Avionics - Wikiparency

# Avionics **Avionics** — a [[Portmanteau|portmanteau]] of *aviation* and *[[Electronics|electronics]]* — is the electronic systems carried aboard [[Aircraft|aircraft]] and spacecraft: the radios that talk to the ground, the instruments and computers that measure and hold the aircraft's state, the navigation that knows where it is, the [[Autopilot|autopilot]] and [[Fly-by-wire|fly-by-wire]] flight controls that move it, the engine controllers, the collision- and terrain-warning systems, the recorders, the weather radar, and the mission sensors and data links of military aircraft. This page is the Avionics hub of Wikitube: the pair's skeleton, section by section, with one microsim per section that puts the governing arithmetic under the reader's hand. The [[Pitot–static_system|pitot–static]] sim turns two pressures into airspeed and altitude; the [[Global_Positioning_System|GPS]] sim solves four unknowns from pseudoranges and lets a fifth satellite catch a lie; the [[Instrument_landing_system|ILS]] sim shows why the needles get twitchy near the runway; the [[Radar]] sim is the fourth-root range equation; and the [[MIL-STD-1553]] sim shows that a data bus is a schedule. The sister hub [[Aviation]] carries the airframes the same electronics fly; six sections are shared between the two pages and built once. ## Links (Wikipedia order)  `ACARS` · `Acronyms_and_abbreviations_in_avionics` · `ADS-B` · `Aerial_reconnaissance` · `Africa` · `Air_defense` · `Air_navigation` · `Air_traffic_control` · `Air_traffic_management` · `Airband` · `Airborne_early_warning` · `Airborne_radio_relay` · `Airbus_A350` · `Airbus_A380` · `Aircraft` · `Aircraft_Data_Network` · `Aircraft_Electronics_Association` · `Aircraft_heading` · `Airliner` · [[Alternating_current]] · `Amplitude_modulation` · `Anti-submarine_warfare` · `ARINC` · `ARINC_429` · `ARINC_629` · `ARINC_664` · `Arinc_708` · `ARINC_717` · `ARINC_825` · `ASTOR` · `Astrionics` · `Autopilot` · `Aviation_Week_&_Space_Technology` · `Avidyne_Corporation` · `Avionic_bay` · `Avionics_Full-Duplex_Switched_Ethernet` · `Avionics_software` · `Bendix_Aviation` · `Boeing_777` · `Boeing_787` · `Boeing_Starliner` · `Bowman_(communications_system)` · `Business_aviation` · `CAN_bus` · `Cathode_ray_tube` · `Clear-air_turbulence` · `Cockpit` · `Collins_Aerospace` · `Commercial_Standard_Digital_Bus` · `Controlled_flight_into_terrain` · `Coronal_mass_ejection` · `Cryptography` · `Dipping_sonar` · `Direct_current` · `DO-178C` · `E-3D` · `Electronic_counter-countermeasures` · [[Electronics]] · `Emergency_locator_beacon` · `Emergency_position-indicating_radiobeacon` · `Environmental_Control_and_Life_Support_System` · `European_Geostationary_Navigation_Overlay_Service` · `Federal_Aviation_Administration` · `Flight_control_surfaces` · `Flight_recorder` · `Fly-by-wire` · `Forward_looking_infrared` · `Fourth_generation_jet_fighter` · `Galactic_cosmic_rays` · `Garmin` · `GE_Aviation_Systems` · `General_aviation` · `Glass_cockpit` · `GPS` · `Ground-proximity_warning_systems` · `Grumman_F-14_Tomcat` · `Gulfstream_Aerospace` · `Head-up_display` · `Health_and_usage_monitoring_systems` · `Helicopter` · `Honeywell_Aerospace` · `IEEE_1394b` · `India` · `Inertial_navigation_system` · `Infrared_search_and_track` · `Instrument_meteorological_conditions` · `Integrated_modular_avionics` · `Israel_Aerospace_Industries` · `Joint_Planning_and_Development_Office` · `JSTARS` · `JTRS` · `Lawrence_Sperry` · `Leonardo_(company)` · `Life-support_system` · `Lightning_detector` · `Link_11` · `Link_16` · `Link_22` · `Local-area_augmentation_system` · `LORAN` · `Magnetron` · `McDonnell_Douglas_F-15E_Strike_Eagle` · `Merlin_HM_Mk_1` · `MIL-STD-1553` · `MIL-STD-1760` · `Military_aircraft` · `Morse_code` · `Navigational_aid` · `NEXRAD` · `Next_Generation_Air_Transportation_System` · `Nimrod_MRA4` · `Operating_temperature` · `Orion_(spacecraft)` · `Panasonic_Avionics_Corporation` · `Parker_Aerospace` · `Parker_Hannifin` · `Passive_infrared_sensor` · `Philip_J._Klass` · `Police_helicopter` · `Portmanteau` · `Radar` · `Radiation_hardening` · `Radio_communication` · `Radio_navigation` · `Radiotelegraphy` · `Raytheon` · `Retrofit` · `Rockwell_Collins` · `Satellite_navigation` · `Searchlight` · `Selex_ES` · `Simplex_communication` · `Single_European_Sky_ATM_Research` · `Solar_flare` · `Sonobuoy` · `Space_Shuttle` · `SpaceX_Dragon_2` · `Stormscope` · `Target_acquisition` · `Telegraph_key` · `Terrain-following_radar` · `Terrain_awareness_warning_system` · `TETRA` · `Thales_Group` · `The_Boeing_Company` · `Thrust` · `Time-Triggered_Protocol` · `Tizard_Mission` · `TM_(triode)` · `Traffic_alert_and_collision_avoidance_system` · `Transponder` · `Triode` · `Turbulence` · `Two_way_radio` · `Ultra_high_frequency` · `United_States_Navy` · `Universal_Avionics_Systems_Corporation` · `UTC_Aerospace_Systems` · `Vacuum_tube` · `Very_high_frequency` · `VHF_omnidirectional_range` · `WAAS` · `Weather_radar` · `Wind_shear` · `World_War_I` · `World_War_II` · `Zeppelin` ## History Avionics as a discipline began when electronics replaced the pilot's hands and eyes one function at a time: Lawrence Sperry's gyroscopic autopilot of 1914, radio navigation between the wars, radar and the first digital computers in the Second World War, inertial navigation in the 1950s, and satellite navigation, fly-by-wire and the glass cockpit from the 1970s on.