TWR visibility

[asayankee]

Reference?
(I believe you, just for future arguments)

Tower employees are "certified weather observers" and are therefore legal to use as "official" sources of weather. Remember, that ATIS can be up to an hour old. Yes you are able to accept an approach

 

[Oakum_Boy]

From

2-6-6. REPORTING WEATHER CONDITIONS
a. When the prevailing visibility at the usual point
of observation, or at the tower level, is less than
4miles, tower personnel shall take prevailing
visibility observations and apply the observations as
follows:
1. Use the lower of the two observations (tower
or surface) for aircraft operations.
2. Forward tower visibility observations to the
weather observer.
3. Notify the weather observer when the tower
observes the prevailing visibility decrease to less than 4 miles or increase to 4 miles or more.

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx


2-6-7. DISSEMINATING WEATHER
INFORMATION
TERMINAL. Observed elements of weather information shall be disseminated as follows:
a. General weather information, such as “large
breaks in the overcast,” “visibility lowering to the
south,” or similar statements which do not include
specific values, and any elements derived directly
from instruments, pilots, or radar may be transmitted to pilots or other ATC facilities without consulting the weather reporting station.
b. Specific values, such as ceiling and visibility,
may be transmitted if obtained by one of the
following means:
1. You are properly certificated and acting as
official weather observer for the elements being reported.
NOTE
USAF controllers do not serve as official weather
observers.
2. You have obtained the information from the
official observer for the elements being reported.
3. The weather report was composed or verified
by the weather station.
4. The information is obtained from an official
Automated Weather Observation System (AWOS) or
an Automated Surface Observation System (ASOS).




These two sections seem to contradict each other, however it seems that if they state the visibility, then they have been certificated, and are acting as the official observer for the elements being reported.

Source: http://www.faa.gov/airports_airtraffic/air_traffic/publications/at_orders/media/ATC.pdf

 

[Flyin2low]

Takeoff and Landing requirements use surface visibilty reports, either in RVR or SM. If RVR is reported, it is controlling for the operation in question. The tower vis report (@75'AGL) is just to give operators a better understanding of the actual conditions, but doesn't override the reported vis (RVR+SM)

 

[moonship]

We = Great Lakes

 

[regionalcap]

Takeoff and Landing requirements use surface visibilty reports, either in RVR or SM. If RVR is reported, it is controlling for the operation in question. The tower vis report (@75'AGL) is just to give operators a better understanding of the actual conditions, but doesn't override the reported vis (RVR+SM)

I always thought it could override the reported visibility except for RVR. It is coming from a certified weather observer.

 

[Flyin2low]

I always thought it could override the reported visibility except for RVR. It is coming from a certified weather observer.

Nope. Like I said before, tower vis is reported at 75' AGL. Most runways are about 75' below that. If you are operating on a runway, RVR or reported surface vis are the only two things that can meet a takeoff/landing ops spec. Only an updated surface observation can override a surface observation.

 

[Oakum_Boy]

If the tower controller is the official weather observer on the field, then the prevailing visibility from that location is whats reported on the METAR/ATIS.

However, if the tower says "tower visibility xxxx", that's just an advisory thing until the surface observation is updated.

In the mean time, you have to use the lower of the tower visibility or surface observation.

Is that right?

 

[rptrain]

unless tower visibility is the "usual point of observation" it is added as advisory information. surface visibility, the prevailing visibility from the usual point of observation (usually an ASOS sensor), is the controlling value. unless RVR is installed and operating.

http://www.nws.noaa.gov/oso/oso1/oso12/fmh1/fmh1ch6.htm

 

[GuppyWN]

ATIS/AWOS/METAR is king unless you have an RVR for the particular piece of pavement you are using.

Tower visibility is meaningless in legalities.

Quit making it hard.

Gup

 

[trainer8]

At the 121 airlines I've been at(3) none were authorized to do contact approaches. Anyone know of a 121 carriers ops specs that allow these? I don't.

ALG used to allow contact aprroaches, but their FOM required VFR mins at the aerodrome to accept the request the approach.

 

[Captzaahlie]

RVR rules....

CYA know your OPS SPECS don't get burned!


Here's one for ya, "can you get mono from riding a monorail"?

Sorry I couldn't resist......

This thread should be in the private pilot instrument section. My apologies in advance for the sarcasm.

 

[Captzaahlie]

Even though they are 121, turbo prop operators have different rules than jet operators.

that's way too vague a comment......
many have the same rules and in some cases the only reason turbo props have different rules are because it can be done safely in a TP and not in a jet....

 

[CallmeJB]

You can't shoot the ILS for 1R because the RVR reported for 1R is less than 1200. However if 1L is long enough to land on or if the wind will let you land on 19L (and it isn't reporting an RVR) then you can shoot the ILS for either of those runways because you have the 1/2sm.

Hate to be nit picky, but if 1R has RVR reporting, so does 19L. It's the same piece of pavement, with the same transmisometers (sp?).

Now if you have four of them, can one be inop? Which ones are controlling? Ahh! Let's not start that.

John

 

[great cornholio]

Hate to be nit picky, but if 1R has RVR reporting, so does 19L. It's the same piece of pavement, with the same transmisometers (sp?).

Now if you have four of them, can one be inop? Which ones are controlling? Ahh! Let's not start that.

John

I was thinking the same thing, but wasn't sure if all (or most) runways with RVR always have 3 transmisometers, or if there was a case were only 1 direction had only touchdown RVR.

 

[purduedchi]

I actually had this happen up in SYR to me. My company tried to suspend me for..get this "refusing to land an airplane". ATIS vis was fluctuating between 1/2 mile and 1 mile. Of course the ILS was OTS and the only approach was a VOR approach. Cat B required 3/4 and C+D required 1 1/4 mile. Being that Cat C was our lowest category I began holding. All RVR's were OTS as well, but tower was calling a tower vis of 3-4 miles. The only ones shooting approches were PDT because they were Cat B. To make a long story short my dispatch saw that PDT was getting in and then wrote me up for refusing to land. My flight managers tried to hang me instead of sticking up for me...so I ended the meeting and came back for another one with our POI. He basically referred our FM's to the piece of info that OakumBoy posted. I wish our FM's could have been suspended for being idiots. Basically it goes in this order:

Touchdown RVR
ATIS
Tower vis.
Tower vis can be used instead of ATIS if it is greater than 4 miles
Then again you always have the trump card..."in the interest of safety" I decided to divert...etc.