not enough visibility?

aterpster said:
For a Part 121 operator no doubt about it. They also would have to have an approved weather reporting source, typically a station agent at a place like this.

The interesting question: Does the on-demand 135 operator need some sort of FSDO approval to fly into this airport? The airport is important to the town of Ridgecrest. In fact, I am surprised it doesn't have automated weather by this time.
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We were in Jetsteams under a 135 certificate at the time still. Don't know if it would be different unscheduled.
 
Ron Levy said:
There is no general regulatory requirement for by-location approval for on-demand 135 operations. Any such requirement would be in their individual ops specs, although I've never heard of such.
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Interesting that a weather report comes up for the airport in Foreflight.
 
OpSpecs give areas of operations. Like "authorized to operate in North America excluding the magnetic anoylomy zone in Canada"

I've never seen specific airport authorized but I suppose some could be excluded. Plus requirement like paved runway, or IAP served could be attached. Each OpSpec has a section of "Approved Operations" and "Not Approved Operations" also. That's where it list types of approaches authorized and not authorized.
 
Captain said:
OpSpecs give areas of operations. Like "authorized to operate in North America excluding the magnetic anoylomy zone in Canada"

I've never seen specific airport authorized but I suppose some could be excluded. Plus requirement like paved runway, or IAP served could be attached. Each OpSpec has a section of "Approved Operations" and "Not Approved Operations" also. That's where it list types of approaches authorized and not authorized.
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I think that's typical of on-demand 135 operators. The scheduled carriers (121 or 135 commuter ops) get controlled more tightly.
 
Captain said:
OpSpecs give areas of operations. Like "authorized to operate in North America excluding the magnetic anoylomy zone in Canada"

I've never seen specific airport authorized but I suppose some could be excluded. Plus requirement like paved runway, or IAP served could be attached. Each OpSpec has a section of "Approved Operations" and "Not Approved Operations" also. That's where it list types of approaches authorized and not authorized.
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We could not accept an approach (outside an emergency, then ATC reads it to you) that was not in our company supplied Jeppesen manual; that manual was considerably thinner than my own subscription for the same region.:dunno:
 
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Henning said:
We could not accept an approach (outside an emergency, then ATC reads it to you) that was not in our company supplied Jeppesen manual; that manual was considerably thinner than my own subscription for the same region.:dunno:
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Typical for scheduled operations.
 
Henning said:
We could not accept an approach (outside an emergency, then ATC reads it to you) that was not in our company supplied Jeppesen manual; that manual was considerably thinner than my own subscription for the same region.:dunno:
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That's true. Our Jepps had all our city pairs and possible alternates and that's where we went. At one point I carried Jepps for Get-mo (Guantanamo Bay, Cuba) for an alternate. Always sorta wanted to divert there to say I did it...I never did.

But the 121 OpSpecs didn't (I don't believe) list approved airports. It did list 'special airports' that were in mountianous terrain, but that's as close as it got. Those special airports required specific training for all pilots each year in recurrent (read a 30 minute power point).
 
Captain said:
That's true. Our Jepps had all our city pairs and possible alternates and that's where we went. At one point I carried Jepps for Get-mo (Guantanamo Bay, Cuba) for an alternate. Always sorta wanted to divert there to say I did it...I never did.

But the 121 OpSpecs didn't (I don't believe) list approved airports. It did list 'special airports' that were in mountianous terrain, but that's as close as it got. Those special airports required specific training for all pilots each year in recurrent (read a 30 minute power point).
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It's been a long time, but our Ops Specs listed each Regular, Provisional, and Refueling Airports. There was a separate list of alternate-only airports.
 
aterpster said:
It's been a long time, but our Ops Specs listed each Regular, Provisional, and Refueling Airports. There was a separate list of alternate-only airports.
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I remember the same rules and restrictions in our OpSpec, I'm talking 15 years ago.
 
aterpster said:
It's been a long time, but our Ops Specs listed each Regular, Provisional, and Refueling Airports. There was a separate list of alternate-only airports.
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Oh snap! You're right.

Grrrrrr, dang I hate being wrong. Okay, everything I said so far disregard. (just this thread Henning.)

; )
 
Captain said:
Oh snap! You're right.

Grrrrrr, dang I hate being wrong. Okay, everything I said so far disregard. (just this thread Henning.)

; )
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I might be getting old but I haven't forgotten everything just yet.;)
 
Henning said:
Look where the runway is located and you tell me when the last time you think LIFR existed there since say the Mesazoic era lol. They write protocols that meet operational realities, amazing.
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I could be wrong but AFaIK, even in the desert, it rains now and then. Plus there's always the possibility of reduced visibility from blowing dust or maybe even smoke from a fire in the Sequoias.
 
gismo said:
I could be wrong but AFaIK, even in the desert, it rains now and then. Plus there's always the possibility of reduced visibility from blowing dust or maybe even smoke from a fire in the Sequoias.
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As I said earlier in the thread, some winters that area gets steady significant rain storms that can last two or three days. China Lake pretty much shuts down then so the "Z" IAP would likely be available. As to smoke or even blowing dust you will see the airport before you need to. Keep in mind you still have very accurate GPS guidance in the extended visual segment.
 
