How Do Airports Safely Manage Parallel Runway Operations?

Informative Airports, FAA, ICAO, landing, runways Youssef Yahya 4 days ago 0 Comments

With over 100 airports around the world featuring parallel runways, including renowned hubs like London Heathrow (LHR), Hartsfield-Jackson Atlanta (ATL), and Dubai International (DXB), airport regulators globally have implemented numerous safety regulations to manage operations efficiently. In this article we explain the factors influencing safe parallel runway operations.

Modes of Parallel Runway Operations

According to SKYbrary, parallel runway operations are divided into four distinct modes:

Independent Parallel Approaches: This method allows two aircraft to simultaneously use adjacent Instrument Landing Systems (ILS) for landing. Radar separation minima are not required.

Dependent Parallel Approaches: In this mode, aircraft also use the ILS, but they must maintain a separation based on radar monitoring.
Simultaneous Departures: Parallel runways can be used to conduct simultaneous takeoffs, increasing airport efficiency.
Segregated Parallel Operations: This mode is a combination, with one runway dedicated to landings and the other for departures. Some configurations also allow one runway to handle both arrivals and departures.

These operational modes are critical for ensuring safe and efficient aircraft movements at airports with parallel runway systems.

Minimum Distance Regulations for Parallel Runways

The U.S. Federal Aviation Administration (FAA) has established minimum distance requirements for aircraft operating on parallel runways to prevent any potential conflicts. These standards are divided into various categories:

For Category I or Category II aircraft, which weigh no more than 12,500 pounds (5,669 kg) and are powered by single or twin-engine turboprops, the minimum distance between runway centerlines must be 300 feet (91.4 meters). The edges of adjacent runways must be at least 200 feet (60.96 meters) apart.

If one of the aircraft involved is a Category III aircraft, the minimum separation increases to 500 feet (152.4 meters) between runway centerlines, with a required 400 feet (121.9 meters) distance between the runway edges.
Heavy aircraft, defined by the FAA as those with a takeoff weight of 300,000 pounds (136,077 kg) or more, demand even greater separation. For these large aircraft, such as the Antonov An-124 Ruslan, the minimum distance between runway centerlines must be 700 feet (213.3 meters), while the edges of adjacent strips need to be separated by at least 600 feet (182.8 meters).

For simultaneous but opposite direction operations, different rules apply depending on the time of day. During daylight hours, runway centerlines must be separated by at least 1,400 feet (426.7 meters), while the distance must double to 2,800 feet (853.4 meters) during night operations. Moreover, the edges of parallel runways in opposite directions are “not authorized” by the FAA.

Factors Affecting Parallel Runway Capacity

Several factors influence the operational capacity of parallel runways. SKYbrary has identified weather conditions and terminal configurations as significant factors that can either enhance or restrict the use of parallel runways. For example, adverse weather, such as strong winds or turbulence, can lower runway capacity due to the increased separation required for safety. Additionally, taxiways connecting terminals to parallel runways pose a risk for incursions, a critical concern for safety.

One notable example occurred in January 2023, when an American Airlines Boeing 777 crossed JFK’s parallel runway 4L/22R while a Delta Air Lines Boeing 737 was already taking off, forcing the Delta aircraft to abort its takeoff to avoid a potential collision.

Safety Risks Associated with Parallel Runway Operations

The International Civil Aviation Organization (ICAO) highlights several safety risks linked to parallel runway operations, particularly under challenging weather conditions. The organization advises against conducting independent instrument approaches to parallel runways that are separated by 3,400 feet (1,035 meters) to 5,000 feet (1,525 meters) during rough weather, such as in the presence of windshear or turbulence.

Additionally, ICAO stresses the importance of proper communication between air traffic controllers (ATC) managing independent parallel approaches. For instance, slow aircraft may not be able to create enough spacing during these operations, resulting in potential risks for runway incursions.

Training Requirements for Air Traffic Controllers

The proper training of air traffic controllers is crucial for the safe management of parallel runway operations. ICAO mandates that ATC personnel be thoroughly trained before being allowed to manage parallel instrument runways. This includes simulator-based training to help controllers recognize, react to, and mitigate potential deviations of aircraft during parallel operations.

Controllers assigned to manage parallel runway operations must demonstrate the requisite skills and knowledge to ensure safe and efficient aircraft handling. ICAO recommends that this training be divided between approach controllers and aerodrome controllers, with specialized focus areas for each group.