ILS with 3/8 mile visibility?
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trcsmith
Filing Flight Plan
And your quoting from wikipedia..... 
aterpster
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aterpster
All the Jepp charts say RVR 1800 becomes 1/2 mile when the RVR is OTS.
Palmpilot
Touchdown! Greaser!
The text you quoted doesn't match what I'm seeing in the article currently. The current version of the article, which was last edited on November 22nd, cites Table 3-5a in FAA Order 8260.3b as a source, but I don't have time to look that up right now.
aterpster
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aterpster
Table attached. RVR 1800 becomes 1/2 s.m. when RVR is OTS.
Hmmmm....perhaps I should double-check this with my wife's cookbook.
I just looked this morning at my buddy's Ipad with jepp charts. KLAX Los Angeles. ILS 06R had visibility of 3/8 mile listed in the minimums box. There were other runways with ils approaches there at LAX that had 3/8 shown as well.
Yet the FAA charts show 1/2 mile.
Can anyone else veryify the 3/8 mile on the jepp charts?
Yet the FAA charts show 1/2 mile.
Can anyone else veryify the 3/8 mile on the jepp charts?
aterpster
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aterpster
Yep. Whose on first?
Palmpilot
Touchdown! Greaser!
My paper Jepp subscription is current, and that's what it says under "RVR 18" when all components are operational. (It also has a note that says "RVR 18 with Flight Director or Autopilot or HUD to DA.") When the TDZ or CL is out, it reverts to "RVR 24 or 1/2."
Might have found the reason. aTerpster posted the chart for terps change 23. here's the change 21 chart (snipped)
HATh Range RVR SM M RVR SM M RVR SM M RVR SM M
200 18001 2 3/8 5501 2 2600 1/2 750 3000 5/8 1000 4000 3/4 1200
201 - 210 18001 2 3/8 550 1 2 2600 1/2 750 3000 5/8 1000 4000 3/4 1200
211 - 220 18001 2 3/8 550 1 2 2600 1/2 800 3500 5/8 1000 4000 3/4 1200
As you can see, 3/8 mile ** is ** listed as the vis value for the minimum box. However, the 3/8 is annotated with a superscript 3, for note 3 at the bottom of the table. That note says "....for DOD use"
here's the link to the out of date terps;
http://www.faa.gov/documentLibrary/media/Order/8260_3B-CHG21.pdf
on page 3 - 21
So...can we expect jepp to revise the vis to 1/2?
HATh Range RVR SM M RVR SM M RVR SM M RVR SM M
200 18001 2 3/8 5501 2 2600 1/2 750 3000 5/8 1000 4000 3/4 1200
201 - 210 18001 2 3/8 550 1 2 2600 1/2 750 3000 5/8 1000 4000 3/4 1200
211 - 220 18001 2 3/8 550 1 2 2600 1/2 800 3500 5/8 1000 4000 3/4 1200
As you can see, 3/8 mile ** is ** listed as the vis value for the minimum box. However, the 3/8 is annotated with a superscript 3, for note 3 at the bottom of the table. That note says "....for DOD use"
here's the link to the out of date terps;
http://www.faa.gov/documentLibrary/media/Order/8260_3B-CHG21.pdf
on page 3 - 21
So...can we expect jepp to revise the vis to 1/2?
aterpster
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aterpster
Don't hold your breath.
aterpster
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aterpster
Dead Stick
Line Up and Wait
If you're Part 91 it's all about FLIGHT visibility, so what's the issue? Just descend on the GS to the DH and look up. If you see the runway you land, if you don't you go missed. If you really want to get serious about landing, and the runway has a working approach lighting system, you can also apply the provisions of 91.175 (c)(3) - depending upon conditions, that can get you down to 100' above the TDZE.
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Exactly, flight visibility, though applies whether part 91 or not. It's almost as if you actually read the thread.
However, the issue was/is whether that flight visibiltiy required is 3/8 (published on jepp plates) or 1/2.
The answer is specific to each and every airport.
You have found only one of many odd ball aspects to
a specific airport or runway.
