Threat and Error Management (TEM)

Threat and Error Management is the practice of planning and thinking ahead to predict/identify any potential errors and threats and manage or mitigate those that do occur. Understanding TEM will enable a pilot to think and plan in advance, for eventualities that can lead to an airspace infringement and then develop strategies to avoid it. By spending time on the ground, pre-flight, to consider these factors you will be better prepared for many of the things that can wrong in the air.

What is a THREAT?

Threats are events or things that occur outside your control which require your attention if safety is to be maintained. Threats are beyond the influence of you as the pilot and they increase the complexity of the flight.

Examples of Threats that may lead to airspace infringements include:

  • Distraction caused by task or passengers
  • Airspace including NOTAM’d activity
  • Weather inc. thermal activity
  • Fatigue / Stress
  • In-flight malfunctions
  • Lack of recent experience (skill fade) or Complacency

What is an ERROR?

Errors are actions or inactions that lead to the unwanted or unsafe deviation from the plan. Errors leading to deviation from the plan have the potential to reduce safety margins which could then lead to unforeseen issues and an airspace infringement.

Examples of Errors that may lead to airspace infringements include:

  • Navigation errors leading to vertical, or lateral deviations
  • Misinterpretation of chart
  • Incorrect altimeter setting
  • Missed calls / incorrect phraseology
  • Misinterpretation of instructions or clearances
  • Unsynchronised Direction Indicator

How do I MANAGE it?


It is essential that you spend time on the ground planning and anticipating possible threats associated with the flight. Detailed planning will provide the opportunity to develop mitigations (for example, action in the event of weather changes, the actual winds being different from the forecast).

It is a requirement that you always complete a full NOTAM brief and understand what each NOTAM is telling you including the activity times if the NOTAM covers multiple days. If you are unsure, contact the NOTAM sponsor; many NOTAM include a telephone contact number for further information. Understand what each NOTAM series refers to and the risk associated with it. NATS offers a free facility for NOTAM briefing at  By using a narrow route brief rather than an area brief, you will reduce the number of NOTAM to a manageable number.

If you use a Moving Map to carry out your NOTAM brief, make sure you understand how and why activities are depicted as well as checking that current data has been downloaded. It is also important to remember that Moving Map APPs are not regulated by the CAA, and users should note that the depiction of aeronautical information on VFR Moving Maps may be different to the UK Aeronautical Information products accessed via the NATS AIS website, such as VFR charts, the UK AIP and NOTAM information (NATS AIS is the authorised source of UK aeronautical information provided on behalf of, and regulated by, the CAA). Pay particular attention to airspace structures and their boundaries in relation to the intended route and altitude and refer to the UK AIP and the Skyway Code ( to ensure airspace requirements (for example, for ATZ, TMZ and RMZ) are fully understood. By thinking in 3-dimensions you will be able to plan climb and descent points; building into your plan the ‘Take 2’ (see below) and altimeter setting guidance, and you will reduce the probability of making a vertical infringement.

Carry out a thorough meteorology self-brief and ensure that you have the complete forecast weather picture for the whole of your intended route and alternates as well as areas of turbulence and thermal activity. Check the Metforms 214 and 215 as part of your pre-flight briefing.

Annotate your chart or knee board with useful information or mitigations such as wind direction (and/or max drift), locations of airspace or useful frequencies.


If you don’t already, consider using a Moving Map to increase situational awareness and obtain timely airspace alerts. If you are carrying out instruction or examination duties, be aware of the increased likelihood of distraction. Recent analysis shows instructors were involved in around 1 in 6 airspace infringements; the majority were not using a Moving Map and were either distracted or failed to appreciate their proximity to controlled airspace.

When able, Take 2 by remaining 2NM laterally or 200 feet vertically clear of the edge/base of controlled airspace to reduce the consequences of turbulence, distraction or external influences. The recommended 200 feet distance may need to be increased during flights where turbulence or thermic conditions are encountered to prevent inadvertent climbs into controlled airspace.

Obtain an Air Traffic Service or use a Frequency Monitoring Code (also known as a Listening Squawk) with mode ‘S’ or ‘C’ selected, rather than squawking 7000/2000 and operating autonomously. By doing so, any inadvertent airspace infringement can be resolved in a timely manner thereby reducing the safety risk to other air traffic inside notified airspace.

Self-brief (including passengers or students) planned procedures prior to commencing each significant part of the flight (for example, turning points and the approach to an airfield). Use all available briefing material to increase situational awareness before you fly; the Airspace and Safety Initiative website ( has a great deal of resource and guidance that will help identify Threats and possible Errors.

Prioritise tasks and manage workload to avoid being overloaded or distracted. Using checklists and briefing passengers or students of impending cockpit tasks and increases in workload will manage the risk of errors through distraction If in doubt, hold or orbit and remember that help and assistance is available from ATC or D&D (121.500MHz) for VHF equipped aircraft.

Post-Flight Review the flight and consider what went well along with what threats were encountered and what errors were made during the flight. Think about how well these were managed and what could have been done differently to improve the management of similar threats and errors during future flights.