[^ellingson96] The market and the modern architecture are the two subsections below; the rest of the page takes each system in the pair's order. ### Modern avionics *Main article: [[Integrated_modular_avionics]] · See also: [[ARINC_653]]* Where a federated aircraft gave every function its own box, integrated modular avionics runs many functions as partitions on shared processors and keeps them apart in time and memory: an ARINC 653 schedule gives each partition a window in every minor frame, a partition that overruns waits for its next window, and the display never loses its time to the maintenance job.[^arinc653] The sim is that schedule. <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Integrated_modular_avionics.html" data-title="Integrated modular avionics"></div> *Try:* raise the maintenance partition's demand past its window and watch its backlog grow while the display bars stay untouched; tick "federated" to see the same work in three boxes. Connects to: [[#Radiation and the environment]] · [[#Aircraft networks]] · [[#Aircraft flight-control system]] #### Radiation and the environment *Main article: [[Radiation_hardening]] · See also: [[Single-event_upset]], [[Cosmic_ray]]* At cruise altitude the flux of cosmic-ray neutrons is hundreds of times the sea-level value, and a single particle can flip a bit in a memory cell — a single-event upset. Avionics is hardened by process, by redundancy and by voting; the existing Wikitube sim shows the upset rate against altitude and feature size. <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/Radiation_hardening.html" data-title="Radiation hardening"></div> *Try:* climb from sea level to cruise altitude and watch the upset rate climb with the neutron flux. Connects to: [[#Modern avionics]] · [[#Satellite navigation]] ### Market The avionics market divides into the transport aircraft, business and general aviation, and military segments, each with its own certification regime and its own suppliers; the sections below describe the systems, not the companies, and the pair article carries the industry figures. ## Aircraft avionics ### Communications *Main article: [[Airband]] · See also: [[Line-of-sight_propagation]], [[Very_high_frequency]], [[ACARS]], [[Controller–pilot_data_link_communications]]* Aircraft talk to the ground on the VHF airband, 118–137 MHz, in amplitude-modulated voice on 25 kHz or 8.33 kHz channels, and the real limit of the band is not power but the horizon: 1.23(√h1 + √h2) nautical miles for heights in feet, about 230 nmi from 35 000 ft. Inside the horizon the link budget — transmitter power less free-space loss against a noise floor of *kT0BF* — has tens of decibels to spare; past it the signal falls off a cliff and HF or satellite communication takes over.[^ellingson96][^nichols389] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Airband.html" data-title="Airband"></div> *Try:* fly the aircraft past the station's horizon and watch the received power drop off the chart; climb to 45 000 ft and get it back. Connects to: [[#Surveillance: transponders and ADS-B]] · [[#Navigation]] · [[#Military communications]] #### Surveillance: transponders and ADS-B *Main article: [[Automatic_Dependent_Surveillance–Broadcast]] · See also: [[Secondary_surveillance_radar]], [[Transponder_(aeronautics)]], [[Air_traffic_control_radar_beacon_system]]* Secondary radar asks and the transponder answers, once per antenna sweep, so a plot goes stale by the aircraft's speed times the sweep period; ADS-B has the aircraft broadcast its own satellite position every second, and the plot is stale by at most a second's travel. This section is shared with the [[Aviation]] hub, where air traffic control is the subject; here the sim is the surveillance itself.