Destination airport weather minimums

[z987k]

135.219 - No person may take off an aircraft under IFR or begin an IFR or over-the-top operation unless the latest weather reports or forecasts, or any combination of them, indicate that weather conditions at the estimated time of arrival at the next airport of intended landing will be at or above authorized IFR landing minimums.

Pretty straight forward, here's the scenario.

METAR - 010553Z 36004KT 1/4SM R07R/2000V2400FT FG VV003 01/M01 A2992 RMK AO2 SLP132 4/008 T00061011 10006 21011 50004

TAF - 010537Z 0106/0212 VRB03KT 1/4SM FZFG OVC001
TEMPO 0110/0114 4SM BR SCT001 BKN008
FM011400 02004KT 4SM BR SCT002 OVC010
FM012100 02005KT P6SM SCT010 BKN100
FM020600 36008KT P6SM VCSH BKN050

ETA is 1200Z. I don't see a problem with launching. The forecast states that temporarily from 10-14Z, the visibility will be 4SM. More than enough for the ILS.
I have been told that I am incorrect, and that legally I cannot launch because the "weather reports or forecasts or any combination thereof" in the forecast includes the first line. Since that line is worse weather, then according to 8900.1 3-2050, it is controlling. More or less, I've been told the TEMPO means nothing in regards to launching or determining alternates unless it's worse than the other part of the forecast.
Hopefully I am articulating what was told to me.

This seems counter intuitive. If we truly took all the available weather products for an area there's be lots of times I could never launch anywhere. For example if an Area forecast said there would be widespread less than 1/4SM, but the TAF for an airport in that area reads P6SM all day long, and the metars concur, it would be stupid to not be able to go... but that's any combination thereof and the worse of the two controlling.

I guess what I'm looking for is validation that, in fact the TEMPO portion of the TAF can not be used for determining destination and alternate weather if the normally forecasted portion is worse. I didn't find anything super relevant in chief council opinions.

 

[Tommay85]

Who told you you were wrong? What you're being told seems equivalent to a 141 flight school telling you "ZOMG, thunderstorm within 30 miles, you'll die!".

 

[Capt. Chaos]

I would assume you can't do 1800rvr mins on the approach? Not sure how your ops specs read, but we would be stuck waiting on the FZFG in the TAF not the vis.

 

[auw2fly]

From the NOAA website:

"The TEMPO group is used for any conditions in wind, visibility, weather, or sky condition which are expected to last for generally less than an hour at a time (occasional), and are expected to occur during less than half the time period. The TEMPO indicator is followed by a four-digit group giving the beginning hour and ending hour of the time period during which the temporary conditions are expected. Only the changing forecast meteorological conditions are included in TEMPO groups. The omitted conditions are carried over from the previous time group."

So from your example, at your ETA the weather could be either 1/4 mile vis and 100-foot ceiling, or 4 miles vis with an 800-foot ceiling, but there's no way to know for sure, as the TEMPO line weather will occur occasionally over the listed period of time.

 

[gotWXdagain]

^ This. There is alot of misunderstanding that TEMPO means that during the entire time the TEMPO condition is charted for, it will be that condition, when actually TEMPO is used to describe "off and on" weather. Looking at your TAF example, when you get to the destination it could either be a great day to shoot the ILS and get good actual, or a great day to be wishing you hadn't taken off to begin with. The point being, you don't know.


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[z987k]

From the NOAA website:

"The TEMPO group is used for any conditions in wind, visibility, weather, or sky condition which are expected to last for generally less than an hour at a time (occasional), and are expected to occur during less than half the time period. The TEMPO indicator is followed by a four-digit group giving the beginning hour and ending hour of the time period during which the temporary conditions are expected. Only the changing forecast meteorological conditions are included in TEMPO groups. The omitted conditions are carried over from the previous time group."

So from your example, at your ETA the weather could be either 1/4 mile vis and 100-foot ceiling, or 4 miles vis with an 800-foot ceiling, but there's no way to know for sure, as the TEMPO line weather will occur occasionally over the listed period of time.

There you go. You'd think something as simple as exactly what TEMPO means would be something I'd know by this point. Thanks.

 

[ppragman]

You can't launch on a tempo.

