Part 121 Weather Scenario

[Orange Anchor]

What's the background for that requirement?

http://www.nws.noaa.gov/asos/amscom.htm

This paper discusses some problems with ASOS as well as stating, "In order to get a representative picture of conditions at an ASOS-supported airfield, users should learn to consider a series of ASOS reports rather than to assume a single ASOS snapshot is likely to represent the "smoothed" conditions typically reported by the observer."

IF one is to ensure they have the absolute most up-to-date wx to the minute, one would also need to listen to the ATIS crossing the FAF to ensure no special had been issued. In 27yrs with the airlines, I never heard of anyone doing that.

 

[Polar742]

Regardless, since you have some questions about the legality and the advice here, while probably correct, is not official, I would definitely file a NASA and have the other pilot do also.

In doubt.. FILE!

http://asrs.arc.nasa.gov/report/electronic.html

Or if you have a ASAP program, use that. The ASAP program can get the manual changed if the explanation of what you were doing wasn't clearly explained procedurally.

If the ASAP report is accepted, then it is converted into a ASRS report as well.

 

[Orange Anchor]

Or if you have a ASAP program, use that. The ASAP program can get the manual changed if the explanation of what you were doing wasn't clearly explained procedurally.

If the ASAP report is accepted, then it is converted into a ASRS report as well.

No one would put in their Ops Manual they had to check the wx as they cross the FAF. Even with advanced FMS, you would need to hit the FAF only a few seconds after the latest ASOS to ensure you are legal and no one is going to do that.

Maybe good for a class about theory but it would be highly impractical and from some of the FAA guys I worked with, I would bet they would merely look at you with dismay. ???

I could be wrong.

 

[zmiller4]

I could be really missing something, but if the controller clearing you for the approach gives you the current weather and it's above minimums/wind requirements, aren't you pretty much covered unless they notify you of a change otherwise?

 

[jtrain609]

I didn't ask my question clearly enough. What I was wondering was "do I need to have more current weather than the 45 minute old ATIS in order to legally shoot an approach?"

An ATIS is valid for one hour unless otherwise superseded by a special report as OA has noted. If a new ATIS is released, the local controller will advise you of such. You can assume that your ATIS is valid for one hour unless told otherwise.

 

[jtrain609]

No one would put in their Ops Manual they had to check the wx as they cross the FAF. Even with advanced FMS, you would need to hit the FAF only a few seconds after the latest ASOS to ensure you are legal and no one is going to do that.

Maybe good for a class about theory but it would be highly impractical and from some of the FAA guys I worked with, I would bet they would merely look at you with dismay. ???

I could be wrong.

Well, I see a keyboard in front of me right now, not a yoke; so I'd assume we're talking about theory here.

So I'll say again, if you're using an ASOS as your weather, when does it expire? We know when an ATIS expires, but when does an ASOS expire? That's the principal argument.

 

[Polar742]

No one would put in their Ops Manual they had to check the wx as they cross the FAF. Even with advanced FMS, you would need to hit the FAF only a few seconds after the latest ASOS to ensure you are legal and no one is going to do that.

Maybe good for a class about theory but it would be highly impractical and from some of the FAA guys I worked with, I would bet they would merely look at you with dismay. ???

I could be wrong.

I concur, I think I didn't explain my point correctly. I agree with you.

Perhaps this would make the procedure of when to get the applicable weather in a format that is more "user-friendly" (to steal a overused phrase), or bolster the training program in initial indoc to help the newbies to 121 understand the rule better.

That's what I was intending, but fell short of explaining.

 

[jtrain609]

I concur, I think I didn't explain my point correctly. I agree with you.

Perhaps this would make the procedure of when to get the applicable weather in a format that is more "user-friendly" (to steal a overused phrase), or bolster the training program in initial indoc to help the newbies to 121 understand the rule better.

That's what I was intending, but fell short of explaining.

I'll also remind ya'll, this was taught at a part 135 company, not a part 121 company. I think the assumption was that you'd have the ASOS on Com 2 while you're heading from the IAF to the FAF.

 

[kellwolf]

An ATIS is valid for one hour unless otherwise superseded by a special report as OA has noted. If a new ATIS is released, the local controller will advise you of such. You can assume that your ATIS is valid for one hour unless told otherwise.

Not always. If the controller is too busy to let you know that an ATIS was released prior to you hitting the marker, are you still illegal? By your argument, the answer would be "yes" since you wouldn't have an up to the minute snapshot of the WX. Like I said earlier, if you go with the "monitoring ASOS" theory, you should be asking for WX updates from a tower controller/approach controller as you cross the fix. The only difference in the information is the delivery method.

Besides, my ops manual says we either monitor company freq or guard on #2. Doesn't leave any room for ASOS.

