1/2 mile vis

[MNFlyboy]

Discussion topic in the pilot lounge the other day; how to determine if you legally have a half mile vis.

Discussion started during a conversation regarding 135 ops and when it's legal to shoot the approach, but also, when is it legal to land if the wx goes lower than 200 & 1/2 during an ILS. You have to have you're flight visibility so the question was, "How do you know if you have you're 1/2 mile visibility or not?"

At 200' on the ILS, and you have the approach lighting system, you can descend to 100' below the DA, and then if you pickup the runway environment, great, but how do you determine your half mile?

The best answer that I came up with was that on a 3 degree glide slope, at approx 140' agl, you are about 1/2 mile away from the thousand foot boxes on the runway, so if you can see them, you've got your half mile. But is there some other way to use the MALSR/other ALS to determine your 2650' visibility? It would seem that if you're on the ILS at 100' and all you can see is the runway #'s, that's not good enough to land? I know we might be thinking "Hell, if I can see the tarmac, I'm putting it down!" The question is, though, is that legal under 135/121?

This came up on an interview, too, so I thought this might be good discussion here.

Thanks for your participation in advance!

 

[Monk]

In flight visibility, like the line from robin hood men in tights... I guess I have half a mile.

 

[SurferLucas]

MALSR/ALSF I/II systems are 2,400ft-3,000ft from first sequence flasher to the runway. If you have the full ALS, then you have 1/2 mile vis.

 

[BobDDuck]

Does it matter? If you, at mins, see the ALS and then within 100 below mins find the runway, you've met all legal requirements to land and the visibility is no longer controlling.

 

[LucasM]

It's not like after you fly your app. to mins and see the runway your going to go missed just because you couldn't quite make out the 1/2 mile. PIC is responsible for determining in flight visibility. If a fed were to stop you after you taxi up and says "Son I'd sure like to know why you flew that approach when the weather reports are saying visibility is below mins..." "Well, sir, I broke out at X altitude above mins and and I could see the runway... soo I landed on it".

Now say you were a few miles out on the LOC and tower/approach reports the airport is below mins, that's a different story

 

[MNFlyboy]

So let's make it interesting, you're inside FAF, tower calls 1/4mi, RVR is unavailable so you can continue, but you land and the fed does ask you why you landed.

"I had a 1/2mi vis, sir"

I understand that looking straight down at the runway if you see it you will probably land, I'm just saying for the sake of argument, you could see the ALS and.stuff beneath you, but forward vis may not be as good, so how do you prove or know that you have a half mile. "I saw, therefore I land" may not cut it with the fed.

"How do you know you had 1/2mi?" He says.

 

[LucasM]

It'd really be your word against his/hers. How do they know you couldn't see 1/2 mile down the runway? You said you could, you landed. No harm, no foul. Then you both walk away glaring at each other and say "until we meet again..."

 

[Monk]

in flight vis takes president over ground equipment, fed would have to be standing on the runway to say " no you didn't"

 

[eightballfreight]

Does it matter? If you, at mins, see the ALS and then within 100 below mins find the runway, you've met all legal requirements to land and the visibility is no longer controlling.

Proof?

 

[jeflies]

Depends on what day of the week it is and who your talking to. This argument never dies.

Here's my .02 cents.

From a legal standpoint (ie in court) the only thing that will admitted as evidence are METARS and ATC updates on RVRs.

Arguing that you had it in sight and landed doesn't magically make the current weather what was required for the approach.

You can probably get away with it but always remember, how would/could you defend yourself against published weather that's below mins in court.


Sent from my iPhone

 

[Tommay85]

Depends on what day of the week it is and who your talking to. This argument never dies.

Here's my .02 cents.

From a legal standpoint (ie in court) the only thing that will admitted as evidence are METARS and ATC updates on RVRs.

Arguing that you had it in sight and landed doesn't magically make the current weather what was required for the approach.

You can probably get away with it but always remember, how would/could you defend yourself against published weather that's below mins in court.


Sent from my iPhone

This

My additional .02 cents.

If it goes below inside of the FAF, cool, I can continue and "take a look", but until I hear something that says the vis is higher(updated automated weather, or a new RVR report/vis from a controller), I'm planning on going missed.

