June 21, 201411 yr The CAT II Decision Height doesn't change - it's set by law in the EU at a minimum of 100 ft. Anyway, the PMDG chart in the tutorial and the current Netherlands AIP chart both show that the OCH is 89ft for a ACFT CAT D on RWY 18R. The problem is that the OP still doesn't know the difference between OCH and Decision Height, despite 30 posts on the sugect. Gerry Howard
June 21, 201411 yr Commercial Member The CAT II Decision Height doesn't change - it's set by law in the EU at a minimum of 100 ft. While it isn't "law" per se, here in the States, it's the same here. It could change over three years because of a survey adjustment (rare, though - and just playing devil's advocate at this point). The problem is that the OP still doesn't know the difference between OCH and Decision Height, despite 30 postss on the sugect. Gotcha - yeah, he's a simmer who's just getting into it, and is attempting to go a little too quickly, thus the lack of base knowledge. Kyle Rodgers
June 21, 201411 yr It could change over three years because of a survey adjustment (rare, though - and just playing devil's advocate at this point). the Decision Height is referenced to the height of the airfield so it don't see why it should ? Gotcha - yeah, he's a simmer who's just getting into it, and is attempting to go a little too quickly, thus the lack of base knowledge. Even despite others taking the time to explain it to him. Gerry Howard
June 21, 201411 yr Commercial Member the Decision Height is referenced to the height of the airfield so it don't see why it should ? Correct. However, despite popular sim belief, regulatory agencies do not have access to every single bit of geographical data, and geography does actually change. This is why, when looking at airport charts and data, you will often find a "surveyed" field/marker (example for KIAD - it's just after the elevation field). Occasionally, fields are re-checked for accuracy and the data is updated accordingly. Additionally, the reference point may be moved to be more accurate, or to better match the runway environment. Kyle Rodgers
June 21, 201411 yr True, but the definition of CAT II Decision Height is: Decision height is the wheel height above the runway elevation by which a go-around must be initiated unless adequate visual reference has been established and the aircraft position and approach path have been assessed as satisfactory to continue the approach and landing in safety. so that doesn't change Gerry Howard
June 21, 201411 yr Author gerry i appreciate all your help and patience along the way and kyle has already told me not to drink from a fire hose lol but sometimes it does get hard and alot of things are confusing some of what you said. so i took a step back and digesting small pices. my terp of OCH is a height above an obstacle like buildings radio mass etc you have to be above this height at all times. and if you have a DH that is lower you still cant go below OCH you have to stay at OCH. Please tell me thats right lol thanks alot guys once again. vernon! Vernon Howells
June 22, 201411 yr What i'm trying to get at is if the OCH is lower than DH i will use 100 for mins cat II ? yes...Yes...YES! Gerry Howard
June 22, 201411 yr Dude... you have two heights... Decision height, and obstacle clearance height (henceforth called DH and OCH). If DH is lower that OCH, would you use the DH and risk not clearing the obstacle, or would you follow the OCH to not hit anything, which would put you above DH, which is ok? And in contrast, if DH is higher than OCH, would you follow the OCH and break the DH which is the minimum you should be at, or would you follow the DH which would put you above the obstacle? This is not a question of 100ft or 89ft or whatever. You have a DH and an OCH. Use your head to figure it out Cristi Neagu
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