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Interim Recommendation issued to: Civil Aviation Safety Authority

Recommendation details
Output No: IR19980253
Date issued: 08 December 1998
Safety action status:
Background:

SUBJECT

Safety Concerns Relating to the Class G Airspace Demonstration.


BACKGROUND

Australia is harmonising with elements of the International Civil Aviation Organisation (ICAO) air traffic services standards and recommended practices. ICAO has developed an alphabetical airspace classification system ranging from A to G. Each classification indicates the level of air traffic control service provided, with Class G airspace having the least service.

The plan for Australia's move to this harmonised approach is known as "Airspace 2000". The implementation of Airspace 2000 commenced on 26 February 1998 with the demonstration of Class E airspace in the Canberra-Ballina region.

Airspace 2000 is altering some long-standing practices unique to the Australian aviation industry.

An important aspect of the Airspace 2000 program is its integration with The Australian Advanced Air Traffic System (TAAATS).

On 22 October 1998 the Civil Aviation Safety Authority (CASA) commenced a demonstration of new operating rules and procedures for Class G Airspace. The demonstration is being conducted in the Canberra-Ballina region in Class G Airspace below 8,500 feet.

Key features of the demonstration are that it:

removed directed traffic information (DTI) provided by flight service;

introduced a national advisory frequency (NAF); and

introduced a radar based traffic information service subject to radar coverage and air traffic controller workload.

The Bureau of Air Safety Investigation (BASI) is conducting a systemic investigation of the demonstration. The investigation is part of its normal systems safety investigation role.


SAFETY DEFICIENCY

The overall program management of the Class G Airspace Demonstration has been deficient because critical safety issues have not been addressed.


FACTUAL INFORMATION

Related occurrences

9805078 - The crew of a BAe Jetstream was maintaining the aircraft at 5,000 ft for separation from a descending Beechcraft King Air. The sector controller transmitted radar information on the Jetstream to the pilot of the King Air. This transmission was not acknowledged by the King Air pilot and was subsequently reported to have been over-transmitted by another pilot. The King Air was observed on radar to descend through the level of the Jetstream. The two aircraft passed each other with approximately 600 ft vertical separation and 0.5 NM horizontal displacement. The investigation is continuing.

9804984 - Prior to departing Lismore the pilot of a Beechcraft King Air transmitted taxi and departure reports on the Lismore/Casino/Ballina mandatory broadcast zone frequency (MBZ) but received no replies. He then contacted Brisbane Centre for a radar information service and was advised that there was no radar observed traffic. The pilot of a SAAB 340, which had just departed Casino, was monitoring the Brisbane Centre frequency and heard this report. He then contacted the pilot of the King Air to arrange separation. Shortly after, the pilot of the King Air saw the SAAB 340 pass underneath his aircraft. Subsequently, the pilots established that they had both transmitted the required MBZ reports but neither had heard the other's transmissions. The SAAB 340 pilot was not required to monitor the Brisbane Centre frequency, but by doing so he enhanced the crew's situational awareness. The investigation is continuing.

In both of these incidents, prior to the introduction of the Class G Airspace Demonstration, the crews would have been alerted as to each other's existence through the provision of directed traffic information.


Project monitoring

As part of the Bureau's monitoring of the Class G Airspace Demonstration, an investigation team was formed to collect and analyse information relating to the development and conduct of the demonstration. The team conducted interviews with staff and obtained data from the Civil Aviation Safety Authority (CASA), Airservices Australia and the aviation industry.

The Bureau's investigation team has noted that CASA had a safety case process for the Class G Airspace Demonstration, and that CASA is closely monitoring the operational progress of the demonstration.

However, the Bureau's initial analysis of the information obtained identified a number of major safety concerns:

a) The independent review process for the introduction of airspace changes was removed when CASA, as the regulator and safety auditor of the airspace system, also actively assumed the primary role for the design, safety analysis, promotion and management of the Airspace 2000 program from Airservices Australia in late 1997.

