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Suppose you are on an IFR flight plan and are coming in to land at your destination.

The weather at the destination is reporting 600RVR due to dense fog. The fog isn't very high as you can see through the fog while on approach and can see the approach lights and part of the runway lights. The weather above the fog layer is VMC. The lowest visibility for an ILS approach that can be executed by the pilots is 1800RVR.

  • Can the pilots accept a visual approach even though the airport is reporting IMC?
  • Are there other factors that should be considered on an approach like this?
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    $\begingroup$ The question in the title and the question in the body are quite different. In the title question you imply legality of the pilot executing a actual landing with the field in sight despite weather being reported below minimums. In the second part, you question ATC being able to offer the visual approach. To me it is unclear what you are actually driving at. $\endgroup$
    – Michael Hall
    Feb 17, 2020 at 17:42
  • $\begingroup$ I am looking to answer if I can get and accept a VFR approach clearance under that scenario. $\endgroup$
    – wbeard52
    Feb 17, 2020 at 17:58
  • $\begingroup$ If you have the field in sight and are in a position to land safely I believe that trumps and called weather. But why would the "visual approach" distinction matter? You have been flying a published instrument procedure prior, correct? $\endgroup$
    – Michael Hall
    Feb 17, 2020 at 18:06
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    $\begingroup$ @wbeard52 Note that a "VFR approach" and "visual approach" are two very different things! $\endgroup$
    – 60levelchange
    Feb 17, 2020 at 18:28
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    $\begingroup$ @MichaelHall Actually, if you cancel IFR, ATC would not be allowed to clear you (can't approve VFR when weather is below VMC). But if you are IFR and report field in sight, you can fly a visual approach (which is an IFR procedure!) $\endgroup$
    – 60levelchange
    Feb 18, 2020 at 12:30

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A visual approach can not be authorized by ATC during true IMC.

5–4–23 Visual Approach a. A visual approach is conducted on an IFR flight plan and authorizes a pilot to proceed visually and clear of clouds to the airport. The pilot must have either the airport or the preceding identified aircraft in sight. This approach must be authorized and controlled by the appropriate air traffic control facility. Reported weather at the airport must have a ceiling at or above 1,000 feet and visibility 3 miles or greater. ATC may authorize this type approach when it will be operationally beneficial. Visual approaches are an IFR procedure conducted under IFR in visual meteorological conditions. Cloud clearance requirements of 14 CFR Section 91.155 are not applicable, unless required by operation specifications.

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I was in this situation at the end of my very first solo cross-country flight many years ago.

I was in a Piper Archer, in the middle of the night, after flying from Marathon, FL to Lexington, KY (with two stops in between).

Forty miles out, the field was beautiful VFR with calm winds.

Thirty miles out, ATC advised that the visibility had dropped to 6SM.

Ten miles out, ATC advised that the visibility had dropped to 1SM, so I requested a contact approach to expedite my arrival before the visibility got even worse. That's when they advised that it had actually dropped to 1/2SM, which is lower than the 1SM requirement for a contact approach, and lower than the 3/4SM minimum for the approach in use (ILS 22).

I requested vectors for the ILS 4 instead (minimum visibility of 1800 RVR), and after a little bit of mental gymnastics by the controller, they said "Sure, why not? Nobody else is out here anyway, so we can switch the airport around."

By the time that I was on final, they advised that RVR was down to 800 feet. I could see the runway lights perfectly, but could also see the fog sitting over the airport.

I momentarily debated what to do (I was tired, and didn't really want to divert... at least I had made the extra fuel stop and had plenty of fuel left though!) before realizing that while I could legally continue the approach, I would almost certainly have to go missed at a very low altitude when I entered the fog since 14 CFR 91.175 states (emphasis mine):

§91.175 Takeoff and landing under IFR
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(d) Landing. No pilot operating an aircraft, except a military aircraft of the United States, may land that aircraft when—
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(2) For all other operations under this part and parts 121, 125, 129, and 135, the flight visibility is less than the visibility prescribed in the standard instrument approach procedure being used.

While the flight visibility was fine at the moment, as soon as I entered the fog, it would drop below minimums, and I would not be allowed to land.

Note also that this was for an actual instrument approach. If it was visual, than I would have also had to avoid the "ground cloud" (aka fog) by the cloud clearance requirements specified in 14 CFR 91.155 by staying 1000 ft. above it.

If you have reason to believe that this isn't the case (maybe it's patchy fog and it's clear at the beginning of the runway), then you can go ahead and fly the approach, and land as long as you don't enter the fog and lose the required visibility or airport/runway environment spelled out earlier in the same regulation.