Ron Levy said:
Not true. Since the visibility required is "flight visibility" (not ground visibility as reported by a ground observer or ground-based device) and by definition flight visibility is measured from the cockpit, if you see that far, you do have the required minimum visibility per 91.175.
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Well, by definition, flight visibility is the average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night. Can you explain how a pilot actually does this?
 
alfadog said:
Here is a method I saw somewhere and actually did on a club 172m.

With a friend sitting in the cockpit, measure the distance from asphalt to his eye level. Let us say it is 6 feet. Have him look directly down over the nose. Measure from beneath him to the closest point he can see on the asphalt. Let us say it is 49 feet.

Calculate the rough ratio. 49/6 = 12 (close enough). Remember 12. Flying along at 1000 feet, if you can see the ground directly over the nose, you have at least 2 nm vis; 1,000 x 12 = 12,000'.
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I don't think that's close enough, 49/6 is a lot closer to 8 than it is to 12.
 
gismo said:
I could be wrong but AFaIK, even in the desert, it rains now and then. Plus there's always the possibility of reduced visibility from blowing dust or maybe even smoke from a fire in the Sequoias.
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Yeah, but its rare. The rain there is rarely IMC BTW, the cloud bases will typically be up pretty high; it only happens once or twice a year, and normally it's the rotor winds breaking off the mountains and the down bursts that keep operations from going in on those days. I don't think they have scheduled service but I haven't been there in over a decade and a half.
 
roncachamp said:
Well, by definition, flight visibility is the average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night. Can you explain how a pilot actually does this?
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Go back up the thread -- you'll see that I did a long way back.
 
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Ron Levy said:
I'm not sure how the FAA would like that as a way to determine whether or not you have 2 sm flight vis. I think they'd rather hear that you could see an object on the ground two miles ahead. How you determine that it is 2 sm is a bit more difficult, but I think alfadog's method is supportable.
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But visibility is a horizontal distance and that object on the ground is some 1300 feet below.
 
roncachamp said:
But visibility is a horizontal distance and that object on the ground is some 1300 feet below.
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I guess you are going to have a real problem flying instrument approaches. The rest of us (including every FAA Inspector I've ever met) get it.
 
Henning said:
Yeah, but its rare. The rain there is rarely IMC BTW, the cloud bases will typically be up pretty high; it only happens once or twice a year, and normally it's the rotor winds breaking off the mountains and the down bursts that keep operations from going in on those days. I don't think they have scheduled service but I haven't been there in over a decade and a half.
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That kind of rain and then there is the other kind that is stagnent and heavy from a wintertime monsoon type condition. Those events have been known to washout Highway 14 in the Red Rock Canyon area.

They had scheduled service for many years, but not at present.

Edit: Correction, summertime monsoon conditions. One year a three day event like that flooded basements on the Naval base.
 
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aterpster said:
That kind of rain and then there is the other kind that is stagnent and heavy from a wintertime monsoon type condition. Those events have been known to washout Highway 14 in the Red Rock Canyon area.

They had scheduled service for many years, but not at present.
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Even the monsoonal rain will typically have greater than 2 or 3 miles down low during the daytime.
 
Back to the "fly visual" situation, I see the NDB DME or GPS A approach into Hailey Idaho KSUN uses a 5 mile visibility requirement, for all categories. Anyone know why it is so high compared to 2 miles for cat A and B for IYK?
 
aterpster said:
No doubt about it. It is more a question of ceiling.
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Exactly, if you have the ground by the MAP, the vast likelihood is you will make it. If you don't, might as well do the missed then because there's no way you'll make it. The only times the ceiling gets below a couple of thousand it's 0/0, one or the other, you don't really get in between (you don't get 0/0 every year either, maybe not every decade). There's only so many variations you get in 4 days a year.;)
 
Henning said:
Exactly, if you have the ground by the MAP, the vast likelihood is you will make it. If you don't, might as well do the missed then because there's no way you'll make it. The only times the ceiling gets below a couple of thousand it's 0/0, one or the other, you don't really get in between (you don't get 0/0 every year either, maybe not every decade). There's only so many variations you get in 4 days a year.;)
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Nonetheless, with that kind of rain I suspect they will let you have the RNAV Z, for an all-around better operation.
 
aterpster said:
Nonetheless, with that kind of rain I suspect they will let you have the RNAV Z, for an all-around better operation.
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I'm sure, there's nobody operating in those Rs in that weather. It's that coming from the west, that's a nice expeditious approach if you know you're gonna break out.
 