Previously Airservices Australia conducted these airspace change activities and CASA had a clearly defined process for monitoring and evaluating this process. However, when CASA assumed the role formerly exercised by Airservices Australia, no system was put in place to ensure that CASA's own work was similarly evaluated for the Class G Airspace Demonstration. No such system is yet in place.

b) The CASA safety case process did not provide an integrated summary of all hazards considered, and their associated risk levels, mitigators, and anticipated effectiveness of the mitigators. In addition, the CASA safety case process did not include a "full qualitative and quantitative evaluation by technical experts" of Airspace 2000 (which includes Class G Airspace). Such an evaluation was proposed by the acting Chairman of CASA in a letter to the Chairman of Airservices Australia following the CASA Board meeting of 25-26 September 1997.

c) The pilot education programs of both CASA and the aviation industry, as primary mitigators for hazards associated with the airspace changes, were not implemented effectively (in terms of the originally planned program, as well as the changes introduced subsequent to the issue of Aeronautical Information Publication Supplement 48/98). A lack of pilot knowledge continues to be a major operational safety concern.

d) There has been a lack of support from elements of the aviation industry for the conduct of the demonstration. Such a lack of support had been recognised by CASA and a UK Civil Aviation Authority review team (engaged by CASA), as a significant risk to the success of the demonstration.

e) There are continuing problems associated with congestion of the NAF, a planned primary mitigator for hazards associated with the changes. This frequency congestion can prevent the transfer of vital information between pilots.

f) The Airspace 2000 plan proposed the introduction of Class E Airspace corridors through Class G airspace on any route where traffic density required, or where such corridors were requested by industry. These E corridors were a planned mitigator against the removal of DTI, but were not implemented for the Class G Airspace Demonstration.

g) There are safety deficiencies associated with the current frequency management procedures, particularly during departures and arrivals at uncontrolled aerodromes (as shown in the occurrences described above). Pilots are required to monitor a number of different frequencies during these high workload phases of flight and may consequently not receive critical radio transmissions, or may receive late advice of other traffic.

h) Pilots and air traffic services staff have been advised of changes to the demonstration through numerous Notices to Airmen, which have been issued in an ad hoc and reactive manner. This continues to cause confusion among pilots and air traffic services staff.

i) As yet, the investigation team has not found evidence to indicate that CASA's safety case process has considered the following safety issues associated with the Class G Airspace demonstration:

the full impact of each of the changes to the Class G Airspace Demonstration procedures and design that were implemented subsequent to the issue of Aeronautical Information Publication Supplement 48/98 on 13 August 1998;

the full impact of the removal of DTI, particularly the potentially detrimental effects on situational awareness for VFR pilots (for example a VFR pilot may now need to monitor two or three frequencies to maintain awareness of IFR traffic, when previously only one frequency was required); and

operational difficulties associated with two concurrent sets of procedures, one for the demonstration airspace and one for the existing system.

j) As yet, the investigation team has not found evidence to indicate that there was:

a clear transfer of roles and responsibilities from Airservices to CASA for the management of Airspace 2000 (which includes Class G Airspace);

a comprehensive and systematic analysis of pilot tasks under the Class G Airspace Demonstration model (including an examination of the combined effects of all the changes on workload, situational awareness and crew coordination, as well as the development and testing of specific operational procedures);

a systematic comparison of the Class G Airspace Demonstration model (including consideration of the Australian aviation system and environment) with appropriate overseas airspace systems;

a clear rationale for conducting the demonstration prior to the introduction of TAAATS; and

a proactive evaluation of the effectiveness of the pilot education program prior to the introduction of the demonstration.

It is not possible at this stage to compare the overall safety level of the Class G Airspace Demonstration with that of the previous system. However, due to the safety concerns listed above, the following interim recommendations are made.

For further information please see report `Systemic Investigation into the Class G Airspace Demonstration'.