The reason it can vary is due to the in depth ananlysis of the
airport and things you may not be able to percieve.
It's quite common for the oppisate direction of the same runway
to have quite different numbers, yet be the same surface.
You have found only one of many odd ball aspects to
a specific airport or runway.
The reason it can vary is due to the in depth ananlysis of the
airport and things you may not be able to percieve.
It's quite common for the oppisate direction of the same runway
to have quite different numbers, yet be the same surface.
Dead Stick
Line Up and Wait
This entire thread is really quite pointless for the Part 91 pilot. What does it matter? After all, all that matters to legally be able to land out of an ILS is that the runway is in sight at the DH.
bbchien
Touchdown! Greaser!
Here you go. At a 3% GS, 200 feet is 3800 feet from the threshold. That means that the very brightest components of the ALS have to extend some ways out since 3/8 of 6,000 is 2250 feet. If the TDZE is x-hundred feet into the runway, and since 3800-2250 is 1550 feet, so guess which components of the MALSR (or whatever part of what LAX's got) needs to be visible at 1550-(x-hundred) feet from the threshold......
aterpster
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aterpster
Also, the 3/8 is pointless to the commerical operator as well. Because it cannot be used unless the RVR is inop, which is almost never.
And, the non-commercial pilot has a tough time landing when RVR is below limits. Tough time in the sense that the FSDO may very well make an inquiry about how the RVR was not right that day.
Palmpilot
Touchdown! Greaser!
I believe some people on this board fly under other parts of the regs.
For the sake of newbies who might be reading this, seeing the approach lights is sufficient down to 100 feet above the TDZE. (See 91.175(c)(3) for more details.)
roncachamp
Final Approach
There have been times I could clearly see the antenna farm seven miles away, and also clearly see the patch of fog engulfing the RVR that was indicating 800 feet or so. Was the RVR right that day? Was it inop?
Palmpilot
Touchdown! Greaser!
Dead Stick
Line Up and Wait
The point is that IF you're at DH and IF you can see the runway (and all of the other normal assumptions) THEN you can continue to a landing without regard to what the reported ceiling or RVR is. However, in 35 years of commercial flying including a few thousand approaches with countless ILSes to minimums, I have never busted minimums and I've never encountered an example of the scenario ATERPster pointed out. Now all of that is for 91 Ops, of course the 121 and 135 guys play to a different set of rules.
aterpster
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aterpster
It was nonetheless the legal minimum.
One very clear night I was flying with a friend in his 310 to land at Portland, Oregon.
The city lights were twinkling it was so clear.
The airport wx was reported as 1/4 in fog. The airport is in the river bottom. The world disappeared at about 50 feet. This was 1962. I don't recall whether we were provided an RVR reading or whether they even had RVR.
Dead Stick
Line Up and Wait
I'm not trying to be argumentative, you are one of the guys I look to for solid advice, but...
If the "the world dissappeared" at 50' the runway wouldn't have been insight. Again, there is nothing to preclude a rejected landing at any time during an approach. Oh well, enough of this sparing. What's your opinion of how the election turned out?
gismo
Touchdown! Greaser!
IME, on the GS at a 200 ft DA puts you 2300-2800 ft from the threshold because the GS penetrates the runway 1000-1500 feet down the runway from the threshold. And AFaIK the flight visibility requirement only applies to descending below 100 AGL and landing, IOW I think as long as you can see the specific components of the ALS/RLS at 200 AGL you can continue down to 100 AGL without evaluating the actual visibility.
gismo
Touchdown! Greaser!
The runway could easily have been "in sight" prior to descending into the fog but if you lost sight of the runway before touching down you would be well advised to go around. That said, you might need better than 200 ft/nm climb gradient to clear obstacles if you go around at 50 AGL over the runway.
gismo
Touchdown! Greaser!
