Aerospace Engineering

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Where I read random articles from across the web to bore you to sleep with my soothing voice.

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Benjamin Boster.

Today's episode is from a Wikipedia article titled Aerospace Engineering.

Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft.

It has two major and overlapping branches,

Aeronautical engineering and astronautical engineering.

Avionics engineering is similar,

But deals with the electronic side of aerospace engineering.

Aeronautical engineering was the original term for the field,

As flight technology advanced to include vehicles operating in outer space.

The broader term aerospace engineering has come into use.

Aerospace engineering,

Particularly the astronautics branch,

Is often colloquially referred to as rocket science.

Overview.

Flight vehicles are subjected to demanding conditions,

Such as those caused by changes in atmospheric pressure and temperature,

With structural loads applied upon vehicle components.

Consequently,

They are usually the products of various technological and engineering disciplines,

Including aerodynamics,

Propulsion,

Avionics,

Materials science,

Structural analysis,

And manufacturing.

The interaction between these technologies is known as aerospace engineering.

Because of the complexity and number of disciplines involved,

Aerospace engineering is carried out by teams of engineers,

Each having their own specialized area of expertise.

History.

The origin of aerospace engineering can be traced back to the aviation pioneers around the late 19th to early 20th centuries.

Although the work of Sir George Cayley dates from the last decade of the 18th to mid 19th century.

One of the most important people in the history of aeronautics and a pioneer in aeronautical engineering,

Cayley is credited as the first person to separate the forces of lift and drag,

Which affect any atmospheric flight vehicle.

Early knowledge of aeronautical engineering was largely empirical,

With some concepts and skills imported from other branches of engineering.

Some key elements,

Like fluid dynamics,

Were understood by 18th century scientists.

In December 1903,

The Wright brothers performed the first sustained controlled flight of a powered heavier than air aircraft lasting 12 seconds.

The 1910s saw the development of aeronautical engineering through the design of World War I military aircraft.

Between World Wars I and II,

Great leaps were made in the field,

Accelerated by the advent of mainstream civil aviation.

Notable airplanes of this era include the Curtiss JN-4,

The Farman F-60 Goliath,

And the Fokker Trimotor.

Notable military airplanes of this period include the Mitsubishi A6M-0,

The Super Marine Spitfire,

And the Messerschmitt Bf 109 from Japan,

United Kingdom,

And Germany respectively.

A significant development in aerospace engineering came with the first operational jet engine powered airplane,

The Messerschmitt Me 262,

Which entered service in 1944 towards the end of the Second World War.

The first definition of aerospace engineering appeared in February 1958,

Considering the Earth's atmosphere and outer space as a single realm,

Thereby encompassing both aircraft aero and spacecraft space under the newly coined term aerospace.

In response to the USSR launching the first satellite,

Sputnik,

Into space on October 4,

1957,

US aerospace engineers launched the first American satellite on January 31,

1958.

The National Aeronautics and Space Administration was founded in 1958 as a response to the Cold War.

In 1969,

Apollo 11,

The first manned space mission to the Moon took place.

It saw three astronauts enter orbit around the Moon,

With two,

Neil Armstrong and Buzz Aldrin,

Visiting the lunar surface.

The third astronaut,

Michael Collins,

Stayed in orbit to rendezvous with Armstrong and Aldrin after their visit.

An important innovation came on January 30,

1970,

When the Boeing 747 made its first commercial flight from New York to London.

This aircraft made history and became known as the Jumbo Jet,

Or whale,

Due to its ability to hold up to 480 passengers.

Another significant development in aerospace engineering came in 1976,

With the development of the first passenger supersonic aircraft,

The Concorde.

The development of this aircraft was agreed upon by the French and British on November 29,

1962.

On December 21,

1988,

The Antonov An-225 Miraya cargo aircraft commenced its first flight.

It holds the record for the world's heaviest aircraft,

Heaviest airlifted cargo,

And longest airlifted cargo,

And has the widest wingspan of any aircraft in operational service.

On October 25,

2007,

The Airbus A380 made its maiden commercial flight from Singapore to Sydney,

Australia.

This aircraft was the first passenger plane to surpass the Boeing 747 in terms of passenger capacity with a maximum of 853.

The development of this aircraft began in 1988 as a competitor to the 747.

The A380 made its first test flight in April 2005.

Elements Some of the elements of aerospace engineering are radar cross-section,

The study of vehicle signature apparent to remote sensing by radar,

And the study of aerodynamics.

