IRImplementing rule
CS HPT-DSN.E.410Approach surface
(a)Applicability: The purpose of an approach surface is to protect a helicopter during the final approach to the FATO by defining an area that should be kept free from obstacles to protect a helicopter in the final phase of the approach to land manoeuvre.
(b)Description: An inclined plane or a combination of planes or, when a turn is involved, a complex surface sloping upwards from the end of the safety area and centred on a line passing through the centre of the FATO (see Figures E-1, E-2, E-3 and E-4 and Table E-1).
(c)Characteristics:
(1)The limits of an approach surface should comprise:
(i)an inner edge horizontal and equal in length to the minimum specified width/diameter of the FATO plus the safety area, perpendicular to the centre line of the approach surface and located at the outer edge of the safety area;
(ii)two side edges originating at the ends of the inner edge diverging uniformly at a specified rate from the vertical plane containing the centre line of the FATO; and
(iii)an outer edge horizontal and perpendicular to the centre line of the approach surface and at a specified height of 152 m (500 ft) above the elevation of the FATO.
(2)The elevation of the inner edge should be the elevation of the FATO at the point on the inner edge that is intersected by the centre line of the approach surface. For heliports intended to be used by helicopters operated in performance class 1, the inclined plane may be raised directly above the FATO.
(3)The slope(s) of the approach surface should be measured in the vertical plane containing the centre line of the surface.
(4)In the case of an approach surface involving a turn, the surface should be a complex surface containing the horizontal normals to its centre line and the slope of the centre line should be the same as that for a straight approach surface (see Figure E-3).
(5)In the case of an approach surface involving a turn, the surface should not contain more than one curved portion.
(6)Where a curved portion of an approach surface is provided, the sum of the radius of the arc defining the centre line of the approach surface and the length of the straight portion originating at the inner edge should not be less than 575 m.
(7)Any variation in the direction of the centre line of an approach surface should be designed so as not to necessitate a turn radius less than 270 m. [Figure or form omitted from this preview — available in the Avioverse workspace library.]
| Note 1 - Dark grey shaded area requires the same characteristics as the safety area | Note 2 - Angle between take-off climb/ approaches surfaces from centreline to centreline depicted for illustration purposes only Note 3 - Offset take-off climb/approach surface rotated around centre point of FATO |
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Figure E-1. Obstacle limitation surfaces — Take-off climb and approach surface
[Figure or form omitted from this preview — available in the Avioverse workspace library.] Figure E-2. Take-off climb/approach surface width
[Figure or form omitted from this preview — available in the Avioverse workspace library.] Note 1 - Any combination of curve and straight portion may be established using the following formula: S+R ≥ 575 m and R ≥ 270 m where S = 305 m, where S is the length of the straight portion and R is the radius of turn. Note any combination ≥ 575 m will work. Note 2 - The minimum length of the centre line of the curve and straight portion is 1 075 m but may be longer depending upon the slope used. See table E-1 for longer lengths. Note 3 - Helicopter take-off performance is reduced in a curve and as such a straight portion along the take-off climb surface prior to the start of the curve should be considered to allow for acceleration.
Figure E-3. Curved approach and take-off climb surface for all FATOs
| SURFACE AND DIMENSIONS | SLOPE DESIGN CATEGORIES | ||
|---|---|---|---|
| A | B | C | |
| APPROACH AND TAKE-OFF CLIMB SURFACE: | |||
| Length of inner edge | Width of safety area | Width of safety area | Width of safety area |
| Location of inner edge | Safety area boundary (Clearway boundary if provided) | Safety area boundary | Safety area boundary |
| Divergence: (1st and 2nd section) | |||
| Day use only | 10 % | 10 % | 10 % |
| Night use | 15 % | 15 % | 15 % |
| First section: | |||
| Length | 3 386 m | 245 m | 1 220 m |
| Slope | 4.5 % (1:22.2) | 8 % (1:12.5) | 12.5 % (1:8) |
| Outer width | (b) | N/A | (b) |
| Second section: | |||
| Length | N/A | 830 m | N/A |
| Slope | N/A | 16 % (1:6.25) | N/A |
| Outer width | N/A | (b) | N/A |
| Total length from inner edge (a) | 3 386 m | 1 075 m | 1 220 m |
| (a) The approach and take-off climb surface lengths of 3 386 m, 1 075 m and 1 220 m associated with the respective slopes, bring the helicopter to 152 m (500 ft) above FATO elevation. (b) 7 rotor diameters overall width for day operations or 10 rotor diameters overall width for night operations. | |||
| Note: The slope design categories depicted above represent minimum design slope angles and not operational slopes. Slope category ‘A’ generally corresponds with helicopters operated in performance class 1; slope category ‘B’ generally corresponds with helicopters operated in performance class 3; and slope category ‘C’ generally corresponds with helicopters operated in performance class 2. | |||
Table E-1. Dimensions and slopes of obstacle limitation surfaces for all visual FATOs
[Figure or form omitted from this preview — available in the Avioverse workspace library.] a) Approach and take-off climb surfaces – “A” slope profile – 4.5 % design
[Figure or form omitted from this preview — available in the Avioverse workspace library.] b) Approach and take-off climb surfaces – “B” slope profile – 8 % and 16 % design
[Figure or form omitted from this preview — available in the Avioverse workspace library.] c) Approach and take-off climb surfaces – “C” slope profile – 12.5 % design
Figure E-4. Approach and take-off climb surfaces with different slope design categories
IR · CS HPT-DSN.E.410 — Regulation (EU) No 139/2014 · ED Decision 2019/012/R · Aerodromes Easy Access Rules · EAR revision 13 Mar 2026