Flight Path Monitoring


Flight path monitoring means the observation and interpretation of the flight path data, aircraft-configuration status, automation modes and on-board systems appropriate to the phase of flight. It involves a cognitive comparison of real-time data against the expected values, modes and procedures. It also includes observation of the other pilot and timely intervention in the event of a deviation.

This definition covers anytime the aircraft is in motion, including during taxi. It also includes continuous awareness of both the trajectory and energy state of the aircraft.


Monitoring covers an extensive behavioural skill set that all pilots are expected to apply in the cockpit. The designated Pilot Flying (PF) is responsible for flying the aircraft in accordance with the operational brief and for monitoring the flight path. The Pilot Monitoring (PM) will have an explicit set of activities designated by the Standard Operating Procedures (SOPs) , and as such will have a specific and primary role to monitor the aircraft’s flight path, communications and the activities of the PF. Both pilots are responsible for maintaining their own situation awareness gained through cross-checking each other’s actions, communication of intent and diligent observation of the PF selections, mode activations and aircraft responses. Predictive monitoring supports anticipation of expected threats and the mitigation of consequences. Reactive monitoring enables the identification of unexpected/pop-up threats and mitigation of consequences; the detection and correction of errors; and the recognition of and recovery from undesired aircraft states.


The cognitive processes engaged during monitoring are complex and involve the selective application of mental resources to encode the sensory inputs whilst performing a goal directed task. The senses relating to flight path monitoring are mainly visual and auditory, but tactile inputs from the flight controls (e.g. stick shaker, aeroplane buffet, etc.) can influence the monitoring task particularly in the event of a stall. Similarly, the smell and taste senses can alert the flight crew to fumes in the cockpit and therefore also perform a monitoring stimulus. Intent also forms an important part of monitoring and provides a baseline against which to monitor. Intent relates to system behaviour (what it is going to do), aircraft handling (predicted flight path/aircraft manoeuvrability) and Pilot Flying’s intent (the plan). Timely, accurate monitoring activities will result in outputs that, following crew judgement and decision making, can take the form of:

  • Verbalization to other pilot or self;
  • Non-verbal communication in the form of gesture/eye contact;
  • Note-taking in the case of auditory monitoring;
  • Reinforcement of collective situation awareness; and,
  • Maintenance of the mental model of the aircraft state.

Regarding physical ergonomics, pilots must be able to see and hear all information relevant to their monitoring tasks. Their seat positions must be adjusted to the design eye position to enable each pilot to view the internal displays and controls whilst maintaining an adequate view of the external scene. The optimal seat position is usually set by reference to two small balls on the central windscreen pillar. The balls appear aligned only when the pilot’s eye is at the design position.

Vision is a very complex subject and involves the ability of the eye to adapt to different lighting levels (called adaptation), focus on the information (normally referred to as accommodation) and to perceive information, such as texts and graphics, as legible at the required viewing distance (called visual acuity). Adaption, accommodation and acuity all vary with, and are affected by, age. Pilots need to be aware if they are experiencing any difficulty with focus, adaption or legibility of the displayed information as this will certainly compromise the monitoring task. Medical professionals will be able to advise on correction or treatment if necessary.

Hearing can be impaired by accumulation of wax in the outer ear (which is easily remedied), a head cold which blocks the Eustachian tube and prevents equalization of pressure or by infections in the middle ear. Hearing can be expected to deteriorate with age particularly with the higher frequencies. In addition, high ambient noise environment or distractions/interruptions in the cockpit can impact the clarity of aural messages. Under all circumstances, if there is any ambiguity related to information received aurally then ask for it to be repeated.

Barriers to Monitoring

Many factors hamper monitoring, including system and ergonomic design, organisational factors and external environment. But the biggest concern relates to human vulnerabilities, such as complacency/inattention, distraction, low attentional resource, low arousal, disorientation, tiredness etc, and stressors (i.e., workload, etc.). These concerns arise from some relatively recent accidents and incidents.

Safety experts emphasize that it can be difficult for humans to effectively monitor for errors and deviations on a continuous basis when errors and deviations rarely occur, particularly in a highly automated environment. This holds true over the range of workload conditions experienced by the flight crew members. Monitoring during high-workload periods is critical because these periods present situations in rapid flux and because high workload increases vulnerability to error. However, studies show that poor monitoring performance can be present during low-workload periods as well. Lapses in monitoring performance during lower-workload periods are often associated with boredom, complacency, or both.

