AVIONICS for dummies

Introduction – MOSA, IMA, HAMOSA, and IT Virtualization Architecture

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Avionic Systems have traditionally been driven by hard real-time requirements, military standard

network interfaces, rugged processors, and high robustness languages (ex Ada) to satisfy safety and

security requirements Size, power, weight, and cost are critical parameters for avionics systems as

they directly affect mission endurance and mission effectiveness. The need to leverage COTS

processing, networking, and software has lead to wide spread use of Modular Open Systems

Architectures (MOSA) for avionics embedded systems. For a subset of those systems, requiring

certification, Integrated Modular Avionics (IMA) architectures have been developed leveraging ARINC

653 with time and space partitioning More recently, the need to support multiple level security

exchanges between platforms has driven the need for High Assurance MOSA (HAMOSA) based on

MILS/MLS technology. Extending the computing environment for connection to the Global

Information Grid (GIG) places new requirements for interoperability to support Windows and Linux

applications.

Communication Systems

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®VHF

®HF

®ACARS / AIRCOM

®Secal decoders

®SATCOM

arinc 429

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Unlike military standards, the ARINC 429 Specification is not a public document.
Aeronautical Radio, Inc. (ARINC) holds the copyright. Therefore, this
blog presents a commentary and review of the ARINC 429 Specification
but does not reproduce any sections of it.

ARINC itself is not a standard nor is it a piece of equipment. ARINC is an acronym
for Aeronautical Radio, Inc. The ARINC organization is the technical,
publishing and administrative support arm for the Airlines Electronic Engineering
Committee (AEEC) groups. The AEEC was formed in 1949 and is considered
the leading international organization in the standardization of air transport
avionics equipment and telecommunication systems. AEEC standards define
avionics form, fit, function, and interfaces. The AEEC is comprised of 27 airline
and related organizations. Representatives have engineering, operational, and
maintenance experience within their organization.

ARINC specifications are divided into four numbering systems and two basic
types. The numbering systems include the 400, 500, 600, and 700 series. The
groups are divided into general design requirements and terminal design standards
(characteristics). General Design requirements include the 400 and 600
series of documents. Specific terminal design and testing criteria (characteristics)
are set forth in the 500 and 700 series. The 500 series define older mostly
analog avionics equipment, much of which is still used in modern aircraft with
updated technologies. The 400 series documents are considered the general
design and supporting documents for the 500 series avionics equipment characteristics.
Similarly, the 600 series documents are considered the general design
and support documents for the 700 series of avionics equipment characteristics.
However, there may be some exceptions; suffice it to say that 700 series terminals
are generally digital systems. The 500 and 700 series documents are equipment
specific and, among other things, define how the unit shall operate,
including the input and output pathways for digital and analog information.

ARINC standards define design and implementation of everything from testing
requirements to navigational (NAV) systems to in-flight entertainment. Some
of the newer specifications cover digital systems, testing, development, and
simulation criteria. Aside from the specifications themselves, there are a number
of subgroups, other avionics organizations, and private manufacturers, all
of whom publish information regarding the implementation of avionics systems,
e.g. the General Aviation Manufacturer’s Association (GAMA), who
defines subgroup functionality.

Some of the most prevalent ARINC standards are ARINC 419, ARINC 575,
ARINC 429, ARINC 615, and ARINC 629. Of course, numerous others exist,
and many of the 500 series are considered obsolete. Generally, three specifications
define the characteristics of avionics buses: ARINC 419, ARINC 429, and
ARINC 629. A few of the avionics terminal specifications define their own
unique bus architecture, such as ARINC 709, which includes a high speed
RADAR imaging bus. ARINC 419 is the oldest and is considered obsolete.
However, it is important from a maintenance viewpoint. The vast majority of
avionics terminals employ ARINC 429 for their avionics bus. Currently, only
the Boeing 777 employs ARINC 629.

ADA in safety critical applications

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Ada Safety Critical.
This book gives an overview of how Ada is used in safety critical applications.

iontegrated modular avionics

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INTEGRATED MODULAR AVIONICS IMA

SATELLITES

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Receivers are auxiliary systems mounted on several types of satellites. This substantially reduces the program's cost.

