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Mode Aviation
Reference No. AR201300057
Date reported 09 July 2013
Concern title Use of multiple radar vectors by ATC to achieve the required spacing
Concern summary

The concern related to ATC instructing flight crews, especially fatigued international flight crews, to make multiple heading changes to achieve separation instead of allowing them to slow down or conduct a holding pattern.

Industry / Operation affected Aviation: Air transport
Concern subject type Aviation: Flight crew

Reporter's concern

The reporter expressed a safety concern regarding the issuing of multiple radar vectors by ATC to inbound aircraft to achieve aircraft spacing.

The reporter stated that rather than issuing a holding pattern or instructing flight crew to reduce aircraft speed to slow aircraft down, ATC elect to issue numerous radar vectors. This creates more work for the flight crew and adversely affects fuel management and arrival schedules. This is particularly relevant to long haul international flight when flight crew are fatigued and are entering a critical phase of flight.

The reporter advised that this method of air traffic management appears to run contrary to concepts such as 'gate-to-gate' and 'continuous descent arrivals'.

Operator's response (Operator 1)

Airservices Australia (Airservices) appreciates the opportunity to respond to the reported safety concern regarding the issuing of multiple radar vectors by ATC to inbound aircraft to achieve aircraft spacing.

Due to the de-identified nature of the report, Airservices is unable to substantiate or investigate the specific reported workload and air traffic management concern. Aircraft may be subject to air traffic delays for a variety of reasons. Airservices would like to provide the following clarification on ATC procedures used to manage air traffic delays. These procedures can vary depending on a number of circumstances and include ground delay programs implemented for Sydney, Brisbane and Perth airports (long haul flights are not subject to this program). Aircraft fuel efficiency is an important consideration in the design of ATC delay management procedures. On most occasions when delays are necessary, enroute ATC will initially instruct aircraft to reduce speed and then issue vectors at cruising levels. ATC will only provide aircraft with holding instructions during the cruise phase of flight when extensive delays are being experienced. Through the use of speed control and radar vectoring, ATC is able to position the aircraft to cross a metering point (fix) at a specific time thereby managing the required delay during an economical phase of flight where there are generally less airspace constraints. In addition, transferring the majority of the delay to the cruise phase of flight provides the aircraft with more airspace opportunities for continuous descent approach profiles during the aircraft's approach to an airport.

Airservices notes that the combined use of aircraft speed control and radar vectoring during the cruise phase of flight also increases the opportunity for aircraft to fly the published standard terminal arrival route (STAR). These ATC techniques have been shown to efficiently manage air traffic and minimise the impact on arrival schedules compared to the use of holding instructions.

During the descent phase of flight ATC will utilise holding instructions when delays are large enough that radar vectoring would create additional airspace issues. Airservices notes that safe aircraft holding manoeuvres require restrictive altitude requirements in order to retain separation in or with the holding pattern. In these situations, speed control and radar vectoring instructions may also be used to ensure the required delay is appropriately managed.

Regulator's response (Regulator 1)

CASA has reviewed the content of this REPCON and notes the reporter's observations regarding ATC radar vectoring, particularly the workload for long haul international flight crew. CASA will use the information provided by the reporter to update the intelligence associated with CASA surveillance activities. CASA notes the response of Airservices to this REPCON and would encourage the reporter to share with Airservices the dates and locations of similar events so that Airservices can fully investigate under their Safety Management System. CASA expects that Airservices would provide a 'without prejudice' response to the reporter.

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Last update 24 March 2014