Potential challenges and barriers to effective monitoring include:

  • Time Pressure – Time pressure can exacerbate high workload and increase errors. It can also lead to rushing and “looking without seeing."
  • Lack of Feedback – When monitoring lapses occur, pilots are often unaware that monitoring performance has degraded.
  • Design of SOPs – Procedures may fail to explicitly address monitoring tasks.
  • Automation – Pilots’ inadequate mental model of autoflight system modes. Pilots may not have a complete or accurate understanding of all functions and behaviours of the autoflight system. Some aspects of automated systems for flightpath management are not well matched to human information processing characteristics.
  • Training – Training may overlook the importance of monitoring and how to do it effectively. Lack of emphasis on monitoring may occur in training and evaluation.


While different types and levels of pilot training may involve pilots with differing levels of competence, the training of flight path monitoring should include uniform objectives and standards. Therefore, because the same monitoring concepts apply to all pilots, course content should not differentiate between different types of training courses. A graduated approach should be taken in developing an integrated pilot monitoring training program. It should start with solid grounding in theoretical knowledge, followed by instructor-led case studies. This should include videos and finally line-oriented flight training (LOFT), progressively building on each layer of content:

  • Knowledge – Without proper knowledge of systems and automation, the flight crew will not be able to understand nor predict the aircraft’s behaviour.
  • Skill – Without the necessary skills to operate the aircraft effectively, a flight crew will be overwhelmed by the flight path monitoring tasks.
  • Discipline – Discipline is a foundation for monitoring. Adherence to division of duties is essential for managing workload.
  • Attitude – Developing the right attitude often is the most important aspect of a training program.

Monitoring requires motivation and discipline and must be a continuous effort. The primary aim for flight crew members should be to effectively monitor the flight path, but first, flight crews must be well-trained in flying skills, discipline and behaviours . Without these, effective monitoring may not be possible.

Accidents & Incidents

On 2 September 2016, an ATR72-600 cleared to join the ILS for runway 28 at Dublin continued 800 feet below cleared altitude triggering an ATC safe altitude alert which then led to a go around from around 1000 feet when still over 5nm from the landing runway threshold. The Investigation attributed the event broadly to the Captain’s inadequate familiarity with this EFIS-equipped variant of the type after considerable experience on other older analogue-instrumented variants, noting that although the operator had provided simulator differences training, the -600 was not classified by the certification authority as a type variant.

On 27 April 2020, an ATR 72-200 freighter crew attempted a night takeoff in good visibility aligned with the edge of runway 06 and did not begin rejecting it until within 20 knots of the applicable V1 despite hearing persistent regular noises which they did not recognise as edge light impacts and so completed the rejection on the same alignment. The Investigation noted both pilots’ familiarity with the airport and their regular work together and attributed their error to their low attention level and a minor distraction during the turnround after backtracking.

On 22 August 2019, the left engine of a Boeing 737-800 failed for unknown reasons soon after reaching planned cruise level of FL360 twenty minutes after departing Samos, Greece and two attempted relights during and after descent to FL240 were unsuccessful. Instead of diverting to the nearest suitable airport as required by applicable procedures, the management pilot in command did not declare single engine operation and completed the planned flight to Prague, declaring a PAN to ATC only on entering Czech airspace. The Investigation noted that engine failure was due to fuel starvation after failure of the engine fuel pump.

On 13 September 2016, a Boeing 737-300 made an unstabilised approach to Wamena and shortly after an EGPWS ‘PULL UP’ warning due to the high rate of descent, a very hard landing resulted in collapse of the main landing gear, loss of directional control and a lateral runway excursion. The Investigation found that the approach had been carried out with both the cloudbase and visibility below the operator-specified minima and noted that the Captain had ignored a delayed go around suggestion from the First Officer because he was confident he could land safely as the two aircraft ahead had done.

On 10 April 2018, a Boeing 737-800 crew making a night takeoff from Brasilia did not see a small aircraft which had just landed on the same runway until it appeared in the landing lights with rotation imminent. After immediately setting maximum thrust and rotating abruptly, the 737 just cleared the other aircraft, an Embraer 110 whose occupants were aware of a large aircraft passing very low overhead whilst their aircraft was still on the runway. The Investigation attributed the conflict primarily to controller use of non-standard phraseology and the absence of unobstructed runway visibility from the TWR.

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