There are many tasks that the pilots must do before landing; most notably, they must know on which runway to land. They will be usually assigned a runway by the air traffic controllers on the airport.
There are four active runways on Ruzyně: 06/24 and 13/31. The Runway 04/22 has been closed for a long time now, because it's too short and can't handle the new aircraft. Let me explain a bit more about the names of runways. Each runway is called by a two-digit number between 01 and 36. This number denotes the closest heading in tens of degrees from the magnetic north.
Since the first runway on Ruzyně is oriented east-north-east (or 65 degrees from the magnetic north measured clockwise), it is called Runway 06 (pronounced Runway Zero Six). When taking off from this runway, pilots would be flying towards north-east. The runway (just like most runways in the world, with a few exceptions - most notably runways close to a mountain range) can however be used from the opposite direction as well - and thus the other end of this runway is called Runway 24 (pronounced Runway Two Four). When referring to both directions, the name Runway 06/24 is used. The second runway is oriented east-south-east (or 127 degrees magnetic), it is called Runway 13. The other direction of this runway is Runway 31.
Aircraft usually take off and land into the wind, because it allows them to use lower speed during takeoff and landing. Because the prevailing winds around Ruzyně are westerly, it is Runway 24 that is used the most often. Runway 13/31 is only used if the wind does not allow 06/24 to be used; aircraft landing and taking off from 13/31 must go over downtown Prague, which is pretty noisy, so the authorities try to use it as infrequently as possible. Because the capacity of Runway 06/24 is becoming too low, a new runway parallel to 06/24 will be built in the next years. Once it is finished, this runway will be called 06R/24L and the the original 06/24 will be renamed to 06L/24R. L means Left (as seen by the pilot during approach), R means Right. (If there were three parallel runways, the middle one would be called with a C letter added.) The new runway will allow parallel takeoffs and landings, effectively doubling the capacity of the active runways.
Runway 24, because it's the runway used most often, is better equipped than the other runways in Ruzyně; most notably, it is equipped with Instrument Landing System Category IIIb. Instrument Landing System (or ILS) is a set of instruments that guide pilots onto the runway. The more modern the equipment on the ground and in the airliner, the more guidance it provides. Modern ILS also allows an airliner to land even in very bad weather; in the case of Runway 24 in Ruzyně, properly equipped aircraft with a properly trained crew can land mostly on autopilot.
While I do not have any pictures of the ILS equipment (and there's really not much to see apart from an array of transcievers on the ground), I am going to describe another instrument that helps pilots land. This instrument is called PAPI (pronounced as pappy), or Precision Approach Path Indicator, and it is a set of four lights mostly left (or rarely right) of the aiming point of the approach end of the runway. If the approaching aircraft is on the correct glide slope (which is usually a line pointing 3 degrees up from the base of the runway), the pilots will see two red and two white lights. If the aircraft is just a little higher than the optimal path, the pilots will see one red and three white lights. Four white lights mean the aircraft is way too high, three red and one white lights mean that the aircraft is a little low and four red lights mean that the pilots should immediately start climbing, because they're way too low - and way too close to the ground. When the aircraft is, say, five nautical miles from the airport, the pilots would see two red and two white lights as long as they stay within about 25 meters of vertical tollerance from the glide slope; any more than that, either up or down, and they would need to correct the altitude for landing - although when using instrument approches, the pilots will only use PAPI as another way of verifying that the instrument approach is proceeding as expected.
When airliners are landing during low visibility (either during the night, during fog, or during any other atmospheric conditions that decrease visibility), the runway will be lit. If the runway can't be lit, it can't be used in those conditions. While I don't have the space (or pictures) to describe the whole runway lighting system, I have to mention at least one specific set of lights. The sequenced flashing lights just in front of the runway (when watching from the cockpit during an approach) are called the rabbit. The air traffic controller can adjust their intensity according to the pilots' needs, the lights can also be turned off completely when they are too bright. If this is the case, the pilots will ask the air traffic controller to kill the rabbit (this piece of information was brought to you by Luks pet bunny).
Copyright notice: Text and images copyright by Michal Řeháček.