 

[jeflies]

This is how I always understood this. Anything printed on a TAF regardless if its associated with a TEMPO or BECMG should be considered for planning. In other words, if anything less than 1/2 miles (assuming ILS) is printed then you gotta wait.

From 0547Z until 1400Z its going to be 1/4 mile. End of story. For flight planning purposes. You have to wait it out.

Having a TEMPO that's above minimums within that 1/4 mile window doesn't satisfy 135.219 in my opinion.

 

[adk]

I know 121 is generally different, but a 121 operator wouldn't be able to launch with that forecast.

 

[Tommay85]

Hmm, I've been wrong about tempos this entire time! Should have been dead a long time ago!

I disagree about an area forecast superseding a TAF though...

But, when it doubt, $%#@ it!

 

[ppragman]

This is how I always understood this. Anything printed on a TAF regardless if its associated with a TEMPO or BECMG should be considered for planning. In other words, if anything less than 1/2 miles (assuming ILS) is printed then you gotta wait.

From 0547Z until 1400Z its going to be 1/4 mile. End of story. For flight planning purposes. You have to wait it out.

Having a TEMPO that's above minimums within that 1/4 mile window doesn't satisfy 135.219 in my opinion.

Now, to muddy the waters a bit,

No person may take off an aircraft under IFR or begin an IFR or over-the-top operation unless the latest weather reports or forecasts, or any combination of them, indicate that weather conditions at the estimated time of arrival at the next airport of intended landing will be at or above authorized IFR landing minimums.

One could say that a 10SM CLR with a wide temp and dewpoint spread in the latest METAR could "indicate" that the wx will be good enough at ETA. Even a moderately crummy METAR that indicates above mins might be good enough if the trip is short. If I will only be in the air 30 minutes, then current conditions may be the best information. 135 gives you just enough room to hang yourself.

 

[z987k]

I do hate how someone can write -

TAF - 010537Z 0106/0212 0000KT M1/4SM FZFG VV001

But the Metar for the past 5 hours is -

36015KT 10SM CLR 15/M27

And you can't launch.

 

[Autothrust Blue]

I do hate how someone can write -

TAF - 010537Z 0106/0212 0000KT M1/4SM FZFG VV001

But the Metar for the past 5 hours is -

36015KT 10SM CLR 15/M27

And you can't launch.

Have you tried weather shopping? "Optimized" forecasts are awesome.

"Yeah, we're going to Klamath..."

 

[z987k]

Have you tried weather shopping? "Optimized" forecasts are awesome.

Yeah, I don't think we're that fancy.

Played airport appreciation today waiting for fog in pasco.

 

[Tommay85]

I do hate how someone can write -

TAF - 010537Z 0106/0212 0000KT M1/4SM FZFG VV001

But the Metar for the past 5 hours is -

36015KT 10SM CLR 15/M27

And you can't launch.

I hate it when some genius puts the weather equipment in the lowest part of the field! Or the RVR sensors in the ditch! But I do LOVE when other pilots know what these sensors look like and point their engines at them! I'm looking at you Southwest!

 

[jtrain609]

I know 121 is generally different, but a 121 operator wouldn't be able to launch with that forecast.

EDIT: What about 3585?

 

[F9DXER]

What are the airports around your projected destination calling for?

 

[ppragman]

I do hate how someone can write -

TAF - 010537Z 0106/0212 0000KT M1/4SM FZFG VV001

But the Metar for the past 5 hours is -

36015KT 10SM CLR 15/M27

And you can't launch.

File to some better airport, via your actual destination. If you roll over the top of "KABC" enroute to "KDEF" and the weather is good enough, shoot the approach at your real destination.

 

[z987k]

File to some better airport, via your actual destination. If you roll over the top of "KABC" enroute to "KDEF" and the weather is good enough, shoot the approach at your real destination.

I'm familiar with this trick, but I've been told if you get a super nasty FAA guy they can violate you since where you filed to wasn't your intended destination.

 

[msmspilot]

I'm familiar with this trick, but I've been told if you get a super nasty FAA guy they can violate you since where you filed to wasn't your intended destination.

Under what regulation? The only thing you have to watch for is you don't need to file to a GA reliever airport in the middle of the push and expect to switch to ATL or JFK en route and not get a phone call. But that's about flow control, not just that you changed destination.