The weather satellites that carry the SARSAT receivers are in "ball of yarn" orbits, inclined at 99 degrees. The longest period that all satellites can be out of line-of-sight of a beacon is about two hours.

The first satellite constellation was launched in the early 1970s by the Soviet Union, Canada, France and the USA.

Some geosynchronous satellites have beacon receivers. Since end of 2003 there are four such geostationary satellites (GEOSAR) that cover more than 80% of the surface of the earth. As with all geosynchronous satellites, they are located above the equator. The GEOSAR satellites do not cover the polar caps.

Since they see the Earth as a whole, they see the beacon immediately, but have no motion, and thus no doppler frequency shift to locate it. However, if the beacon transmits GPS data, the geosynchronous satellites give nearly instantaneous response.

28. HISTORY

The original impetus to the program in the U.S. was the loss of Congressmen Hale Boggs and Nick Begich in the Alaskan wilderness on October 16, 1972. A massive search effort failed to locate them. The result was a

U.S.

law mandating that all aircraft carry an emergency locator transmitter. Technical and organizational improvements followed.

Cospas-Sarsat is an international organization that has been a model of international cooperation, even during the Cold War. SARSAT means Search And Rescue SATellite. COSPAS is a Russian acronym with the same meaning. A consortium of Russia, the U.S., Canada and

France

formed the organization in 1982. Since then 29 others have joined.

Cospas-Sarsat defines standards for beacons, auxiliary equipment to be mounted on conforming weather and communication satellites, ground stations, and communications methods. The satellites communicate the beacon data to their ground stations, which forward it to main control centers of each nation that can initiate a rescue effort.

The U.S. Coast Guard once promoted an emergency beacon on maritime VHF emergency channels. It now promotes the superior Cospas-Sarsat system, and no longer services

STATUTORY EMERGENCY EQUIPMENT

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Most general aviation aircraft in the

U.S.

are required to carry an ELT, depending upon the type or location of operation, while most commercial airliners are not. 14 CFR 91.207. However, in commercial aircraft, a cockpit voice recorder or flight data recorder must contain an underwater detection beacon.

Most commercial off-shore working vessels with passengers are required to carry a self-deploying EPIRB, while most in-shore and fresh-water craft are not.

Most beacons are brightly-colored, waterproof, fit in a cube about 30 cm on a side, and weigh 2-5 kg. They can be purchased from marine suppliers, aircraft refitters, and (in Australia and the

United States

) hiking supply stores. The units have a useful life of 10 years, operate across a range of conditions (-40°C to 40°C), and transmit for 24 to 48 hours. As of 2003 the cost varies from US$139 to US$3000, with varying performances. Although modern systems are significantly superior to older ones, even the oldest systems provide an immense improvement in safety, compared to not having a beacon

EMERGENCY POSITION-INDICATING RESCUE BEACON

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Emergency position-indicating rescue beacons (EPIRB), Emergency Locator Transmitters (ELT) and Personal Locator Beacons, are radio transmitters that operate as part of the Cospas-Sarsat Satellite System. When activated, the beacons send out a distress signal that allows the beacon to be located by the satellite system and search and rescue aircraft to locate the people, boats and aircraft needing rescue. They are a component of the Global Maritime Distress Safety System.

EPIRBs are used for maritime emergencies, where ELTs are used in aircraft applications and PLBs are used for personal use.

The basic purpose of the emergency beacons is to get people rescued within the "golden day" when the majority of survivors can still be saved.

Between 1982 and 2002, these systems enabled the rescue of 14,700 people. As of 2002, there are roughly 82,000 registered beacons, and over 500,000 of the older unregistered type.Most beacons are brightly-colored, waterproof, fit in a cube about 30 cm on a side, and weigh 2-5 kg. They can be purchased from marine suppliers, aircraft refitters, and (in Australia and the

United States

Between 1982 and 2002, these systems enabled the rescue of 14,700 people. As of 2002, there are roughly 82,000 registered beacons, and over 500,000 of the older unregistered type.

FLIGHT DATA RECORDER

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The flight data recorder (FDR) refers generically to a class of recorders used to record specific aircraft performance parameters. A separate device is the cockpit voice recorder (CVR), although some recent types combine both in one unit. Popularly known as the black box used for aircraft mishap analysis, the FDR is also used to study air safety issues, material degradation, and jet engine performance. These ICAO regulated "black box" devices are often used as an aid in investigating aircraft mishap, and these devices are typically one of the highest priorities for recovery after a crash, second only to bodies of victims. The device's shroud is usually painted bright orange and is generally located in the tail section of the aircraft.

