Metar says wx below mins. Forecast above mins. 45 min flt

S

smig

Well-Known Member
Lets say you are going on a 45 minute flight. The latest Metar says the weather at destination is 1/4 mile. You need 1/2 to land. The forecast says you will have 1 mile vis.

Can you takeoff for your destination?

I have heard two different interpretations....

1. You can takeoff if your planned arrival time will be outside the metars hourly observation time.

2. You must wait until the metar goes above mins, since a metar doesn't have an expiration time. It is valid until the next observation, which is usually but doesn't have to be on the top of the hour.

Whatcha think?

ETA: this is a 121 flight
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

Part 91 you can take off 0/0 and shoot the app 0/0 just need all the required stuff to land.
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

Under what rules are you planning this flight?
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

I should have added, this is 121
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

If your block time falls entirely within the METAR, then you can dispatch by it.

However, a 45 minute flight, you will still probably be very hard pressed to stay withing the valid period.

Do make note of the last 3 or so METARs too, to watch for a more accurate trend than the forecast.

I've seen this quandry before. Mainly it seems to be that the forecast is not acceptable, but people want to get the flight done under the METAR.

Just remember, the ultimate goal is to not get 1) Hurt 2) Bend metal 3) scare pax (if you have them) 4) don't need to file a report due to your wrong -and liberal (in the correct definition of the word, not the implied-and wrong- causehead definition). Any of which could lead to a violation. ;)

Have fun and stay safe.
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

§ 121.613 Dispatch or flight release under IFR or over the top.

top Except as provided in §121.615, no person may dispatch or release an aircraft for operations under IFR or over-the-top, unless appropriate weather reports or forecasts, or any combination thereof, indicate that the weather conditions will be at or above the authorized minimums at the estimated time of arrival at the airport or airports to which dispatched or released.
[Doc. No. 6258, 29 FR 19222, Dec. 31, 1964, as amended by Amdt. 121–33, 32 FR 13912, Oct. 6, 1967]
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

A good rule to go by; Always picture yourself to the left of the administrative law judge explaining why you did what you did.
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

Itchy said:
A good rule to go by; Always picture yourself to the left of the administrative law judge explaining why you did what you did.
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What? Thats like sitting around debating on what the reg's say.
A good rule to go by: Don't due things in flying out of fear-do or don't do them because thats what the reg's/sop's say you can or can't do.
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

Common sense should prevail. Just because it's legal or not doesn't always mean it's safe.
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

higney85 said:
Common sense should prevail. Just because it's legal or not doesn't always mean it's safe.
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Of course not.

But that doesn't matter in the 121 game.

We have numerous OpSpec exceptions that allow us to go when the METAR says one thing, yet the forecast has the conditions improving. . .hell. . .what's the number, 3580 or something like that.

I never personally run into such a situation, but it was always available.

In 121, you're going. . .and you'll take a look too, and you'll most likely shot an approach again before you dip on out to your alternate.
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

It's 3585 and deals with "TEMPO" remarks in a forecast period.

Then there is the "marginal" conditions.

Both of which require a 2nd alternate.

However, neither really relates to the METAR.

I did, however, delay a flight I diverted due to a series of METARS.

I was in EYW, and ASA had cancelled several flights on the CR7 out of there (Not sure of the cause. Although for the longest I never thought ASA mechanics had upper bodies because all I saw were legs dangling from the engine or right under a panel by the slats ;) ) It was in February, which is when the fog hits central FL.

I had talked dispatch in to getting me a flag stop in FLL, so I could take 37 people and 55 bags out of EYW, gas up there since I needed an alternate for MCO.

The forecast for MCO wasn't bad, but the METARs all had 1/4SM or less of vis.

We landed in FLL, and for 3 hours the vis trend headed south.

The dispatcher and I conferred and came to the agreement that we'd wait until it was legal vis on the METAR since the flight could, concievably, be completed in the valid period.

Not a big deal, but really the only application I ever used of the METAR as a controlling document.
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

surreal1221 said:
I never personally run into such a situation, but it was always available.

In 121, you're going. . .and you'll take a look too, and you'll most likely shot an approach again before you dip on out to your alternate.
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3585... and if you look at the history of that exemption you will find it was developed due to a few Airline Lobby Groups (read: ATA). It's one of the most BS things I've ever seen out there.

Also, your last sentence isn't really that accurate. There have been plenty of times where I've launched with an alternate and never got anywhere close to shooting an approach at my destination airport before heading to the alternate. In fact, in all the times I've diverted only two have involved going down to mins at the destination and not seeing anything.
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

All 3585 does is give relief to TEMPO conditions in the forecast, allowing you to still dispatch. I'm sure we all knew that though.

I think it's a far better tool, once it's understood, than the "marginal conditions" BS, which totally allows an operator to define it's own "marginal conditions".

Both of which require a second alternate.

While 3585 was intended for longhaul operations that might cross 2, 3 or more forecast periods where the TEMPO condition might just disappear, it's applied now about everywhere.