[^ellingson96] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Automatic_Dependent_Surveillance–Broadcast.html" data-title="Automatic Dependent Surveillance–Broadcast"></div> *Try:* switch from SSR to ADS-B and watch the stale-distance sawtooth collapse from kilometres to metres. Connects to: [[#Communications]] · [[#Radar]] · [[Aviation#Air traffic control]] ### Navigation *Main article: [[Radio_navigation]]* Before satellites an aircraft found itself by radio: a bearing to a beacon, a distance from a transponder, a hyperbolic line from the time difference between two stations. The existing Wikitube sim draws the lines of position; the three subsections below are the modern stack — air data, inertial navigation and satellite navigation — and the landing system that brings the stack to the runway. <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/Radio_navigation.html" data-title="Radio navigation"></div> *Try:* move the aircraft and watch its lines of position from two stations cross. Connects to: [[#Air data]] · [[#Satellite navigation]] · [[#The instrument landing system]] #### Air data *Main article: [[Pitot–static_system]] · See also: [[Airspeed]], [[Altimeter]], [[Air_data_computer]], [[Pitot_tube]], [[International_Standard_Atmosphere]]* Two pressures make three instruments. The pitot tube stops the air and reads the total pressure; the static port reads the ambient pressure; their difference, the impact pressure, gives the calibrated airspeed, the static pressure alone gives the pressure altitude against the standard atmosphere, and its rate of change gives the vertical speed. The air-data computer turns the same two pressures and the outside temperature into true airspeed, Mach number and density altitude.[^marchman32][^ruijgrok405] Block the pitot and the airspeed indicator becomes an altimeter; block the static port and every instrument lies at once.[^faaweather95] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Pitot–static_system.html" data-title="Pitot–static system"></div> *Try:* select "pitot blocked" and climb: the indicated airspeed rises while the true airspeed does not; select "static blocked" and watch the altimeter freeze. Connects to: [[#Monitoring]] · [[#Inertial navigation]] · [[Aviation#General aviation]] #### Inertial navigation *Main article: [[Inertial_navigation_system]] · See also: [[Attitude_and_heading_reference_system]], [[Schuler_tuning]], [[Fibre-optic_gyroscope]], [[Ring_laser_gyroscope]]* An inertial system integrates accelerometers and gyros to dead-reckon without any signal from outside, and its error grows with time: an accelerometer bias as *t²*, a gyro drift as *t³*, until Schuler tuning — a platform that behaves like a pendulum as long as the Earth's radius, period 84.4 minutes — bounds the accelerometer term and leaves a drift of about a nautical mile per hour for a navigation-grade gyro of 0.01 °/h.[^teunissen33][^dyer] GNSS aiding resets the error to metres and a dropout lets it grow again from there. <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Inertial_navigation_system.html" data-title="Inertial navigation system"></div> *Try:* turn Schuler tuning off at 1 °/h and watch the error run away in a cubic; turn GNSS aiding on and give it a thirty-minute dropout. Connects to: [[#Air data]] · [[#Satellite navigation]] · [[#Monitoring]] · [[Aviation#Weight and balance]] #### Satellite navigation *Main article: [[Global_Positioning_System]] · See also: [[Satellite_navigation]], [[Dilution_of_precision]], [[Receiver_autonomous_integrity_monitoring]], [[Wide_Area_Augmentation_System]]* A GPS receiver measures its distance to each satellite it can hear, offset by its own clock error, and solves four unknowns — three of position and one of time — from four or more pseudoranges; the geometry of the satellites in view multiplies the ranging noise into the position error (dilution of precision), and a fifth satellite lets the receiver test whether the residuals fit the noise and exclude a satellite that lies (RAIM).[^teunissen21][^teunissen81] Augmentation systems such as WAAS broadcast corrections that bring the error under a metre. <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Global_Positioning_System.html" data-title="Global Positioning System"></div> *Try:* put a 100 m fault on the highest satellite with RAIM on and watch it excluded; raise the mask angle to 40° and lose the fix. Connects to: [[#Inertial navigation]] · [[#The instrument landing system]] · [[#Surveillance: transponders and ADS-B]] #### The instrument landing system *Main article: [[Instrument_landing_system]] · See also: [[Autoland]]* The ILS is two radio planes: a localizer that marks the runway's centreline and a glideslope that marks a 3° path to it, each as a difference in the depth of modulation of two tones. The cockpit needles read angle, not distance, so a full-scale deflection is 3100 ft of offset at ten miles and 430 ft at the threshold — the needles get twitchier as the runway nears — and the category minima say how low the crew may follow them.