Helicopter Operations (ATC Aspects)

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Helicopter Operations (ATC Aspects)

20TH ANNUAL CONFERENCE, Cairo, Egypt, 02-06 May 1981

WP No. 29

Helicopter Operations (ATC Aspects)

 

At the 19th Annual Conference, the title subject was placed on the 1980/81 work programme of SC 1, with a view to the early development of IFATCA policy.

Member Associations were requested to provide SC 1 with details of any special national procedures which they used for control of helicopter operations. To assist them in this task SC 1 prepared and circulated a questionnaire in August 1980. (Appendix A). Seventeen MA’s replied to the questionnaire. The information provided covered thirty -eight Air Traffic Units, with helicopter movements rates from one per day to over nine hundred per day, and with every variety of helicopter operation represented.

Current ICAO documentation makes no special provision for helicopter operations, due primarily to the fact that, until recently, helicopter operations have been national , rather than international in character.

Recognising that international helicopter operations are increasing, and that this trend can be expected to continue, ICAO has recently (October 19800 established a HELICOPTER OPERATIONS STUDY GROUP (HELIOPS). The Heliops Study Group is tasked with identifying any problems associated with international helicopter operations which may require the development of ICAO specifications within the next five years.

Amongst the subjects which the study group expects to cover is “ATS Procedures”.

Particular aspects of helicopter operations have already been examined by other ICAO Study Groups viz:

1. Surface Movement, guidance and Control (SMGC) Study group:

a) Use of apron areas for landing/take-off of helicopters;

b) Need for definition of “air-taxing”.

2. RTF Study Group:

a) Need for special helicopter RTF phraseologies for use during landing, take-off or ground manoeuvring.

In June 1978 the European Air navigation Planning Group (EANPG) adopted a report “Guidance Material on measures required to ensure the Safety of Helicopter operations over the High seas”.

This guidance material (the main part of which is included as Appendix to the WP) derives from the experience gained by various states in helicopter operations over the North Sea in support of oilfield development. Much of the material will be of interest to IFATCA in its development of policy, and will be discussed below. It may be of interest that IFALPA are currently developing policy recommendations based on this EANPG guidance material.

MA’s provided comprehensive details of the ATC procedures and airspace organisation developed to cater for the current high levels of helicopter activity over the North Sea. These procedures are outlined in the EANPG Guidance Material.

The various procedures in use for North Sea helicopter operations have been subject to constant refinement in the light of operational experience and as such represent what is practical rather than that which is simply theoretical. It is suggested that they provide a sound basis for the development of detailed ATC procedures for helicopter operations, not only over the North Sea but in any area where helicopters operate, or are expected to operate, in substantial numbers.

Most MA’s described local procedures developed to facilitate helicopter access to airfields during VFR or Special VFR operations. These procedures generally involve the use of low-level route defined by visual landmarks, and where possible aligned so as to provide emergency landing areas and to minimise noise disturbance on the ground. Specific altitudes may be necessary for operation on the routes so as to ensure separation between helicopters on the routes and the fixed-wing arrival/departure paths.

At smaller airfields such procedures may be only locally promulgated and only suited to locally based operators; those applicable to more important airfields are normally promulgated more widely. For example, an extensive helicopter route structure has been established in the London Control Zone and full details are published in the UK – AIP. Guidance on such procedures is contained in the EANPG report, see Annex B para 2.6.

As yet, there has been only limited demand for the development of IFR inbound/outbound procedures suitable for helicopter operation. This reflects the continuing problem for helicopters in operating consistently under IFR, partly because of the various stability and icing problems, and partly because of the lack of suitable instrumentation in many smaller helicopters, – the latter stemming from the fact that many of the tasks historically undertaken by helicopters require VMC conditions e.g. pipeline patrols and survey work.

