Guidelines for Dealing with Unusual/Emergency Situations in ATC

Guidelines for Dealing with Unusual/Emergency Situations in ATC


The current reality is that many air traffic controllers (ATCO’s) could go through extensive periods of time without having to deal with emergency or abnormal traffic situations. These are situations which present anything out of the ordinary. Because of this infrequency, it is crucial that ATCOs maintain a level of constant awareness and be kept in practice for dealing with any potential situation to ensure that safety is not compromised when an unusual/emergency event occurs.


In April 1996 a workshop was held at the EUROCONTROL Institute of Air Navigation Services (IANS), Luxembourg on the handling of unusual and emergency situations. As a result of the workshop a deliverable titled “Guidelines for Controller Training in the Handling of Unusual/Emergency Situations” was produced in 2003. The background material for the deliverable has been provided by Germany, Switzerland, The United Kingdom and The Netherlands. Additional input and advice was provided by aircrew personnel from Deutsche Lufthansa (DLH).

In “Guidelines for Controller Training in the Handling of Unusual/Emergency Situations” a ‘checklist’ approach is proposed for use by EUROCONTROL in order to ensure proper handling of any unusual and emergency situation which requires controller action.

These checklists are designed to help the supervisor as well as the controller(s) handling the unusual or emergency situation. The idea of the checklists is to create step by step plans on how to work for the common goal, and to better coordinate the operation. An observer/ assistant working with the controller who uses the checklist will be in a position to provide better quality support as it will be clear what the controller is doing, including the sequence of the completed and pending actions.


A simple set of acronyms has been provided which may make it easier for controllers to remember the immediate actions, or sequence of actions, to be followed on initial notification in event of unusual/emergency situation.

The use of abbreviations and acronyms in the checklists is common in the ATC world and it seems logical, therefore, to recommend a few relevant checklist possibilities:


  • Recognise that there is a problem
  • Identify the relevant aircraft and arrange for special code Squawk
  • Separate - Give the pilots airspace in which to operate and give them time
  • Communicate with adjacent sectors/colleagues/supervisors as appropriate


  • Time - Give the pilot time to sort out the immediate problem on receipt of first notification that there is a difficulty
  • Airspace - Give the pilot freedom of the adjacent airspace - get other aircraft out of the way, and off the frequency
  • Silence - The controller should clear the frequency and not raise more questions than are necessary


  • Squawk - Acknowledge the call; make sure the correct squawk is produced
  • Silence - Keep the Radiotelephony (RTF) to as low a level as possible - where possible assign a single frequency to the incident
  • Separate - Provide appropriate and adequate airspace for the pilot to execute any essential manoeuvres
  • Shout - Ask for assistance from the ATC supervisor and/or colleagues


  • Quiet - Keep the frequency clear
  • Recognise that there is a problem when the message is received
  • Separate - Provide airspace
  • Time - Give the pilot time to work on it


  • Announcing and acknowledging the emergency or problem, getting the pilot to make the appropriate squawk
  • Taq - Giving the pilot time, airspace and quiet
  • Information exchange pilot/controller and controller/controller
  • Solving the problem as a team controller/controller and controller/pilot


  • Acknowledging the emergency or problem, getting the pilot to make the appropriate squawk
  • Separate the traffic and support the pilot in so far as is possible
  • Silence - Keep the RTF to a minimum; give the pilot time to think
  • Advise supervisor and appropriate colleagues on other sectors


  • Acknowledge the call; get the squawk
  • Separate the aircraft from other traffic. Give it room to manoeuvre
  • Silence - on the frequency. Provide separate frequency where possible - this prevents unnecessary clutter for the pilots
  • Inform those who need to know and those who can help; inform others as appropriate
  • Support the pilots in any way possible - Start to think of alternative routings, etc.
  • Time - Give the pilots time to collect their thoughts, don’t harass them for information. Time produces good decisions

A number of European ANSPs have successfully adopted the ASSIST principle, which was pioneered by the Deutsche Flugsicherung GmbH (DFS) who are entrusted with controlling the air traffic in Germany.

Below is attached the ASSIST video, powered by EUROCONTROL:


Related Articles

The ASSIST principle underlies the following articles comprising the “Guidance for Controllers” Section of SKYbrary:

The EUROCONTROL deliverable, as well as the SKYbrary Team, explicitly denotes that the application of any of these acronyms and mnemonics should not be enforced to the ANSPs. Each State/organisation should ensure its own training guidelines and should use if necessary a checklist or an acronym mnemonics which could facilitate a proper response to any unusual/emergency situation.

NATS Flight Deck Procedures Video

There will be times when controllers will have to cope with unusual situations such as weather avoidance or aircraft emergencies. It is important for controllers to have knowledge of the flight deck procedures that will be used by aircrew in such situations. The following video describes the generic procedures followed by aircrew in certain unusual situations:

Further Reading





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