Airport Planning & Mgmt

Airport Planning & Management Class: 5 & 6

Airfield, Aerodrome and Airport: An airfield is an area where an aircraft can land and take off. It may or may not be equipped with any navigational aids or markings. The area needs to be free from any structure around which can obstruct movement of aircraft. Many grass strips are also designated as airfields.

An airfield is called an aerodrome when it is equipped with air traffic control facility. An aerodrome does usually have runways equipped with NAVAIDS and facilities to control aircraft in air from ground with radio technology. Though the common reference of airport includes airfield and aerodrome also, a full-fledged airport needs to have airfield, aerodrome and one or more terminal buildings for the comfortable movement of passengers and air cargo.

The physical parts of an airport can be broadly divided into three parts as • • •

Airside Terminal Building and City side

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Airport Planning & Management Class: 5 & 6

The airside installations, operation and its effective management are vital for every airport. It basically includes 1. Runway 2. Taxiway 3. Holding bays 4. Apron 5. Bays/stands 6. Runway lights 7. Runway markings 8. Navigational aids or NAVAIDS as • NDB (Non directional beacon) • DVOR • DME • Localizer • Glide Path • Outer marker A terminal building could be made for passengers, cargo and for any other specific purposes. A PTB (Passengers Terminal Building) comprises the basic physical parts as 1. Front side of the PTB or the verandah 2. Visitors Area 3. Check-in Area 4. SHA or Security Hold Area (sterile area) 5. BMA (Baggage Make Up area) 6. BBA (Baggage Brake Up area) 7. Passengers Meet and Greet area 8. Airlines offices 9. Office of the regulatory agencies 10. Lounges of Business class or Executive Class passengers 11. Check-in counters 12. Frisking booths and XBIS machines 13. Various concessionaires 14. Counters for Tour and Travel agencies 15. counters for Taxi services The city side area comprises: 1. 2. 3. 4.

Parking area Reserved parking area Approach road Directional signage Page: 2

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Airport Planning & Management Class: 5 & 6

Runways: A Runway is the basic requirement of an airport. The pavement where aircrafts land, roll and take off is called a runway. Regulations regarding the management and planning of runway is governed by ICAO SARP Annex-14. As per the guidelines the runway is properly painted with various markings and equipped with visual and instrumental aids. Runway orientation: Runway orientation is basically decided on prevailing wind directions over the area. The runway which is oriented into the prevailing wind is known as Primary Runway. However, in many areas wind directions are not always same. If the runway is oriented towards the most common crosswind direction, it is called Crosswind Runway. Many airports have more than one runway parallel to each other. Such runways are called Parallel Runway and denoted by R, L and C meaning Right, Left and Centre as its position. Runways are defined by their orientations with respect to magnetic north. The angle from magnetic north is divided by 10 and rounded to the nearest integer. The lower n umber is always indentified first.

Runway length and width: The characteristics that determine the length and width of the runway are • aircraft sizes that are to be operated on the runway and • the prevailing atmospheric conditions. The maximum gross take off weight, acceleration rate, safe lift off velocity of the aircraft are the factors to be considered while determining the length. Moreover, elevation above the sea level (MSL) and outside air temperature are also two factors affecting the runway length for the fact that air at higher elevation and at higher temperature is less dense than cooler air and air closer to sea level. The density of the air is a significant determinant in the takeoff performance of aircraft. The width of runway varies from 50 to 200 feet and Page: 3

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Airport Planning & Management Class: 5 & 6

length from 2500 feet to 23,270 feet being the Area 51 airport at Las Vegas having the longest runway of 23270 feet (7090 meters). Runway markings: For guidance to the pilots of aircraft, runways are painted with three kinds of markings like • Visual runway markings • Non precision Instrument marking and • Precision Instrument markings A visual runway is intended solely for aircraft operation using visual approach procedure. A Non-precision Instrument runway is one having an instrument approach procedure using air navigation facility with only horizontal guidance. A precision Instrument Runway is one having an Instrument approach procedure using a precision instrument landing system, ILS or Precision Approach Radar (PAR) which provides both horizontal and vertical guidance to the runway. The common runway markings are Runway designators, Centre line, threshold marking and aiming points.

Runway Center Line: Runway Centre line identifies the centre of the runway and provides alignment guidance during take off and landing. This marking consists a line of uniformly spread strips and gaps in while color. Runway Threshold marking: Runway threshold marking identifies beginning of the runway that is available for landing. It consists eight longitudinal strips of uniform dimension disposed symmetrically about the runway centre line. Number of strips depends upon the width of the runway. Runway aiming point: This marking gives visual aiming point to the pilots. It consists two rectangular marking broad white strips, 1000 feet away from the runway threshold.

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Airport Planning & Management Class: 5 & 6

Runway touchdown zone marking: This marking indentifies the touch zone for landing operation. They are marked to provide information in 500 feet separation for a distance up to 2500 feet from the threshold. It is a group of one, two or three rectangular bars symmetrically arranged in pairs about the runway center line. Runway side strips: It gives the edge of the runway. It is a continuous white strips located at each side. Runway Lighting: Runway lighting is extremely important for night time aircraft operation or in poor visibility weather conditions. There are three kind of light arrangements in and around the runway. • Approach lighting systems • Visual glide slope indicators • Runway end identifiers Approach lighting system (ALS): Approach lighting system is to guide the pilot to identify the runway and to align the centre line. They extend back from the runway called the approach area to a distance of 2400 to 3000 feet for precision Instrument runway and 1400 to 1500 feet for non precision instrument runways.

