human factors

Axis Interactions

• Aircraft dynamics involve complex interactions between axes:
  • Pitch Changes: Affect both altitude and airspeed.
  • Roll Changes: Intended for heading adjustments, also impact pitch and can increase stall risk.
• The skilled pilot must form a very accurate mental model of these flight dynamics to achieve effective control.
  • Conventionally, the difficult task of learning to control the aircraft has been addressed through many hours of training both in flight simulators and in the air to move the declarative knowledge of flight dynamics to effective procedural knowledge.
• Aircraft designers have been moving toward incorporating human factors display principles to design more "user-friendly" displays.  Given the sluggish nature of aircraft dynamics, a valuable feature on almost every advanced display is the availability of prediction (of future aircraft position) and preview (of future command input). Farther in the future and less well established in terms of its benefits is the implementation of 3-D displays

Maintaining Situation Awareness

Pilots need to maintain awareness of both external hazards and the state of automated systems. Effective display design is crucial for providing the right information at the right time:

• Head-Up Displays (HUDs): Allow monitoring without looking away from the outside view, though they must avoid clutter.
• Integrated Electronic Displays: Offer a broader view but must balance detail and precision to avoid reducing tracking accuracy.

Aircraft pilots must reliably execute a series of actions during flights. These actions can be routine (e.g., lowering landing gear, setting flaps) or contingent on unpredictable circumstances (e.g., closed runways, engine failures). Failure to follow procedures can be fatal, as demonstrated by the 1987 Detroit Metropolitan Airport crash, where neglecting to set the flaps led to a deadly accident.

• Checklists: Used to ensure all procedures are followed. Errors can occur due to top-down processing or distractions in a multitask environment. Due to the vast amount of procedural information (FAA Regulations, aircraft operating manuals), pilots cannot be expected to remember everything. To aid their prospective memory (remembering to do the right things at the right time), checklists are used. Checklists are extensive, covering different flight phases (preflight, taxi, takeoff) and operating conditions (normal, engine out, fire). Common error with checklists:
  • Top-Down Processing Errors: Under time pressure, pilots might "see" items in their expected state even if they are not.
  • Multitask Environment Distractions**: Distractions can cause pilots to skip steps in the checklist. Attention diverted by another task may return to the checklist at a later step, skipping the pending one.
• Human Factors Solutions to these errors:
  • Redundant Participation:
    • Involves two crew members verifying checklist items.
    • The "challenge and response" method: One crew member challenges the other to check an item and waits for a verbal response before proceeding.
  • Automation:
    • Automation can redundantly check and report the status of switches and tasks.
    • Electronic checklists may require pilots to actively confirm completion, ensuring monitoring of task status.

Teamwork in Piloting:

• Pilots operate as part of multiple teams:
  • Flight Deck Team: Collaboration with other flight crew members.
  • Air Traffic Control Team: Interaction with air traffic controllers managing their sector.
  • Onboard Mission Team: Coordination with personnel on specific missions (e.g., cabin crew, medical personnel, military operators).

Communication Importance:

• Communication, primarily via voice, is critical in aviation:
  • Incidents from Breakdown: Over half of flying incidents result from communication breakdowns.
  • Voice Communication Vulnerability: Errors can arise from both bottom-up and top-down processing.
  • Key Information Omissions: Failures often occur because essential information is not relayed, not just because of misheard statements.

Hierarchical Communication Challenges:

• Breakdowns often happen due to hierarchical dynamics:
  • Junior Crew Reluctance: Junior members may hesitate to point out issues to senior captains.
  • Senior Crew Responsibility: Senior members need to foster an open environment for information sharing.

Cockpit Resource Management (CRM):

• In response to these issues, CRM training was developed:
  • Training Components: Case studies of communication breakdowns. Simulated flight exercises with behavior critiques. Guidelines for fostering open communication and clear information sharing.
  • Guidelines: Emphasize assertiveness and clarity (e.g., direct statements about altitude).