[^aim119] Autoland couples the autopilot to the same two planes and adds a flare law. <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Instrument_landing_system.html" data-title="Instrument landing system"></div> *Try:* fly 0.15 nmi right and 120 ft high at five miles and read the dots; close to half a mile with the same offset and watch both needles peg. Connects to: [[#Navigation]] · [[#Autopilot]] · [[#Monitoring]] ### Monitoring *Main article: [[Flight_instruments]] · See also: [[Electronic_flight_instrument_system]], [[Glass_cockpit]], [[Engine-indicating_and_crew-alerting_system]]* The six-pack is three systems in six dials: the pitot–static instruments (airspeed, altimeter, vertical speed), the vacuum gyros (attitude, heading) and the electric gyro (turn coordinator); a glass cockpit's primary flight display shows the same data from the same probes and an attitude-heading reference system. Knowing which system feeds which instrument is how a pilot tells which one is lying when a pump or a bus fails.[^phak8] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Flight_instruments.html" data-title="Flight instruments"></div> *Try:* fail the vacuum pump and watch the attitude indicator and heading indicator drift while the PFD holds; fail the electrical bus and watch the PFD go dark. Connects to: [[#Air data]] · [[#Head-up display]] · [[#Inertial navigation]] #### Head-up display *Main article: [[Head-up_display]] · See also: [[Synthetic_vision_system]]* A head-up display projects the flight symbology on a combiner in the pilot's line of sight, collimated to infinity so the eye need not refocus between the symbols and the world; the flight-path vector it shows is where the aircraft is going, not where its nose points. The existing Wikitube sim draws the symbology over the scene. <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/Head-up_display.html" data-title="Head-up display"></div> *Try:* pitch and bank the aircraft and watch the flight-path vector part from the boresight. Connects to: [[#Monitoring]] · [[#The instrument landing system]] ### Aircraft flight-control system *Main article: [[Fly-by-wire]] · See also: [[Aircraft_flight_control_system]], [[Flight_control_modes]]* In a fly-by-wire aircraft the pilot's inceptor commands a computer, the computer commands the actuators, and the control law between them can stabilise an airframe built unstable, enforce the envelope and change its modes with the phase of flight. This section is shared with the [[Aviation]] hub; the existing Wikitube sim is the loop. <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/Fly-by-wire.html" data-title="Fly-by-wire"></div> *Try:* disturb the aircraft and watch the control law bring it back where the bare airframe would diverge. Connects to: [[#Autopilot]] · [[#Engine control]] · [[Aviation#The flight envelope]] · [[Aviation#Fly-by-wire]] #### Autopilot *Main article: [[Autopilot]] · See also: [[Autothrottle]], [[Autoland]]* An autopilot is a cascade of loops: the inner loop holds attitude, the next holds heading and altitude, the outer follows a track or a glidepath from the navigation systems, and the autothrottle holds speed or thrust alongside. The existing Wikitube sim is the cascade. <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/Autopilot.html" data-title="Autopilot"></div> *Try:* change the commanded altitude and watch the loops answer from the inside out. Connects to: [[#Aircraft flight-control system]] · [[#The instrument landing system]] · [[#Aircraft management systems]] #### Engine control *Main article: [[FADEC]] · See also: [[Compressor_stall]], [[Compressor_map]]* A full-authority digital engine controller sits between the thrust lever and the fuel valve so that the compressor never stalls: on the compressor map the running line sits below the surge line, a slammed lever would drive the operating point across it, and the FADEC's acceleration schedule holds the surge margin while the spool catches up.[^ruijgrok176][^nasaglenn] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/FADEC.html" data-title="FADEC"></div> *Try:* slam the lever with the FADEC on and watch the point ride the gold schedule; slam it with the FADEC off and watch the surge. Connects to: [[#Autopilot]] · [[Aviation#The jet age]] · [[Aviation#The turbofan]] ### Fuel Systems *Main article: [[Aircraft_fuel_system]]* The fuel system is tanks, pumps, valves and gauging, and on a large aircraft it is also a centre-of-gravity control: fuel moved to a tail trim tank in cruise walks the CG aft at constant weight and trims the aircraft with less drag, and the burn sequence walks it back. This section is shared with the [[Aviation]] hub, where the moments are the subject; the sim is the same aircraft with a trim tank.