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Controller Detection of Manoeuvring Area Conflicts – Guidance for Controllers

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Article Information
Category: Runway Incursion Runway Incursion
Content source: EUROCONTROL EUROCONTROL
Content control: SKYbrary About SKYbrary

Description

This article describes the best practices to be used by air traffic controllers to maximize the chance of detecting an occupied runway or preventing conflicts on the manoeuvring area.

Typical Scenarios

  • Taking off or landing on a runway that is already occupied;
  • Entering a runway for which an aircraft has received a take-off or landing clearance;
  • Two aircraft departing/landing on intersecting runways;
  • Runway crossing after an aircraft has received a take-off or landing clearance;
  • Conflicts not involving departing or landing aircraft.

Contributing Factors

The manoeuvring area conflicts usually include at least one of the following events:

  • Loss of communication
  • Non standard R/T phraseology used
  • Incorrect ATC clearance
  • Incorrect readback/hearback
  • Non-conformance with ATC clearance due to:
    • spatial/positional confusion
    • misinterpretation or mishear of the clearance
    • procedural non compliance
    • poor CRM and lack of situational awareness
    • expectation and continuation biases
  • Local environment specifics such as taxiways layout, marking and signage (e.g. not fully compliant to the provisions of ICAO Annex 14), no single runway occupancy frequency, etc

A dedicated study identified the four most frequent ATC contributing factor areas that are present in the sequence of events leading to runway incursions:

  • Memory - most commonly a failure to check/monitor i.e. not following normal practice
  • Perception - most commonly a failure to see something
  • Operational environment - commonly distractions, visual impairments and noise.
  • Communication errors - incomplete, incorrect or ambiguous RTF.

Recommendations

The advice given in this section is derived from best practices, experience and common sense. It is not intended to replace or supersede local instructions and procedures.

  • Use of concise and unambiguous phraseology reduces the chance of an unexpected aircraft manoeuvre.
  • TWR controllers should follow strictly local procedures related to marking the occupied runway (either via a paper/electronic strip bay or via other established means and procedures);
  • Performing a structured scan (e.g. checking the manoeuvring area, then the strip bay, then the A-SMGCS, etc. before issuing a clearance) helps ensure that no conflicting clearances are issued and to confirm that all clearances are properly complied with.
  • A thorough scan of the manoeuvring area during or prior takeover mitigates the risk of previous controller failing to properly hand over the working position.
  • Use of memory aids may help mitigate the risk of forgetting issued clearances.
  • Maintaining situational awareness at all times is an important prerequisite to safe and smooth operations. If direct observation is not possible, other methods and tools should be used to monitor the obscured areas (e.g. cameras, surveillance systems, etc.).
  • Compliance with taxi instructions should be closely monitored and assistance is to be provided especially if the crew appears to be unfamiliar with the aerodrome or there is an unintuitive procedure established.
  • As a general rule if there is a doubt that a certain instruction could be misinterpreted (e.g. for instance hesitance is detected during the crew readback) or a doubt exists about the possible crew intention, the controller should be proactive to resolve in unambiguous way the possible areas of concern particularly if there are precursors that misunderstanding could arise.
  • Whenever possible, runway entering/crossing clearances should be issued separately (e.g. the aircraft/vehicle is first cleared to the holding point and the runway clearance is issued only after there is a reasonable certainty that it is safe to cross or enter the runway). This also mitigates the risk of communication loss.
  • It is preferable to confirm (either visually or using surveillance) that the aircraft/vehicle is approaching the intended holding point before issuing a line up or clearance to enter/cross the runway. This helps mitigate the risk of runway incursion and should be used whenever practicable as workload permits.
  • It is preferable to confirm (either visually or using surveillance) that the aircraft has lined up on the correct runway before issuing a take-off clearance. This helps mitigate the risk of a take-off roll commencing from a wrong runway or a taxiway and should be used whenever practicable and as workload permits.
  • The issuing of “a time-block clearance” to vehicles (sometimes used at less busy aerodromes, e.g. “Cleared to cross runways/taxiways for the next 60 minutes”) should be avoided. Each vehicle movement on the manoeuvring area should be subject to a separate clearance and the runway/taxiways should be marked as occupied according to the local procedures.
  • The level of familiarity of some crews could be low about certain airports, particularly if it has a complex layout (or closed taxiways due construction work, recent change in the taxiway layout/signage), the controllers should be prepared to provide progressive taxi instructions.

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Further Reading