Henning said:
I'm sure, there's nobody operating in those Rs in that weather. It's that coming from the west, that's a nice expeditious approach if you know you're gonna break out.
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I think Net Jets would if they had a deal to take someone in or out of there.

I used to fly in weather similar to that on a regular basis. It isn't convective activity.
 
aterpster said:
I think Net Jets would if they had a deal to take someone in or out of there.

I used to fly in weather similar to that on a regular basis. It isn't convective activity.
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Oh, I was referring to the people who own the Restricted airspace won't be using it.
 
roncachamp said:
Actually, you didn't, as your explanation was inconsistent with the definition of flight visibility.
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I think it's what we engineers call an approximation, which in many situations is good enough for practical purposes.
 
Palmpilot said:
I think it's what we engineers call an approximation, which in many situations is good enough for practical purposes.
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With commercial operations reported visibility or RVR is required. In most scheduled commercial operations the standard approach is an ILS, LNAV/VNAV, or LPV approach to a runway with ALS. The way airlines train and their crews fly: if the first portion of the ALS is clearly in view at DA you continue the approach and land unless you lose visual reference below DA. (That is the pragmatic measurement of flight visibility in those circumstances.) That (losing visual reference below DA) seldom happens with reported visibility and virtually never happens when RVR is reported.

In the case of fly visual to airport at Inyokern, assuming the commercial operator is operating a CAT C airplane, the reported visibility at the airport must be not less than 3 miles. Let's say it is just 3 miles.

If the pilot has what he considers to be adequate visual reference at the MAP and at MDA he then continues while continuing to assess whether, with his judgment and experience, he continuously has 3 miles flight visibility. If a fed is sitting on the jump seat he will be no more qualified than the flight crew to make an exact determination. It is called "reasonableness" back up by the airport's reported visibility. Further, depending upon the operator's specifications for this type of IAP, the pilot may be permitted to descend below MDA prior to having the airport in sight.
 
aterpster said:
If the pilot has what he considers to be adequate visual reference at the MAP and at MDA he then continues while continuing to assess whether, with his judgment and experience, he continuously has 3 miles flight visibility. If a fed is sitting on the jump seat he will be no more qualified than the flight crew to make an exact determination. It is called "reasonableness" back up by the airport's reported visibility. Further, depending upon the operator's specifications for this type of IAP, the pilot may be permitted to descend below MDA prior to having the airport in sight.
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I am not looking for comment on the advisability of descending below the MDA if the flight visibility is satisfied on reaching the MDA, but do you assume it is permitted at any point on the FAS, or just past the VDP if one is specified on the approach, or at the MAP?
 
John Collins said:
I am not looking for comment on the advisability of descending below the MDA if the flight visibility is satisfied on reaching the MDA, but do you assume it is permitted at any point on the FAS, or just past the VDP if one is specified on the approach, or at the MAP?
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You use what you have at the MAP in this approach best I can tell.
 
John Collins said:
I am not looking for comment on the advisability of descending below the MDA if the flight visibility is satisfied on reaching the MDA, but do you assume it is permitted at any point on the FAS, or just past the VDP if one is specified on the approach, or at the MAP?
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Part 91 only, I agree with you. There is no regulatory constraint once in the "fly visual to airport" segment. A Part 121 operator who has scheduled ops into such an airport could have some restriction, but my guess is they more than likely would not.

I think a lot has to do with previous entries in good weather, thus having good "local" knowledge.
 
I hadn't done the calculation for the height of the glidepath at FAF and the MAP before, but it is interesting to me. At the FAF DIVAC, the minimum altitude is 5300 feet MSL and the Baro-VNAV altitude of the glidepath calculates to 5302 feet, or essentially identical. However, if you remain on the glidepath, you will be at 4245 feet MSL at the MAP at BISAC verses the MDA of 4100 feet MSL. IOW, if you use the advisory glidepath, you will be 145 above the MDA at the MAP. If you don't use the advisory glidepath and do a steeper dive and drive to the MDA, once at the MDA and before reaching the MAP, are you permitted to descend further if you have the required visibility? For part 91, I think so, but am not sure.
 
John Collins said:
I hadn't done the calculation for the height of the glidepath at FAF and the MAP before, but it is interesting to me. At the FAF DIVAC, the minimum altitude is 5300 feet MSL and the Baro-VNAV altitude of the glidepath calculates to 5302 feet, or essentially identical. However, if you remain on the glidepath, you will be at 4245 feet MSL at the MAP at BISAC verses the MDA of 4100 feet MSL. IOW, if you use the advisory glidepath, you will be 145 above the MDA at the MAP. If you don't use the advisory glidepath and do a steeper dive and drive to the MDA, once at the MDA and before reaching the MAP, are you permitted to descend further if you have the required visibility? For part 91, I think so, but am not sure.
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Why not? 91.175 is waived.
 
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