Exemption 3585

ljg said:
Also, PROBS aren't coded in the first 9 hours of a TAF anymore in the US - so the likelihood of using 3585 domestically on a PROB group is slim to none.
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Company generated ram taf's still have a prob coded when needed. Only the nws has switched to the ICAO format. As I said earlier, 9l northeast Saab routes will most likely still get it.

90% of the time, you will look at the weather, call company and say "we can't go". Magically, they send you new weather with a coded ramtaf start, which will let them use 3585. Nothing like buying the weather you need:)

As I said in the top short version that would get you past your oral. Unless you just want to say " or and or"


Kell, Cat II, IIIa or otherwise doesn't do you a bit of good in BHB:)
 
ljg said:
Fixed a few things...
Just trying to help. Oh, and the BECMG group is a MAIN body element, not a conditional remark. If it were still used in the US, it couldn't be used for 3585.
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Are you saying the weather that is "BECMG" is the main body, or the original wx is the main body with the BECMG the conditional?

I always thought that the original weather was main body with the "BECMG" the conditional.

(Fake) Example:

CYVR 211738Z 2118/2224 12005KT 1/8SM VV001
BECMG 2122/220000 16006KT 3SM BKN003
FM220000 16006KT P6SM SCT025 BKN050

Could you dispatch for an an arrival time of 2000z on the 21st? I'd say no...
 
v1valarob said:
I actually have not seen it yet at Colgan in my 2 years.
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dispatched 3 times my first week as CA but only once since. JHW, BFD were always socked in.

the easiest way for me to remember it was

HALF, HALF, FULL

Half required vis (conditional statement) at destination

Half Required ceiling and vis (derived mins in condition statement) at first alternate

Full derived ceiling and vis at second alternate

Always requires 2 alternates!
 
zmiller4 said:
Are you saying the weather that is "BECMG" is the main body, or the original wx is the main body with the BECMG the conditional?

I always thought that the original weather was main body with the "BECMG" the conditional.

(Fake) Example:

CYVR 211738Z 2118/2224 12005KT 1/8SM VV001
BECMG 2122/220000 16006KT 3SM BKN003
FM220000 16006KT P6SM SCT025 BKN050

Could you dispatch for an an arrival time of 2000z on the 21st? I'd say no...
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I believe Both the FM group and the BECMG group are main body elements. They both represent a significant, permanent change to the weather. I believe the only difference is that one is immediate, and the other is more gradual and ultimately permanent change to the weather.

I had to look this up, but I have an (old) copy of ICAO Annex 3 - here's what the recommendation of when to use the BECMG group says:

6.2.12 - "The change indicator "BECMG" and the associated time group shall be used to describe changes where the meteorological conditions are expected to reach or pass through specified threshold values at a regular or irregular rate and at an unspecified time during the time period."

To me, the "reach or pass through" language indicates a permanent change, which would make it fall more in line with a MAIN body element.

Zmiller, you couldn't dispatch the flight in your example for Vancouver because at 20z, you haven't hit a forecast change group at all. Assuming you had a 1/2sm landing minimum, that flight couldn't be dispatched legally until your ETA was 0000z on the 22nd.

Here's a TAF where using 3585 and a BECMG group would be a bad idea:

(fake)
CYVR 211738Z 2118/2224 12005KT 1/2SM VV001
BECMG 2120/220000 16006KT 1/4SM BKN003
FM220600 16006KT P6SM SCT025 BKN050

Say your ETA is 2000Z on the 21st. With the BECMG, the meteorologist has no doubt that the 1/4sm is going to happen - just not sure when exactly. The forecast would be sure that you'd have 1/4sm by the end of the BECMG group. If you consider a BECMG a conditional remark, then 3585 would allow for dispatch. I don't necessarily agree with that doing that. There's no reasonable assurance that the flight could get in.
 
TUCKnTRUCK said:
Company generated ram taf's still have a prob coded when needed. Only the nws has switched to the ICAO format. As I said earlier, 9l northeast Saab routes will most likely still get it.
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Good point, thanks. Flight movement forecasting shouldn't be used just because you need to suddenly legalize an illegal flight. PS, always kind of wondered - what does the RAM in RAM TAF stand for??
 
FWIW, BCMG was a conditional statement in our opspec/FOPPM.

It is also a conditional on BobDDuck provided. The Becoming statement, when i was working up in the Mt. Washington Observatory was considered not to be a body element, because the time period was unsure.

Think of it like," We know that the weather is going to be 3 miles vis, but at some point, fog will move in reducing Vis to 1/4 mile" Normally you could not launch, but odds are, you would be able to get in still..

A main body statement is to cover a time period with known, similar conditions. The conditional statements were to reflect periods of change. If that was not the case, you would never see the main body elements, as weather doesn't immediately change, every line would be BCMG. With the models available to us today, they can get pretty picky about it.
 
I have something from my airline that spells it out in plain English. I will get it to you as soon as possible.
 
TUCKnTRUCK said:
FWIW, BCMG was a conditional statement in our opspec/FOPPM.

It is also a conditional on BobDDuck provided. The Becoming statement, when i was working up in the Mt. Washington Observatory was considered not to be a body element, because the time period was unsure.

Think of it like," We know that the weather is going to be 3 miles vis, but at some point, fog will move in reducing Vis to 1/4 mile" Normally you could not launch, but odds are, you would be able to get in still..
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You lose me right there TUCK, I'm really trying to understand your viewpoint. Are you saying you could operate into conditions in a BECMG that are below landing minimums at an ETA? With 3585, the expectation has to be that the conditions will be at or above landing/alternate minimums at the ETA, and a BECMG group ultimately suggests a permanent, long-term change to the weather from ICAO Annex 3. I see no way that you can dispatch into that.