There's A LOT of case law that says you're going to lose against the word of the FAA. One case I'm aware of where the pilot won, was a SW crew that landed on a runway that was clear, but the weather reports were reporting below mins. I don't remember why. Weather machine was in a valley or malfunctioning, the FAA guy was parked in the only fog bank in the area or whatever. At any rate, it took statements from other crews and the tower to win the case. Meanwhile, that process took months to settle where the pilots were not working. It's not worth it, go missed.

 

[Houston]

I read a great many opinions in this thread, but I don't see any references or supporting court cases. Does anyone have something more concrete than opinion?

 

[Tommay85]

I read a great many opinions in this thread, but I don't see any references or supporting court cases. Does anyone have something more concrete than opinion?

Nope! It's all non-sense!

I'll post some stuff tomorrow. Too lazy tonight. ie my excuse for not backing anything up.

 

[Houston]

There's A LOT of case law that says you're going to lose against the word of the FAA. One case I'm aware of where the pilot won, was a SW crew that landed on a runway that was clear, but the weather reports were reporting below mins. I don't remember why. Weather machine was in a valley or malfunctioning, the FAA guy was parked in the only fog bank in the area or whatever. At any rate, it took statements from other crews and the tower to win the case. Meanwhile, that process took months to settle where the pilots were not working. It's not worth it, go missed.

Just wanted to ensure you knew that I was making my post at the same time you were. My question about court cases was not intended to be in response to your comment, which I didn't even see until after I hit enter (which also happens to be about the same time I see my spelling errors, just as they go down the wire).

 

[Tommay85]

Just wanted to ensure you knew that I was making my post at the same time you were. My question about court cases was not intended to be in response to your comment, which I didn't even see until after I hit enter (which also happens to be about the same time I see my spelling errors, just as they go down the wire).

Rogahhh,

This was a hot button item at Flight Express when I was there. I'll see if I can find some of it.

 

[msmspilot]

Rogahhh,

This was a hot button item at Flight Express when I was there. I'll see if I can find some of it.

I can sum up for you.

If the cop pulls you over for speeding, and you say you weren't, he's still going to write the ticket and tell you to fight it in court. In court, it's going to be your word against a radar gun. You might be able to argue the gun's calibration or something like that, but in the end, it comes down to the judge believing you or a computer.

If the FAA sees you land with the AWOS/RVR reporting below minimums, it's going to be your word against theirs. If it's malfunctioning equipment, you might be able to argue it, if you can find other witnesses, but you're still fighting your word against the METAR recordings. Not an easy fight.

Does it matter? If you, at mins, see the ALS and then within 100 below mins find the runway, you've met all legal requirements to land and the visibility is no longer controlling.

I would love to know the reasoning behind this one. 91.175(d) talks about landing under IFR, and it mentions no pilot may land when "the flight visibility is less than the visibility prescribed in the standard instrument approach procedure being used."

 

[Landis]

I would love to know the reasoning behind this one. 91.175(d) talks about landing under IFR, and it mentions no pilot may land when "the flight visibility is less than the visibility prescribed in the standard instrument approach procedure being used."

So what's the definition of Flight Visibility?

 

[msmspilot]

So what's the definition of Flight Visibility?

I'll answer the question, but I was replying to "visibility is no longer controlling."

Flight visibility is indeed the visibility the pilot has from his seat, but again, how are you going to argue when the METAR has been reporting 1/4 or M1/4 for an hour, and the tower has been reporting 1000RVR for the past hour, and you're going to claim you had the 1/2 mile? I mean, if the report is 2200 and you need 2400, ok, I think anyone can see how that would work.

 

[Patrick]

Seriously splitting hairs here, but from a legal standpoint, I have no interest in going up against the FAA.

I've had an occasion or two where it's been reported at 1/2 mile, and I've shot an ILS and had to go missed. I've had the weather drop inside the FAF to below 1/2, and I've continued the approach, only to go missed.

If we're talking normal CAT 1 ILS here, if it's reported under 1/2 mile, there's no point in flying the approach- both from a legal argument, and a practicality argument.

 

[TFaudree_ERAU]

If the cop pulls you over for speeding, and you say you weren't, he's still going to write the ticket and tell you to fight it in court. In court, it's going to be your word against a radar gun. You might be able to argue the gun's calibration or something like that, but in the end, it comes down to the judge believing you or a computer.

There aren't any provisions in the rules of the road to allow a driver to determine that his speed is anything other than what's indicated on the speedometer (barring any wheel/tire mods and a letter that states the speedometer is inaccurate because of that)