not enough visibility?

Discussion in 'Cleared for the Approach' started by olasek, Apr 7, 2012.

  1. John Collins

    John Collins Pattern Altitude

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    You can descend below the MDA at the MAP as long as you have the required flight visibility. There is no requirement to remain at the MDA after the MAP on the "fly visual". 91.175 doesn't apply for the "fly visual".
     
  2. John Collins

    John Collins Pattern Altitude

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    I re-read and did not find the part dealing with when you could start your descent. There is no requirement to remain at the MDA.
     
  3. John Collins

    John Collins Pattern Altitude

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    And you can descend from the MDA if you have the flight visibility, no need to wait until you see the runway.
     
  4. John Collins

    John Collins Pattern Altitude

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    One reason that pilot's assume that with a "fly visual", that they have to remain at the MDA or treat the DA as a MDA until they have the runway in sight is the way it is depicted on the AeroNav charts. I think it would be clearer if they did not chart a level segment as that is not what is intended.
     
  5. Henning

    Henning Ejection Handle Pulled

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    Thank's John, most excellent. So yeah, the FAA has approach that says 'man up' because you can f- yourself here'. :lol:
     
    Last edited: Apr 9, 2012
  6. aterpster

    aterpster Pattern Altitude

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    Nonetheless it is wise to remain at MDA until fairly close in because then obstacle clearance is assured. In fact, there is no penalty for remaining at MDA until overhead the airport, check the wind, then enter traffic for the favored runway. There is lots of room on the west side before the mountains start rising. (see attach)

    What I think is misleading, though, is the circle-to-land maneuvering area to goes into the resticted area. The boundary is not very far away.

    This airport seldom has bad weather. But, when it does it is a hard driving rain, which would almost certainly make the "Z" IAP available because nothing is going on then at China Lake.
     

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  7. Captain

    Captain Final Approach

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    So I'm thinking my IAP to a contact approach analyogy wasn't too far off the mark.
     
  8. roncachamp

    roncachamp Final Approach

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    How does the pilot determine the visibility from the cockpit in flight?
     
  9. poadeleted20

    poadeleted20 Deleted

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    One looks out the windshield and estimates the distance to the farthest object on the ground s/he can see.
     
  10. roncachamp

    roncachamp Final Approach

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    That's called guessing.
     
  11. denverpilot

    denverpilot Taxi to Parking

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    Not if you know the area. If you don't, yes. An easy educated guess.

    Telephone poles are typically a standard distance apart. Roads are typically a standard size. Buildings. Etc etc etc.

    Ron's estimate isn't as inaccurate as it may sound if any standard sized objects are in sight.

    There do be dragons here with optical illusions, however. ;)
     
  12. poadeleted20

    poadeleted20 Deleted

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    No, it's called "flight visibility" by the FAA.
     
  13. Palmpilot

    Palmpilot Touchdown! Greaser!

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    Since you used an IFR GPS to get to the MAP, won't the GPS be counting up the distance from the MAP? If so, I would say that when it gets to 5 without the airport coming into view, time to execute plan B.

    If I hadn't previously flown into this airport in VFR conditions, then depending on what I saw out the window, I might do the same as you and start a missed at the MAP if the visibility were less than five miles.
     
  14. Palmpilot

    Palmpilot Touchdown! Greaser!

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  15. Henning

    Henning Ejection Handle Pulled

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    Sure sounds like it; seems it takes it even one step further since a controller can't recommend the procedure and here it's written.
     
  16. Henning

    Henning Ejection Handle Pulled

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    Judgement, same way we call 2 mile base.
     
  17. Captain

    Captain Final Approach

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    (golf clap) Nice answer.
     
  18. Henning

    Henning Ejection Handle Pulled

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    Welcome to the world of equipment operating. It's called referencing to a known mental and/or otherwise visible standard to scale against (like section lines or city blocks); you are correct in thinking the information would be highly suspect to be incorrect. When I ask guys to tell me how far off a bridge they are without referencing the radar they do not do particularly well at it lol. You end up with an upside down 'W' for a Bell Curve though and most people can come close enough. The people in the center dip have usually over 10 years in the trade. Thing is they leave it up to PIC, remember, the MINIMUM in flight visibility is 2 miles, you can choose to bail out at MAP with greater if you're not comfortable.
     
    Last edited: Apr 10, 2012
  19. roncachamp

    roncachamp Final Approach

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    And just as accurate.
     
  20. roncachamp

    roncachamp Final Approach

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    And you can continue with less than the minimum required visibility, as long as your guess on the visibility is at least the minimum.
     