Visual Glide Slope Indicator: Visual glide slope Indicators are lighting system located adjacent to runway on the airfield to assist aircraft with visually based vertical alignment on approach to landing. The five kind of visual indicators are • • • • •

VASI PAPI Tricolor VASI systems Pulsating systems Alignment of element systems

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Airport Planning & Management Class: 5 & 6

VASI (Visual Approach Slope Indicators): VASI is a system of lights so arranged to provide visual descent guidance information during an aircraft’s approach to a runway. These lights are visible form 3 to 5 miles during a day and up to 20 miles or more during night. VASI may consist of 2, 4,6,12 or 16 light units arranged in bars referred to as near and far bars. Sometimes it consists one additional bar called middle bar. Usually VASI is placed on one side of the runway but when it consists more light units, the units are located on both sides of the runway.

The basic principle of the VASI is that of color differentiation between red and white. Each light unit projects a beam of light having a while segment in the upper part of the beam and red segment in the lower part of the beam. The light units are arranged so that the pilot using the VASIs during an approach will see the combination of lights associated with their height relative to the approach path. On two-bar VASI, the glide slope is associated with the pilot seeing red lights emanating from the far bar and white lights from the near bar. If the aircraft is below the glide path, both bars would be seen as having red lights. PAPI (Precision Approach Path Indicators): The PAPI uses light units similar to the VASI but they are installed in a single row of their two or four light units. These systems have an effective visual range of about 5 miles during day and up to 20 miles at night. The row of light units is generally installed on the left side of the runway. Like VASI, lights are equipped with red and white beam that project various degree of glide path to the runway. The PAPI are said to be more precise than VASIs because it allows the pilot to judge approximately how many degrees above or below the glide path by the number of red versus white lights observed.

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Airport Planning & Management Class: 5 & 6

PAPI observing two red and two white lights denotes on glide path, three red and one white light denotes slightly ( by 0.2 degree) below the glide path, four red lights denote 0.5 or more degrees below the glide slope. Tri Color Visual Approach Slope Indicators: This is a single light unit projecting a three-color visual approach path to the runway. The below glide path indication is red, the slightly below and above glide path indications are amber, and on the glide path indication is green.

Pulsating Visual Approach Slope Indicators: Pulsating Visual Approach Slope Indicators normally consist of a single light unit projecting a two color visual approach path to the runway. The on glide path indication is steady white light. The slightly below glide path indication is a steady red light. If the aircraft descends further below the glide path, the red light begins to pulsate. The above glide path indication is a pulsating white light. The pulsating rate increases as

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Airport Planning & Management Class: 5 & 6

the aircraft gets further above or below the desired glide slope. The usual range of the system is about 4 miles during the day and up to 10 miles at night. Alignment of elements systems: It is installed on some small general aviation airport. They are low-cost systems consisting the three painted plywood panels, normally black and white or fluorescent orange. Some of these systems are lighted for night use. The range of such systems is three quarter of a mile. To use this system, pilot positions the aircraft so the elements are in alignment. If the aircraft is above the slope, the centre panel will appear to be above the outer two panels. If the pilot is below the glide path the centre panel will appear to be below the outer two panels. Runway Edge Identifier Lights (REIL): Runway End Identifier Lights are installed at many airfields to provide rapid and positive identification of the approach end of a runway. The system consists of a pair of synchronized flashing lights located laterally on each side of the runway threshold. Runway Edge Light System: Runway edge lights are used to outline the edge of runway during periods of darkness or reduced visibility. Runway edge lights are white, except on instrument runways where yellow lights replace white on the last 2000 feet or half the runway length whichever is less to form a caution zone for landing. The lights marking the ends of the runway emit red light toward the runway to indicate the end of the runway to a departing aircraft and emit green outward from the runway end to indicate the threshold to landing aircraft. Runway Centerline Lighting System (RCLS): They are located along the runway centerline and are spaced at 50 feet separations. When viewed from the landing threshold, the runway centerline lights are white until the last 3000 feet of the runway. The white lights begin to alternate with red for the next 2000 feet and for the last 1000 feet of runway, all centerline lights are red.

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Airport Planning & Management Class: 5 & 6

Taxiways: The major function of taxiways is to provide access for aircraft to travel to and from the runways to other areas of the airport. Taxiways are identified as • Parallel taxiways • Entrance taxiways • Bypass taxiways • Exit taxiways A parallel taxiway is aligned parallel to an adjacent runway. Exit and Entrance taxiways are typically oriented perpendicular to the runway or the parallel taxiway. Entrance taxiways are located near the departure end of runways; exit taxiways are located at various points along the runway to allow landing aircraft to efficiently exit the runway after landing. By pass taxiways are located at areas of congestion at busy airports. They allow aircraft bypass other aircraft parked on the parallel or entrance taxiways in order to reach the runway for take off. Taxiway markings: The taxiway centerline is a single continuous yellow line, 6 to 12 inches in width. Taxiway edge marking is continuous markings consisting of a continuous double yellow line, with each line being 6 inches in width spaced 6 inches apart. Taxiway lighting: Many airports are equipped with taxiway lighting to facilitate the movement of aircraft on the airfield at night or in poor visibility conditions. Taxiway lighting includes taxiway edge lights, taxiway centerlines lights, clearance bar lights, runway guard lights and stop bar lights. These light emit blue light. Clearance bar lights are installed at holding positions on taxiways in order to increase the conspicuity of the holding position in low visibility conditions. Clearance bars consists of three in-pavement steady burning yellow lights. Runway Guard lights are installed at intersections of runways and taxiways. They are either a pair of elevated flashing yellow lights installed on either side of the taxiway or a row of in-pavement yellow lights installed across the entire runway, at the runway holding position marking. Stop bar lights are used to confirm instructions form air traffic controller’s clearance to enter or cross an active runway in low-visibility conditions.

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