IFR aka instrument flight rules, means that the pilot can not see because conditions are below the minima to allow for visual flight rules. Literally.
A few months ago, I purchased a small scanner and began finding and then listing to the radio frequencies used by near by air traffic. Most of these conversations are one-sided, pilots only, because air traffic control is too far away for my little scanner to pick up. One day soon after I got my scanner, there was a pretty significant rain storm going on. It was clear to me that the pilots I was listening to were not able to see, so had to be flying under IFR. One pilot came over the scanner asking "what's going on down there?" Meaning she may have been asking the controller what she might expect when she reached her destination airport. Or perhaps she was just curious. I could not hear the controllers response, but did hear her say thank-you. A short time later, I heard another pilot ask the same question.
I recently found out IFR student pilots use special glasses where the lateral and forward vision is clouded leaving only clear vision for the instruments. One brand name is foggles. Unless they cheat, wearing foggles means that they can not see out side the cockpit, and must rely on their instruments. Of course, the plane must have IFR instruments that include navigation equipment, one example being a Garmin GPS.
Flying under IFR means that you can fly a plane in or above the clouds. You navigate by flying from way station to way station. Each way station is assigned a specific radio frequency. As I understand it, the pilot tunes the navigation equipment, e.g. garmin GPS, to that radio frequency. Using the instruments in the plane you fly towards that way station. When you pass that way station, you get the frequency for the next way station from your flight plan, which may be on a knee board in your lap and fly towards that way station.
Finally, you are ready to approach the airport where you will land, with what is known as an ILS (instrument landing system) runway. You continue to fly from way station to way station until you reach the assigned frequency for the final runway approach. You pop out of IFR at about 200 feet above the runway, on final approach. When you pop out of IFR, you will be lined up with the extended center line of the runway. (Yes, there is a line down the middle of the runway.) Since you are already lined up with the extended center line of the runway, you do not have to maneuver at low altitude. You make the actual landing under VFR. Many GPS devices used in IFR planes will have these ILS approach plates loaded into memory, when you pass one way station, the GPS finds the next way station from memory and so on up to and including the final ILS approach.
I learned about these way stations, by the way, by listening to my scanner. I often listen to the band used by planes approaching and preparing to fly through the NY airspace in the vector over my house. To give you some perspective, I live on the edge of the class B airspace surrounding Newark-Liberty International Airport. Thanks to my copy of the sectional map covering this airspace, I learned that one of these way stations is located only a few miles from my house.
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Note (added July 2012): I'd like to thank a couple of my tanker pilot
friends whom I corresponded with as I was preparing the articles in
this series for their time and help. Here is a complete list of articles
in this series with hyperlinks:
1. Introduction (Jan 4)
2. VFR, I can see (Jan 6)
3. IFR, I can't see but I have instruments (Jan 8)
4. Fog (Jan 11)
5. Inversions (Jan 12)
6. Flying fires: VFR or IFR? (Jan 13)
7. Reflections (Jan 18)
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