  21. Henning

    Henning Ejection Handle Pulled

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    Exactly. The number represents a comfort scale to the pilot. 3 miles is minimum for VFR and 1 mile is minimum to need instruments, so the pilots comfort level should be above that required for when they switch to instruments and less than what they would have navigating pilotage. That level of comfort is what the pilot should use to make the determination.
     
  22. alfadog

    alfadog En-Route

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    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'.

    One caveat. For best accuracy, you have check that the airplane on the ramp has the same sight picture to the horizon as cruise.

    edit: Actually you should be the one sitting in the pilot's seat. My friend was the same height as me so I let him have the easy job :) You could even do this yourself at a bit more effort.
     
    Last edited: Apr 10, 2012
  23. Henning

    Henning Ejection Handle Pulled

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    Another good one over flat terrain & water is horizon is 3 miles for every 6' height of eye and you judge by a percentage of their distance to the horizon.
     
  24. roncachamp

    roncachamp Final Approach

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    And if the pilot's level of comfort is 1 1/2 miles he's okay to continue on the approach?
     
  25. poadeleted20

    poadeleted20 Deleted

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    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. This has been tested before the NTSB, and they agreed on this point -- see Administrator v. Pisarek.
    http://www.ntsb.gov/legal/o_n_o/docs/Aviation/4338.pdf
    Of course, if the ground vis is 1/16 sm and you continue based on your own determination of 2 sm flight vis, and it ends badly, you may still, like Pisarek, be cooked for 91.13 careless/reckless, but that's a different issue.
     
    Last edited: Apr 10, 2012
  26. poadeleted20

    poadeleted20 Deleted

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    Sure -- if the pilot has the required flight vis, which in this case is 2 statute miles. The pilot's level of comfort is not a legal issue.
     
  27. poadeleted20

    poadeleted20 Deleted

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    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.
     
  28. aterpster

    aterpster Pattern Altitude

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    I believe I recall that The giant TRACON (Joshua) that controls that vast area established a special telephone number a long time ago for pilots to call an ask about the status of the many restricted areas out there. Another option is to ask the first Joshua controller on hand off.
     
  29. aterpster

    aterpster Pattern Altitude

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    Flying for hire you need both flight and ground visibility.
     
  30. poadeleted20

    poadeleted20 Deleted

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    If you mean 135, 121, etc, yes, but there is for-hire flying (such as a corporate pilot) that doesn't fall under that rule. In any event, I thought we were looking at the basic Part 91 situation. Throw in those other Parts and the discussion changes.
     
  31. aterpster

    aterpster Pattern Altitude

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    I don't think so. "Captain" was taking it to his training department early in the thread. The concept of "Fly visual to airport" applies the same to commercial and non-commercial operators.

    As an aside these two IAPs were established to meet the requirements of a commuter carrier that served the airport at the time.

    Edit: When the commuter operated there they had their own weather observer. The G/A guy is on his own at this airport, which is not insignificant when it is socked in with out of those unusual (but not rare) winter rainstorms.
     
    Last edited: Apr 10, 2012
  32. Henning

    Henning Ejection Handle Pulled

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    The pilot calls it 2 miles and continues, that's the way it's set up still. Remember, the spirit of IFR lies with people named Doolittle and Jeppesen, not lawyers and bureaucrats. It's what the 'command' in pilot in command is about.
     
  33. poadeleted20

    poadeleted20 Deleted

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    Except it doesn't. Commercial operators must have both the requisite flight visibility and the ground visibility reported and above mins; the rest of us need only the requisite flight vis which we can determine for ourselves.
     
  34. Henning

    Henning Ejection Handle Pulled

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    Don't they also have to have the approach approved for use on their certificate? I remember way less tricky/risky approaches having pilot minimum attached to them at Express 1.
     
  35. aterpster

    aterpster Pattern Altitude

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    Oh, Ron, please, the concept is identical for all operators.
     
  36. poadeleted20

    poadeleted20 Deleted

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    Fine, but the context of that part of the discussion was Steven's questions about visibility minimums, and that part is different.

    Thread creep -- bleah.:vomit:
     
  37. aterpster

    aterpster Pattern Altitude

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    It crept early on. :lol:
     
  38. aterpster

    aterpster Pattern Altitude

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    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.
     
  39. poadeleted20

    poadeleted20 Deleted

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    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.
     
  40. HPNPilot1200

    HPNPilot1200 En-Route

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    As far as I know, OpSpec approval for authorized airports is only required for commuter part 135 under OpSpec C070. Our OpSpecs authorizes us to dispatch to an airport under IFR that does not have weather reporting as long as an alternate airport is available with approved weather reporting that is forecast to be at or above IFR landing minimums.