# Converting RVR values to statute miles

Discussion in 'Flight Following' started by BlackManINC, Dec 23, 2015.

1. ### BlackManINCPre-Flight

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Converting RVR values to statute miles (and vice versa)

At Laguardia airport (KLGA) on runway 4, an RVR value of 1 3/8 statute mile visibility is given for the localizer only approach.

https://skyvector.com/files/tpp/1513/pdf/00289IL4.PDF

Regulations states that when converting RVR values, you never interpolate, just use the next greatest number. So how would one convert 1 3/8 statue miles into feet?

My formula: 1.375 * 5280 = 7,260 ft

RVR

Visibility (statute miles)

1600 1/4

2400 1/2

3200 5/8

4000 3/4

4500 7/8

5000 1

6000 1 1/4

Last edited: Dec 23, 2015
2. ### KritchlowFinal Approach

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I don't have that approach in front of me, but generally RVR is only used for a precision approach.

3. ### BlackManINCPre-Flight

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Oh wait, I see what you are saying. I was referring to the localizer approach with a visibility of 1 3/8 statue miles. I basically just wanted to know how I would get that in feet, or RVR to be technical. I came up with 7,260 feet.

4. ### KritchlowFinal Approach

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In addition, "rvr better than 6000" is the highest report.

5. ### flyingronTouchdown! Greaser!

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RVR is largely immaterial for non-commercial (135/121) operators. The visibility that is controlling is what you see out the window not RVR. The only conversion from RVR that is necessary is when the minimums reference RVR (such as the 50 in some of the minimums for this approach) which is equivalent to a mile of flight visibiltity.

6. ### BlackManINCPre-Flight

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So the actual RVR value is never given for the sake of simplicity if its greater than 6000 ft?

7. ### BlackManINCPre-Flight

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Well I'm thinking of it from an aircraft dispatchers perspective. If I have to derive minimums for the intended runway for the alternate airport, I have to know exactly what the new minimums actually are. So if the pilot is shooting a LOC only approach on a runway with 1 3/8 SM, I as a dispatcher would have to increase the ground visibility by sometimes a mile. So 1 3/8 equates to 7,260 ft, then his new minimums for the alternate would technically be the following:

RVR: 12260ft Ground visibility: 2 5/8 statute mile

Last edited: Dec 23, 2015
8. ### flyingronTouchdown! Greaser!

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You follow what your opsecs say actually. When RVR exceeds 6000 it either gets reported as P6000 or just omitted from the METAR.

And you've lost me, alternate minimums are not given in RVR. They are given in MILES unless your opsecs have an DEFINED alternative procedure.

9. ### BlackManINCPre-Flight

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Right, well that's what I meant. In the op specs, for say Spirit Airlines for example, alternate minimums are always increased by either 1 SM or 1/2 SM. Increasing a LOC approach of 1 3/8 SM by 1 SM will give you a new minimum of about 2 5/8 SM.

10. ### CaptainFinal Approach

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When deriving mins you don't add the half mile or mile to the RVR, you add it to the SM vis. Y'all making this way too hard.

If the derived mins add 200 and 1/2 to the approach (2 rwy, 2 navaid) and both appchs have 200 and 1/2 mins then your derived mins are 400 and 1. Or 600 and 1 1/2 if on one navaid or rwy. You don't add 1 mile to 2400 feet...that'd be wierd.

RVR is for shooting the appch and is used by the pilot. It tells the vis (controlling) AT the runway.

11. ### Sluggo63Line Up and Wait

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12. ### KritchlowFinal Approach

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And, as you can see, it only goes to 6000.

13. ### flyingronTouchdown! Greaser!

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Again, you won't see a reported RVR over 6000. That's as high as it goes. There's no point in extending the table to compute some unusable value that some imaginary opspec might use.

14. ### KritchlowFinal Approach

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That's my point, with the exception of "better than 6000".

15. ### BlackManINCPre-Flight

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So if I'm adding 200 1/2 to an approach with 400-3/4, that would make the new derived minimums 600-1 right?

16. ### flyingronTouchdown! Greaser!

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400+200 is 600

3/4 + 1/2 = 1 1/4

17. ### BlackManINCPre-Flight

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Did you get the 1/4 from the RVR conversion chart?

18. ### flyingronTouchdown! Greaser!

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What RVR conversion chart. If you're increasing 3/4 SM visibility by 1/2 SM, you don't need any stinking chart, it's third grade arithmetic.

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You don't need to look at the RVR conversion chart when you are adding fractions of statute miles.

20. ### Banjo33Line Up and Wait

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Maybe he "learned" via Common Core!

21. ### BlackManINCPre-Flight

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Not at all, I had to "relearn" the formula since I don't remember the last I actually had to do it. And what the hell is "common core" anyway?