Heck, even CHQ used it when they were flying PIT-JST in a J31.
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

I had it applied on a flight from CLT to AVL about a month ago. The TAF was showing 2 miles and OVC002 but there was a tempo for 1/4 VV001. Also the last three METARS were all at 1/4 (which was NOT shown in the body of the TAF). My scheduled arrival time was outside the coverage of the current METAR so my dispatcher wanted me to go under 3585 (with alternates of GSP and CLT). I convinced him for an 18 minute flight it was a sort of stupid idea.
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

BobDDuck said:
Also, your last sentence isn't really that accurate. There have been plenty of times where I've launched with an alternate and never got anywhere close to shooting an approach at my destination airport before heading to the alternate. In fact, in all the times I've diverted only two have involved going down to mins at the destination and not seeing anything.
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You win.

I wasn't going to head down the road of stating the various requirements needed to shoot the approach. Or the ADs that affect our ability to go to flaps 45. . .blah blah blah.

Nevertheless, the last sentence wasn't meant to be 100% factual and serious - more or less the sense that the company (dispatcher or CP) will push a pilot through the utilization of 3585 and various other means, far more numerous than I feel like going into. That and the company took my books so. . .what the hell do I know. I just know that during ground school we had to essentially memorize (yeah - poor form, blah blah blah) the various stipulations of the numerous ways they would find it legal for us to launch.
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

BobDDuck said:
I had it applied on a flight from CLT to AVL about a month ago. The TAF was showing 2 miles and OVC002 but there was a tempo for 1/4 VV001. Also the last three METARS were all at 1/4 (which was NOT shown in the body of the TAF). My scheduled arrival time was outside the coverage of the current METAR so my dispatcher wanted me to go under 3585 (with alternates of GSP and CLT). I convinced him for an 18 minute flight it was a sort of stupid idea.
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Yeah, I agree that's the wrong application....

When the CP gets on the phone and says "Go". Say OK. takeoff, go hold for whatever, 'till you have to go pee or something, then go divert.

Land, call the dispatcher, then ask what he wants you to do with the pax.

Fill out an irregularity report (I used to love the sarcastic approach on ones like this). Make sure you highlight how much jet fuel was wasted and how many passnegers were inconvenienced.

They prolly won't ask you to do that again.
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

smig said:
Lets say you are going on a 45 minute flight. The latest Metar says the weather at destination is 1/4 mile. You need 1/2 to land. The forecast says you will have 1 mile vis.

Can you takeoff for your destination?

I have heard two different interpretations....

1. You can takeoff if your planned arrival time will be outside the metars hourly observation time.

2. You must wait until the metar goes above mins, since a metar doesn't have an expiration time. It is valid until the next observation, which is usually but doesn't have to be on the top of the hour.

Whatcha think?

ETA: this is a 121 flight
Click to expand...

If the forcast (TAF) for our arrival time is better than the needed approach minimums then we can dispatch. (Even with a crappy metar. Generally an alternate is needed of course.)

We run into this scenario every once in a while during the winter with Sun Valley, Idaho. Sometimes it works and sometimes it doesn't. (Then it is off to the alternate and often the passengers get bussed to Sun Valley.) Naturally I have learned to not completely trust the TAF and always make sure I have a good solid "OUT."

BTW even if we can dispatch in the above scenario, it does not always happen. We might hold off if we don't trust the weather or if newer TAFs are due to be issued.

As a new captain I remember getting dispatched from LAX to OXR (Oxnard) with the same issue. Metar was at like 1/4 mile and forcast for arrival was at 1/2 vis. So no matter how you sliced it, it was going to be tight. Discussed it with dispatch, they wanted us to go and could legally dispatch. PAX were well briefed on the situation and we ended up holding for nearly an hour on a fix on the ILS. Despite the legal to dispatch TAF, It never went above 1/4 and we went back to LAX.


I actually needed to use 3585 this winter. I think that was the second time I have ever truly needed it. I may have saved the release somewhere. I'll have to dig it up.
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

smig said:
Lets say you are going on a 45 minute flight. The latest Metar says the weather at destination is 1/4 mile. You need 1/2 to land. The forecast says you will have 1 mile vis.

ETA: this is a 121 flight
Click to expand...

Dispatch cat II and go. 1/4 is all you need.
 
Re: Metar says wx below mins. Forecast above mins. 45 min fl

Lee D said:
If the forcast (TAF) for our arrival time is better than the needed approach minimums then we can dispatch. (Even with a crappy metar. Generally an alternate is needed of course.)
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Actually you can't dispatch with a crappy metar if your arrival will fall within the metar's valid period. The regs say the both the weather reports (which is the metar) and the forecast must be at least minimums at your eta. (bafanguy was nice enough to post this reg earlier in the post 121.613)

If the 12:00 metar says 1/4 mi vis, and you are on a short 15 minute flight and due in at 12:30, you can't dispatch the aircraft.

Where the gray area is... lets say we are scheduled to depart at 12:30. The block time is 31 minutes, which gets us in at 13:01. Can we dispatch if the 12:00 metar says 1/4 mile? Remember, a metar does not expire, it is valid until the next observation.
 
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