TUCKnTRUCK said:
A main body statement is to cover a time period with known, similar conditions. The conditional statements were to reflect periods of change. If that was not the case, you would never see the main body elements, as weather doesn't immediately change, every line would be BCMG. With the models available to us today, they can get pretty picky about it.
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The BECMG group ultimately reflects a permanent change to a period of known, similar, conditions. The forecaster is just unsure of when the ultimate change will start occurring.
 
ljg said:
You lose me right there TUCK, I'm really trying to understand your viewpoint. Are you saying you could operate into conditions in a BECMG that are below landing minimums at an ETA? With 3585, the expectation has to be that the conditions will be at or above landing/alternate minimums at the ETA, and a BECMG group ultimately suggests a permanent, long-term change to the weather from ICAO Annex 3. I see no way that you can dispatch into that.
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Regardless of how any of us want to interpret Annex 3, the company can still legally dispatch you with the BECMG under 3585. As far as it relates to BECMG, whatever wx is predicted to become doesn't "officially" happen until the end of that time period. That is what makes it a conditional statement.
 
JaceTheAce said:
I have something from my airline that spells it out in plain English. I will get it to you as soon as possible.
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Ha, I have it right here in my computer case, but no scanner at the crashpad. Definitely upload it because it really does explain 3585 well!
 
SRA_kbad said:
Ha, I have it right here in my computer case, but no scanner at the crashpad. Definitely upload it because it really does explain 3585 well!
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Yeah, it does a great job explaining the extremely confusing topic. I have it in my flight bag... I really need an electronic copy of it since I've had more then 3 or 4 people ask for it.
 
Rocketman99 said:
As far as it relates to BECMG, whatever wx is predicted to become doesn't "officially" happen until the end of that time period. That is what makes it a conditional statement.
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That's actually incorrect:
http://aviationweather.gov/static/help/taf-decode.php#Wind

BECOMING Group: ie. (BECMG 2224) The BECMG group is used when a gradual change in conditions is expected over a longer time period, usually two hours. The time period when the change is expected is a four-digit group with the beginning hour and ending hour of the change period which follows the BECMG indicator. The gradual change will occur at an unspecified time within this time period. Only the conditions are carried over from the previous time group.
 
Yes, I know that is the definition for the BECMG group, but that differs from how you actually apply it. Say the wx is supposed to improve from being below mins you can't use it until the end of the BECMG period. For all intents and purposes the wx is the previous main body block until the end of the BECMG period. That is how it is considered a conditional group for 3585 purposes.
 
A lot of military installations only use BECMG in the body of the TAF (other than conditional statements) which would lead me to believe BECMG is part of the main body. That said, our opspecs specify BECMG as conditional.

KVPS 2123/2219 30008KT 9999 -SHRA VCTS FEW045CB BKN210 QNH2997INS
TEMPO 2123/2201 VRB10G20KT 8000 -TSRA BKN045CB
BECMG 2201/2202 VRB06KT 9999 NSW FEW030 QNH2999INS
TEMPO 2212/2215 VRB15G25KT 3200 TSRA BKN030CB T32/2218Z T23/2210Z 212300

EDIT: I'm glad I'm not going to Eglin tonight.
 
Don't worry about understanding 3585, it's just theory for a very rare scenario. Just memorize the answer. Your examiners won't ask you to describe it because they don't know what it is either nor have they actually practiced it. Some have and it makes for good cockpit conversation.............................................
 
Bob, Military fields aren't the only ones using BECMG as a main body element:

LSZH 212025Z 2121/2303 35004KT 9999 FEW060 BKN090 TX19/2214Z TN08/2205Z
BECMG 2209/2211 06009KT
BECMG 2218/2221 VRB03KT CAVOK

OTBD 212044Z 2200/2306 34012KT 7000 SCT120
BECMG 2205/2207 34018G28KT 4000 BLDU SKC
TEMPO 2205/2215 1000 BLDU
BECMG 2218/2220 34015KT

SAEZ 212210Z 2200/2224 33005KT CAVOK TX16/2218Z TNM02/2209Z
BECMG 2210/2212 32012KT

PS, I'm glad I'm not going to DOHA tonight!
 
Rocketman99 said:
Yes, I know that is the definition for the BECMG group, but that differs from how you actually apply it. Say the wx is supposed to improve from being below mins you can't use it until the end of the BECMG period. For all intents and purposes the wx is the previous main body block until the end of the BECMG period. That is how it is considered a conditional group for 3585 purposes.
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Yes, but if the weather is deteriorating from being above mins to below landing mins in the BECMG group. For all intents and purposes you would assume it happens at the earliest possible time of the BECMG group, and then remains permanent. If you say it's a conditional remark then they can dispatch it legally with 3585 just as easily as they could in your own example.

EDIT: I understand you obviously have to always completely follow company OpSpecs and SOP's. If they say it's a conditional remark, it's a conditional remark at that particular carrier. But that's not the intent of 3585 and does not limit in any way the judgment of the PIC and dispatcher.
 
Agreed. Per our OpSpecs BECMG is a conditonal for purposes of dispatch under 3585 's all I'm saying.

Now I think we've both probably sufficiently confused the OP who was just looking for an explanation of 3585. :)
 
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