It is clear that this situation is unlikely to continue. Most large and many smaller types, particularly those in executive charter operations, are fully capable of IFR operation, and continued advances are being made towards solving the problems of helicopter icing. These improvements are likely to extend helicopter operations by allowing consistent, regular IFR operation. This may well benefit ATS Units providing en-route services by allowing use of higher altitudes/levels for helicopter operations and so “spreading the load”. In the airfield environment, however, any demand for integration of a significant amount of IFR helicopter traffic into fixed- wing IFR traffic patterns may adversely affect runway capacity due to the helicopters relatively lower operating speed.

For example, the use of 3nm radar separation between helicopters making instrument approaches at, for example, an approach speed of 60kts. Produces a landing rate of approximately 20 per hour. By comparison, fixed-wing aircraft normally achieve landing rates of approximately 36 per hour.

Whilst light helicopters are normally able to operate to/from small helipads, the larger commercial types e.g. S-61 require a substantial strip or runway length. MA’s provided details of helipads and STOL strips which are in use at various locations for helicopter operation. Such facilities can allow helicopter operations to take place completely independently of runway movements, provided that proper care is taken when selecting suitable locations. Where possible helipads/STOL strips should be separated from runways in vortex wake terms; access to them should not involve runway crossings (although this will depend on the relative positions of apron areas, runways and main helicopter routes into the airfield); and should be operated in conjunction with a suitable route structure into/out of the airfield designed to minimise conflicts with fixed-wing runway traffic.

Some MA’s have commented on the difficulty of recognising a helicopter as such from an RTF call, particularly if the registration is used rather than a company trip number. Requesting the type of aircraft may not resolve the problem due to the large number of types in operation, both fixed-wing and helicopters, and the difficulty for the average controller in knowing which are helicopters. Clearly, any confusion or misunderstanding of type as being fixed-wing or helicopter can have very serious consequences, particularly in the approach/aerodrome environment where the difference in operating abilities are most clearly marked. A possible solution would be to require helicopters to prefix initial RTF calls to each ATS Unit with a suitable identifying word e.g. helicopter. This procedure is already in use by some MA’s.

The ICAO RTF Study Group concluded that no special phraseologies were required to cover helicopter landing, take-off or ground manoeuvring. Response from MA’s confirms this view, except that several phrases appear to be in use to cover airborne taxi manoeuvres e.g. Hover, hover-taxi, air-taxi. Of these “air-taxi” appears to be the most widely used phrase (and will be used in this WP).

As noted in para 1.4 a), the SMGC Study Group is examining the requirement for a definition of “air-taxing”. This problem, which has also been noted by MA’s, stems from the fact that a helicopter which is air taxing must be considered as being “in flight” as far as the Rules of the Air are concerned. Annex 2 Chapter 2.2 requires that an aircraft “ in flight” shall be operated in accordance with the general rules and either the visual or instrument flight rules. Clearly this is not appropriate to a helicopter which is air taxing and which should be subject only to those rules which apply to operation on the manoeuvring area.

MA’s reported wide variations in the freedom of helicopters to air-taxi over an airfield surface. Some states allow direct point to point air-taxing, others require that helicopters air-taxi only above existing taxiways. Visibility from helicopter cockpits is very much better than from fixed- wing aircraft, and an air taxiing helicopter is capable of rapid changes of direction given freedom from surface obstructions. Provided that due allowance is made for airfield conditions, in particular visibility, direct air-taxi routings are both expeditious and safe, and benefit helicopter operator and ATC by allowing greater flexibility in airfield operations. This is especially the case at airfields with limited taxiways. However, at airfields with extensive taxiways and ground installations direct routings may be of little practical value.

Many states allow helicopters to land or take-off from the apron. This procedure, normally used only for light helicopters, in possible only because of the excellent visibility from, and manoeuvrability of, the helicopter. In many instances the procedure is operationally safe and expedition; in others it can be operationally highly questionable. However, Annex 2 and Annex 14 define the manoeuvring area as “ That part of an aerodrome to be used for take-off and landing of aircraft and for the surface movement of aircraft associated with take-off and landing, excluding aprons. As the apron not form part of the manoeuvring area it is not appropriate to the landing and take-off of helicopters, and many ATC clearance to do so must be of doubtful validity. It will be apparent that for many aerodromes the termination of helicopter flight at a point on the manoeuvring area, with subsequent taxiing to the apron , will solve the problem of helicopter movement on the apron. At others, removal of the freedom for helicopters to operate to and from the apron would severely restrict flexibility and expedition. This problem is currently being reviewed by the SMGC Study group, as noted in Para 1.4).