Output text

IR980253 - The Bureau of Air Safety Investigation believes that the Class G Airspace Demonstration has served its purpose. In the light of the safety concerns identified by this investigation, BASI recommends that the Civil Aviation Safety Authority should now terminate the demonstration.

The results of the demonstration should be subject to a comprehensive evaluation that specifically addresses the safety concerns identified by BASI.

The evaluation process should take into account the time required to:

- review and analyse the demonstration;

- refine the model where required and conduct a proper safety analysis; and

- provide a comprehensive and effective education and training program for any subsequent changes to Class G Airspace.

If this is not achieved, the deficiencies identified in this investigation are likely to be repeated, thereby seriously compromising the successful introduction of future changes to airspace including reintroduction of Class G Airspace incorporating Radar Information Service and National Advisory Frequency.

The Bureau of Air Safety Investigation simultaneously issues the following related interim recommendations to the Civil Aviation Safety Authority:

IR980260 - "The Bureau of Air Safety Investigation recommends that the Civil Aviation Safety Authority review program management policies and procedures for current and proposed changes to the aviation system, in the light of experience gained from the present Class G Airspace Demonstration".

IR980261 - "The Bureau of Air Safety Investigation recommends that the Civil Aviation Safety Authority, the Department of Transport and Regional Services and Airservices Australia review and clarify the roles and responsibilities of the respective organisations in relation to the regulation, design and management of airspace to ensure the safety integrity of the aviation system".

The Bureau of Air Safety Investigation simultaneously issues IR980261 to the Department of Transport and Regional Services and Airservices Australia as IR980256 and IR980257 respectively.

Initial response
Date issued: 21 December 1998
Response from: Civil Aviation Safety Authority
Action status: Closed - Accepted
Response text:

This document provides CASA's responses to the safety concerns raised by the Bureau of Air Safety Investigation (BASI), Air Safety Interim Recommendation No IR 980253. The format used is to print each of BASI's concerns in bold type followed by CASA's response.

a)"The Independent review process for the introduction of airspace changes was removed when CASA, as the regulator and safety auditor of the airspace system, also actively assumed the primary role for the design, safety analysis, promotion and management of the Airspace 2000 program from Airservices Australia in late 1997.

Previously Airservices Australia conducted these airspace change activities and CASA had a clearly defined process for monitoring and evaluating this process. However, when CASA assumed the role formerly exercised by Airservices Australia, no system was put in place to ensure that CASA's own work was similarly evaluated for the Class G Airspace Demonstration. No such system is yet in place".

CASA Response:

In view of the fact that a review is being conducted in accordance with a Ministerial Direction, it is considered inappropriate to respond to the above concern at this time.


b)"The CASA safety case process did not provide an integrated summary of all hazards considered, and their associated risk levels, mitigators, and anticipated effectiveness of the mitigators. In addition, the CASA safety case process did not include a "full qualitative and quantitative evaluation by technical experts" of Airspace 2000 (which includes Class G Airspace). Such an evaluation was proposed by the acting Chairman of CASA in a letter to the Chairman of Airservices Australia following the CASA Board meeting of 25-26 September 1997".

CASA Response.

With the exception of the late changes made on 4 November 1998, the Authority considers that the safety case addressed the principal concerns mentioned above. The main hazards were identified and consolidated in the updated safety case, the remainder being contained in its appendices.

A multiple risk analysis of the Class G Demonstration was undertaken in line with accepted methodologies, any one of which would normally be considered as adequate, The analysis of risk associated with the Class G Airspace Demonstration included:

1. Quantitative modelling based data, validated models, and analysed assumptions (Airservices Safety Case - included in CASA Safety Case);

2. Experienced judgement (AEP) and UK CAA Review (see CASA Safety Case); and

3. Trial Implementation (BASI was involved in the monitoring process and was provided with regular reports).


c)"The pilot education programs of both CASA and the aviation industry, as primary mitigators for hazards associated with the airspace changes, were not implemented effectively (in terms of the originally planned program, as well as the changes introduced subsequent to the issue of Aeronautical Information Publication Supplement 48198). A lack of pilot knowledge continues to be a major operational safety concern".

