Aircraft Safety Systems: Enhancing Flight Operations

Posted on Jan 30, 2025 in Architecture

Aircraft Safety Systems: Enhancing Flight Operations

Principal Risk Elements to Safe Aircraft Flight Operations

  • Loss of power
  • Loss of control
  • Stopping
  • Failure of aircraft structure
  • Aircraft fires
  • Mid-air collisions

Jet Engine Safety Contributions

  • Major increases in power, especially at high altitudes
  • More power available for engine failure situations
  • Much simpler controls = fewer opportunities for human failure
  • Ability to cruise at high altitudes, above most bad weather
  • Ability to climb quickly through bad weather
  • Dramatically increased reliability
  • Stronger airframes as a result of jet engine power, speed, and pressurization requirements

Airframe & Airports: Stopping Systems

  • Tire fuse plugs to prevent hot tire explosions
  • Anti-skid systems
  • Auto-braking systems in landing or aborted takeoff
  • Speed brakes and spoilers
  • Thrust reversers
  • Grooved runways
  • Engineered Materials Arresting Systems (EMAS)

Flight Deck: Man-Machine Interface and Crew Facilitation

  • Crew warning and alerting systems (WAS)
  • Aircraft Communications Addressing and Reporting System (ACARS)
  • Flight Management Systems (FMS)
  • Multiple flight control computers
  • Weather detection systems
  • Digital display systems (“glass cockpits”)
  • Heads-Up Displays (HUDs)
  • Electronic Flight Bags (EFBs)
  • Central Maintenance Computer System (CMCS)

Flight Deck Design Safety Enhancements

  • Simpler designs on many things, such as fuel management
  • Manufacturer standardization of cockpits between models
  • Crew alerting and monitoring systems
  • Moving map display
  • Engine indicating and crew alerting system (EICAS)
  • Glass cockpit displays with color
  • Aircraft Communications Addressing and Alerting

Central Maintenance Computer System

  • Used by maintenance personnel after flights
  • A centralized portal for:
    • Fault information storage
    • Real-time data monitoring
    • Systems testing
  • Provides for standardized systems testing interfaces
  • Greatly reduces time to diagnose and correct problems
  • Greatly increases “dispatch reliability”

Aircraft Communications Addressing and Reporting System (ACARS)

  • Communicates automatically and on command between the aircraft and airline ground base
  • Uses compressed digital format for short burst, high-volume transmissions
  • Automatically transmits all key operating parameters, systems health, and fault data
  • Ground personnel may query and monitor the systems at any time
  • Can be used to diagnose in-flight faults and make rapid ground repairs
  • Also used for ATC messaging, manifesting, flight scheduling info/data, etc.
  • Greatly reduces crew communications workload

Flight Management System (FMS)

  • FMS is the integration of four major systems:
    • Flight Management Computer System (FMCS)
    • Digital Flight Control System (DFCS)
    • Autothrottle (AT)
    • Inertial Reference System (IRS)
  • FMS has four major functions:
    • Automatic flight control
    • Performance management
    • Precision navigation
    • Systems monitoring

Flight Control Computers

  • Elevator/Aileron Computers (ELACS):
    • Primary control of elevators and ailerons
  • Spoiler/Elevator Computers (SECs):
    • Primary control of spoilers
    • Back-up control of roll and pitch via spoilers and elevators
  • Flight Augmentation Computers (FACs):
    • Control rudder for turn coordination and yaw damping
    • Compute flight envelope limits
    • Compute wind shear and speed information for Primary Flight Display (PFD)

Aircraft: Crew Alerting Systems

  • Multiple annunciators and warnings (visual and aural)
    • Fuel state
    • Improper gear, flap, spoiler, speed brake positioning
    • Engine and fuselage fires
    • Airspeed and altitude
  • Ground Proximity Warning System (GPWS & EGPWS)
  • Traffic Collision Avoidance System (TCAS)
  • Engine-Indicating and Crew-Alerting System (EICAS/ECAM)

Aircraft Stopping Systems

  • Slowing and stopping heavy jet airplanes is critical for safe operations on varied runway lengths and surface conditions
  • Several systems have been developed to reduce landing accidents:
    • Anti-skid
    • Auto-brakes
    • Speed brakes
    • Spoilers
    • Thrust reversers
    • Fuse plugs in tires
    • Engineered Materials Arrestor Systems (EMAS)

Cabin Safety

  • Loss of pressurization: passenger emergency O2
  • Improved seat and seat belt designs
  • Improved emergency exit lighting
  • Use of fire/fume retardant materials in cabin furnishings
  • Improved escape and water survival equipment

The Big Airplane Effect

  • Wake turbulence:
    • Especially hazardous in landing and takeoff
    • Heavier aircraft generate more powerful wakes
    • Risk is loss of control and airframe damage
  • Wake vortices (wake turbulence at altitude):
    • Occur in-flight when passing through the track of a heavy airplane
    • Unpredictable, invisible, possibly violent, up to 5 miles behind heavies
    • Can lead to upset
  • Jet blast:
    • Hot, powerful exhaust gases, perhaps > 200 kts
    • Direct force upsets and damages light aircraft and other equipment and facilities
    • Propels FOD with damaging force
  • Poor visibility from large airplane cockpits