Broadening CRM:

• CRM has evolved to include:
  • Wider Team Inclusion: Relevant for all teams, including cabin crew and air traffic controllers, as well as teams outside aviation (e.g., medical operating rooms).
  • Resource Inclusion: Covers all resources, including automated systems and the pilot's attentional resources.

CRM Effectiveness:

• CRM programs have proven effective:
  • Accident Rate Reduction: Significant drops in accident rates have been observed in organizations after implementing CRM programs.

Stringent Training and Licensing:

• Higher Standards: Training and licensing for pilots are much stricter compared to driving, reducing the prevalence of alcohol, fatigue, and age-related impairments.
• Perceived Risk: The higher perceived risk in flying contributes to these stringent requirements.

Physical and Psychological Stressors:

• Aircraft Environment: Loaded with potential stressors affecting performance both directly and indirectly.
• Student Pilots:
  • Psychological Stress: High risk of crashing increases stress, especially during early solo flights.
  • Cognitive Breakdowns: Stress can lead to breakdowns in information-processing skills, highlighting the need for extensive use of flight simulators for emergency training.

Other Stressors for Pilots:

• Military Pilots: Face combat danger, high gravitational forces, and physical restrictions.
• Light Aircraft Pilots: Prone to motion sickness and spatial disorientation, especially when flying in clouds.
• High Workload: Imposed on single pilots in bad weather, military pilots in combat, pilots before landing, and helicopter pilots on low-ground missions.
• Environmental Stressors: Vibration, noise, and heat can enhance physical stress, particularly for helicopter pilots.

Aircraft Automation

Forms of Automation:

• Autopilots: Assist with tracking tasks and reduce workload.
• Route Planners: Aid in navigation.
• Collision Avoidance Monitors: Enhance traffic and terrain monitoring.
• Flight Management Systems: Optimize flight paths for economic benefits (fuel conservation).

Human Factors in Automation:

• Many automation guidelines stem from accident analysis and research.
• Emphasis on human-centered automation to ensure safety and efficiency.

Role and Responsibilities:

• Air traffic controllers (ATCs) are responsible for managing the safe and efficient flow of aircraft through airspace, similar to industrial process control but with unique complexities:
  • Multiple Entities: Controllers manage multiple aircraft, each with dynamic interrelationships.
  • Conflicting Goals: They must balance safety (wide separation) with efficiency (high throughput of aircraft).

Types of Air Traffic Controllers:

• Tower Controllers: Manage aircraft on the ground, taxiing, takeoff, and landing.
• Terminal Radar Approach Controllers (TRACON): Control aircraft within 20-50 miles of airports using radar displays.
• En Route Controllers: Manage cross-country air traffic between TRACON areas, also using radar.

Control Process

• Verbal and Discrete Control: ATC uses verbal instructions or "clearances" to pilots, making voice communication critical.
• Inputs and Goals: Controllers aim to maximize traffic flow while ensuring safety through maintaining minimum separation between aircraft.
• Visual-Spatial Mental Model: Controllers interpret radar data, flight strips, and radio communications to maintain a "big picture" of the airspace.

System Sluggishness

• Delayed Response: Commands to aircraft (speed, altitude, heading) take time to manifest, necessitating prediction and planning.
• Predictor Displays: These aids help controllers anticipate future positions and potential conflicts.

Teamwork and Communication:

• Two Teams:
  • Controller and Pilots**: Ensuring coordinated actions.
  • Controllers at a Facility**: Handing off aircraft between sectors and providing mutual support.
• High Workload: The second source of difference from much of process control concerns work- load. Unlike process control, ATC workload is consistently high, with adaptive and maladaptive effects.

Safety and Efficiency:

• Redundancy and Professionalism: The ATC system is highly safe due to redundancy and skilled workforce.
• Pressure for Automation: There is ongoing pressure to automate ATC functions to improve efficiency and reduce delays.