Aerodrome Training Course Module 3 Aerodrome Physical Characteristics
Learning Outcome Participants will gain an overview of the required physical characteristics for aerodromes including: • Application aerodrome reference code • Runways • Taxiways • Aprons With the access to reference documents they will be able to determine the physical characteristics required for specific aircraft types.
Aerodrome Reference Code Provides a simple method for interrelating the numerous specifications concerning the characteristics of aerodromes to ensure they are suitable for aeroplanes that are intended to operate at the aerodrome. Consists of 2 elements • Code number element 1 corresponding to aeroplane reference field length (Definition -Aeroplane reference field length. The minimum field length required for take-off at maximum certificated take-off mass, sea level, standard atmospheric conditions, still air and zero runway slope, as shown in the appropriate aeroplane flight manual prescribed by the certificating authority or equivalent data from the aeroplane manufacturer. Field length means balanced field length for aeroplanes, if applicable, or take-off distance in other cases.) • Code Letter element 2 corresponds to the wing span or the outer main gear wheel span, whichever is more demanding
Runways Location and Orientation • Type of intended operation (non-instrument or instrument) • Need to ensure that the required take-off and approach obstacle limitation surfaces are not infringed • Environmental impact – minimize noise on residential areas • Prevailing winds – 20kts max x-wind component for runways 1500m and over • Usability factor of the aerodrome to be not less than 95% for aeroplanes that the aerodrome is intended to serve
Runways Length - Adequate to meet operational requirements of the aeroplanes for which the runway is intended Width -
Runways – Parallel Operations Minimum Separation Distance • Non-instrument – 210m Code 3 & 4, 150m Code 2, 120m code 1 • Instrument – 1035m independent parallel approaches 915m dependent parallel approaches 760m independent parallel departures 760m segregated parallel operations • PANS OPS and PANS ATM additional Requirements 1035m-1310m SSR 2.5sec update 0.06° accuracy 1310m-1525m SSR 5sec update 0.3° accuracy 1525m≤ radar (PRIM or SSR) 5 sec/3°
Runway Slopes - Longitudinal • The slope computed by dividing the difference between the maximum and minimum elevation along the runway centre line by the runway length should not exceed: — 1 per cent where the code number is 3 or 4; and — 2 per cent where the code number is 1 or 2. • Along no portion of a runway should the longitudinal slope exceed: — 1.25 per cent where the code number is 4, except that for the first and last quarter of the length of the runway the longitudinal slope should not exceed 0.8 per cent; — 1.5 per cent where the code number is 3, except that for the first and last quarter of the length of a precision approach runway category II or III the longitudinal slope should not exceed 0.8 per cent; and — 2 per cent where the code number is 1 or 2.
Runways – Sight Distances • Where slope changes cannot be avoided, they should be such that there will be an unobstructed line of sight from: — any point 3 m above a runway to all other points 3 m above the runway within a distance of at least half the length of the runway where the code letter is C, D, E or F; — any point 2 m above a runway to all other points 2 m above the runway within a distance of at least half the length of the runway where the code letter is B; and — any point 1.5 m above a runway to all other points 1.5 m above the runway within a distance of at least half the length of the runway where the code letter is A.
Runways slopes - Transverse • To promote the most rapid drainage of water, the runway surface should, if practicable, be cambered except where a single crossfall from high to low in the direction of the wind most frequently associated with rain would ensure rapid drainage. The transverse slope should ideally be: — 1.5 per cent where the code letter is C, D, E or F; and — 2 per cent where the code letter is A or B; • but in any event should not exceed 1.5 per cent or 2 per cent, as applicable, nor be less than 1 per cent except at runway or taxiway intersections where flatter slopes may be necessary. • For a cambered surface the transverse slope on each side of the centre line should be symmetrical
Runways - Surface Design objectives • Constructed without irregularities that would adversely affect take-off or landings or loss of friction • Constructed to provide good friction characteristics when runway is wet • Surface texture depth should not be less than 1.0mm Maintenance objectives • Kept clear of loose objects (FOD) • Prevent formation of harmful irregularities • Friction testing and corrective action to remain above minimum friction level
Runway – Pavement Types Flexible Rigid
Runway/Pavement Strength • ACN- Aircraft Classification Number (Number expressing the relative effect of an aircraft on a pavement for a specified standard subgrade strength) • PCN – Pavement Classification Number (Number expressing the bearing strength of a pavement for unrestricted operations) • ACN/PCN meant as means for publishing pavement strength in AIP it is not a design or an evaluation tool • Requires reporting of • Pavement type R or F • Subgrade category • Maximum tyre pressure • Pavement evaluation method
Runways - Shoulders • Provided – when code is D or E and runway width less than 60m when code is F • Width – extend symmetrically each side so that overall width of runway and shoulders is – 60m Code D or E; 75m code F • Slope – flush with surface it abuts and not to exceed 2.5% transverse • Strength – capable of supporting aeroplane without inducing structural damage and supporting ground vehicles
Runways Turn Pads • Required for code D, E, F where end of runway not served by taxiway to facilitate 180° turns. • May be located on either side but left preferable • Intersection angle with runway should not exceed 30°
Runway Strips • A defined area including the runway and stopway, if provided, intended: • To reduce the risk of damage to aircraft running off the runway • To protect aircraft flying over it during take-off or landing operations • Graded portion in event of an aeroplane running off the runway Width graded portion – extend 75m either side centreline Code 3, 4 - extend 40m either side centreline Code 1, 2 Surface graded portion - flush with runway or shoulder - longitudinal slope 1.5% code 4, 1.75% code 3 - transverse slope 2.5% code 3,4 (5% 1st 3m drainage) - strength to minimize hazards in event aircraft running off runway • Objects – shall satisfy the relevant frangibility requirement in chapter 5 Annex 14 volume 1.