[^amt239] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Aircraft_fuel_system.html" data-title="Aircraft fuel system"></div> *Try:* move 30 kg to the tail tank and watch the cruise CG walk aft at constant weight; burn the fuel wing-first and tail-last. Connects to: [[Aviation#Weight and balance]] · [[#Aircraft management systems]] ### Collision-avoidance systems *Main article: [[Traffic_collision_avoidance_system]] · See also: [[Airborne_collision_avoidance_system]]* TCAS interrogates the transponders of nearby aircraft, tracks their range and closure, and issues a traffic advisory and then a coordinated resolution advisory — climb or descend — when the time to the closest approach falls below its thresholds. The existing Wikitube sim, moved to its canonical title this run, plays the encounter. <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Traffic_collision_avoidance_system.html" data-title="Traffic collision avoidance system"></div> *Try:* fly two aircraft toward each other and watch the advisory escalate as the time to closest approach shrinks. Connects to: [[#Surveillance: transponders and ADS-B]] · [[#Terrain awareness]] · [[Aviation#Air traffic control]] #### Terrain awareness *Main article: [[Terrain_awareness_and_warning_system]] · See also: [[Ground_proximity_warning_system]], [[Controlled_flight_into_terrain]]* A terrain awareness and warning system compares the aircraft's position and flight path with a terrain database and warns ahead of the ground; the ground-proximity warning system it grew from looked only down, with a radio altimeter. This section is shared with the [[Aviation]] hub, where controlled flight into terrain is the accident it closes. The existing Wikitube sim, moved to its canonical title this run, draws the look-ahead envelope. <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Terrain_awareness_and_warning_system.html" data-title="Terrain awareness and warning system"></div> *Try:* descend toward rising terrain and watch the caution and then the warning fire ahead of the ridge. Connects to: [[#Collision-avoidance systems]] · [[#Satellite navigation]] · [[Aviation#Aviation accidents and incidents]] ### Flight recorders *Main article: [[Flight_recorder]] · See also: [[Underwater_locator_beacon]], [[Aliasing]], [[Nyquist–Shannon_sampling_theorem]]* A flight data recorder samples each parameter at a fixed rate — accelerations several times a second, attitudes and altitude once a second, slower channels less often — into a loop of the last 25 hours, and the rate decides what an investigator can reconstruct: a 0.8 Hz oscillation sampled at 1 Hz reads as a 0.2 Hz wobble that never happened, because the samples fit the alias as well as the truth.[^tiberius108][^app-b] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Flight_recorder.html" data-title="Flight recorder"></div> *Try:* sample the 0.8 Hz roll at 1 Hz and watch the red alias wave pass through every dot; raise the sample rate past twice the frequency and the wobble disappears. Connects to: [[#Monitoring]] · [[#Collision-avoidance systems]] ### Weather systems *Main article: [[Weather_radar]] · See also: [[Lightning_detector]]* Airborne weather radar reads rain as reflectivity — Marshall and Palmer's *Z = 200 R^1.6*, so 20 mm/h is about 44 dBZ — and its X-band pulses are attenuated by the same rain they measure, which hides whatever lies behind a strong cell. Tilt decides whether the beam sees the cell or overshoots it.[^marshall][^faaweather116] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Weather_radar.html" data-title="Weather radar"></div> *Try:* raise the cell to 150 mm/h and 20 km wide and watch the cell behind it vanish from the display; switch to C band and watch it come back. Connects to: [[#Wind shear]] · [[#Radar]] #### Wind shear *Main article: [[Wind_shear]] · See also: [[Airborne_wind_shear_detection_and_alert_system]], [[Downburst]]* A reactive wind-shear system computes the F-factor from the aircraft's own accelerations — the rate of change of the headwind over *g* less the downdraft over the airspeed — and calls the alert when it passes a threshold; a predictive system reads the same shear ahead with the weather radar's Doppler channel. This section is shared with the [[Aviation]] hub, where the flight through the microburst is the subject; here the alert is.[^ruijgrok199] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Airborne_wind_shear_detection_and_alert_system.html" data-title="Airborne wind shear detection and alert system"></div> *Try:* watch the red F-factor trace cross the alert line at 17 s and the escape follow; raise the shear and watch it fire earlier. Connects to: [[#Weather systems]] · [[#Monitoring]] · [[Aviation#Wind shear]] ### Aircraft management systems *Main article: [[Flight_management_system]] · See also: [[Electronic_flight_bag]]* The flight management system plans the descent backwards from the runway: the top of descent is the energy height to lose divided by the idle gradient, the cost index sets the cruise Mach, and a late clearance leaves energy on board that has nowhere to go.