Definition

Land and Hold Short Operations (LAHSO) is an air traffic control procedure that requires pilot participation. Air traffic control may clear a pilot land and hold short of an intersecting runway, an intersecting taxiway, an approach/departure flight path, or of a predetermined point. Pilots are expected to promptly inform the controller if the hold short clearance cannot be accepted.

Source: FAA Aeronautical Information Manual 4-3-11.

Description

LAHSO is a procedure currently used mainly in the United States, Canada and Australia to balance the needs for increased airport capacity and system efficiency, consistent with safety. LAHSO operation allows simultaneous take-offs and landings and or simultaneous landings when a landing aircraft is able and instructed by the controller to land and stop (hold short) before reaching a specific point, e.g. an intersecting runway/taxiway. 

LAHSO operations may be considered voluntary procedures, with participating aircraft classified as either active (when an aircraft is issued a hold short requirement and is alerted about traffic on a crossing runway) or passive (when an aircraft has unrestricted use of the full runway length and is alerted about traffic on a crossing runway).

Prerequisites

LAHSO is not necessary or feasible at every airport. But where LAHSO is useful, requirements include ATC control and suitable runway configurations and markings, airport signage, taxiway markings, and lighting.  In general, LAHSO requires good collaboration among all participants to ensure safe operation. New regulations require, among other things, the implementation of a LAHSO development team consisting of representatives from air traffic control, airport managers, and airport users, as well as an annual safety review of LAHSO operations.

Additionally, further requirements must be fulfilled, including establishing:

• Available Landing Distance (ALD)
• Rejected Landing Procedures (RLP) if applicable
• Hold Short Point signage, marking, and lighting

One of the most important provisions is that the pilot-in-command retains final authority to accept or decline any LAHSO clearance. Pilots are expected to decline a LAHSO clearance if they believe it will compromise safety.

Risk Factors

Although LAHSO may lead to significant increase in traffic capacity its application comes along with inherent safety risks which need to be properly managed. The prominent risks are:

• Runway incursion;
• Loss of safe separation;
• Loss of safe wake vortex separation; and,
• Loss of safe terrain clearance

Risk factors to be considered by the pilot/crew before accepting a LAHSO clearance include among others:

• Actual runway condition (LAHSO is allowed on dry runways only)
• Cross- and, tailwind-components (e.g. FAA limits tailwind to maximum 3kts)
• Wind-shift or turbulence during flare (increase of flare distance)
• Planned turnaround time (required brake cooling time requirements)
• Complexity of rejected landing procedure (traffic/terrain awareness)
• Human Factors influencing aircraft handling and decision-making:
  • Fatigue
  • Low on-type-experience
  • Unfamiliarity with the aerodrome
  • Pressure or expectation to use LAHSO by ATC or by the airline
  • Pressure to complete the landing to avoid traffic disruption
  • Reluctance for rejected/balked landing (e.g. due to lack of training or proficiency) 

Solutions

LAHSO requires airport operators to undertake specific actions including the installation and maintenance of required markings, signs, and in-pavement lighting. For example, if it is to be used by ATC in the U.S., the FAA requires that the runways involved have:

• Only one designated hold short point per operational direction on a runway.
• A hold short line on the landing runway prior to the intersecting runway or taxiway.
• Holding position signs on both sides of the runway adjacent to the runway hold lines.
• A sign with a white inscription on a red background is installed adjacent to these holding position markings.
• In-pavement pulsing white lights at the LAHSO hold short point.

Further requirements for airport operators and ATC include the installation and operation of electronic glideslopes (e.g. by an ILS) or visual glide slope indicators such as PAPI or VASI, especially if it is intended to use LAHSO during night times as well.

Additionally, if LAHSO is in effect, the ATIS must announce either generally “LAHSO in effect/in progress” or specifically e.g. “Expect landing on RWY 32 to hold short of RWY 24”.