Fluid mechanics The study of fluid flow around objects,

Specifically aerodynamics concerning the flow of air over bodies,

Such as wings or through objects such as wind tunnels.

Astrodynamics The study of orbital mechanics including prediction of orbital elements when given a select few variables.

While few schools in the United States teach this at the undergraduate level,

Several have graduate programs covering this topic,

Usually in conjunction with the physics department of said college or university.

Statics and Dynamics Engineering Mechanics The study of movement,

Forces,

Moments in mechanical systems.

Mathematics In particular calculus,

Differential equations,

And linear algebra.

Electric technology The study of electronics within engineering.

Propulsion The energy to move a vehicle through the air or in outer space is provided by internal combustion engines,

Jet engines,

And turbo machinery or rockets.

A more recent addition to this module is electric propulsion and ion propulsion.

Physical engineering The study of mathematical modeling of the dynamic behavior of systems and designing them,

Usually using feedback signals,

So that their dynamic behavior is desirable,

Stable without large excursions with minimum error.

This applies to the dynamic behavior of aircraft,

Spacecraft,

Propulsion systems,

And subsystems that exist on aerospace vehicles.

Aircraft Structures Design of the physical configuration of the craft to withstand the forces encountered during flight.

Aerospace engineering aims to keep structures lightweight and low cost while maintaining structural integrity.

Materials science Related to structures,

Aerospace engineering also studies the materials of which the aerospace structures are to be built.

New materials with very specific properties are invented or existing ones are modified to improve their performance.

Solid mechanics Closely related to material science is solid mechanics which deals with stress and strain analysis of the components of the vehicle.

Nowadays there are several finite element programs such as MSC,

PATRON,

NASTRON,

Which aid engineers in the analytical process.

Aerial elasticity The interaction of aerodynamic forces and structural flexibility,

Potentially causing flutter,

Divergence,

Etc.

Avionics The design and programming of computer systems on board an aircraft or spacecraft and the simulation of systems.

Software The specification,

Design,

Development,

Test,

And implementation of computer software for aerospace applications including flight software,

Ground control software,

Test and evaluation software,

Etc.

Risk and reliability The study of risk and reliability,

Assessment techniques,

And the mathematics involved in the quantitative methods.

Noise control The study of the mechanics of sound transfer.

Aerial acoustics The study of noise generation via either turbulent fluid motion or aerodynamic forces interacting with surfaces.

Flight testing Designing and executing flight test programs in order to gather and analyze performance and handling qualities data in order to determine if an aircraft meets its design and performance goals and certification requirements.

The basis of most of these elements lies in theoretical physics such as fluid dynamics for aerodynamics or the equations of motion for flight dynamics.

There is also a large empirical component.

Historically,

This empirical component was derived from testing of scale models and prototypes,

Either in wind tunnels or in the free atmosphere.

More recently,

Advances in computing have enabled the use of computational fluid dynamics to stimulate the behavior of the fluid,

Reducing time and expense spent on wind tunnel testing.

Those studying hydrodynamics or hydroacoustics often obtain degrees in aerospace engineering.

Additionally,

Aerospace engineering addresses the integration of all components that constitute an aerospace vehicle,

Subsystems including power,

Aerospace bearings,

Communications,

Thermal control,

Life support,

Etc.

And its life cycle,

Design,

Temperature,

Pressure,

Radiation,

Velocity,

Lifetime.

Three programs.

Aerospace engineering may be studied at the advanced diploma,

Bachelor's,

Master's,

And PhD levels in aerospace engineering departments at many universities and in mechanical engineering departments at others.

The few departments offer degrees in space-focused astronautical engineering.

Some institutions differentiate between aeronautical and astronautical engineering.

Graduate degrees are offered in advanced or specialty areas for the aerospace industry.

A background in chemistry,

Physics,

Computer science,

And mathematics is important for students pursuing an aerospace engineering degree.

In popular culture,

The term rocket scientist is sometimes used to describe a person of great intelligence,

Since rocket science is seen as a practice requiring great mental ability,

Especially technically and mathematically.

The term is used ironically in the expression,

It's not rocket science,

To indicate that a task is simple.

Strictly speaking,

The use of science in rocket science is a misnomer,

Since science is about understanding the origins,

Nature,

And behavior of the universe.

Engineering is about using scientific and engineering principles to solve problems and develop new technology.

However,

Science and engineering are often misused as synonyms.

