Easy explanation of Planning VS operational minima?
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Easy explanation of Planning VS operational minima?
I do not understand the difference between "Planning" and "Operative" minima. If I ask you, what is Planning minima what would you reply?
If I ask you, what is Operative minima, what would you reply?
Thanks in advance!
If I ask you, what is Operative minima, what would you reply?
Thanks in advance!
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Well, at the risk of coming across smug one is for planning and one is for actual in-flight operations.
For example, I have to plan not based on destination weather but on alternate airport weather. As soon as I am airborne, the alternate minima kind of goes out the window and we begin using charted minima.
For example, say I am going from A to B with C as the alternate.
In flight planning, I really only care about the weather at C. I mean, I care about B as well, but I know I am definitely going to end up at C if B doesn’t work out, so I plan on ending up at C, and hope I’ll make B. That way, I’m not surprised if and when I end up at my alternate.
Now in order to plan for C I have to use weather minima of, say, 600-2. That is a cloud base of 600 ft. and a visibility 2 miles. It doesn’t matter if an instrument approach at C allows me to go down to 200-1/2, I have to assume 600-2 are the minimums because that’s what the government says. It’s a little “fudge factor” that says the weather has to be better than minimums, and these alternate weather minimums differ based on the number of runways and the type of approaches at the alternate airport.
Once I’m airborne, that alternate restriction no longer applies. If airport C drops below 600-2, I’ll have to specify a new alternate airport for ATC, but I’m not restricted from trying to land at airport C with the reduced weather.
Now, why would I try for airport C and not do to the new airport D? Well, maybe C is on the way to D and C happens to be a company base where my passengers will be looked after, while D is a back-of-beyond type place that only permits me to get gas.
I should also add that, once airborne, the charted minima (less any authorization from the government) is used at whatever airport I approach, be that airport A, B, C, or D.
I hope that doesn’t muddy the waters any.
For example, I have to plan not based on destination weather but on alternate airport weather. As soon as I am airborne, the alternate minima kind of goes out the window and we begin using charted minima.
For example, say I am going from A to B with C as the alternate.
In flight planning, I really only care about the weather at C. I mean, I care about B as well, but I know I am definitely going to end up at C if B doesn’t work out, so I plan on ending up at C, and hope I’ll make B. That way, I’m not surprised if and when I end up at my alternate.
Now in order to plan for C I have to use weather minima of, say, 600-2. That is a cloud base of 600 ft. and a visibility 2 miles. It doesn’t matter if an instrument approach at C allows me to go down to 200-1/2, I have to assume 600-2 are the minimums because that’s what the government says. It’s a little “fudge factor” that says the weather has to be better than minimums, and these alternate weather minimums differ based on the number of runways and the type of approaches at the alternate airport.
Once I’m airborne, that alternate restriction no longer applies. If airport C drops below 600-2, I’ll have to specify a new alternate airport for ATC, but I’m not restricted from trying to land at airport C with the reduced weather.
Now, why would I try for airport C and not do to the new airport D? Well, maybe C is on the way to D and C happens to be a company base where my passengers will be looked after, while D is a back-of-beyond type place that only permits me to get gas.
I should also add that, once airborne, the charted minima (less any authorization from the government) is used at whatever airport I approach, be that airport A, B, C, or D.
I hope that doesn’t muddy the waters any.
It should be detailed in your Ops manual, but in our world:
Operational minima are those published on the approach plates.
Planning minima will be be those published minima plus company approved buffers (e.g. maybe a couple of hundred feet is added to any applicable cloud base minima, perhaps 500 metres to any visibility minima).
When planning for a sector the forecast minima for any alternates (ETOPS, other required en-route, and any destination alternates) need to be above planning minima.
Once you are en-route the planning minima is irrelevant and then the weather at the alternates simply needs to remain at or above the operational minima....
There will no doubt be national differences, specific rules concerning alternate minima etc...again Ops manual is the go to....
Operational minima are those published on the approach plates.
Planning minima will be be those published minima plus company approved buffers (e.g. maybe a couple of hundred feet is added to any applicable cloud base minima, perhaps 500 metres to any visibility minima).
When planning for a sector the forecast minima for any alternates (ETOPS, other required en-route, and any destination alternates) need to be above planning minima.
Once you are en-route the planning minima is irrelevant and then the weather at the alternates simply needs to remain at or above the operational minima....
There will no doubt be national differences, specific rules concerning alternate minima etc...again Ops manual is the go to....
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Taking this topic to something specific if you can answer this . For planning purposes when any of the destination / alternates has a precision approach then only the stated RVR is taken into consideration for planning purposes . But what about once you are flying ? You are inbound somewhere and you get constant reports that RVR for that ILS is above minima but ceiling is below minima (and it never gets better or is actually dropping). Do you go for that approach or not .
I am not sure what the answer is . In real life years ago we were trying an ILS . Everyone was going around and it’s seemed it was due to a very low cloud base . However the tower was only reporting the RVR which was above minima . Just like the others we reach minima and never saw and went around . The reason was the low ceiling which wasn’t stated by the tower .
I am not sure what the answer is . In real life years ago we were trying an ILS . Everyone was going around and it’s seemed it was due to a very low cloud base . However the tower was only reporting the RVR which was above minima . Just like the others we reach minima and never saw and went around . The reason was the low ceiling which wasn’t stated by the tower .
