Figure 14-32.  Pulsating visual approach slope indicator.  Figure 14-33.  Runway lights.  14-18  Control of Airport Lighting  In-Runway Lighting  low intensity runway lights (LIRL). The HIRL and MIRL  have variable intensity settings. These lights are white, except  on instrument runways where amber lights are used on the  last 2,000 feet or half the length of the runway, whichever  is less. The lights marking the end of the runway are red.  Taxiway centerline lead-off lights—provide visual guidance  to persons exiting the runway. They are color-coded to warn  pilots and vehicle drivers that they are within the runway  environment or ILS critical area, whichever is more restrictive.  Alternate green and yellow lights are installed, beginning  with green, from the runway centerline to one centerline light  position beyond the runway holding position or ILS critical  area holding position.  Taxiway centerline lead-on lights—provide visual guidance  to persons entering the runway. These “lead-on” lights are  also color-coded with the same color pattern as lead-off  lights to warn pilots and vehicle drivers that they are within  the runway environment or ILS critical area, whichever is  more conservative. The fixtures used for lead-on lights are  bidirectional (i.e., one side emits light for the lead-on function  while the other side emits light for the lead-off function). Any  fixture that emits yellow light for the lead-off function also  emits yellow light for the lead-on function.  Runway centerline lighting system (RCLS)—installed on some  precision approach runways to facilitate landing under adverse  visibility conditions. They are located along the runway  centerline and are spaced at 50-foot intervals. When viewed  from the landing threshold, the runway centerline lights are  white until the last 3,000 feet of the runway. The white lights  begin to alternate with red for the next 2,000 feet. For the  remaining 1,000 feet of the runway, all centerline lights are red.  Touchdown zone lights (TDZL)—installed on some precision  approach runways to indicate the touchdown zone when  landing under adverse visibility conditions. They consist of  two rows of transverse light bars disposed symmetrically  about the runway centerline. The system consists of steady- burning white lights that start 100 feet beyond the landing  threshold and extend to 3,000 feet beyond the landing  threshold or to the midpoint of the runway, whichever is less.  Land and hold short lights—used to indicate the hold short  point on certain runways which are approved for LAHSO.  Land and hold short lights consist of a row of pulsing white  lights installed across the runway at the hold short point.  Where installed, the lights are on anytime LAHSO is in effect.  These lights are off when LAHSO is not in effect.  Airport lighting is controlled by ATC at towered airports. At  nontowered airports, the lights may be on a timer, or where an  FSS is located at an airport, the FSS personnel may control the  lighting. A pilot may request various light systems be turned  on or off and also request a specified intensity, if available,  from ATC or FSS personnel. At selected nontowered airports,  the pilot may control the lighting by using the radio. This  is done by selecting a specified frequency and clicking the  radio microphone.  [Figure 14-34]  For information on pilot  controlled lighting at various airports, refer to the Chart  Supplement U.S. (formerly Airport/Facility Directory).  Below glidepath  Above glidepath  On glidepath  Pulsating white Pulsating red Steady white  Threshold  Slightly below glidepath  Steady red 