Land and hold short operations
Land and Hold Short Operations (or LAHSO[1], pronounced "La-So") is an aeronautical term for operations that involve aircraft landing and holding short of an intersecting runway, taxiway or some other designated point on a runway. LAHSO is an air traffic control procedure that requires pilot participation to balance the needs for increased airport capacity and system efficiency, consistent with safety. LAHSO Clearance use is voluntary and a pilot may deny a LAHSO clearance at their discretion. If a pilot denies a LAHSO clearance the Air Traffic Controller must revector the aircraft to ensure adequate separation from other aircraft landing or departing an intersecting runway or crossing down field.
The name for this category of procedures was previously SOIR (Simultaneous Operations on Intersecting Runways), but the guidelines for LAHSO incorporates all of the SOIR definitions and expands upon them now.
Types
There are three main types of LAHSO.
- LAHSO of Intersecting Runway: In this LAHSO, a landing plane is instructed to land and hold on the runway before the intersection of it and another runway, which will have another aircraft taking off or landing when they arrive.
- LAHSO of Intersecting Taxiway: In this LAHSO, a landing plane is instructed to land and hold on the runway before the intersection of it and a taxiway, which will have other aircraft taxiing for takeoff or parking when they arrive.
- LAHSO of Point on Runway: In this LAHSO, a landing plane is instructed to land and hold on the runway before a designated point. This form of LAHSO is the newest, and is used when safety precautions are needed due to hazards concerning other runways, taxiways, or any of a number of other hazards for a landing plane that may be present on their runway (ice, for instance).
Requirement for LAHSO: Pilots should only receive a LAHSO clearance when there is a minimum ceiling of 1,000 feet and 3 statute miles visibility. The intent of having "basic" VFR weather conditions is to allow pilots to maintain visual contact with other aircraft and ground vehicle operations.
Notes
- A heightened level of situational awareness is necessary for these procedures.
- Although used in the US, many countries do not permit the use of LAHSO clearances, and some airlines' operating procedures do not allow the acceptance of LAHSO clearances in those countries that do permit it.
- In the US, pilots have the authority to decline a land-and-hold-short clearance. Air traffic control must then re-vector the aircraft to provide adequate separation.
- Student pilots or pilots not familiar with LAHSO should not participate in the program.
References
Other sources