[^afh87][^ruijgrok212] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Flight_management_system.html" data-title="Flight management system"></div> *Try:* clear the descent at 80 nmi instead of the planned 126 and read the excess altitude at the runway. Connects to: [[#Autopilot]] · [[#Satellite navigation]] · [[Aviation#Air transport]] ## Mission or tactical avionics ### Military communications *Main article: [[Link_16]] · See also: [[Tactical_data_link]], [[Time-division_multiple_access]], [[Frequency-hopping_spread_spectrum]]* Link 16 deals 1536 time slots per 12-second epoch among its participants and hops each pulse across 51 channels between 969 and 1206 MHz, so a jammer that covers ten channels takes a fifth of the hops and a Reed–Solomon (31,15) code recovers most messages; only a barrage over the whole band, wide enough to lose the 17 dB processing gain, breaks the net.[^ellingson179][^steer224][^milstd6016] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Link_16.html" data-title="Link 16"></div> *Try:* widen the jammer from 10 channels to all 51 and watch the coded message rate fall from 86 % to zero. Connects to: [[#Communications]] · [[#ESM/DAS]] ### Radar *Main article: [[Radar]] · See also: [[Radar_cross_section]], [[Pulse-Doppler_radar]], [[Radar_horizon]], [[Airborne_early_warning_and_control]]* The echo falls with the fourth power of range, so the detection range grows only with the fourth root of transmitter power, antenna gain squared and target cross section; the receiver's noise floor *kT0BF* and the signal-to-noise ratio it needs set the threshold, the pulse width sets the resolution, and the pulse repetition frequency sets the range beyond which an echo is ambiguous.[^ellingson96][^nichols389] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Radar.html" data-title="Radar"></div> *Try:* raise the peak power from 100 kW to 1 MW and watch the detection ring grow by less than a factor of two; raise the PRF until the ring passes the unambiguous ring. Connects to: [[#Weather systems]] · [[#ESM/DAS]] · [[#Surveillance: transponders and ADS-B]] · [[Aviation#Air traffic control]] ### Sonar *Main article: [[Sonobuoy]] · See also: [[Sound_speed_profile]], [[SOFAR_channel]], [[Underwater_acoustics]], [[Sonar]]* Sound in the sea bends toward the depth where it travels slowest: rays launched in the warm mixed layer duct along the surface, rays that dive through the thermocline are refracted back up from the deep, and between the two lies a shadow zone where a hydrophone hears nothing. A sonobuoy dropped from a maritime patrol aircraft hangs its hydrophone at a chosen depth in that geometry, and the passive sonar equation says how far it hears.[^munk][^manual11] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Sonobuoy.html" data-title="Sonobuoy"></div> *Try:* raise the hydrophone from 200 m into the mixed layer and get contact; deepen the layer and watch the trapped rays follow it. Connects to: [[#Radar]] · [[#Electro-optics]] ### Electro-optics *Main article: [[Forward-looking_infrared]] · See also: [[Infrared_search_and_track]], [[Infrared_window]], [[Thermography]], [[Planck's_law]]* Every warm body radiates by Planck's law, and its peak wavelength is Wien's 2898 μm·K over the temperature: a 600 K exhaust peaks near 4.8 μm and a 300 K body near 10 μm, which is why mid-wave infrared sees engines and long-wave infrared sees people. The atmosphere is transparent in two windows, 3–5 and 8–12 μm, with a carbon-dioxide notch at 4.3 μm, and a FLIR image is the band radiance through them.[^manual10][^planck] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Forward-looking_infrared.html" data-title="Forward-looking infrared"></div> *Try:* switch the band from MWIR to LWIR and watch the background rise to grey; lengthen the path to 10 km and watch the target fade. Connects to: [[#Sonar]] · [[#Radar]] ### ESM/DAS *Main article: [[Radar_warning_receiver]] · See also: [[Electronic_warfare]], [[Radar_jamming_and_deception]], [[Electronic_counter-countermeasure]]* One way beats two: the radar's echo comes back as *R⁻⁴* but the radar warning receiver hears the radar's own transmission as *R⁻²*, so the receiver hears the radar the moment it clears the horizon, long before the echo climbs out of the noise. A jammer's advantage grows as *R²* until burn-through, where the echo's power overtakes it.