The airport traffic control tower supervisor/controller in charge must terminate LAHSO for any situation or weather condition that, in their judgment, would adversely affect LAHSO.

ATCOs should be aware that a go-around is, in normal operation, always the default option for pilots – not the landing. Therefore, it is important for both ATCOs and pilots/crews to plan for action in the event of a go-around. If a go-around is initiated, pilots/crews must maintain safe separation from other aircraft by themselves, as it may be impractical for ATC to provide standard separation. However, special instructions for rejected landings may exist and ATC might issue traffic information and, if appropriate – based on the relative position of aircraft, instructions for avoiding other aircraft. Regardless of any avoiding action instruction, pilots/crews should always defer to any TCAS RA.

Situational awareness is vital to the success of LAHSO. Therefore, pilots/crews should have airport ground/taxi charts always readily available and should have a thorough understanding of the airport markings, signage, and lighting associated with LAHSO. Any specifics on an airport regarding LAHSO, e.g. special pilot-controller radio communication requirements, should be reviewed prior departure or arrival.

Additional operational restrictions for LAHSO should help to ensure that LAHSO can be safely conducted in routine operation, e.g. ATC may authorize LAHSO only, if: 

• The runway is clear and dry,
• The winds are within given limits (e.g. maximum 3kts tailwind and 20kts crosswind),
• No low-level windshear or microburst activity reported or indicated,
• Ceiling and visibility are within given limits (e.g. 1500ft/5miles for runways without VGSI or 1000ft/3miles with VGSI)
• Traffic information is exchanged, and a read-back must be obtained from the landing aircraft with a LAHSO clearance

Pilots receiving and accepting ATC LAHSO instructions in the form "Cleared to land Runway 'AA', Hold Short of Runway 'BB'," must either exit Runway 'AA', or stop at the holding position prior to runway 'BB'.

Pilots/crews are not required to accept a LAHSO clearance but if they do, the pilots-in-command are expected to satisfy themselves that their aircraft can safely land and stop within the Available Landing Distance, which ATC will also provide upon request. If landing long becomes likely, then a go-around or rejected landing is expected rather than the possibility of violating a LAHSO clearance.

It should be noted that some airlines specifically prohibit the acceptance of LAHSO on safety grounds based upon their operational risk assessment procedures. 

Important Considerations for Pilots

• Pilots should make sure they have accurate landing performance data for LAHSO, and that they use correct procedures to obtain it if receiving this data by ACARS. For example, pilots normally request landing data through ACARS by entering current conditions and selecting a runway, i.e., 12L. But, depending on the software, the correct designation for landing on runway 12L to hold short of taxiway A might be 12L/A. It is easy to forget this step, especially if the pilot does not often use LAHSO procedures. This error can lead to a crew attempting a LAHSO operation when the aircraft is too heavy to stop within available distance.
• Even if the landing data indicates the aircraft can stop within the available distance, an airline’s operation specifications may preclude a particular LAHSO operation. For example, landing data may indicate the aircraft can accomplish a landing with 5,850 feet of landing distance available. But the operations specifications may require 6,000 feet for any LAHSO operation. Crews should be thoroughly familiar with their operations specifications and standard operating procedures (SOPs).
• Pilots should understand the difference between a published missed approach procedure and a rejected landing procedure and know when each applies. For example, SOPs might specify that for a given runway, pilots will fly the published missed approach procedure if going around at or above decision height (DH) or minimum descent altitude (MDA)—and that they will use the rejected landing procedure if going around below DH or MDA. For a given runway, the turns and altitudes for an RLP and a published missed approach could be entirely different.
• Pilots should also understand that not every LAHSO runway has an RLP. Prior to accepting any LAHSO clearance, pilots should check flight publications and know what to do if a go-around becomes necessary.

Further Reading

• ICAO Doc 9870 App B - Best Practices on the Flight Deck
• European Action Plan for the Prevention of Runway Incursions App D - Flight Crew Best Practices