Physics are the electronic systems used on aircraft,

Artificial satellites,

And spacecraft.

Avionics systems include communications,

Navigation,

The display and management of multiple systems,

And the hundreds of systems that are fitted to aircraft to perform individual functions.

These can be as simple as a searchlight for a police helicopter,

Or as complicated as the tactical system for an airborne early warning platform.

The term avionics is portmanteau of the words aviation and electronics.

The term avionics was coined in 1949 by Philip J.

Klass,

Senior editor at Aviation Week and Space Technology Magazine,

As a portmanteau of aviation electronics.

Radio communication was first used in aircraft just prior to World War I.

The first airborne radios were in zeppelins,

But the military sparked development of light radio sets that could be carried by heavier-than-air craft so that aerial resonance biplanes could report their observations immediately in case they were shot down.

The first experimental radio transmission from an airplane was conducted by the U.

S.

Navy August 1910.

The first aircraft radios transmitted by radio telegraphy,

So they required two-seat aircraft with a second crewman to tap on a telegraph key to spell out messages by Morse code.

During World War I,

AM voice two-way radio sets were made possible in 1917 by the development of the triode vacuum tube,

Which were simple enough that the pilot in a single-seat aircraft could use it while flying.

Radar,

The central technology used today in aircraft navigation and air traffic control,

Was developed by several nations,

Mainly in secret,

As an air defense system in the 1930s during the run-up to World War II.

Many modern avionics have their origins in World War II wartime developments.

For example,

Autopilot systems that are commonplace today began as specialized systems to help bomber planes fly steadily enough to hit precision targets from high altitudes.

Britain's 1940 decision to share its radar technology with its U.

S.

Ally,

Particularly the Magnetron vacuum tube,

In the famous Tizard mission,

Significantly shortened the war.

Modern avionics is a substantial portion of military aircraft spending.

Aircraft like the F-15E and the now-retired F-14 have roughly 20 percent of their budget spend on avionics.

Most modern helicopters now have budget splits of 60-40 in favor of avionics.

The civilian market has also seen a growth in cost of avionics.

Flight control systems,

Fly-by-wire,

And new navigation needs brought on by tighter airspaces have pushed up development costs.

The major change has been the recent boom in consumer flying.

As more people begin to use planes as their primary method of transportation,

More elaborate methods of controlling aircraft safely in these high restrictive airspaces have been invented.

Avionics plays a heavy role in modernization initiatives like the Federal Aviation Administration's FAA Next Generation Air Transport System project in the United States and the Single European Sky ATM Research Initiative in Europe.

The Joint Planning and Development Office put forth a roadmap for avionics in six areas.

Published routes and procedures,

Improved navigation and routing.

Negotiated trajectories,

Adding data communications to create preferred routes dynamically.

Relegated separation,

Enhanced situational awareness in the air and on the ground.

Low visibility,

Ceiling approach,

Departure.

Allowing operations with weather constraints with less ground infrastructure.

Surface operations to increase safety in approach and departure.

ATM efficiencies,

Improving the ATM process.

The Aircraft Electronics Association reports $1.

73 billion avionics sales for the first three quarters of 2017 in business and general aviation.

A 4.

1% yearly improvement.

73.

5% came from North America.

Forward fit represented 42.

3%.

While 57.

7% were retrofits as the US deadline of January 1,

2020 for mandatory ADS-B out approach.

The cockpit of an aircraft is a typical location for avionic equipment,

Including control,

Monitoring,

Communication,

Navigation,

Weather,

And anti-collision systems.

The majority of aircraft power their avionics using 14 or 28 volt DC electrical systems.

However,

Larger,

More sophisticated aircraft,

Such as airliners or military combat aircraft,

Have AC systems operating at 400 Hz,

150 volts AC.

There are several major vendors of flight avionics,

Including Panasonic Avionics Corporation,

Honeywell,

Which now owns Bendix King,

Universal Avionics Systems Corporation,

Rockwell Collisions,

Now Collins Aerospace,

Sales Group,

GE Aviation Systems,

Garmin,

Raytheon,

Parker Hanifin,

UTC Aerospace Systems,

Now Collins Aerospace,

Celex ES,

Now Leonardo SPA,

Shadden Avionics,

And Avidin Corporation.

International standards for avionics equipment are prepared by the Airlines Electronic Engineering Committee,

AEEC,

And published by ARINC.

