I’m currently listening to KMSP Tower (currently ILS) and pilots are receiving instructions as follows: “RVR 3000, mid-point 2400, rollout 1800.” What does that mean? *please note numbers are fictional.
There’s a nonuniform visibility obstruction so the Runway Visual Range varies at different points on the runway. I think the basic RVR number is at the touchdown point, the mid-point is the midpoint, and rollout is at the far side of the runway (probably not the end, but maybe 500-1000ft from the end).
If the OP’s question is “What is An RVR?” here is the relevant section of the Airman’s Information Manual:
Scroll down to paragraph 7-1-15, about 2/3rds down. Or, search for “Runway Visual Range”.
Thanks for the AIM link pthomas745. Cleared up my confusion. Category II landings at KMSP this morning due to fog.
Wikipedia has an RVR page with a pretty picture of a transmissometer:
On the bottom of that page is an FAA link to a real time RVR status monitor. I’ve never seen it before, but just playing around with it for a minute or so, it appears to give real time RVR status for major airports, and clicking on each airport’s link gives detailed info. ( A “Table Help” link at the top of an individual airport page shows you the legend for the airport chart.)
RVR status page:
Awesome link Thomas! The forecast is calling for thick fog again tomorrow here in MSP. I’ll be monitoring the comms and the RVR page. …and another productive day in the office