CASA Response:

Noted. A comprehensive pilot education package was mailed out to every AOC holder, some six weeks prior to the original commencement date of the demonstration (the cost of which was $.5M). However, it is acknowledged that there were deficiencies with respect to pilot education in some quarters and that, with hindsight, such issues could have been better handled by all concerned. Some changes to airspace design were introduced two weeks prior to implementation, but these were minor in comparison to the overall package and did -not involve changes to pilot procedures. The Authority sent information on these changes to all pilots licence holders.


d)"There has been a lack of support from elements of the aviation industry for the conduct of the demonstration. Such a lack of support had been recognised by CASA and a UK Civil Aviation Authority review team (engaged by CASA), as a significant risk to the success of the demonstration".

CASA Response.

Noted. As pointed out by BASI, both CASA and the UK CAA Review Team recognised the apparent lack of support by some elements of the aviation industry and the potential risk to the success of the demonstration. It is considered that there might have been greater industry support had there been more active industry involvement earlier in the proceedings leading up to the demonstration which, in turn, would have probably led to better understanding and hence pilot education in the industry.


e)"There are continuing problems associated with congestion of the NAF, a planned primary mitigator for hazards associated with the changes. This frequency congestion can prevent the transfer of vital information between pilots".

CASA Response:

Problems of congestion on the NAF were identified as a potential hazard prior to the demonstration but it was determined that this hazard could only be assessed fully during the course of the demonstration. This was covered in the report prepared by the UK CAA. This matter was also raised, and addressed, in CASA's monitoring reports which showed that congestion was limited to two periods of short duration at peak times each day. Some of the pilot reports received, from aircraft operations conducted at higher altitudes, indicated higher levels of congestion than was observed by CASA staff.


f)"The Airspace 2000 plan proposed the introduction of Class E Airspace corridors through Class G airspace on any route where traffic density required, or where such corridors were requested by industry. These E corridors were a planned mitigator against the removal of DTI, but were not implemented for the Class G Airspace Demonstration".

CASA Response:

It would appear that there is a misunderstanding of the concept with respect to E corridors. Class E Airspace was available from 8,500 FT above the entire area covered by the Class G Airspace Demonstration. 'E' corridors were planned as a mitigator for the removal of DTI further west, outside the radar environment.


g)"There are safety deficiencies associated with the current frequency management procedures, particularly during departures and arrivals at uncontrolled aerodromes (as shown in the occurrences described above). Pilots are required to monitor a number of different frequencies during these high workload phases of flight and may consequently not receive critical radio transmissions, or may receive late advise of other traffic".

CASA Response:

Noted. This is a complex and controversial issue. It is acknowledged that there were some workload difficulties associated with frequency management. The changes introduced on 4 November 1998 which mandated the M13Z frequency in MTAs alleviated the problems for arriving/departing RPT flights.


h)"Pilots and air traffic services staff have been advised of changes to the demonstration through numerous Notices to Airmen, which have been issued In an ad hoc and reactive manner. This continues to cause confusion among pilots and air traffic services staff".

CASA Response:

This criticism is acknowledged. At the time when the demonstration was terminated, action was well advanced to issue a replacement AIP Supplement (intended to be 69198). The intention was that this AIP Supplement should replace AIP Supplements 48198 and 66198, together with all of the NOTAM that had been issued. The intended replacement AIP Supplement consolidated all material into a single document, the purpose being to minimise the risk of confusion.


i)"As yet, the investigation team has not found evidence to indicate that
CASA's safety case process has considered the following safety issues
associated with the Class G Airspace Demonstration:

The full impact of each of the changes to the Class G Airspace Demonstration procedures and design that were implemented subsequent to the issue of Aeronautical Information Publication Supplement 48198 on 13 August 1998";

CASA Response:

Changes introduced subsequent to the issue of AIP Supplement 48198 were not subject to the safety case process because they were introduced to address concerns raised by the airlines which, principally, focussed on problems associated with frequency management and workload. It is acknowledged that changes introduced after the demonstration commenced were not subject to a formal safety analysis process.