[^nichols389][^ellingson96] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/Radar_warning_receiver.html" data-title="Radar warning receiver"></div> *Try:* lower the receiver's sensitivity to −40 dBm and watch both ranges land on the chart; raise the jammer's power and watch the burn-through range shrink. Connects to: [[#Radar]] · [[#Military communications]] ### Aircraft networks *Main article: [[MIL-STD-1553]] · See also: [[ARINC_429]], [[Avionics_Full-Duplex_Switched_Ethernet]], [[CAN_bus]]* A data bus is a schedule. MIL-STD-1553's bus controller commands every transfer on a 1 Mbit/s dual-redundant bus: a command word, up to 32 data words and a status word at 20 μs each, plus the terminal's response time and a gap, so about 28 full messages fit a 20 ms minor frame. ARINC 429 is a one-way 100 kbit/s word bus; AFDX is switched Ethernet with a bandwidth-allocation gap per virtual link.[^milstd1553][^arinc429] <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/flight/MIL-STD-1553.html" data-title="MIL-STD-1553"></div> *Try:* ask for 40 messages of 32 words in a 10 ms frame and watch the schedule overflow in red. Connects to: [[#Modern avionics]] · [[#Monitoring]] · [[#Engine control]] ## See also [[Aviation]] · [[Aircraft]] · [[Aerospace_engineering]] · [[Avionics_software]] · [[Flight_deck]] · [[Glass_cockpit]] · [[Integrated_modular_avionics]] · [[Radio_navigation]] ## Notes [^ellingson96]: Ellingson, *Radio Systems Engineering*, pp. 96–107 (thermal noise, sensitivity, the radio horizon). [^ellingson179]: Ellingson, pp. 179–180 (spread spectrum and processing gain). [^nichols389]: Nichols et al., *Cyber-Human Systems, Space Technologies, and Threats*, pp. 389–403 (link budgets in decibels). [^steer224]: Steer, *Microwave and RF Design: Radio Systems*, pp. 224–227 (frequency hopping). [^teunissen21]: Teunissen, *Network Quality Control*, pp. 21–37 (least-squares positioning and DOP). [^teunissen33]: Teunissen, *Network Quality Control*, pp. 33–35 (error propagation in dead reckoning). [^teunissen81]: Teunissen, *Testing Theory*, pp. 81–111 (the overall model test and data snooping — RAIM's statistics). [^dyer]: Dyer and Davis, *Measurement and Instrumentation*, the inertial-sensor chapter (pages to pin in the article pass). [^tiberius108]: Tiberius and Mulder, *Engineering Signal Analysis*, pp. 108–122 (sampling and aliasing). [^marchman32]: Marchman, *Aerodynamics and Aircraft Performance*, pp. 32–40 (airspeed measurement). [^ruijgrok176]: Ruijgrok, Voskuijl and Varriale, *Elements of Airplane Performance*, pp. 176–180 (jet propulsion). [^ruijgrok199]: Ruijgrok et al., pp. 199–201 and 392–395 (wind shear). [^ruijgrok212]: Ruijgrok et al., pp. 212–235 (climb, descent and the performance diagram). [^ruijgrok405]: Ruijgrok et al., pp. 405 and 411 (airspeeds and the standard atmosphere). [^afh87]: FAA, *Airplane Flying Handbook* FAA-H-8083-3C, pp. 87–105 (energy management). [^faaweather95]: FAA, *Aviation Weather Handbook* FAA-H-8083-28B, pp. 95–109 (the standard atmosphere and pressure instruments). [^faaweather116]: FAA, *Aviation Weather Handbook*, pp. 116–133 (convective weather, wind shear and airborne radar). [^amt239]: FAA, *Aviation Maintenance Technician Handbook — General* FAA-H-8083-30B, pp. 239–241 (weight and balance). [^phak8]: FAA, *Pilot's Handbook of Aeronautical Knowledge* FAA-H-8083-25C, chapter 8 (flight instruments). [^aim119]: FAA, *Aeronautical Information Manual*, §1-1-9 (instrument landing system). [^arinc653]: ARINC Specification 653 (avionics application software standard interface); RTCA DO-178C (software considerations in airborne systems). [^milstd6016]: MIL-STD-6016 (tactical data link message standard) — public figures for Link 16's slots, hops and code. [^milstd1553]: MIL-STD-1553B (digital time division command/response multiplex data bus). [^arinc429]: ARINC Specification 429 and ARINC 664 Part 7 (AFDX). [^nasaglenn]: NASA Glenn Research Center, Beginner's Guide to Propulsion — compressor maps and surge margin. [^app-b]: 14 CFR Part 121, Appendix B (flight recorder parameters and sampling intervals) — the rates in the sim are a subset, to be verified against the eCFR text in the article pass. [^marshall]: Marshall and Palmer, "The distribution of raindrops with size", *Journal of Meteorology* 5 (1948), pp. 165–166. [^munk]: Munk, "Sound channel in an exponentially stratified ocean, with application to SOFAR", *J. Acoust. Soc. Am.* 55 (1974), doi:10.1121/1.1914492. [^manual11]: Wikitube sub-manual 11, §9.3 (impedance boundaries; Portal Book 091, pp. 38–47). [^manual10]: Wikitube sub-manual 10, §5.1 (Portal Books 119, pp. 278–280, and 097, p. 99 — infrared radiometry). [^planck]: Planck, "Ueber das Gesetz der Energieverteilung im Normalspectrum", *Annalen der Physik* 4 (1901), pp. 553–563. ## Further reading - Ellingson, S. W., *Radio Systems Engineering* (2023) — Portal Book 011. - Steer, M., *Microwave and RF Design: Radio Systems* (2019) — Portal Book 010. - Teunissen, P. J. G., *Testing Theory* and *Network Quality Control* (2024) — Portal Books 033 and 034. - Tiberius, C. and Mulder, J., *Engineering Signal Analysis* (2026) — Portal Book 100. - Dyer, S. A. and Davis, R., *Measurement and