Thursday, July 30, 2009

How to Put Up a Heliport – Part 4: Obstacle-Free Area

Beginning this part and onwards, the standards that will be used on the rest of the heliport topic will be based purely on the standards and recommended practices (SARPs) published by the ICAO.

SARPs are the annexes to the Convention on International Civil Aviation (also known as the Chicago Convention), an international agreement aimed to harmonize aviation rules and regulations between contracting States. Thus, States who have signed into this agreement are obliged to follow the ICAO SARPs.

As per the standards and recommended practices (SARPs) published by the ICAO, the size of the required obstacle-free area depends upon the overall length or width; whichever is greater, of the largest helicopter intended to operate on the heliport. It also depends on the type of helicopter to be operated on the heliport. Please refer to the helicopter’s flight manual to obtain accurate data for the helicopter’s overall length/width.

AS 365 Overall Length

Depending on the type of helicopter (performances classes) and the type of heliport (elevated or surface-level), there are 3 to 4 portions of the required obstacle-free area, these are:

1. The Final Approach and Takeoff Area (FATO)
2. The Safety Area
3. The portion between the Safety Area and the beginning (inner edge) of the Approach-Departure Surface
4. The over-run portion of the FATO (for surface level heliports serving Performance Class 1 Helicopters)

THE FINAL APPROACH AND TAKEOFF AREA (FATO)

The required dimensions of the FATO depend upon the performance class of the helicopter. For heliports to be used by performance class 1 helicopters, the size of the FATO should not be less than the dimensions prescribed in the helicopter’s flight manual.

If there is no specific size requirement of the FATO in the flight manual of a performance class 1 helicopter, the FATO should have the same dimensions as with the heliports utilized by performance class 2 and class 3 helicopters.

When choosing the size of the FATO, as far as practicable, the dimension to be used should be the one which has more stringent requirements.

The FATO can be of any shape, but as a minimum, a FATO is required to have a dimension that should be of sufficient size to contain an area within which can be drawn a circle of diameter not less than 1.5 times the over-all length or width, whichever is the greater, of the longest or widest helicopter the heliport is intended to serve.

FATO Top View

The FATO of heliports that will be used by performance class 1 helicopters should have bearing strength sufficient to accommodate rejected take-offs. One of the reasons for the requirement of an over-run area is that performance class 1 helicopters are normally eligible for chartered commercial passenger flights so their heliport should have an over-run area for rejected takeoffs.

FATO with Over-run

FATO with over-run side view

For surface level heliports, the surface of the FATO should be resistant to the effects of rotor downwash; be free of irregularities that would adversely affect the take-off or landing of helicopters; and should provide ground effect (air cushion between the helicopter rotors and the surface below).

The FATO’s overall slope in any direction should not exceed 3% and no portion of the FATO should have a local slope of more than 5%.

FATO side front back view

THE SAFETY AREA

Surrounding the FATO is the safety area (synonymous to a road shoulder).

For Visual Meteorological Condition (VMC) Operation (day operation with clear visibility), safety areas extend outward from the periphery of the FATO for a distance of at least 3 m or 0.25 times the over-all length/width, whichever is greater, of the largest helicopter the heliport intended to serve.

This means that if the overall length of the helicopter is less than 12 m, the width of the safety area from the edge of the FATO is always 3m. Likewise, if the overall length of the helicopter is more than 12 m, the width of the safety area that extends from the edge of the FATO will be equal to 1/4 of the helicopter’s overall length.

FATO with Safety Area

For Instrument Meteorological Condition (IMC) Operation (night operation, or, day operation with very low visibility), the safety area surrounding a FATO should extend laterally to a distance of at least 45 m on each side of the centre line; and longitudinally to a distance of at least 60 m beyond the ends of the FATO.

FATO with IMC safety area

For both VMC and IMC operation, there should be no fixed object in the safety area except for frangible objects, which, because of their function, must be located on the area (such as heliport lightings). Likewise, there should be no mobile object on the safety area during helicopter operations.

Objects whose functions require them to be located on the safety area should not exceed a height of 25 cm when located along the edge of the FATO. These objects should not also penetrate a plane originating at a height of 25 cm above the edge of the FATO and sloping upwards and outwards from the edge of the FATO at a gradient of 5 per cent.