"The full impact of the removal of DTI, particularly the potentially detrimental effects on situational awareness for VFR pilots (for example a VFR pilot may now need to monitor two or three frequencies to maintain awareness of IFR traffic, when previously only one frequency was required)";

CASA Response.

The contention that the full impact of the removal of DTI was not subject to a formal safety analysis is disputed. The original safety case prepared by Airservices in 1996 addressed this issue in detail. It is also noted that BASI has stated that "it is not possible at this stage to compare the overall safety level of the Class G Airspace Demonstration with that of the previous systems.

In terms of situational awareness for VFR aircraft, there was no change from the one frequency they were required to monitor enroute. There were, however, other complications introduced by the removal of Flight Service, such as coordination with ATC for clearances through restricted areas.


"Operational difficulties associated with two concurrent sets of procedures, one for the demonstration airspace and one for the existing system".

CASA Response:

The issue of demonstration area boundaries was identified and given careful consideration by the safety education cadre and was given prominence in the safety education material which was produced. The Authority is satisfied that adequate procedures existed for the en-route situation but acknowledges that the issue of boundary aerodromes was not addressed until after the commencement of the demonstration.


j)"As yet, the investigation team has not found evidence to indicate that there was a clear transfer of roles and responsibilities from Airservices to CASA for the management of Airspace 2000 (which includes Class G Airspace)";

CASA Response.

The Airspace 2000 Program Definition Plan clearly defines the management structure for the project and the roles of the respective agencies.


"A comprehensive and systematic analysis of pilot tasks under the Class G Airspace Demonstration model (including an examination of the combined effects of all the changes on workload, situational awareness and crew coordination, as well as the development and testing of specific operational procedures)";

CASA Response:

This issue was the subject of extensive discussion with airlines prior to the commencement of the demonstration during the course of which pilot workload scenarios (including timings and radio procedures for two pilot operations) were considered, the CASA safety case refers. It is true to say that a comprehensive and systematic analysis of pilot tasks was not carried out. However, advice from the UK CAA Review Team was that this could not be resolved prior to the demonstration and that it could only be fully addressed by close monitoring of the demonstration.


"A systematic comparison of the Class G Airspace Demonstration model (including consideration of the Australian aviation system and environment) with appropriate overseas airspace systems";

CASA Response.

No formal comparison of the Class G Airspace Demonstration model with appropriate overseas airspace systems was carried out. However, it was widely understood that the Demonstration model was very similar to the airspace models implemented in a number of other countries. Moreover, an ICAO compliance matrix was prepared (see attached).

It should also be noted that the UK CAA report drew a comparison between the Australia Demonstration model and the British Class G airspace.

In addition, a considerable body of work was developed, subsequent to the failed implementation of 11/11/93, which extensively relies on comparisons with overseas systems. This material was taken into consideration in the development of Airspace 2000.


"A clear rationale for conducting the demonstration prior to the introduction of TAAATS"; and

CASA Response:

In response to the BASI Interim Recommendation No. IR970112, CASA sought to maximise the use of available radar coverage in the Canberra - Ballina area, especially where RPT flights were concerned.

Implementation of the Class G demonstration is not TAAATS dependent and the introduction of TAAATS would not have required a change to the Class G Demonstration procedures. It is a commonly held misconception that TAAATS incorporates an airspace design. This is incorrect. TAAATS will be capable of supporting multiple designs and classes of airspace.

CASA was concerned to neither delay nor disrupt TAAATS and sought to implement the Class G Demonstration in the window of opportunity offered by Airservices.


