CHAPTER C — MASTER PLANNING SECTION CI: PRINCIPLES
C1.5 STEP 3 — AIRFIELD CONFIGURATION
C1.5.1 STEP 3a — Airfield Configuration Overview
The airport authority and the airport planning team must have a comprehensive understanding of the airfield configuration options that exist. There are essentially six airfield configurations for airport planners to choose from, all of which are defined within the following Clauses and Figures C1-1 through C1-6 inclusive. These all have various operational advantages and disadvantages, and it should be noted that while six airfield configurations exist to choose from, only four are deemed recommended by IATA for green-field or blue-sea situations. Please refer to the table within Clause C1.5.8 for further information.
Airfield configurations are determined by the number, position and orientation of existing and proposed runways and their support taxiway networks. This factor will greatly influence the position of all other primary and secondary support facilities.
When determining the position of new runways, several related factors need to be assessed in order that the new infrastructure can make best use of the existing or proposed new site's unique conditions.
C1.5.2 STEP 3b — Adjacent Airports, ATC, Airspace & Routes
Each airport has to coexist and operate within much larger national or international air traffic systems. Individual airports utilise vast tracks of airspace in order to accommodate the procedures required to allow aircraft to approach, hold, land and take-off. As a result, any extensive growth plan should be discussed and carefully co-ordinated with the relevant air traffic control authority, such that feasible recommendations can be developed and impractical concepts eliminated. Other factors may also come into play, including coordination with military controlled airspace and aircraft movements.
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C1.5.1 STEP 3c — Meteorological Conditions and Runway- Wind Orientation
The main criteria for the orientation of runways are the prevailing winds. Historical data will have to be retrieved to determine their direction, frequency and strength. As a general rule, the principal traffic
runway at an airport should be oriented as closely as practicable in the direction of the prevailing winds.
ICAO specifies that runways should be oriented so aircraft may land with crosswind components of 20km/hr or less at least 95 percent of the time for runways of 1500m or more. Optimum runway directions are determined by using a wind-rose.
C1.5.2 STEP 3d — Visual Conditions
Visibility and ceiling heights are very much affected by weather conditions and will influence the choice of runway operations; e.g. whether to select for operations under all weather or visual conditions
only. Fog, turbulence and abnormal rainfall may at times also reduce the capacity of runways. In order for airlines to maintain regular schedules during adverse weather conditions, airports are equipped with approach aids. The category of these aids depends on both the sophistication of the equipment installed at the airport and on board the aircraft. This determines the minimum visibility required for an aircraft to be able to land.
Type of Approach Minimum Decision
Height Visibility Runway Visual Range(RVR)
Non-precision (300 ft) Precision Cat I 200 ft 800m >550m Cat II 100 ft >350m Cat IIIA 50 ft >200m Cat NIB <50ft >50m Cat MIC <50 ft <50m
The minima herein are acceptable only when full facilities are installed and no objects penetrate obstacle clearance surfaces. Category III requires much more sophisticated equipment, which is not commonly installed at airports or in the aircraft using them. Given the small benefit that Category III gives compared to its costs, it is usually not installed at most airports. Cat III is most prevalent in Europe where it is a necessity for the airlines to maintain normal schedules in poor weather conditions.
C1.5.4 STEP 3f-Average Temperature and Altitude Considerations
In general terms, high temperatures will impact on the length of runway required, the rapid exit taxiway positions and the distances that can be traversed by aircraft while taxiing.
High temperatures result in lower air densities which in turn cause lower engine thrust. When determining runway length a correction factor needs to be applied on temperatures above 15 degrees C or 59 degrees F.
Airports that experience excessively high temperatures during the day may find that their operations are restricted due to insufficient runway length being available to support maximum possible take-off weights. In these instances, cargo volumes and/or passenger numbers may be restricted or operations may only be cost effective during cooler early morning or late evening periods.
Altitude, and its resulting effects upon air pressure and other temperature factors also plays an important role in determining the most effective runway configuration for a given facility.
C1.5.5 STEP 3g — Obstacles/Terrain
Obstacles often represent serious constraints to an optimal layout of runways or may in some circumstances have a negative influence on the operation to/from a runway. ICAO Annex 14 specifies that airspace around airports should remain free of obstacles so as to permit the intended aircraft operations at the airport to be conducted safely and to prevent the airport from becoming unusable by the growth of the obstacles around the airport.
Criteria for evaluating such obstacles are contained in the ICAO document Procedures for Air
Navigation Services — Aircraft Operations (PANS OPS).
Features within the natural landscape may also influence the orientation or length of proposed runways. While small obstructions can be removed, cost and the subsequent additional benefits obtained will be the determining factors when considering removal.
C1.5.6 STEP 3h — Obstacle Limitation Requirements
The requirements for obstacle limitation surfaces are specified by the intended use of a runway (i.e. takeoff or landing and type of approach) and are intended to be applied when such use is made of the runway.
In many countries all approaches and departures are conducted under Instrument Flight Rules (IFR) and limited straight-in approaches and defined departure routes.
C1.5.7 STEP 3i — Runway Configuration Options
Where figures are stated in this chapter outlining possible aircraft movement rates per hour, it
should be
noted that the figure quoted is heavily dependent on the composition of the aircraft mix, meteorological
conditions, the navigation aids available, and ATC separation standards of the country in question. For more information on runway capacity please refer to Section F5.