HISTORY

The first prototype FDR was produced in 1957 by Dr David Warren of the then Aeronautical Research Laboratories of Australia. In 1953 and 1954, a series of fatal mishaps on the de Havilland DH106 Comet prompted the grounding of the entire fleet pending an investigation. Dr Warren, a chemist specializing in aircraft fuels, was involved in a professional committee discussing the possible causes. Since there had been no witnesses, and no survivors, Dr Warren began to conceive of a crash survivable method to record the flight crew's conversation, reasoning they would likely know the cause.

Despite his 1954 report entitled "A Device for Assisting Investigation into Aircraft Accidents" and a 1957 prototype FDR named "The ARL Flight Memory Unit", aviation authorities from around the world were largely uninterested. This changed in 1958 when Sir Robert Hardingham, the Secretary of the UK Air Registration Board, became interested. Dr Warren was asked to create a pre-production model which culminated into the "Red Egg", the world's first commercial FDR by the British firm, S. Davall & Son. The "Red Egg" got its name from the shape and bright red color. Incidentally, the term "Black Box" came from a meeting about the "Red Egg", when afterwards a journalist told Dr Warren, "This is a wonderful black box."

DESIGN

The design of today's FDR is largely governed by the European Organisation for Civil Aviation Equipment in its EUROCAE ED-122 (Minimum Operational Performance Specification for Crash Protected Airborne Recorder Systems). In the United States, the Federal Aviation Administration (FAA) regulates all aspects of U.S. aviation, and cites design requirements in their Technical Standard Order, TSO-C124a, which mostly refers back to ED-122 (like many other countries' aviation authorities).

Currently, EUROCAE specifies that a recorder must be able to withstand an acceleration of 3400 g (33 km/s²) acceleration for 6.5 milliseconds. This is roughly equivalent to an impact velocity of 270 knots and a deceleration or crushing distance of 450 mm. Additionally, there are requirements for penetration resistance, static crush, high and low temperature fires, deep sea pressure, sea water immersion, and fluid immersion.

Modern day FDRs are typically plugged into the aircraft's fly-by-wire main data bus. They record significant flight parameters, including the control and actuator positions, engine information and time of day. There are 88 parameters required as a minimum by current U.S. federal regulations (only 29 were required until 2002), but some systems monitor many more variables. Generally each parameter is recorded a few times per second, though some units store "bursts" of data at a much faster frequency if the data begins to change quickly. Most FDRs record more than a day's worth of data.

Recently aviation authorities have begun to place FDRs in the empennage. In this position, the entire front of the aircraft acts as a "crush zone" to reduce the shock that reaches the recorder. Also, modern FDRs are typically double wrapped, in strong corrosion-resistant stainless steel or titanium, with high-temperature insulation inside. Additionally, since the recorders are sometimes crushed into unreadable pieces, or never located, some modern units are self-ejecting, with radio and sonar beacons (i.e. emergency locator transmitter).

Smiths Aerospace Crash Protected Recorders

GLASS COCKPITS

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Advances in computing power and flat panel LCD displays have made the glass cockpit possible. Glass cockpits are loosely defined as aircraft flight decks where information is presented on one or more electronic displays. They offer significantly lower pilot workloads and improved situational awareness over traditional "steam gauge" flight decks.

Glass cockpits were first introduced on airliners and military aircraft. Recently, they have started to appear in general aviation aircraft such as the Cirrus Design SR20 and Lancair designs.

GLOBAL POSITIONING SYSTEM (GPS)

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The use of the Global Positioning System (GPS) has changed aircraft navigation both in the en-route phase and approach (landing) phases of flight.

Aircraft have traditionally flown from one radio navigation aid ("navaids") to the next (e.g., from VOR to VOR). The paths between navaids are called airways. While this is rarely the shortest route between any two airports, the use of airways was necessary because it was the only way for aircraft to navigate with precision in instrument conditions. The use of GPS has changed this, by allowing "direct" routing, allowing aircraft to navigate from point to point without the need for ground-based navigation. This has the potential to save significant amounts of both time and fuel while en-route.