"A proactive evaluation of the effectiveness of the pilot education program prior to the introduction of the demonstration".

CASA Resonse:

There was no proactive evaluation of the effectiveness of the pilot education programme prior to the commencement of the demonstration. However, in accordance with the communication strategy, a number of information sessions were held to assess the effectiveness of the training material. In addition, a 'hot line' was put into operation several weeks prior to the commencement of the demonstration which provided further feedback on frequently asked questions and areas of misunderstanding.

The establishment of monitoring processes (such as a 'hot line', ESIRs, pilots' reports, airborne monitoring etc.) once the demonstration had commenced, provided a variety of inputs from which it was possible to make an assessment of the effectiveness of the pilot education programme. The most common areas of difficulty were identified and the information repeated in Aiming Higher which was distributed to all pilots.

 

Further correspondence
Date issued: 24 December 1998
Response from: Civil Aviation Safety Authority
Response status: Closed - Accepted
Response text:

Following discussion of your Bureau's interim report IR980253 with this Authority's Chairman and members of the Board, CASA would like to submit for your consideration, the attached comments.


Further CASA comment on BASI interim report IR980253

The Bureau of Air Safety Investigation issued an interim report IR980253 on 8 December, 1998, in relation to occurrences where aircraft were approaching or departing aerodromes.

Under the heading "Factual Information" BASI made the following statement:

"in both these incidents, prior to the introduction of the Class G airspace demonstration, the crews would have been alerted as to each other's existence through the provision of directed flight information."

The prime reason for the introduction of the Class G demonstration was because of a previously reported serious breakdown of separation, where the provision of a directed traffic information service failed. There have been many reports of incidents under similar circumstances in the airspace system before the demonstration.

BASI also made the following statement in the report:

"G - there are safety deficiencies associated with the current frequency management procedures particularly during departure and arrivals at uncontrolled aerodromes as shown in the occurrences described above. Pilots are required to monitor a .number of different frequencies during these high workload phases of flight, or may not receive critical radio transmissions, or may receive late advice of other traffic."

BASI points out that these safety deficiencies have been ongoing for many years, and were a serious safety problem in the airspace before the demonstration. Over 100 incidents have been reported where pilots have not received critical information on other traffic and this problem was clearly annunciated in the BASI report RP9301 where it was stated:

"Another difficulty at present is that when changing from the surrounding area frequency to the MTAF, broadcasts can be missed. Even with two radios, broadcasts can be overtransmitted or multiple transmissions confused."

"Interviewed crews pointed out that there is thus no means by which a faulty transmitter, incorrect frequency selection or overtransmission may be detected."

"Each of the occurrences investigated during the six week study period and a large percentage of all RPT occurrences in MTAF areas involved a failure to obtain correct traffic information."

BASI points out that CASA has legislated on 16 November 1998 and the CASA Director has signed a Civil Aviation Order to mandate a third party in the terminal area for RPT aircraft of over 10 passengers. This will substantially reduce this endemic problem in the existing airspace system.

It also should be pointed out that in relation to occurrence 9805078, the descending Beechcraft Kingair did not comply with the requirements as listed in AIP Supplement H48198 Annex B para 5.2:

"Pilots of IFR fights intending to conduct an instrument approach in IMC and who have not been able to confirm that the aircraft's radio is functioning and on the correct frequency for the aerodrome, either from another aircraft, through a third party, a UNICOM or an Aerodrome Frequency Response Unit, should contact the ATC unit providing services in the overlying airspace and request known IFR traffic. Provision of this service by ATC will not necessarily include information about all IFR traffic in the area".

If the Kingair pilot had complied with the regulation, the pilot would have been given information on the Bae Jetstream.

It should be noted that BASI has omitted from the report that in a number of incidents during the demonstration period, the chance of a collision was reduced by the use of radar.

 

 
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Last update 01 April 2011