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Recommendation issued to: AirServices Australia

Recommendation details
Output No: R20030057
Date issued: 04 August 2003
Safety action status: Closed
Background: Why this Recommendation was developed

Output text

Safety Recommendation

The Australian Transport Safety Bureau recommends that Airservices Australia conduct a review to establish the extent of the use of non-standard levels in situations initiated by pilots and in situations initiated by controllers.

Initial response
Date issued: 01 February 2005
Response from: AirServices Australia
Action status: Closed - Accepted
Response text:

An internal hazard identification workshop was undertaken using pilots and controllers to review the extent of hazards associated with the assignment of non standard levels. The workshop report is attached for your review. The review determined that to not have the flexibility to use non-standard levels would significantly increase the number of level changes and thereby increase the level of risk beyond the current level. As can be seen from the report a number of recommendations were made to assure that the extent and operation of the use of non-standard levels was optimised.

Further correspondence
Date issued: 28 April 2005
Response from: AirServices Australia
Response status: Closed - Accepted
Response text:

Firstly, let me apologise for the very late response to this recommendation. Unfortunately the recommendation did not get processed in accordance with our usual management practices.

The text of this recommendation was as follows: "The Australian Transport Safety Bureau recommends that Airservices Australia conduct a review to establish the extent of the use of non-standard levels in situations initiated by pilots and in situations initiated by controllers".

A workshop on the application of non-standard levels was conducted in December 2003 with industry consultation occurring through 2004. The workshop and industry consultation did not determine with any accuracy the extent of use of non-standard levels. Review within Airservices Australia equally has not been able to definitely determine a quantitative figure on their utilisation. Their use varies within the year with factors such as jet stream effects.

Documentation within MATS and AIP limit the circumstances within which ATC can initiate the use of non-standard levels (see below). Airservices Australia believes that these are appropriate, and our Check and Standardisation regime confirms that these are being utilised by ATC:

AIP ENR 1.7 -- 6
3.1 Selection of Levels
3.1.1 Flights must be planned in accordance with levels selected from the tables at Section 5. Any part of a flight that will take place south of 45S must be planned in accordance with levels selected from the tables at Section 6. 3.1.2 Within controlled airspace, ATC may assign and pilots may request a level that does not accord with the tables in Section 5.

Assigning levels Level assignment shall take into account:
a. separation;
b. terrain clearance;
c. provision for radio failure;
d priority. When practicable, the pilot requested level should be accommodated. When adjustment of a level is necessary for entry to, or leaving controlled airspace, the adjustment should be made within controlled airspace. Cruising levels conforming to the appropriate table of cruising levels (See "Tables of Cruising Levels" Annex 4-8) should be assigned as necessary to provide separation between aircraft. Levels not conforming to these tables may be assigned when traffic or other circumstances require. Unless coordination is effected, aircraft entering airspace where RVSM is not applied shall be assigned a level complying with the accepting sector's table of cruising levels before the sector boundary, or by the time or distance specified by the accepting sector.
Non standard levels When a non standard level is assigned, controllers should consider: a. workload implications;
b. coordination implications;
c. the effect on other aircraft at standard levels.
Priority for level assignment Level assignment shall generally be determined as follows:
a. aircraft at standard flight levels shall be afforded priority over aircraft at nonstandard flight levels;
b. aircraft assigned a level shall have priority over aircraft requesting that level;
c. when two or more aircraft are at the same level, the preceding aircraft shall have priority.
Variation to standard assignable levels Where standard assignable levels have been implemented for arriving and departing aircraft, assignment of other than agreed levels must be subject to specific coordination.
Aircraft at non-standard cruising levels Aircraft operating at other than a level conforming to the table of cruising levels for the particular direction of flight or notifying intention to cruise at such a level, shall be advised accordingly and the pilots intentions sought.

I would also note that the workshop determined that mandating the absolute use of standard levels across the board will increase the level of risk beyond that evident in the current circumstances.

Further correspondence
Date issued: 17 February 2011
Response from: AirServices Australia
Response status: Closed - Accepted
Response text:

Since the release of this report in 2003, Airservices has been investigating the issue of non standard routes and non standard levels in respect of recommendations R20030056 and R20030057.

As you would be aware, flight planning errors of this type are routinely and reliably tracked through the ESIR application. Airservices analysed this data and ascertained that non standard routes are not normally a significant contributory factor to
Breakdown of Separation.

Nonetheless, over the past several years we have invested significantly in examining technical solutions that would detect flight planning errors and highlight them to the controller.

Our investigations determined that it was not feasible to use either NAIPS (Airservices' flight planning system) or to develop a separate database to process flight plans prior to entering the Eurocat system. Further, we determined that the cost of implementation in Eurocat for a warning system is high, and as Airservices has now commenced work on its future ATS system the lead time and cost does not support further work in this area.

We discussed the use of non standard levels with CASA a number of years ago and it was determined that the number of changes of level that would be incurred if standard levels were required to be utilised in all cases would introduce an increased level of risk into the system.
In addition, since this incident a number of changes have been introduced to improve instruction to both pilots and air traffic controllers on the use of non standard levels.

The Aeronautical Information Publication (AlP) was updated on 18 November 2010 and now specifically states that a pilot must only request a non conforming level when it is determined by the pilot in command to be essential to the safety of the flight and its occupants.

Airservices' Manual of Air Traffic Services (MATS) captures this same procedure and this will be further enhanced in June with an additional requirement that the controller must make an assessment of the safety impact to all traffic against any operational penalty to the aircraftprior to assigning the non conforming level and that this assessment must be updated regularly.

The other key safety enhancement is that a pilot must now report to ATC when the aircraft can return to a conforming level. ATC is required to make this request if not volunteered by the pilot.

As demonstrated above, Airservices has seriously considered the issues raised in this report and has determined that there are no further reasonable steps that can be taken to address the recommendations.

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Last update 03 April 2012