Runway Edge Lights
Runway edge lights outline the edges of a runway during darkness or periods of lowered visibility. The lights are described as being low, medium, or high intensity runway lights, abbreviated as LIRL, MIRL, and HIRL, respectively. MIRL may be operated on a medium or low intensity setting. HIRL may be operated on high, medium, and low settings.
Runway edge lights are white, except on instrument runways where they are yellow for the last 2,000 feet or half the runway length, whichever is less.
On either end of the runway, the lights emit either red or green light to indicate the friendly or unfriendly end of the runway approaching. A departing aircraft would see the lights at the far end of the runway as red. An arriving aircraft sees the lights at the approach threshold as green, while the lights at the far end of the runway are red.
Runway End Identifier Lights (REILs)
Many airports install REILs to provide rapid and positive identification of the approach end of the runway. REILs are a pair of synchronized flashing lights located laterally on each side of the runway threshold. They may be omnidirectional or be setup to emit light in the direction of the runway's approach area.
REILs aid in identifying a runway that is surrounded by a lot of other lights, such as at an airport surrounded by city lights. They also aid in pointing out a runway that lacks contrast with surrounding terrain or making a runway more visible in poor weather conditions.
Runway Centerline Lighting System
Some runways have installed runway centerline lights to aid in the visibility of the runway centerline, spaced at 50 foot intervals. The lights are white until the last 3,000 feet of the runway. At this point, they begin to alternate between red and white. For the last 1,000 feet of runway, all centerline lights are red.
Touchdown Zone Lights
Some runways have installed touchdown zone lights, which point out the touchdown zone to arriving pilots. Touchdown zone lights consist of two rows of transverse white light bars disposed symmetrically about the runway centerline, beginning 100 feet beyond the landing threshold and extending to 3,000 feet beyond the landing threshold or midpoint of the runway.
Taxiway Centerline Lead-Off Lights
Alternating green and yellow lights are sometimes installed in a runway to aid pilots in exiting the runway onto a taxiway.
Taxiway Centerline Lead-On Lights
Alternating green and yellow lead on lights are sometimes installed in a runway to aid pilots entering a runway from a taxiway.
Land and Hold Short Lights
Land and hold short lights are used to indicate hold short points on runways. They consist of a row of pulsing white lights installed across the runway at the hold short point. The lights are turned on to indicate that land and hold short operations are in effect.
When land and hold short operations are in effect, tower may issue a clearance to land on a runway to hold short of another taxiway or runway. For example, "Cessna 66769, cleared to land runway nine right, hold short of taxiway sierra".
Pilots should decline any LAHSO clearance when it could compromise safety. The tower controller would much rather have a pilot decline a clearance than accept it when that pilot is not 100% sure it is safe to accept that clearance.
Available landing distances are published in the airport/facilities directory for each runway and hold short point that may be used by air traffic control.
It is recommended that all pilots, regardless of operation or experience level, decline a LASHO clearance anytime the weather is less than 1,000 feet ceilings or 3 statute miles visibility. Additionally, it is recommended that student pilots never accept a LASHO clearance.
The PIC has the final authority to accept or decline a land and hold short clearance.
Pilots should have the published available landing distance and runway slope information readily available for each airport of intended landing.
Promptly inform ATC if you cannot accept a LAHSO clearance.