Integration of Fixed Wing and Rotary Wing Flights At Airfields

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Integration of Fixed Wing and Rotary Wing Flights At Airfields

24TH ANNUAL CONFERENCE, Athens, Greece, 18-22 March 1985

WP No. 53

Integration of Fixed Wing and Rotary Wing Flights at Airfields

 

Following discussion on agenda item B.6.7 at the 1984 Conference, SC 1 was required to review the subject -Integration of Fixed and Rotary Wing flights at Airfields with a view to developing relevant policy recommendations.

The trend is that all types of helicopters, not just the heavier types associated with the offshore oil industry such as Chinooks, Pumas, Sikorsky etc., but also the light executive/general purpose helicopters, are becoming better IFR equipped for all weather operations. This results in more IFR operations.

Accordingly this paper will concentrate on IFR operations of helicopter flights.

On the ground, integration problems can be caused by the heavier slow moving helicopters. These types require a runway length of a few hundred metres but are slow during the take-off phase of flight. Therefore this can result in longer runway occupancy times. If the runway is used for a mix of traffic rather than all fixed wing or all rotary wing flights a reduction in runway handling capacity will result.

Helicopters are also not really suited for long taxi routes to and from runways. In some circumstances air-taxiing may present ATC with difficulties due to the need to give a safe clearance. It is not always possible to ensure that the take-off position is completely clear of all vehicles etc. Together with the intended air-taxi route being similarly clear. In this situation a clearance to air-taxi may not be issued just to avoid a long ground taxi.

The problems for integration in the air, in the proximity of airfields, especially when a great number of helicopters are operating at the same time, occurs when trying to fit both the helicopter and fixed-winged movements into the same IFR patterns. This is mainly due to the slower speed of the helicopter.

Three possible areas of solutions to these problems could be considered.

Ground Installations

The ideal situation is segregation, thus requiring a separate purpose build heliport. For various reasons, finances, infra-structure, environment considerations, etc., the ideal solution is almost unattainable. A compromise is to provide for helicopter operations, terminals, aprons , maintenance, handling etc., on a part of the airfield that would cause the least inconvenience to fixed-wing operations. This could include the introduction of separate runways or helipads, with their own approach and landing aids for helicopters. In such an environment, helicopters and conventional aircraft could, to a certain extent, be handled independently of each other. The costs for these types of separate facilities, i.e. separate runways, nav-aids etc., will, of course, only be borne if it is economically acceptable. A disadvantage of this compromise approach is that the ATC procedures to support such operations could be complicated. This also could affect the overall ATC capacity, thus possibly cancelling out any advantage of the improved airfield facilities.

Procedural Innovations

Discrete arrival and departure routes are not uncommon today. In spite of the fact that they can complicate the route structure, they have proved both feasible and beneficial in operational practice. It is felt that greater advantage could be taken of the unique operating characteristics of the helicopter by shortening approach procedures, thereby reducing the ILS occupancy or radar approach time. An evaluation of this philosophy would seem worthwhile.

A number of airfields will have approach aids to two or more separate runways that are non- aligned. Therefore, another possibility is to use the approach aid of the subsidiary runway in addition to the main runway to provide for simultaneous helicopter operations. The helicopter approach on the subsidiary runway would be followed by a suitable visual manoeuvre to the helicopter landing runway or helipad. This technique is in use at some airfields, e.g. Schiphol Amsterdam, but if it were to be introduced on a wider basis, it would need careful study to ensure that the procedures were completely safe under all operational circumstances.

The use of reduced separation between fixed-wing and rotary-wing flights should only be utilised during the approach phase, e.g. on radar approaches, and when the helicopter is not going to land on the main runway being used by the fixed-wing operations, but is going to make a visual manoeuvre to land on its own runway or helipad. Due to the slower speeds involved and wake- vortex considerations, precisely how much reduction in reduced horizontal separation is possible would need to be determined locally and authorised at the appropriate ATS authority. It would seem that in most States authorisation may be difficult and therefore widespread use of reduced horizontal separation is unlikely.

At airfields where only one instrument approach aid is available, integration of fixed and rotary winged operations will add to the difficulty. One method is to vector a stream of helicopters to the ILS whilst holding the fixed-winged aircraft, and vice versa.

It is entirely feasible to permit helicopters to land and take off at intermediate intersections of runways, subject to wake vortex considerations.

Technical Advances

Many of the problems seem to be due to the performance characteristics of the helicopter, notably, its forward speed, although there are many examples of fixed-winged aircraft with similar speeds. Recent developments in rotary-winged aircraft have improved their performance envelopes, e.g. higher speeds, increased operating altitudes, ice protection, etc. Therefore, as these newer types come into operational service, they are more amenable to normal ATC procedures. It is anticipated that this sort of development will continue, thus lessening the difference between fixed-and rotary-winged performance, enabling greater compatibility for ATC in a mixed environment.

The avionics equipment currently being fitted to helicopters may permit them to operate to lower weather minima in the future.

To Conclude

The ideal solution of separate heli-airfields is unrealistic on cost and other grounds, although they could be considered for the future , if required.

If possible separate heli-runways or helipads should be provided on existing airfields, together with their own handling facilities and navigational aids.

Local procedures could be modified in such a way that they take additional advantage of the unique characteristics of the helicopter as follows :

  1. utilising separate helicopter arrival and departure routes;
  2. the use of shorter ILS or radar approaches;
  3. utilising approach aids of subsidiary runways followed by a suitable visual manoeuvre and landing on a heli-runway or helipad;
  4. permitting reduced horizontal separation on radar approaches between helicopters and between helicopters and fixed-winged aircraft, subject to authorisation;
  5. permitting landing and take-off at intersections of runways, subject to wake-vortex considerations;
  6. streaming either helicopter or fixed-winged separately to ILS approaches.

Careful evaluation of these revised procedures would be required in order to ensure safe operations under all circumstances.

Current developments of rotary-winged performance envelopes are such that they are becoming more amenable to normal ATC procedures with fixed-winged aircraft. This trend is anticipated to continue.

It is recommended that:

It is recognised that procedures should be developed in order to integrate fixed-and rotary- winged operations at airfields. In developing these procedures cognisance should be taken of the unique operating characteristics of the helicopter. To accommodate such operations, local procedures should be developed to permit :

  1. the development of discrete helicopter departure and arrival routes;
  2. shorter ILS or radar approaches;
  3. approaches to subsidiary runways followed by a suitable visual manoeuvre for landing on a separate heli-runway or helipad;
  4. reduced horizontal separation on radar approaches between helicopters following fixed-winged aircraft, subject to proper authorisation, and wake turbulence;
  5. landing and take-off at intersections of runways, subject to wake vortex considerations.

Last Update: September 20, 2020  

December 1, 2019   343   Jean-Francois Lepage    1985    

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