However, "direct-to" routing causes non-trivial difficulties for the air traffic control (ATC) system. ATC's basic purpose is to maintaining appropriate vertical and horizontal separation between aircraft. The use of direct routing makes maintaining separation harder. A good analogy would be vehicular traffic: Roads are comparable to airways. If there were no roads and drivers simply went directly to their destination, significant chaos would ensue (e.g., large parking lots without barriers or lines). ATC does give clearance for direct routing on occasion, but its use is limited. Projects like free flight propose to computerize ATC and allow greater use of direct routing by identifing potential conflicts and suggesting maneuvers to maintain separation. This is much like the existing Traffic Collision Avoidance System, but on a larger scale and would look further forward in time.

GPS has also significantly changed the approach phase of flight. When horizontal visibility and vertical cloud ceilings are below visual flight rules (VFR) minimums, aircraft must operate under instrument flight rules (IFR). Under IFR, aircraft must use navigational equipment for horizontal and vertical guidance. This is particularly important in the approach and landing phases of flight. The path and procedure used to land on a particular runway is called an instrument approach.

IFR approaches traditionally required the use of ground-based navaids such as VOR, NDB and ILS. GPS offers some significant advantages over traditional systems in that no ground-based equipment is required, reducing cost. This has allowed many smaller airports that cannot justify ILS equipment to now have instrument approaches. GPS receivers for aircraft are also less expensive, use a single small antenna, and require virtually no calibration.

The downside to GPS approaches is that they have higher minimum visibility and ceiling requirements. ILS typically require a cloud ceiling no lower than 200 feet above ground level and horizontal visibility greater than 1/4 mile, while GPS minimums are typically never less than 400 feet and 1 mile. This difference in minimums is because GPS approaches offer horizontal guidance only. Vertical guidance is possible, but GPS accuracy in the vertical is not as high as in the horizontal. To solve this problem, the FAA has implemented the Wide Area Augmentation System (WAAS). GPS receivers with WAAS capability have typical vertical accuracy of 2-3 meters. This is sufficient for ILS-type approaches, i.e., those with vertical navigation. GPS/WAAS receivers certified for vertical navigation GPS approaches are slowly coming to the market.

Although the FAA was initially slow to allow the use of GPS in IFR approaches, the number of published GPS approaches is climbing significantly. However, because ILS has lower minimum visibility and ceiling requirements, ILS remains the "best" type of approach, and the FAA has committed to maintaining ILS installations.

AUXILIARY AND DIAGNOSTIC SYSTEMS

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Commercial aircraft are expensive, and only make money when they are flying. For this reason, efficient operators perform as much service as possible in-flight, and during the turn-around time in a terminal. To make this process possible, embedded computer systems test aircraft systems, and also collect information about faults in equipment that they control. This information is normally collected in an on-board maintenance computer, and sometimes transmitted ahead to help order spares. Although this sounds ideal, in real life, these self-test systems are often not considered flight-critical, and therefore they are sometimes unreliable, and trusted only to indicate that a device requires service.

LORAN

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For a time, LORAN systems, which provide navigational guidance over large areas, were popular particularly for general aviation use. They have declined in popularity with the commercial availability of GPS service.

DME

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Distance Measurement Equipment (DME) is used to give the pilot the information of its distance away from the VOR station, thus with a bearing and distance from a particular known VOR station a pilot can fix his exact position. Such systems are referred to as VOR/DME. DME is also part of a military navigation system widely used in the US, the TACAN (TACtical Air Navigation). A ground station combining VOR and TACAN is known as VOR-TAC. Needless to mention, the frequencies for the VOR and DME or VOR and TACAN are paired by international standards, thus once a pilot tunes onto a particular VOR frequency the airborne equipment will automatically tunes on the co-located DME or Tacan

TRANSPONDER

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The transponder is a transceiver that receives "interrogations" from air traffic control radar systems and replies with a digital code. This secondary radar reply permits the radar system to detect the aircraft more reliably and at greater distances than are possible with primary radar. This system of secondary radars and transponders is known collectively as the air traffic control radar beacon system, or ATCRBS.

A basic "mode A" transponder responds with a 4-digit code with each digit ranging from 0 to 7. This is called a 4,096 code transponder. This pilot sets the code according to the type and status of the flight or as directed by air traffic control.