 

[jtrain609]

Not always. If the controller is too busy to let you know that an ATIS was released prior to you hitting the marker, are you still illegal? By your argument, the answer would be "yes" since you wouldn't have an up to the minute snapshot of the WX. Like I said earlier, if you go with the "monitoring ASOS" theory, you should be asking for WX updates from a tower controller/approach controller as you cross the fix. The only difference in the information is the delivery method.

Besides, my ops manual says we either monitor company freq or guard on #2. Doesn't leave any room for ASOS.

So how do you know your legal to shoot the approach if you're just listening to an ASOS? If it expires every minute, how can you tell the FAA that you were in fact legal for that last approach?

That's all I'm asking.

 

[TUCKnTRUCK]

The approach only may not be commenced, or continued If weather reporting below the required RVR/VIS is reported prior to reaching the FAF, Past the FAF the approach may be continued. Nothing states that it must be the instant asos.

the ATIS will be the most accurate representation of the general conditions, but may not properly be indicating if there is a large rapid change, I.E a fog bank. Conditions for the ATIS machine, are weighted over the last half hour, with the last 10 minutes being double weighted.

The only thing legally "required" for landing is a current Altimeter setting on a visual approach, and that must be obtained by from an FAA approved weather observation system, or observer. If weather is less than VFR, you need visibility. Mostly you will need whatever factors are controlling for your type of operation.

The FAA never states how that weather must be relayed to the pilot though. If your opps people want to send you smoke signals, so long as you get it, your good.

 

[kellwolf]

So how do you know your legal to shoot the approach if you're just listening to an ASOS? If it expires every minute, how can you tell the FAA that you were in fact legal for that last approach?

That's all I'm asking.

Does it EXPIRE every minute, or is it UPDATED every minute?

 

[jtrain609]

I would contend that the valid time is one minute long.

 

[kellwolf]

I would contend that the valid time is one minute long.

I'd need a source on that one.

FYI, for everyone else, John and I aren't just hacking away at each other. This is pretty much how our crash pad was at Skymates.

 

[TUCKnTRUCK]

It doesn't expire, and is valid until a more current one is received.

5.2 One-Minute Observations
Once each minute, ASOS performs internal diagnostic
and QC checks on sensor data and then updates the One
Minute Observation (OMO). The OMO is encoded in
METAR format and includes all basic weather parameters
found in the body of the METAR plus selected automated
remarks. The OMO also accepts manually entered remarks
(via OID keyboard entry), such as variable visibility and
tower visibility. The basic difference between the OMO
and the METAR/SPECI is that the OMO is generally not
transmitted long-line beyond the local FAA or NWS communications
network node (see bullet 3 below). OMO
information is collected during the 60-second period ending
at M+00 and made available to users each minute at
M+23 (23 seconds past the current minute) through the
following media:
OID, VDU, and authorized dial-in user computer
display screens.

42
controller are both signed-off the ASOS, the AUTO report
modifier is restored to the METAR/SPECI report.
When an aircraft mishap occurs, the on-site observer
can (and should) initiate a local special observation. In this
event, the remark “(ACFT MSHP)” is appended to the local
SPECI report, which is sent to the ASOS printer and
stored in memory for 31 days. The long-line version of the
SPECI report is sent without the (ACFT MSHP) indicator.
All ASOS reports that are transmitted through the NWS
long-line communications network are captured at the NWS
Systems Monitoring and Coordination Center (SMCC) and
compiled with other transmitted data into a daily Selective
Records Retention System (SRRS) tape. This tape is sent
to the National Climatic Data Center (NCDC) once a day
for archiving and inclusion in various climatic summaries.
NCDC also directly downloads data from


If the FAA was really going after you, simply pulling the RAPTOR data if your in a radar environment, and co aligning it with the NWS coded archive, would clear you.

If you really wanted to get technical, the Voice transmitted weather is not the actual station transcribed weather accurate to the minute. Many of the sensors require up to a 10 minute data stream to average, and perform QC checks. eg, if the Vis sensor misses 2 recordings over 10 minutes, the data will be omitted.

As long as you get the weather in a reasonable time before crossing the FAF, you are good to go. I am pretty sure that a FED would get all sorts of pissed if a crewmember went heads down, and off freq to get the instant weather as they crossed the FAF, while configuring on a good IMC approach.

Honestly, if you really want to frett the details, then how come you are only looking at the instant weather for a 10m area that is most likely not in your landing zone? How many times have you seen it call 10/clr when you can't see half the runway?

 

[TUCKnTRUCK]

Well, I see a keyboard in front of me right now, not a yoke; so I'd assume we're talking about theory here.

So I'll say again, if you're using an ASOS as your weather, when does it expire? We know when an ATIS expires, but when does an ASOS expire? That's the principal argument.