For those that want to know the rest of the story, I ended up diverting and then had to divert from my alternate (which was clear when I started there but completely covered by unforecast fog when I arrived), and then fly a low visibility approach at a third airport. Once I landed, I went into the FBO and slept for the rest of the night in one of their recliners.

I wouldn't recommend that most people try this on their first solo IFR flight though!!

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Yes, a visual approach can be conducted, if the pilot determines that the conditions are good enough.

6.5.3.3 An IFR flight may be cleared to execute a visual approach provided the pilot can maintain visual reference to the terrain and:

a) the reported ceiling is at or above the level of the beginning of the initial approach segment for the aircraft so cleared; or

b) the pilot reports at the level of the beginning of the initial approach segment or at any time during the instrument approach procedure that the meteorological conditions are such that with reasonable assurance a visual approach and landing can be completed.

ICAO DOC 4444

It is fairly common where I work for shallow patches of fog to develop during early morning and in the evening just after sunset, especially on days with otherwise clear weather. This can result in fairly low RVR values for some parts of the runway, even if the overall visibility is good and there are no clouds. If an approaching pilot has the runway in sight and decides he wants to fly a visual approach, there is nothing wrong with that.

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  • $\begingroup$ I used to be faced with that a lot when bush flying on floats. In the fall on a clear sunny morning after a cold front passage, the warm lakes would all be fogged in with the fog tops level with the tree tops. Sometimes it would be clear enough at one end of a long lake to land, then taxi into the fog following the shore line to the amazed customer's camp. $\endgroup$
    – John K
    Feb 17, 2020 at 18:33
  • $\begingroup$ NAS Whidbey Island was sea level and right on the water. In late summer particularly the fog would roll in and obscure the tower and half the field, while it was clear and a million everywhere else. Reported weather was zero zero, and being single piloted we weren't even allowed to commence an instrument approach if weather was below minimums. However, I would call approach at 20 miles and ask for a visual. They would tell me to "report VMC, field in sight" which I did immediately, and as soon as I did I would be cleared. $\endgroup$
    – Michael Hall
    Feb 17, 2020 at 21:53
  • $\begingroup$ FYI, the original question is tagged faa-regulations, and you provided an ICAO reference, which may not be what they are looking for. $\endgroup$
    – Lnafziger
    Feb 20, 2020 at 0:06
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As Dean F. points out, a visual approach clearance may only be issued if the airport is reporting VFR (or if we don't have the airport weather available to us so we take your word for it that it is VFR). That's in the 7110.65 7–4–3b.

I'm not familiar with all the pilot regulations, and especially with any OpSpec that might prohibit this approach, but I will ask whether having the runway environment in sight negates any otherwise restricting rule. 14 CFR 91.175 quoted by Lnafziger references flight visibility, not ground visibility or RVR; surely the pilot is the reporting source for flight visibility, and seeing the runway lights at sufficient distance overrides any other consideration? Perhaps not; you're the PIC and I won't force you to land if you don't want to.

If you decide that you can't perform a visual approach or an instrument approach, and you can't do a contact approach because reported ground visibility is less than one mile, and you can't cancel IFR and proceed under a Special VFR clearance because, again, ground visibility is less than one mile, the only option left (if you need to land at this specific airport) is to declare an emergency. The .65 discusses SVFR operations and includes this extensive note under paragraph 7–5–7 "Ground Visibility Below 1 Mile" (emphasis mine):

NOTE- Clear an aircraft to land at an airport with an operating control tower, traffic permitting, if the pilot reports the airport in sight. The pilot is responsible to continue to the airport or exit the surface area. 14 CFR Section 91.157 prohibits VFR aircraft (other than helicopters) from landing at any airport within a surface area when ground visibility is less than 1 mile. A pilot could inadvertently encounter conditions that are below SVFR minimums after entering a surface area due to rapidly changing weather. The pilot is best suited to determine the action to be taken since pilots operating under SVFR between sunrise and sunset are not required to be instrument rated, and the possibility exists that flight visibility may not be the same as ground visibility. 14 CFR Section 91.3 authorizes a pilot encountering an inflight emergency requiring immediate action to deviate from any rule of 14 CFR Part 91 to the extent required to meet that emergency. Flight into adverse weather conditions may require the pilot to execute the emergency authority granted in 14 CFR Section 91.3 and continue inbound to land.

The context here is an aircraft already operating SVFR within the surface area when the visibility drops to below one mile, but the suggested solution (declare an emergency and land anyway) seems relevant.

Perhaps the best solution would be to ask ATC if there's a helpful wing-mounted-turbojet aircraft somewhere on the field who could be enticed into doing a high-speed taxi on the runway in the hopes of blowing the fog away from the RVR sensor. (NB: I am not actually recommending this, though I have heard rumors of a similar situation when an air carrier was trying to depart and the RVR was too low.)

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