I don't believe that a below min RVR would preclude a legal landing for a part 91 pilot (or any other pilot if the RVR dropped after the FAF was passed) if the landing truly could be made with sufficient in flight visibility. I'm not talking about a pilot opining that the RVR was off because he was certain the actual flight vis was slightly better but if the runway was truly VMC except for a small area of fog/cloud parked on the visibility sensor that the plane never entered I think you'd be OK FAA wise.
aterpster
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aterpster
It was until 50 feet, although the lights started getting progressively dimmer at perhaps 200 feet. We were young bucks in a far different time. I was giving dual and the owner was flying the airplane. Before any reflected thought occured (if it ever did) we landed rather firmly. Then, the runway lights were again visible, but barely.
50 years ago is a long time. I didn't go with TWA until 2 years later.
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roncachamp
Final Approach
So if a pilot requested the RVR he couldn't then land legally?
roncachamp
Final Approach
Given that the pilot wouldn't know what the RVR was indicating in this case, unless he asked for that info, I'd say you're right.
aterpster
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aterpster
Aren't you required to issue RVR when it is below whatever the specification is in the 7110.65?
roncachamp
Final Approach
From that weighty tome:
"When the observer has reliable reports, or has otherwise determined that the instrument values are not representative of the associated runway, the data must not be used."
Inverted
Cleared for Takeoff
Incorrect. For 121 and 135 RVR is controlling. If RVR is reported, and is below the requirements before reaching the FAF you cannot imitate the approach. If it goes below inside the FAF you can continue to the MAP but must go missed regardless whether you have the runway environment in sight.
denverpilot
Tied Down
Heh. "Imitate". Gotta love autocorrect.
Inverted
Cleared for Takeoff
Dammit! Lol, hopefully everyone knows what I meant.
gismo
Touchdown! Greaser!
I guess you're saying that (for part 121 or 135) if the RVR is below mins when the pilot reaches DA or the MAP and that does make sense if the flight visibility appears to be slightly better than the published vis mins, but is there no exception for an RVR that's too low when the plane could land in VMC?
Originally Posted by gismo
I don't believe that a below min RVR would preclude a legal landing for a part 91 pilot (or any other pilot if the RVR dropped after the FAF was passed) if the landing truly could be made with sufficient in flight visibility. I'm not talking about a pilot opining that the RVR was off because he was certain the actual flight vis was slightly better but if the runway was truly VMC except for a small area of fog/cloud parked on the visibility sensor that the plane never entered I think you'd be OK FAA wise.
Originally Posted by gismo
I don't believe that a below min RVR would preclude a legal landing for a part 91 pilot (or any other pilot if the RVR dropped after the FAF was passed) if the landing truly could be made with sufficient in flight visibility. I'm not talking about a pilot opining that the RVR was off because he was certain the actual flight vis was slightly better but if the runway was truly VMC except for a small area of fog/cloud parked on the visibility sensor that the plane never entered I think you'd be OK FAA wise.
aterpster
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aterpster
121.651 reads a landing may be made if the flight visibility permits and one, or more, of the required visual references are present. This presumes the RVR was at, or above, minimums when passing the FAF.
flyingmoose
Pattern Altitude
I don't know if you misspoke or not but that is not correct. You are not required to go missed if you have the landing environment in sight.
121.651 2 (c) If a pilot has begun the final approach segment of an instrument approach procedure in accordance with paragraph (b) of this section, and after that receives a later weather report indicating below-minimum conditions, the pilot may continue the approach to DH or MDA. Upon reaching DH or at MDA, and at any time before the missed approach point, the pilot may continue the approach below DH or MDA if either the requirements of §91.175(l) of this chapter, or the following requirements are met:
Captain
Final Approach
Incorrect. Why would you even proceed on the IAP past the FAF if you HAD to go missed anyway?
"1,000 above...
500 above...
Lights...
200 above ...runway in sight...going missed."
Yeah, that's not right.
I think you're just confusing the ability part 135 / 121 to shoot the approach. Part 91 you can go take a look if the vis is below min. 121 and 135 you can not...however if you are past the FAF you can continue if the vis drops below mins. If you do break out you don't go missed, you land.
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I emailed Jepp (thanks to aTerpster's info), and a gentlemen emailled me back with this explanation as to why, contrary to terps chg 23, there are so many Jepp ils cat 1 approach charts in the US with 3/8 vis on while the FAA charts have only 1/2.
and
and