When does an ATIS message expire?

Many people incorrectly assume that the lifespan of an ATIS message is an hour. The New hourly atis message is changed with the receipt of the new hourly weather observation, which is included in the ATIS brief. The time noted, is only the time of the weather report, and has no bearing on the ATIS message beyond the weather. If you fly to a field where manual observations are taken, the ATIS message will only change if there is a change in the weather, as the observer is not going to release a new weather brief every hour if no change is noted.

that prob. didn't come across clearly, but, ASOS, ATIS messages do not expire as they are not forcasts. A TAF, sigmet,airmet,surface plot, sig wx plot, eta, aviation, garp model etc, will have a valid window and timeframe. Anything that is surface recorded or actual conditions will remain effective untill the reciept of updated conditions.

 

[MikeD]

When does an ATIS message expire?

From earlier in thread:

An ATIS is valid for one hour unless otherwise superseded by a special report as OA has noted. If a new ATIS is released, the local controller will advise you of such. You can assume that your ATIS is valid for one hour unless told otherwise.

 

[TUCKnTRUCK]

From earlier in thread:

AIM 4-1-13 B
ATIS information includes the time of the latest weather sequence, ceiling, visibility, obstructions to visibility, temperature, dew point (if available), wind direction (magnetic), and velocity, altimeter, other pertinent remarks, instrument approach and runway in use. The ceiling/sky condition, visibility, and obstructions to vision may be omitted from the ATIS broadcast if the ceiling is above 5,000 feet and the visibility is more than 5 miles. The departure runway will only be given if different from the landing runway except at locations having a separate ATIS for departure. The broadcast may include the appropriate frequency and instructions for VFR arrivals to make initial contact with approach control. Pilots of aircraft arriving or departing the terminal area can receive the continuous ATIS broadcast at times when cockpit duties are least pressing and listen to as many repeats as desired. ATIS broadcast shall be updated upon the receipt of any official hourly and special weather. A new recording will also be made when there is a change in other pertinent data such as runway change, instrument approach in use, etc.


The time in the report only indicates when the weather observation was recorded in the NWS database, for dissemination. When I did my internship in the Mt. Washington observatory, we took observations hourly, at the 45's, because transmitting often took 5-10 minutes in bad weather. If we could not transmit, the last valid weather stayed in effect.

Recorded observations do not expire unless they are superseded, So, If you receive an ASOS brief at 1015z, and don't listen to it again until 1020Z, for your assumed purposes, the weather between 1015 and 1020 remained the same.

I know it's just the small details, but the only weather products that expire, are forecasts.

 

[Orange Anchor]

So how do you know your legal to shoot the approach if you're just listening to an ASOS? If it expires every minute, how can you tell the FAA that you were in fact legal for that last approach?

That's all I'm asking.

In theory and if the FAA was sitting in the class on Part 135 theory, I would say that last wx I got said I was legal and that is WHY I continued the approach. Had the last wx I got been below mins, I would have diverted or done a few more holding patterns. And had I arrived at mins and the wx was below mins, I would have gone around.

FWIW, we had a few guys like your -135 guy in the training dept and for the most part, they created more problems for the line check and all checks airmen than they solved. Most of the time they were also heavy into personal technique that was usually better than procedure, according to them. They also like to give 4hr orals until we got a new boss. His effort was to erase any lines between training and actually flying the line. And he advised some of the Supermen that if they couldn't figure out whether or not someone met standard in less than 4 hrs maybe they should be doing something else. Odd thing happened.. the 4 hr orals disappeared.

 

[jtrain609]

In theory and if the FAA was sitting in the class on Part 135 theory, I would say that last wx I got said I was legal and that is WHY I continued the approach. Had the last wx I got been below mins, I would have diverted or done a few more holding patterns. And had I arrived at mins and the wx was below mins, I would have gone around.

FWIW, we had a few guys like your -135 guy in the training dept and for the most part, they created more problems for the line check and all checks airmen than they solved. Most of the time they were also heavy into personal technique that was usually better than procedure, according to them. They also like to give 4hr orals until we got a new boss. His effort was to erase any lines between training and actually flying the line. And he advised some of the Supermen that if they couldn't figure out whether or not someone met standard in less than 4 hrs maybe they should be doing something else. Odd thing happened.. the 4 hr orals disappeared.

Oh I know what you're saying, and believe me I've got stories.

I do think the guy has a valid point, though. Am I saying I follow this? No. Am I saying this is realistic procedure for line flying? No.

But, in the situation your describing, you could transpose it like this:

PNF: Approaching minimums.
PNF: Minimums.
PNF: ....Minimums.
PF: Runway in sight, landing. What'd you say?

Or in other words, weather sources have valid times for a reason. You could just say you never got he updated weather, and ho hum figured nothing had changed.