What GF said...certainly in our case for a precision approach ceiling is not a controlling value (at either the planning or when en-route)...if you have the RVRs you can legally go and shoot the approach...but of course in the rare event you are working to CAT1 minima and it's a solid overcast at 100 feet.........
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'Ceiling' used to be limiting at some French airfields before the level playing field of PANS Ops & EU OPs. It disappeared many years ago. Perhaps Alex85 was remembering those days. Tower may have a cloud base recorder display, but that is over the runway and not at DA point. Hence it is not limiting, as cloud base is a fickle item. Of course it would be prudent to anticipate a GA and plan accordingly.
It was irritating, at some pedantic airfields, where CAT 1,2,3 were all available, but ATC declared the category based on RVR/VIS. They're giving overcast 003 & 1500m, so CAT 1. Like I said, and LTN was a classic case, the valley before the threshold of RW08 & 26 would suck the cloud down and give a lower base than over the airfield. UK was smarter and used to use common sense, so sometimes 300' would also trigger LVO's because they knew that guys would request it for confidence. Of course, traffic flow was taken into account. If I hear the ATIS was giving dodgy weather and not LVO, then a radio call ahead could often have CAT2/3 in place for our arrival at smaller airfields.
It was irritating, at some pedantic airfields, where CAT 1,2,3 were all available, but ATC declared the category based on RVR/VIS. They're giving overcast 003 & 1500m, so CAT 1. Like I said, and LTN was a classic case, the valley before the threshold of RW08 & 26 would suck the cloud down and give a lower base than over the airfield. UK was smarter and used to use common sense, so sometimes 300' would also trigger LVO's because they knew that guys would request it for confidence. Of course, traffic flow was taken into account. If I hear the ATIS was giving dodgy weather and not LVO, then a radio call ahead could often have CAT2/3 in place for our arrival at smaller airfields.
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Galaxy flyer when you say ceiling isn’t a legal minima , are you talking in the context of precision approaches or both precision and Non precision approaches?
Now that you guys provided much helpful answers and I do thank for it , I was going to extend the above question to NPAs . Unlike precision approaches , for planning purposes in the case of NPAs the ceiling is taken into account . After blocks off operating minima apply . So when talking of NPA operating minima do we include in this case the ceiling ?
Now that you guys provided much helpful answers and I do thank for it , I was going to extend the above question to NPAs . Unlike precision approaches , for planning purposes in the case of NPAs the ceiling is taken into account . After blocks off operating minima apply . So when talking of NPA operating minima do we include in this case the ceiling ?
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Just to clarify, in case your are confusing too issues. Planning minima & operation inflight minima, as you seem to understand are just that. NPA and ceilings: you seem to be considering approach bans. In EASA approach bans are based on RVR not ceiling. Thus, you could elect to make an NPA approach with BKN/OVC at or below DA (agl).
However, planning to depart to an NPA would usually require cloud base to be DA + company (EASA) buffer. The planning conditions are only to dictate how many alternates you need, and common sense FOB.
However, planning to depart to an NPA would usually require cloud base to be DA + company (EASA) buffer. The planning conditions are only to dictate how many alternates you need, and common sense FOB.
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RAT 5 , It is more or less the approach ban that I had in mind , even though strictly speaking by the alteration of the approach ban definition a few years ago , I should be getting the latest WX at around 1000 agl in which case for NPAs I could be below the DA.
On a practical level if I were to be getting continuous reports from my destination that vis. is above minimums but getting a cloud base well below the MDA , then I ought to start thinking on which basis I could be justified not going for the approach and diverting to my alternate . If in any case I am bounded only by RVR or visibility , I could shoot the approach (even though I know that cloud base will prevent me from seeing anything ) and not care of the outcome
On a practical level if I were to be getting continuous reports from my destination that vis. is above minimums but getting a cloud base well below the MDA , then I ought to start thinking on which basis I could be justified not going for the approach and diverting to my alternate . If in any case I am bounded only by RVR or visibility , I could shoot the approach (even though I know that cloud base will prevent me from seeing anything ) and not care of the outcome
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even though strictly speaking by the alteration of the approach ban definition a few years ago
Am I missing something; having been out of the game for a few years? Is there more to approach bans than just RVR/VIS?
a cloud base well below the MDA.... I could shoot the approach (even though I know that cloud base will prevent me from seeing anything ) and not care of the outcome
I hope you always care about the outcome, but I suspect that was a throw-away line. I would also expect your company to want you to make the approach, if it's legal. The airmanship considerations are your own. Cloud base could be BKN, and remember my comment about terrain under the approach affecting the cloud. Give it a go, be prepared, and have a plan B to hand: as always.
Am I missing something; having been out of the game for a few years? Is there more to approach bans than just RVR/VIS?
a cloud base well below the MDA.... I could shoot the approach (even though I know that cloud base will prevent me from seeing anything ) and not care of the outcome
I hope you always care about the outcome, but I suspect that was a throw-away line. I would also expect your company to want you to make the approach, if it's legal. The airmanship considerations are your own. Cloud base could be BKN, and remember my comment about terrain under the approach affecting the cloud. Give it a go, be prepared, and have a plan B to hand: as always.
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Am I missing something; having been out of the game for a few years? Is there more to approach bans than just RVR/VIS?