Communications connect the flight deck to the ground and the flight deck to the passengers.

Report communications are provided by public address systems and aircraft intercoms.

The VHF aviation communications system works on the airband of 118 MHz to 136.

975 MHz.

Each channel is spaced from the adjacent ones by 8.

33 kHz in Europe,

25 kHz elsewhere.

VHF is also used for line of sight communication,

Such as aircraft to aircraft and aircraft to ATC.

Amplitude Modulation,

AM,

Is used,

And the conversation is performed in simplex mode.

Aircraft communication can also take place using HF,

Especially for trans-oceanic flights or satellite communication.

Air navigation is the determination of position and direction on or above the surface of the Earth.

Avionics can use satellite navigation systems such as GPS and WAAS,

INS,

Inertial navigation system,

Ground-based radio navigation systems such as VOR or LORAN,

Or any combination thereof.

Some navigation systems such as GPS calculate the position automatically and display it to the flight crew on moving map displays.

Older ground-based navigation systems such as VOR or LORAN requires a pilot or navigator to plot the intersection of signals on a paper map to determine an aircraft's location.

Modern systems calculate the position automatically and display it to the flight crew on moving map displays.

The first hints of glass cockpits emerged in the 1970s when flight-worthy cathode ray tube CRT screens began to replace electromechanical displays,

Gauges,

And instruments.

A glass cockpit refers to the use of computer monitors instead of gauges and other analog displays.

Aircraft were getting progressively more displays,

Dials,

And information dashboards that eventually competed for space and pilot attention.

In the 1970s,

The average aircraft had more than 100 cockpit instruments and controls.

Glass cockpits started to come into being with the Gulfstream G4 private jet in 1985.

One of the key challenges in glass cockpits is to balance how much control is automated and how much the pilot should do manually.

Generally,

They try to automate flight operations while keeping the pilot constantly informed.

Aircraft have means of automatically controlling flight.

Autopilot was first invented by Lawrence Sperry during World War I to fly bomber planes steady enough to hit accurate targets from 25,

000 feet.

When it was first adopted by the U.

S.

Military,

A Honeywell engineer sat in the backseat with bolt cutters to disconnect the autopilot in case of emergency.

Nowadays,

Most commercial planes are equipped with aircraft flight control systems in order to reduce pilot error and workload at landing or takeoff.

The first simple commercial autopilots were used to control heading and altitude and had limited authority on things like thrust and flight control surfaces.

In helicopters,

Auto-stabilization was used in a similar way.

The first systems were electromechanical.

The advent of fly-by-wire and electro-actuated flight surfaces rather than the traditional hydraulic has increased safety.

As with displays and instruments,

Critical devices that were electromechanical had a finite life.

With safety-critical systems,

The software is very strictly tested.

Fuel Quantity Indication Systems,

FQIS,

Monitors the amount of fuel aboard.

Using various sensors such as capacitance tubes,

Temperature sensors,

Densitometers,

And level sensors,

The FQIS computer calculates the mass of fuel remaining on board.

Fuel Control and Monitoring System,

FCMS,

Reports fuel remaining on board in a similar manner,

But by controlling pumps and valves also manages fuel transfers around various tanks.

Refueling control to upload to a certain total mass of fuel and distribute it automatically.

Transfers during flight to the tanks that feed the engines,

E.

G.

From fuselage to wing tanks.

Center of Gravity Control transfers from the tail trim tanks forward to the wings as fuel is expended.

Maintaining fuel in the wingtips to help stop the wings bending due to lift in flight,

And transferring to the main tanks after landing.

Controlling fuel jettison during an emergency to reduce the aircraft weight.

To supplement air traffic control,

Most large transport aircraft and many smaller ones use a Traffic Alert and Collision Avoidance System,

Which can detect the location of nearby aircraft and provide instructions for avoiding a mid-air collision.

Smaller aircraft may use simpler traffic alerting systems such as TPAS,

Which are passive,

They do not actively interrogate the transponders of other aircraft,

And do not provide advisories for conflict resolution.

To help avoid controlled flight into terrain,

Aircraft use systems such as Ground Proximity Warning Systems,

Which use radar altimeters as a key element.

One of the major weaknesses of GPWS is the lack of look-ahead information,

Because it only provides altitude above terrain,

Look down.

In order to overcome this weakness,

Modern aircraft use a Terrain Awareness Warning System.

Commercial aircraft cockpit data recorders,

Commonly known as black boxes,

Store flight information and audio from the cockpit.