The surface of the safety area shall not exceed an upward slope of 4 per cent outwards from the edge of the FATO.

Obstacles at Safety Area

The surface of the safety area shall be treated to prevent flying debris caused by rotor downwash. The surface of the safety area abutting the FATO shall be continuous with the FATO and be capable of supporting, without structural damage, the helicopters that the heliport is intended to serve.

BETWEEN THE SAFETY AREA AND THE INNER EDGE OF THE APPROACH DEPARTURE SURFACE

The portion between the Safety Area and the beginning (inner edge) of the Approach-Departure Surface should also be free from obstacles. The surface of this area should be the same surface as with the safety area.

Portion bet FATO and SA

In the illustration above, for a heliport that will serve a helicopter with an overall length/width of more than 12m, the total required obstacle free area will be twice the helicopter’s overall length on each side of the square. The square shown above applies only to bi-directional paths with 180° separation (example: directly north and directly south approach-departures).

For omni-directional approach-departures (meaning the helicopter may takeoff or land at any direction), the square in the illustration will be rotated accordingly. The rotation will yield to a required obstacle-free radius equal to the helicopter overall length divided by Sine 45° (or 0.707107). For example, a helicopter with an overall length of 13 m operating on an omni approach-departure heliport, the required obstacle-free radius of the heliport will be 13 m divided by 0.707107 which is equal to 18.38m radius or 36.77 m in diameter.

Rotated Square

TUTORIAL/EXPLANATION RECAP:

For VMC Surface-Level Heliports serving performance class 1 helicopters, the obstacle-free areas will be:
1. FATO
2. Safety Area
3. The area between FATO and the inner edge of the approach-departure surface
4. Over-run Area

For VMC Elevated Heliports serving all classes of helicopters, the obstacle-free areas will be:
1. FATO
2. Safety Area
3. The area between FATO and the inner edge of the approach-departure surface

For IMC Surface-Level Heliports serving performance class 1 helicopters, the obstacle-free areas will be:
1. FATO
2. 90 m wide Safety Area that extends 60 m longitudinally beyond the ends of the FATO
3. The area between FATO and the inner edge of the approach-departure surface
4. Over-run Area

For IMC Elevated Heliports serving all classes of helicopters, the obstacle-free areas will be:
1. FATO
2. Safety Area
3. The area between FATO and the inner edge of the approach-departure surface

Next -> Part 5: Approach-Departure Surfaces

Wednesday, July 22, 2009

Definition of Safety

I’m currently on the State Safety Program Training for a week... One definition the speaker would like us to memorized by heart is the definition of safety as stated in the ICAO Document No. 9859 (Safety Management Manual), Second Edition, which asserts that SAFETY is

“the state in which the possibility of harm to persons or of property damage is reduced to, and maintained at or below, an acceptable level through a continuing process of hazard identification and safety risk management”.

There is something in the definition that I don't feel comfortable, which is the notion “below an acceptable level"...

In my opinion, for the sake of clarity, the DEFINITION OF SAFETY should be rephrased to:

“the state in which the possibility of harm to persons or of property damage is reduced to, and maintained at or within, an acceptable level through a continuing process of hazard identification and safety risk management”.

Cheers!

Saturday, July 18, 2009

How to Put Up a Heliport – Part 3: Helicopter to be considered

If you’re planning to buy a helicopter or planning to operate one on a heliport, you should be aware that some helicopters may not be allowed to operate over a populated area. This is because some helicopters are performance-limited in terms of continuing a safe flight when an engine failure occurs.

Helicopters are grouped into three (3) performance classes. These are the performance class 1, performance class 2, and performance class 3 (see definitions in Part 1).

Single-engine helicopters are performance class 3 helicopters. When its engine fails, the helicopter will be forced to land immediately. For this reason, some countries prohibit the operation of performance class 3 helicopters over a populated area.

Some helicopters belong to performance class 2. Although these types of helicopters have more than one engine, they may still need to perform forced landing at a certain point before it reaches its final destination when one of its engines becomes inoperative.

Performance class 1 helicopters are multi-engine helicopter that may have the capability to reach their final destination even if one of its engines became inoperative.

