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11.13.5 Human Factor Considerations


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Since the introduction of the basic instrument flying T designed by the Royal Air Force in 1927, manufacturers have been developing systems that reduce pilot workload.

The above instrument panel has now been developed into the glass cockpit designs that pilots in modern aircraft have become accustomed to. A simple design is shown below. Note that the basic T is still adhered to.

Operating an aircraft has changed as automation has increased. Automation provides the pilot with:

  • Alternate methods of accomplishing tasks.
  • Having more capacity to spare for the job in hand.

With the increased use of automation it is essential that:

  • The automatics work reliably and in a predictable manner.
  • The instruments are easy to read with little or no chance of misunderstanding.
  • The pilots understand the operating limits and limitations of the system.

Part of the problem of difficulty in reading and understanding instruments can be shown with the three pointer altimeter below:

  • The instrument is difficult to read.
  • Making an error in reading the altitude is easy.
  • However, the instrument is accurate.
Flight Crew Functions

Flight crew perform 4 primary functions during flight

  • Flight Management: Flying the aircraft.
  • Communications Management: Monitoring and response to internal and external communications during the flight.
  • Systems Management: Monitoring and actioning of all systems during flight.
  • Task Management: The management of tasks and resources needed in the conduct of the flight.

Human Factors Concepts in Design The primary functions of the flight crew must be taken into account. Most designers and manufacturers take into account the following when designing aircraft automatics:

  • Integration of fail safe concepts for the flight crew.
  • Adapting the automatics for minimal workload for the crew.
  • Easy to understand systems which allow easy monitoring.
  • Better Liveware - Hardware interfacing.
  • Comprehensive information flow.
  • Easy to correct instruments and systems.
  • Sensible error tolerance factors.

Automation has to be seen as a partial, or even total replacement, of the pilot. Obviously, the amount of pilot - machine interface depends upon the level of automation required.

Common Problems with Automation

The advance in computer technology has meant a rapid advance in cockpit automation. There are obvious benefits in the new technology but there are still serious accidents where flight crew management of the systems is inadequate. Corrections are made for these deficiencies, as a problem is uncovered. The most significant areas where there is a breakdown are:

  • Training: Training can cover the essentials of operating the system in normal flight; but is the training sufficient to operate the system in a degraded mode. Over use of the computer can result in a degradation of the pilot's flying skills, especially on NDB approaches.
  • Design Philosophy: There is still the perennial problem of the designer not consulting the pilot. There must be consultation to ensure that problem areas can be dealt with before manufacture. Radical changes have occurred over the last few years with the introduction of concepts such as side stick control.
  • Situational Awareness and Complacency: To maintain situational awareness is essential in all flights. The reliability and accuracy of modern systems lead pilots into an over-reliance on what they think is a no fail system. Boredom results and the pilot becomes inattentive. Reaction times to an emergency when a pilot is in this low-aroused state are slow and prone to errors.
  • Design Protection: Different manufacturers take different approaches to this problem. Some design systems which are intolerant of human error, others allow margins for human error. In either system there must be a crew warning system to ensure that the computer and pilot work together and not against each other.
  • Manual Override: If the situation deteriorates there must be a method of manual reversion for the pilot. Accidents have occurred where the pilot has not been able to revert to manual control and the aircraft has continued on its computer flight path.
  • Information Management: Too much information can confuse and overload the pilot. The time taken to input information means less time to the tasks of lookout and communications. In some aircraft deciding what to display can distract from the task in hand.
  • Automation Management: The computer is always right!
  • Communication: Lack of awareness leads to breakdowns in communications and procedures.
Industry Requirements

To ensure that the implementation of new systems meets the performance standards required industry must follow certain guidelines:

  • Design reviews and evaluation of automation must be carried out before manufacture.
  • Some form of human factors certification of automation must be possible.
  • Validity of all designs must be proven.
  • The role of the pilot must be specified including his task management responsibilities.
  • Training courses have to be developed to ensure that both normal and degraded operations are covered in depth.
  • Standards should be developed for all displays and the colours to be used.
Flight Crew Responsibilities

To ensure that the operation remains safe and that for both normal and emergency procedures the pilots carry out the required task:

Flight Crew Responsibilities

To ensure that the operation remains safe and that for both normal and emergency procedures the pilots carry out the required task:

Normal Operations

All selections and actions are checked by both pilots. One pilot actions the other pilot checks. It must always be remembered:

  • The autopilot is not a pilot but an aid to help workload and situational awareness.
  • Flight parameters must be continuously monitored.
Emergency Procedures

The aircraft must be flown and the following actioned:

  • Time should be taken in identifying the problem.
  • ECAM actions should be followed.
  • Where an irreversible action has to be completed then there must be a positive check by both pilots.
Automation Summary

There are both advantages and disadvantages to automation. Whether you are for or against the automation of the flight deck it must always be remembered that both the computer and the human being are not infallible. Listed below are some of the advantages and disadvantages.


  • Performs most of the control tasks allowing the pilot to perform other higher mental functions.
  • Removes the human element from day to day performance.
  • Can reduce the crew size.
  • Better control of systems making the aircraft more economic


  • Is the pilot reduced to a button pusher?
  • Does the pilot lose interest in the job?
  • Removes the most flexible asset who can resolve non-SOP problems.
  • Automation does cause accidents.
  • Increases the mental workload with the need to monitor the system carefully.
  • Handling skills are infrequently practiced.
  • Complacency and boredom set in.

A recent FAA survey listed the main contributory factors in automated aircraft accidents:

  • Pilot's who have an insufficient knowledge of the systems they are using.
  • Confusion involved when not knowing the mode of flight.
  • Liveware - Software design mismatches.
  • Systems behaviour when modes are changed - what information is being shown.
  • Over reliance on the computer.
  • Non SOP operations.

Note that most of the above are problems with the human element. Automation at its best should help the pilot; at its worst it kills. To make the best of the systems provided the pilot needs to be both trained and motivated to operate at a high performance level.