C1.5.8 STEP 3j — Runway Configuration and Movement/Capacity Assumptions
Runway capacity is fundamentally driven by three factors these are defined as follows:-
1.
Aircraft type and mix This influences aircraft spacing on final approach or departure wherewake vortices occur, as well as runway occupancy time, where aircraft weight and stopping distances are important factors.
2.
Runway design Includes the length available, access to taxiways for entry and exit from runways,the availability of high speed exits and entrances, etc.
3.
Aerodrome design Considers the support infrastructure, including terminal design and accessto gates, and taxiway design, which can influence the ability to get to or from a runway, or to change runways when weather or other conditions require. This factor also includes access to precision landing or departure guidance, runway and taxiway lighting, etc.
4.
Engineered Runway Capacity This is the number of movements (landings and/or departures)that can be expected to occur on a particular runway, or set of runways, assuming that there are no physical or practical constraints to accessing the runway(s). This means that aircraft are able to vacate a runway at a stopping point, or roll directly onto a runway without stopping. It does, however, factor the predicted wake vortex spacing for a known or assumed traffic mix, and assumes known or assumed runway occupancy times for landing or departing aircraft. It is an ideal figure, and cannot generally be achieved or sustained.
5.
Operational Runway Capacity This is the maximum number of movements that a runway canachieve and sustain in normal operating conditions. Note: "Mvts/Hr" denotes Aircraft Movements Per Hour.
Runway Configuration Assessment Table
Runway Configuration
Runway Layout Figure
Configuration Advantages Configuration Disadvantages Configuration
Operational Runway Capacity Single
Runway
Fig C1-1 - Lesser impact on
environment due to reduced apron area and reduced aircraft
movements per hour.
- Runway utilization often
high.
- Recommended choice of
IATA (subject to capacity
- Airport capacity restricted
by
single runway traffic movements
capability.
- Runway emergencies and
maintenance more difficult to manage.
- Cross wind take off and
36-55 Mvts/Hr
Open "V" to "L" Runways
Fig C1-2 - Increased runway Mvts/Hr
yields increased airport ultimate
capacity.
- Varied runway
orientations
can overcome seasonal prevailing cross wind problems.
- Runway emergencies and
maintenance easier to manage
(subject to case).
- Both runways can be used
simultaneously (subject to ATC
control limitations)
- Not a recommended choice
of IATA.
- Open "V" to "L" has larger impact on environment than a single runway and some parallel
runway configurations. - Open "V" to "L" layout occupies larger apron plan area.
- Open 'V" layout does not
naturally lend itself to efficient
apron expansion.
- One runway will always be
more compromised to prevailing
85-90 Mvts/Hr
Runway Configuration Assessment Table (cont'd) Runway Configuration Runway Layout Figure
Configuration Advantages Configuration Disadvantages Configuration
Operational Runway Capacity Intersectin g Runways
Fig C1-3 - Varied runway
orientations
can overcome seasonal prevailing cross wind problems.
- Runway emergencies and
maintenance easier to manage
(subject to case).
- Not a recommended choice
of IATA.
- Both runways cannot be
used
simultaneously.
- Intersecting runway layout
has
larger impact on environment than parallel runway as apron area increased.
- Intersecting runway layout
occupies larger apron plan area
than single runway or parallel runway configurations.
- Intersecting runway layout
does not naturally lend itself to
efficient apron expansion.
- One runway will always be
more compromised to 70-75 Mvts/Hr Qualification: Movements per hour based on two intersecting runways Staggered Runways
Fig C1-4 - Runway utilization can be
high.
- Runway emergencies and
maintenance easier to manage.
- Dedicated takeoff and
dedicated landing runway operations promotes safer multiple runway operations.
- Runway layout naturally
lends itself to efficient apron expansion.
- Recommended choice of
IATA (subject to capacity requirements).
- Cross wind take off and landing can present problems.
60 Mvts/Hr
Dual Parallel Fig C1-5 - Runway utilization can be
high.
- Runway emergencies and
maintenance easier to manage.
- Dedicated takeoff and
dedicated landing runway operations promotes safer multiple runway operations.
- Runway layout naturally
lends itself to efficient apron expansion.
- Recommended choice of
IATA (subject to capacity requirements).
- Cross wind take off and landing can present problems
84-105 Mvts/Hr
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Runway Configuration Assessment Table (cont'd)
Runway Configuration
Runway Layout Figure
Configuration Advantages Configuration Disadvantages Configuration
Operational Runway Capacity Multiple
Parallel
Fig C1-6 - Runway utilization can be
high.
- Runway emergencies and
maintenance easier to manage.
- Dedicated takeoff and
dedicated landing runway operations promotes safer multiple runway operations.
- Runway layout naturally
lends itself to efficient apron expansion.
- Recommended choice of
IATA (subject to capacity requirements).
- Cross wind take off and landing can present problems
120-168 Mvts/Hr
C1.5.9 STEP 3k — Runway Use
Runways and their supporting taxiway connections should observe the following characteristics:
•
Be linked to an efficient airspace system.•
Be supported by an air traffic control service provider that can maximize the potential of any given runway system.•
Reduce, to a safe working minimum, runway occupancy times through the provision of strategicallypositioned rapid exit taxiways.