They are often recovered from an aircraft after a crash to determine control settings and other parameters during the incident.

Weather systems such as weather radar typically Air Inc.

708 on commercial aircraft and lightning detectors are important for aircraft flying at night or in instrument meteorological conditions,

Where it is not possible for pilots to see the weather ahead.

Heavy precipitation,

As sensed by radar,

Or severe turbulence,

As sensed by lightning activity,

Are both indications of strong convective activity and severe turbulence,

And weather systems allow pilots to deviate around those areas.

Lightning detectors like the Stormscope or Strikefinder have become inexpensive enough that they are practical for light aircraft.

In addition to radar and lightning detection,

Observations and extended radar pictures such as Nexrad are now available through satellite data connections,

Allowing pilots to see weather conditions far beyond the range of their own in-flight systems.

Modern displays allow weather information to be integrated with moving maps,

Terrain,

And traffic onto a single screen,

Greatly simplifying navigation.

Modern weather systems also include wind shear and turbulence detection and terrain and traffic warning systems.

In-plane weather avionics are especially popular in Africa,

India,

And other countries where air travel is a growing market,

But ground support is not as well developed.

There has been a progression toward centralized control of the multiple complex systems fitted to aircraft,

Including engine monitoring and management.

Health and usage monitoring systems,

HUMs,

Are integrated with aircraft management computers to give maintainers early warnings of parts that will need replacement.

The integrated modular avionics concept proposes an integrated architecture with application software portable across an assembly of common hardware modules.

It has been used in fourth-generation jet fighters and the latest generation of airliners.

Military aircraft have been designed either to deliver a weapon or to be the eyes and ears of other weapon systems.

The vast array of sensors available to the military is used for whatever tactical means required.

As with aircraft management,

The bigger sensor platforms like the E3D,

JSTARS,

ASTAR,

ASTAR,

Nimrod M4A4,

Merlin HM Mk1 have mission management computers.

Police and EMS aircraft also carry sophisticated tactical sensors.

While aircraft communications provide the backbone for safe flight,

The tactical systems are designed to withstand the rigors of the battlefield.

UHF,

VHF,

Tactical and SATCOM systems combined with ECCM methods and cryptography secure the communications.

Data links such as LINK 11,

16,

22,

And Bowman,

JTRS,

And even Tetra provide the means of transmitting data such as images,

Targeting information,

Etc.

Airborne radar was one of the first tactical sensors.

The benefit of altitude-providing range has meant a significant focus on airborne radar technologies.

Radars include Airborne Early Warning,

AEW,

Anti Submarine Warfare,

ASW,

And even Weather Radar,

ARINC 708,

And Ground Tracking Proximity Radar.

The military uses radar and fast jets to help pilots fly at low levels.

While the civil market has had weather radar for a while,

There are strict rules about using it to navigate the aircraft.

Dipping sonar fitted to a range of military helicopters allows the helicopter to protect shipping assets from submarines or surface threats.

Maritime Support Aircraft can drop active and passive sonar devices,

Sonobuys,

And these are also used to determine the location of enemy submarines.

Electro-optic systems include devices such as the Heads-Up Display,

HUD,

Forward-Looking Infrared,

FLIR,

Infrared Search and Track,

And other passive infrared devices,

Passive infrared sensor.

These are all used to provide imagery and information to the flight crew.

This imagery is used for everything from search and rescue to navigational aids and target acquisition.

Electronic support measures and defensive aids are used extensively to gather information about threats or possible threats.

It can be used to launch devices,

In some cases automatically,

To counter direct threats against the aircraft.

They are also used to determine the state of a threat and identify it.

The avionics systems in military,

Commercial,

And advanced models of civilian aircraft are interconnected using an avionics data bus.

Common avionics data bus protocols with their primary application include aircraft data network,

Ethernet derivative for commercial aircraft,

Avionics full-duplex switched Ethernet,

Specific implementation of ARINC 664 for commercial aircraft,

ARINC 429 generic medium speed data sharing for private and commercial aircraft,

ARINC 664 CADN above,

ARINC 629 commercial aircraft Boeing 777,

ARINC 708 weather radar for commercial aircraft,

ARINC 717 flight data recorder for commercial aircraft,

ARINC 825 CAN bus for commercial aircraft,

For example Boeing 787 and Airbus A350,

Commercial standard digital bus IEEE 1394B military aircraft,

MIL STD 1553 military aircraft,

MIL STD 1760 military aircraft,

TTP time triggered protocol,

Boeing 787,

Airbus A380 fly-by-wire actuation platforms from Parker Aerospace,

TT Ethernet,

Time triggered Ethernet,

Orion spacecraft.