The EANPG Guidance Material previously referred to contains useful information on three of the subjects which SC 1 was requested to consider when developing the policy recommendations associated with this paper.

These are :
a) RTF Coverage requirements
b) Radar/Navigation aid requirements
c) Pressure settings/use of radio altimeters

Little comment has been received from MA’s on these aspects of helicopter operations, either through SC1 questionnaire or separately. It is felt that the EANPG material noted above probably reflects the opinion of MA’s , and could form a basis for IFATCA policy in these areas. However, no specific policy recommendations on these subjects have been made in this WP.

Whilst many MA’s expressed their concern over the problems noted in paras 2.1-10, it is apparent that they are equally concerned to ensure that any solutions to these problems do not adversely effect the operating flexibility of the helicopter.

As on MA remarked – “The controller has the necessary know how and capability for safe helicopter operations”.

To conclude

The EANPG guidance material provides excellent guidance to states on the ATC procedures and airspace organisation required for the safe and efficient conduct of helicopter operations both en-route and in terminal areas.

Increased demand for IFR arrival/departure procedures for helicopters may adversely affect runway capacity if current separation standards are employed.

Provision of properly-located helipads or STOL strips suitable for helicopter operation can assist ATC and benefit all aerodrome users.

A suitable RTF procedure is required to ensure that helicopters are correctly recognised as such on initial contact with an ATS Unit.

A standard RTF phrase is required to cover the airborne taxiing of helicopters.

There is a need for international standardisation of the procedures used by ATC in the airfield environment, as described in paras 2.8 and 2.9 However , any standardisation should not adversely effect the operating flexibility of the helicopter.

ANNEX A HEL/1
HELICOPTER OPERATIONS – ATC ASPECTS

To assist in the preparation of a policy development Working paper for IFATCA 81, SC 1 wishes to obtain information on a world-wide basis concerning ATC handling of the following types of helicopter operation :

a)  Landing/take-off/taxiing

a)  at mixed fixed wing/helicopter airfields;

b)  at helicopter – only terminals.

b)  En-Route

a)  in TMA’s;

b)  in special helicopter operation areas (e.g. off-shore oil rig operations);

c)  in uncontrolled airspace (FIR)

Will you please, on a separate sheet (or sheets) of paper, provide the following information about those of the above types of helicopter operations which are handled by ATS Units in your area.

1. General

1. Name of ATC Unit;

2. Please describe any helicopter operations in your area;

3. What is the average daily helicopter movement rate.

2. Procedures and Separation Standards

1. Describe any special procedures or Air Traffic services which you provide for helicopters.(example: special Helicopter Routes, Special Flight Information services);

2. Describe any special separation standards which are applied to helicopter operations.

3. RTF

1. Describe any special RTF phraseologies used in connection with helicopter operations;

2. Do you consider current RTF phraseologies suitable for use with helicopters;

3. Is low-level RTF coverage adequate for the operations in your area.

4. Radar and Navigation aids

1. What navigation systems are used by helicopters in your area (example: VOR/DME, DECCA, VISUAL);

2. Sescribe any use of radar in connection with helicopter operations;

3. Is low-level radar coverage adequate.

5. Weather

1. describe any problems in helicopter operations caused by weather of terrain.

6. Airfield Operations – if applicable

1. Do you use designated helipads or STOL strips;

2. Are helicopters permitted to land/take-off on the apron;

3. Describe any difference in operating procedures between large (e.g. S-61) and small (e.g. Jet-Ranger) helicopters;

4. Do you allow helicopters to air-taxi from point-point off taxiways;

5. Describe any problems in controlling mixed helicopter and fixed wing traffic.

7. Any Other Comments

Last Update: September 23, 2020  

November 23, 2019   343   Jean-Francois Lepage    1981    

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