600'-2) . For example, KOAK ILS 12 minimum is 200'-1/2. Standard alternate minimum is higher than that PA minimum. Thus, alternate minimum should be 600'-2(standard). But actually, alternate minimum for KOAK ILS 12 is 1400'-3(for CAT D aircraft). I'm very comfused. $\endgroup$ – Aviat May 22 '17 at 12:20
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regarding non-standard alternate minimums -

From the US Terminal Publications, SW-2: OAKLAND, CA METROPOLITAN OAKLAND INTL (OAK) ILS or LOC Rwy 12:

ILS, Category C, 700-2; Category D, 1400-3


If you plan the KOAK ILS RWY12 to Circle to another runway (e.g., RWY30, RWY28L/R, etc.) the published "no approach light" (ceiling/vis) minimums for your approach are:

CAT A/B: 600-1 1/4 (meaning Alternate Minimums are standard, i.e., 600-2, because 600-2 is higher than 600-1 1/4, the published ceiling/vis minimum without approach lights).

CAT C: 700-2 (meaning that this becomes the non-standard minimum because it's higher than the standard alternate minimum of 600-2)

CAT D: 1400-3 (meaning that this becomes the non-standard minimum because it's higher than the standard alternate minimum of 600-2). Since 1400-3 is VMC, no "without approach light" additive (the 1/4 mile) is applied.

NOTES:

  1. See inop component table for visibility additive -which is 1/4 mile vis added- when approach lights are considered inop, as required by TERPS when determining alternate minimums.

  2. From 8260.3C, para. 3-4-1 a. (2): PA. For each approach CAT, select the PA’s ceiling and the PA’s visibility (without approach lights). When more than one line of PA minimums is published on the same chart, use the line with the higher HAT..

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