An emergency locator beacon is a radio beacon,

A portable battery-powered radio transmitter used to locate airplanes,

Vessels,

And persons in distress and in need of immediate rescue.

Various types of emergency locator beacons are carried by aircraft,

Ships,

Vehicles,

Hikers,

And cross-country skiers.

In case of an emergency,

Such as the aircraft crashing,

The ship sinking,

Or a hiker becoming lost,

A transmitter is deployed and begins to transmit a continuous radio signal,

Which is used by search and rescue teams to quickly find the emergency and render aid.

The purpose of all emergency locator beacons is to help rescuers find survivors within the so-called golden day,

The first 24 hours following a traumatic event,

During which the majority of survivors can usually be saved.

CoastBast-SARSAT is an international humanitarian consortium of governmental and private agencies,

Which acts as a worldwide dispatcher for search and rescue operations.

It operates a network of about 47 satellites carrying radio receivers,

Which detect distress signals from emergency locator beacons anywhere on Earth transmitting on the international CoastBast distress frequency of 406 MHz.

The satellites calculate the geographic location of the beacon within 2 kilometers by measuring the Doppler frequency shift of the radio waves due to the relative motion of the transmitter and the satellite,

And quickly transmit the information to the appropriate local first responder organizations,

Which perform the search and rescue.

Defined officially as Emergency Position Indicating Radio Beacon Stations in the ITU Radio Regulations,

These transmit a coded data burst once every 50 seconds,

Conforming to the CST.

001 specification for CoastBast-SARSAT 406 MHz distress beacons.

Compatible with the CoastBast-SARSAT satellite receivers,

The different types include ELTs,

Emergency Locator Transmitters,

Signal Aircraft Distress,

EPIRBs,

Emergency Position Indicating Radio Beacons,

Signal Maritime Distress,

SEPIRBs,

Submarine Emergency Position Indicating Radio Beacons,

REPIRBs designed only for use on submarines.

SSASs,

Ship Security Alert System,

Are used to indicate possible piracy or terrorism attacks on seagoing vessels.

PLBs,

Personal Locator Beacons,

Are for personal use and are intended to indicate a person in distress who is away from normal emergency services,

E.

G.

911.

They are also used for crew-saving applications in shipping and lifeboats at terrestrial systems.

In New South Wales,

Australia,

Some police stations and the National Parks and Wildlife Service provide Personal Locator Beacons to hikers for no charge.

Auxiliary Maritime Beacons,

ENOS Rescue System,

A rescue beacon system designed for use by divers who have drifted away from their dive boats.

Search and Rescue Transponder,

SART,

A specialized radar beacon,

RACON,

That emits a string of 12 dots replaced by arcs and circles when closer,

For display on an X-band radar screen when scanned.

Man-Overboard Beacons,

MSLDs,

Maritime Survivor Locating Devices,

Are Man-Overboard Signaling Devices,

First standardized in 2016.

A Maritime Survivor Locator Device,

MSLD,

Is a Man-Overboard Locator Beacon.

In the US,

Rules were established in 2016 in 47 CFR Part 95.

A MSLD may transmit on 121.

500 MHz,

Or one of these,

156.

525 MHz,

156.

750 MHz,

156.

800 MHz,

156.

850 MHz,

161.

975 MHz,

162.

025 MHz,

AIS SART,

A Handheld Automatic Identification System,

AIS,

Transmitter,

That emits only an emergency beacon.

It does not have a receiver,

And thus cannot be a transponder.

SEND,

Satellite Emergency Notification Devices TRACK PLUS,

Reliable Land Maritime and Aviation Beacons,

SPOT,

IN REACH,

SPIDER TRACKS,

YELLOW BRICK,

AVAILAGE BEACONS,

RECCO,

AVAILAGE TRANSCEIVER,

OTHER BEACONS,

MOUNTAIN LOCATOR UNIT,

AUTOMATIC PACKET REPORTING SYSTEM,

CRASH POSITION INDICATOR,

TRANSPONDER AERONAUTICS,

Can be used as an emergency beacon of sorts by setting it to a SQUAWK 7700,

The distress code.

SEND,

Satellite Emergency Notification Devices