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Daniel choen

Minimum, cat I and II

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Hello,

since i am flying a lot at the UK especially at EGKK i was wondering where is the minimum altitude for the ILS approach on the chart?

here it is:

 

BTW, many airport have a similer chart, whre is the minimum? thanks.

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Hi Daniel,

 

if I recall correctly, for CAT I you use threshold elevation + 200 ft or obstacle clearance altitude (not height), whichever is higher. Make sure to use the right aircraft category, for the NGX it should most often be CAT D (approach speed > 140 kts).

 

Regards,

 

Oli

 

 

Oliver Branaschky

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Oliver,

i have heared that procedures, just wanted to make sure it's not the OCH, it's below 200 ft, and also, someone had told me it's not that, after i said to another guy to use the OCH, so i was a little confused. thanks for clarify that, cheers!

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Oliver is correct. This chart does not show DA/H minima, it only states the OCA/H (Obstacle Clearance). The actual minima is deduced by comparing this to system minima of which the higher of the two is the DA/H. System minima is defined in PANS OPS Flight Procedures. For a Cat 1 approach that is 200' DH baro. For Cat II that is usually 100' DH RA.

 

If you look around you will find charts for Cat 1 approaches with an OCH above 200', which means that the DA/H = OCA/H as the OCA/H is higher than the system minima.

 

This applies for any approach, for example the system minima MDH for an VOR is 250' and 300' MDH for an NDB approach.

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Its the table on the left - bottom - OCA(OCH)

 

Hi Daniel,

 

if I recall correctly, for CAT I you use threshold elevation + 200 ft or obstacle clearance altitude (not height), whichever is higher. Make sure to use the right aircraft category, for the NGX it should most often be CAT D (approach speed > 140 kts).

 

Regards,

 

Oli

 

 

Oliver Branaschky

 

Just to clarify:

 

737_zpsa7e11c52.png

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Kind of confusing chart. I don't recall pilots have to derive any minimums. We used to use Lido and there we had to derive landing mins if GP is out and minimums goes to LOC APP and there was a RAR page with tables where we had to do some math. In standard charts you don't have to do any math, just use ready minimums. There are two numbers in CAT I section (below) - 396'(200) where 396 is DA and 200 is DH or HAT (based on altimeter setting).

 

 

chart_zps156f0464.png

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The chart posted by the thread started is a UK CAA chart. These are not used directly by most operators. I used them for my IMC and IR training because I was too cheap to buy a set of Jepps but I was quite happy to work you the minimums which I would just write on the chart for easy reference :D

 

LIDO, Aerad and Jepps, will use the UK CAA charts along with the AIP to produce their own charts in their own format complete with some of the hard sums already done for you.

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Kind of confusing chart. I don't recall pilots have to derive any minimums.

 

Well the chart isn't in fact confusing, it's just not one many would use for flying (you can of course, because it's the official document issued by a country). Jepp, LIDO and all the like that this info to derive their minima and print them on their charts. The country however doesn't give any minima, only OCA(H). Then as explained above it depends on the ILS CAT, as a CAT I minimum is 200' AFE (baro referenced) the DA will be the higher of that value and the OCA. Same for the other CATs. However it's at company's discretion to use higher minima as these are only the legal minimum values, no one will stop you from going higher if you want. So if you as an operator would like to use 300' for CAT I then do so, that's perfectly legitimate. Just don't think anyone would consider that. :wink: As a pilot you'd probably want to use the highest CAT available since your goal should be to land, not not to land. :Big Grin:

 

B738 is cat C for all normal circumstances. ICAO DOC 8168 explains the classification.

 

sig.gif

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B738 is cat C for all normal circumstances. ICAO DOC 8168 explains the classification.

 

sig.gif

 

It's all make sense. I showed that chart to my pilots and they said they would not feel comfortable to use that format at all.

As for cat C and/or D so it is stated in our 737 AFM and that what we use. Company policy :ph34r: in spite of ICAO DOC 8168.

 

Thx

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