A "mode C" transponder also replies with the pressure altitude of the aircraft encoded to the nearest 100 feet (30 m). Modern "mode S" transponders can respond with a longer digital identifier that is unique for each aircraft (thus allowing each aircraft to be uniquely identified even when there is no voice communication between the aircraft and air traffic control) and can receive digital traffic information from air traffic control radar systems and display them for the pilot.

An IFF transponder, "Identification friend or foe", is used in military aircraft and has additional modes of operation beyond those used in civil air traffic control.

INSTRUMENT LANDING SYSTEM

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The instrument landing system (ILS) is a set of components used to navigate to the landing end of a runway. It consists of lateral guidance from a localizer, vertical guidance from a glideslope, and distance guidance from a series of marker beacons. Optional components include DME and a compass locator, the name given to an NDB placed at the start of the final approach course.

VHF OMNI RANGE

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The VOR system (VHF omni range) is less prone to interference from thunderstorms, and provides improved accuracy. It is still the backbone of the air navigational system today. VOR receivers allow the pilot to specify a radial, that is, a line extending outward from the VOR transmitter at a particular angle from magnetic north. Then, a course deviation indicator (CDI) shows the amount by which the aircraft is off the chosen course. Distance measuring equipment (DME) was added to many VOR transmitters and receivers, allowing the distance between the station and the aircraft to be shown

NON-DIRECTIONAL RADIOBEACON

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The NDB (non-directional radiobeacon) was the first electronic navigation system in widespread use. The original radio range stations were high-power NDBs, and followed nighttime routes previously delineated by colored light beacons. DF (direction finder) and ADF (Automatic Direction Finder) avionics can receive signals from these. A needle shows the pilot the relative heading toward the station compared to the centerline of the aircraft. NDBs use the LF and MF bands, and are still in use today (2005) at smaller airports because of their low cost but their use is quickly being supplanted by GPS. This is due mostly from the higher cost of ADF equipment in the aircraft and maintaining the NDB stations.

Battlefield surveillance

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nRole : battlefield scenario information

¨Relay strategic and tactical real-time battlefield intelligence

¨Radar observation of ground targets and movements

Maritime patrol avionics

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nRoles:

¨Anti-surface warfare

nReconnaissance

nNaval attack

nTargeting

nIntelligence

nCommunication relay

Ground attack Avionics

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nRole : Assist tactical troops on the ground

¨Accurate identification of targets among friendly forces

¨Designate targets by laser

¨Attack fixed and moving targets

¨Close air support (CAS), commanded from the ground

Military Avionics Roles

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1.Air superiority

2.Ground attack

3.Strategic bomber

4.Maritime patrol

5.Battlefield surveillance

6.Airborne early warning

7.Electronic warfare

8.Photographic reconnaissance

9.Air-to-air refuelling

10.Troup / materiel transport

11.Uninhabited aerial vehicle (UAV)

12.Training

Short history of avionics

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n1910s – first experiments with radio and autopilot

n1930s – first electronic aides such as:

¨“blind-flying” panels

¨radio ranging

¨non-directional beacons

¨Ground-based surveillance radar

¨Single-axis autopilot

n1940s : many WWII related developments:

¨VHF communications

¨Identification friend or foe (IFF)

¨Gyroscopic compass

¨Attitude and heading reference systems

¨Airborne intercept radar

¨Electronic warfare

¨Long-range precision radio navigation

¨2-axis autopilot

n1950 :

¨Tactical air navigation (TACAN)

¨Tracking radar

¨Doppler radar

¨Pulse radar

¨Early mission computers

¨Inertial navigation

n1960 :

¨Integrated electronic warfare systems

¨Automated weapon release systems

¨Terrain following radar

¨Head-up-display (HUD)

¨Digital mission computers

AVIONICS definition

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nAvionics = AVIation electrONICS

nRepresents ~50% of the cost of an airborne military platform

nEssential for:

¨Manned aircraft

¨Uninhabited aircraft (UAV)

¨Missiles

¨Other weapon systems

Display Systems

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lHUD (Heads Up Display)

lHDD (Head Down Display)

lHMD (Head Mounted Display)

lAll instrumentation

and gauges