Next -> Part 4: Obstacle-Free Area (FATO plus Safety Area)

How to Put Up a Heliport – Part 2: Site Selection

The first thing to be considered in putting up a heliport is the feasibility of the location. There are three (3) major issues that must be considered when selecting a location for the heliport, these are:

1. Noise Issue

In order to avoid future noise problems, the location of the heliport and orientation of the helicopter paths should be so selected to minimize interference with areas approved for residential use and other noise sensitive areas close to the heliport.

2. Safety Issue
  • Proximity to other Aerodrome. The location of the heliport should be selected so as not to endanger the safety of aircraft operations, taking into consideration the proximity to other aerodromes and landing sites including military aerodromes.
  • Helicopter Paths. For safe missed-approaches, the heliport must have at least two take-off climb and approach paths, separated by not less than 150°. These paths should be so selected so that the helicopter can be maneuvered in the aerodrome traffic circuit clear of any obstructions, and not in conflict with the aerodrome traffic circuit or instrument approach procedure of any other aerodrome. The selected approach and take-off paths are such that an autorotative landing can be conducted without any undue risk to any person on the ground
3. Security Issue

The location should be at the area where sabotage, such as hard objects thrown at the turning rotor blades and other similar security issues, would not likely to occur. The location should be away from higher buildings or terrains that are in close proximity with the heliport.

Next -> Part 3: Helicopter to be considered

How to Put Up a Heliport – Part 1: Terminology Used

There will be terms that will be used all throughout heliport topics. These terms are similar with the ones used by the International Civil Aviation Organization (ICAO). When these terms are used, they have the meanings given below.

Aiming point means a triangular marking, displayed on a FATO, to which point a pilot is required to make the final approach before proceeding to a TALO.

Air taxiway means a defined path on the surface established for the air taxiing of helicopters.

Approach means a series of predetermined maneuvers for the orderly transfer of a helicopter to a point either where a landing may be made or where a helicopter may drop, off-load or pick up persons or load of any description.

Elevated heliport means a heliport located on a raised structure on land.

Final approach and take-off area (FATO) means a defined area over which the final phase of the approach maneuver to hover or landing is completed and from which the takeoff maneuver is commenced and, where the FATO is to be used by performance Class 1 helicopters, includes the rejected takeoff area available.

Helicopter stand means an aircraft stand which provides for parking a helicopter and, where air taxiing operations are contemplated, the helicopter touch-down and lift-off.

Helideck means a heliport located on a floating or fixed off-shore structure.

Heliport means an aerodrome or a defined area on a structure intended to be used wholly or in part for the arrival, departure and surface movement of helicopters.

Obstacle limitation surfaces means surfaces extending outwards and upwards from the FATO or safety area at angles compatible with the flight characteristics of the helicopter, used to evaluate approach and takeoff climb surfaces for clearance of obstacles.

Obstacle means all fixed (whether temporary or permanent) and mobile objects, or parts thereof, that are located on an area intended for the surface movement of the helicopter or that extend above a defined surface intended to protect helicopter in flight.

Overall helicopter length means the maximum length or width, whichever is greater, of a helicopter including its rotors. The overall length is measured, when the rotors are turning, from the tip of the main rotor to the tip of the tail rotor or tail boom (for tail rotor less helicopter). In the case of a tandem rotor helicopter where its width is usually longer than its length, the measurement will be sideways, from the tip of the left rotor to the tip of the right rotor or vice-versa, when rotors are turnings.

Performance Class 1 helicopter means a helicopter with performance such that, in case of critical engine failure, it is able to land on the rejected takeoff area or safely continue the flight to an appropriate landing area, depending on when the failure occurs.

Performance Class 2 helicopter means a helicopter with performance such that, in case of critical power-unit failure, it is able to safely continue the flight, except when the failure occurs prior to a defined point after take-off or after a defined point before landing, in which cases a forced landing may be required.

Performance Class 3 helicopter means a helicopter with performance such that, in case of power-unit failure at any point in the flight profile, a forced landing must be performed.

Safety area means a defined area on a heliport surrounding the FATO which is free of obstacles, other than those required for air navigation purposes, and intended to reduce the risk of damage to helicopters accidentally diverging from the FATO. It should be capable of supporting the weight of a helicopter.

Surface level heliport means a heliport located on the ground or on the water.

Touchdown and lift-off area (TALO) means a load bearing area on which a helicopter may touchdown or lift-off.

Next -> Part 2: Site Selection

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