Runway Strips • Length - Strip shall extend before the threshold and beyond the end of the runway or stopway for a distance 60m code 2,3,4, • Width – -Instrument Code 3 & 4 = 150m (either side centreline) - Instrument Code 1, 2 = 75m - Non-instrument Code 3 & 4 =75m - Non-instrument code 2 = 40m - Non-instrument code 1 = 30m
Runway End Safety Areas • Length – Shall extend 90m from end of runway strip - Should extend as far as practicable and at least 240m • Width – At least twice that of the runway - Should wherever practicable be equal to graded portion • Slopes – Longitudinal below OLS & max 5% downward - Transverse 5% • Surface – clear graded, • Strength – reduce the risk of damage to aircraft and facilitate movement RFFS vehicles
Clearways • Only need to be provided where operating advantage is required by aircraft using unbalanced performance –TODA greater than TORA • Length – Should not exceed half the length of TORA • Width – 75m either side of centreline • Slope – not to exceed 1.25% upwards
Stopways • Only need to be provided where operating advantage is required by aircraft using unbalanced performance –ASDA greater than TORA • Width – Same width as runway • Slopes – Same as for runway • Strength – supporting aircraft without inducing structural damage to the aircraft • Surface – Coefficient of friction to be compatible with runway
Taxiways Design to ensure critical aeroplane when remaining over centreline markings that the following outer main wheel clearances achieved
Taxiways - Width *18m if wheel base greater than 18m **23 if outer main gear wheel span greater than 9m Curves/Intersections Need to implement fillets based on critical aircraft
Taxiways – Rapid Exit • Turn-off curveradius – Code 3 & 4 550m (exit speed 93kph/50kts) Code 1 & 2 275m (exit speed 65kph/35kts) • Intersection angle – optimum 30°, max 45°, min 25° • Straight distance – sufficient for aircraft to come to full stop clear intersecting taxiway
Taxiways SLOPES Longitudinal – 1.5% code C, D, E, F; 3% code A, B. Sight Distance – codeC, D, E, F 3m above taxiway see whole surface for distance of at least 300m Transverse – 1.5% code C, D, E, F; 2% code A, B Shoulders Should be provided each side for code C to F so overall width taxiway and shoulders
Taxiways - Strips Width – Extend symmetrically each side to achieve minimum distance from centreline as per table 3-1 column 11 Graded Portion – Extend symmetrically each as below
Aprons Slopes – maximum 1% on aircraft stands Clearances – between aircraft using stand and other aircraft building object or other aircraft *May be reduced in special circumstances between terminal and nose of aircraft and over any portion of stand provided with visual docking guidance system
Isolated Parking Position • An isolated aircraft parking position shall be designated or the aerodrome control tower shall be advised of an area or areas suitable for the parking of an aircraft which is known or believed to be the subject of unlawful interference, or which for other reasons needs isolation from normal aerodrome activities. • The isolated aircraft parking position should be located at the maximum distance practicable and in any case never less than 100 m from other parking positions, buildings or public areas, etc. Care should be taken to ensure that the position is not located over underground utilities such as gas and aviation fuel and, to the extent feasible, electrical or communication cables.
Practical Exercise • The minimum runway width for a Code 4C runway is? • The distance that a runway strip should extend beyond the end of a Code 2 runway is • A minimum length RESA for a Code 4 runway strip shall extend to at least (a) 90m, (b) 150m (c) 240m past the end of the runway? • Calculate the minimum distances between taxiway centrelines for a Taxiway handling Code D aircraft an a taxiway handling only Code A and B aircraft.