Instrumentation* (2020) — Portal Book 014. - Nichols, R. K. et al., *Cyber-Human Systems, Space Technologies, and Threats* (2023) — Portal Book 089. - Ruijgrok, G. J. J., Voskuijl, M. and Varriale, C., *Elements of Airplane Performance* (2025) — Portal Book 008. - Marchman, J. F., *Aerodynamics and Aircraft Performance*, 3rd ed. (2004) — Portal Book 005. ## External links - [Wikitube microsim set for this hub](https://wikitube-3d-microsims.netlify.app/flight/manifest.json) — every sim on this page and its sources, one JSON row each. - [FAA handbooks and manuals](https://www.faa.gov/regulations_policies/handbooks_manuals) — the Portal Books 006, 007 and 081 and the PHAK. ## Microsims The sims on this page are the Avionics half of the *flight* set built by the Wikitube microsim framework (`MICROSIM_GUIDE/specs/`, pack `PORTAL_Aviation_Avionics`), one per section: [[Integrated_modular_avionics]], [[Airband]], [[Automatic_Dependent_Surveillance–Broadcast]], [[Pitot–static_system]], [[Inertial_navigation_system]], [[Global_Positioning_System]], [[Instrument_landing_system]], [[Flight_instruments]], [[FADEC]], [[Aircraft_fuel_system]], [[Flight_recorder]], [[Weather_radar]], [[Airborne_wind_shear_detection_and_alert_system]], [[Flight_management_system]], [[Link_16]], [[Radar]], [[Sonobuoy]], [[Forward-looking_infrared]], [[Radar_warning_receiver]] and [[MIL-STD-1553]], with the existing [[Radiation_hardening]], [[Radio_navigation]], [[Head-up_display]], [[Fly-by-wire]], [[Autopilot]], [[Traffic_collision_avoidance_system]] and [[Terrain_awareness_and_warning_system]] sims reused in their sections. Each article carries its own sim and the See-also variants built beside it; every number a sim shows comes from `libs/wt-flight.js` with the book, page or standard in the sim's sources, and anything a fit stands in for says ILLUSTRATIVE on screen. ## Minnesota Honeywell's aerospace business grew out of the Minneapolis-Honeywell Regulator Company, whose autopilots, gyros and flight-control electronics were built in Minneapolis from the 1940s; the state remains home to avionics and sensor manufacturing, to Cirrus Aircraft's glass-cockpit singles in Duluth, and to the University of Minnesota's aerospace engineering department.[^mn] [^mn]: Minnesota Historical Society (Honeywell corporate records); Cirrus Aircraft, Duluth; University of Minnesota Department of Aerospace Engineering and Mechanics — institutional sources to be linked in the article pass. ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Avionics) : [Wikitube](https://en.wikitube.io/wiki/Avionics) ## Previous hub tags Room: [[PORTAL_Avionics]]. Legacy hubs: none (new hub seeded 2026-08-05). --- *Text adapted from [Wikipedia](https://en.wikipedia.org/wiki/Avionics), licensed [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/). Seed stub minted 2026-08-05 alongside PORTAL_Avionics.*  ## Microsim-first spine · expanded 2026-08-05 ### Movement I — three.js (live) **Fibre-optic gyroscope.** Two counter-propagating laser beams in a coiled fibre; the Sagnac phase shift between them reads rotation directly. See [[Fibre-optic_gyroscope]] for the live player and full explanatory text. **Ring laser gyroscope.** The same Sagnac principle in a solid ring cavity instead of a coiled fibre — no moving parts but the dither motor. See [[Ring_laser_gyroscope]] for the live player. Both sensing technologies feed [[Inertial_navigation_system|inertial navigation]], the dead-reckoning core of aircraft guidance when GPS is jammed or unavailable. ### Movement II — concept spine (publish-ready, text transferred/sourced 2026-08-05) | Station | Article | Note | |---|---|---| | 1 | [[Radar]] | Full text transfer (Signal-Processing lane) — range/direction/velocity from a returned wave. Shared with [[PORTAL_Aviation]]. | | 2 | [[Inertial_navigation_system]] | Dead-reckoning navigation from accelerometers + gyroscopes; drift vs. GPS fusion. | | 3 | [[Fibre-optic_gyroscope]] | Sagnac-effect rotation sensing, coiled fibre, no moving parts. | | 4 | [[Ring_laser_gyroscope]] | Sagnac-effect rotation sensing, ring cavity, sub-0.01°/hour drift. | | 5 | [[Autopilot]] | Sensor → flight computer → actuator loop; heading/altitude/attitude hold. | | 6 | [[Fly-by-wire]] | Mechanical linkages replaced by electronic signalling + envelope protection. | ## Sibling spine [[Aviation]] is the airframe-and-flight twin of this hub — same aircraft, the physical vehicle these systems fly inside. Shared stations across both spines: [[Aircraft]], [[Helicopter]], [[Air_traffic_control]], [[Radar]]. Portal doors: [[PORTAL_Aviation]] · [[PORTAL_Avionics]]. *Spine expanded 2026-08-05 · Radar full-text transfer, two live three.js gyroscope microsims wired, remaining concept articles Wikipedia-sourced with three.js queued · append-only, 0 deletions.*