TEM Flight Deck Applications
The use of TEM on the flight deck is an important part of the aviation safety management system. It is seen as the last line of defense in controlling risks to the system. These risks are the situations and events which reduce operational safety and the probability of safe flight. TEM on the flight deck has been compared to defensive driving for a motorist in an aviation context i.e. “defensive flying for pilots”. It maximizes safety margins through a proactive philosophy of anticipation, recognition, and recovery through the use of techniques for managing threats, errors and undesired aircraft states. (Merritt & Klinect, 2006).
Flight crews operate in a complex system composed of technological, organizational, environmental and human factors. Effective interaction with all its components is essential if they are to successfully manage the risks posed by everyday operations. An important part of flight deck risk management is the ability of the crew to manage threats, errors and undesired aircraft states that occur as a result of their work activities. Threats and errors are a part of everyday life on the flight deck and have the potential to impact on safe flight by creating undesired outcomes; the objective of TEM on the flight deck is to manage these aspects effectively.
Threats, Errors and Undesired Aircraft States
"Threats are events or errors that occur beyond the influence of the flight crew increasing the operational complexity of a flight" placing attention and management demands on the crew if safety margins are to be maintained. The level of demand threats place on crew range from insignificant and able to be managed discreetly to complex sequences of events interacting with each other requiring significant attention from the crew (Merritt & Klinect, 2006).
The TEM framework groups threats into two broad categories;
|Weather: Thunderstorms, turbulence, poor visibility, wind shear, icing conditions, IMC, extreme temperatures.|
|ATC: Tough-to-meet clearances/restrictions, reroutes, language difficulties and inconsistent terminology or units of measure (QFE/metres), traffic congestion, controller errors, similar call-signs|
|Airport: Confusing or faint signage/markings, runway/taxiway closures, Inoperative or complex navigational aids, poor braking action, contaminated runways/taxiways, birds, airport construction.|
|Terrain: High ground, slopes, lack of visual references (black hole effects and other visual illusions)|
|Operational Pressure: On-time performance pressure, delays, late arriving aircraft or flight crew, poorly matched crew i.e experience with route.|
|Aircraft: Aircraft systems, engines, flight controls, or automation anomalies or malfunctions; MEL/CDL items with operational implications; other aircraft threats requiring flight crew attention.|
|Cabin: Cabin events, flight attendant errors, distractions, interruptions, door security.|
|Maintenance: Aircraft repairs on ground, maintenance log problems, maintenance events and errors|
|Ground/Ramp: Aircraft loading events, fuelling errors, agent interruptions, improper ground support, de-icing|
|Dispatch: Load sheet errors, crew scheduling events, late paperwork, changes or errors|
|Documentation: Errors or missing information in manuals or charts, inadequate SOP's (Standard Operating Procedures).|
"Errors are actions or inactions by the flight crew that lead to events that were not what the organization or flight crew intended or expected". Unmanaged or mismanaged, they can create or contribute to undesired aircraft states which compromise flight safety and increase the probability of adverse events.
The TEM model groups errors under three categories; aircraft handling, procedural and communication errors. This way of classifying errors is based on "primary interaction" or what the crew were doing as the error was committed. (e.g. incorrect flap extension, the crew interact with the aircraft controls so this is classified as an Aircraft handling error)
|Flight Control: Manual handling errors such as speed and position deviations, incorrect flaps, speed brake, auto-brake, thrust reverser or power settings.|
|Automation: Incorrect entries or mode selections i.e. settings for altitude, speed, heading, auto-throttle settings.|
|Systems/Radio/Instruments: Incorrect packs, altimeter, fuel switch or radio frequency settings or incorrect anti-icing techniques.|
|Ground Navigation: Attempting to turn down wrong taxiway or runway, selection of incorrect taxiway, runway or gate, taxi speed too fast and failure to hold in the correct position.|
|Departure from SOP's: Departure from standard operating procedures i.e. intentional or unintentional failure to cross-verify automation inputs, Pilot Flying (PF)/Pilot Not Flying (PNF) Duty PF makes own automation changes, PNF doing PF duties, PF doing PNF duties, deviations from government regulations, flight manual requirements.|
|Briefings: Omitted briefings or items missed i.e. omitted departure, takeoff, approach, or handover briefing.|
|Checklists: Incorrect challenges or responses, items missed, performed from memory, checklist performed late or at the wrong time.|
|Callouts: Omitted or incorrect takeoff, descent, or approach callouts.|
|Documentation: Incorrect weight and balance, fuel information, ATIS, clearance recorded, or misinterpretation of paperwork items i.e metric imperial data, incorrect logbook entries or incorrect application of MEL procedures.|
|Crew to External (ATC): Misinterpreted instructions, missed calls, incorrect read-backs, wrong clearances communicated i.e. for taxiway, gate or runway.|
|Pilot to Pilot: Miscommunication or misinterpretation between crew i.e. handover instructions.|
Undesired Aircraft States
Undesired aircraft states are conditions caused by the crew that could reduce normal margins for safety. These are often the result of poor threat and error management by the crew and require some form of action.
The following table shows some examples of undesired aircraft states based on the three categories in the TEM model.
|Vertical, lateral or speed deviations|
|Unnecessary weather penetration or unauthorized airspace penetration|
|Unstable approach or long, floated, firm or off-centerline landings.|
|Operation outside aircraft limitations|
|Runway or taxiway incursions|
|Wrong taxiway, ramp, gate, or hold spot|
|Taxi above speed limit|
|Incorrect Aircraft Configuration|
|Incorrect systems configuration|
|Incorrect flight controls configuration|
|Incorrect automation configuration|
|Incorrect engine configuration|
|Incorrect weight and balance configuration|
- Procedures that flight deck crew use to manage threats, errors and undesired aircraft states are discussed in TEM Strategies and Countermeasures.