DATA COMM—MIDTERM MODULE 1.pdf

PHILIPPINE STATE COLLEGE OF AERONAUTICS DATA COMMUNICATION MIDTERM MODULE 1-A LearningOutcomes Course Learning Outcomes [CLO] Module Learning Outcomes [MLO] CLO 1. The students will distinguish Topic Learning Outcomes [...

PHILIPPINE STATE COLLEGE OF AERONAUTICS DATA COMMUNICATION MIDTERM MODULE 1-A LearningOutcomes Course Learning Outcomes [CLO] Module Learning Outcomes [MLO] CLO 1. The students will distinguish Topic Learning Outcomes [TLO] the basic concepts of data communication MLO 1. Explain the introduction of CLO 2. By the means of main Data Communication protocols and standards of the MLO 2. Determine the controllers TLO 1. Able to explain the internet they will identify the basic data link introduction to data communication concepts of aircraft addressing, TLO 2. Describe the overview of the and reporting MLO ; Understanding of ARINC of the ACARS and CPLDL. 2  CONTENT PAGE TIME C. Activity/Quiz Enrichment activity 30 60 mins Quiz 60 mins TOTAL 11 hrs and 47mins  AIR-GROUND COMMUNICATION Definition Two-way communication between aircraft and stations or locations on the surface of the earth. Voice Communications Voice/audio communications between an aircraft and the ground are traditionally accomplished using radio telephony, broadcasting and receiving on:  VHF (very high frequency). The frequency band 117.975 - 137.0 MHz is allocated for this purpose and is the most commonly used in civil aviation.  HF (high frequency). These frequencies (3 - 30 MHz) allow the radiowaves to bend and follow the surface of the earth or to be reflected by the ionosphere thus reaching great distances. The HF band is therefore used in oceanic communications.  UHF (ultra high frequency). These frequencies (generally defined as 300 MHz - 3 GHz) are used for military aircraft communications. Visual Communications Communications can be accomplished visually using, for example, and Aldis Lamp to flash messages between aircraft and ground stations in Morse Code or through standard conventions associated with emergency situations. Light signals and pyrotechnics can be used to issue simple instructions to aircraft in flight or on the manoeuvring area. This is sometimes used by aerodrome control towers as a backup in case of radiocommunication failure. For example, a steady green light means "Cleared to land" for traffic in the air and "Cleared for take-off" for traffic on the ground. A red pyrotechnic would mean "Notwithstanding any previous instructions, do not land for the time being" AIRCRAFT COMMUNICATIONS, ADDRESSING AND REPORTING SYSTEM. ACARS (pronounced AY-CARS) is a digital data link system for the transmission of messages between aircraft and ground stations, which has been in use since 1978. At first it relied exclusively on VHF channels but more recently, alternative means of data transmission have been added which have greatly enhanced its geographical coverage. There has also been a rapid trend towards the integration of aircraft systems with the ACARS link. Both have led to rapid growth in its use as an operational communications tool. Modern ACARS equipment now includes the facility for automatic as well as manual initiation of messaging. ARINC guidelines have been defined for all the various avionic components of ACARS. Message Content ACARS messages may be of three types based upon their content: 1. Air Traffic Control (ATC) ATC messages include aircraft requests for clearances and ATC issue of clearances and instructions to aircraft. They are often used to deliver Pre- Departure, Datalink ATIS and en route Oceanic Clearances. However, whilst the ACARS system is currently fulfilling a significant 'niche' role in ATC communications, it is not seen as a suitable system for the more widespread ATC use of datalink referred to as Controller Pilot Data Link Communications (CPDLC). 2. Aeronautical Operational Control (AOC) 3. Airline Administrative Control (AAC) AOC and AAC messages are used for communications between an aircraft and its base. These messages may be of standard form or as defined by users, but all must then meet at least the guidelines of ARINC Standard 618. Any message content is possible including such as:  upload to the aircraft of final load and trim sheets;  upload of weather or NOTAM information;  download from the aircraft of status, position, eta, and any diversion;  download of spot weather observations from aircraft sensors:  download of technical performance data including automatically triggered exceedance or abnormal aircraft system status information, and  'housekeeping' information such as catering uplift requirements, special passenger advice and ETA.  Free Text messaging is also possible. THE ACARS SYSTEM When ACARS was first developed as an ATN component, it was modeled on the existing Telex System. As a consequence, the system architecture is based on three main components: 1. The Aircraft Equipment ACARS equipment onboard an aircraft is called the Management Unit (MU) or, in the case of newer versions with more functionality, the Communications Management Unit (CMU). This functions as a router for all data transmitted or received externally, and, in more advanced systems internally too. The ACARS MU/CMU may be able to automatically select the most efficient air-ground transmission method if a choice is available. A flight deck printer will be provided and a cabin crew terminal may also be available. Flight Crew access to the ACARS system is usually via a CDU which, in more advanced systems, can be used to access up to seven different systems such as the FMS, besides the MU/CMU. Each system connected to the CDU generates its own display pages and accepts keyboard input when selected. Some EFBs may be used as a substitute for access via the CDU. 2.The Service Provider A Datalink Service Provider (DSP) is responsible for the movement of messages via radio link, usually to/from its own ground routing system. ACARS messages are transmitted using one of three possible data link methods: 3.VHF or VDL (VHF Data Link) which is line-of-sight limited SATCOM which is not available in polar regions HF or HFDL (HF Data Link) which has been added especially for polar region communications The main primary DSPs are ARINC and SITA. Until quite recently, each part of the world was covered by a single DSP but competitive offerings are now increasingly available. The Ground Processing System Ground System provision is the responsibility of either a participating ANSP or an Aircraft Operator. Aircraft Operators often contract out the function to either DSP or to a separate service provider. Messages from aircraft, especially automatically generated ones, can be pre-configured according to message type so that they are automatically delivered to the appropriate recipient just as ground-originated messages can be configured to reach the correct aircraft. HOW DOES ACARS WORK? ACARS allows text-based messages to be sent between aircraft and other stations, for example OOOI messages to airline dispatch or maintenance departments, or to request up to date weather reports while in flight. Datalink Service Providers (DSPs – for examples SITA or ARINC) are responsible for the transmission of messages between stations. ACARS messages are received on the aircraft by one of three methods:  VHF (Very High Frequency) – this is for short-range communication limited by line of sight. Also referred to VHF Data Link (VDL).  HF (High Frequency) – HF Data Link (or HFDL) functions at long-range including over the ocean and in polar regions.  SATCOM (Satellite Communication) – SATCOM links are available in most places on the planet except in polar regions. TYPES OF ACARS MESSAGES 1. Air Traffic Control (ATC) – the most common use of ACARS with ATC is for clearances such as Pre Departure Clearance (PDC) and Oceanic Clearance (OCX). Also D-ATIS (Digital Automatic Terminal Information System) falls under the ATC function. 2. Aeronautical Operational Control (AOC) – the AOC function of ACARS is used regularly during a typical flight by the pilots to receive the load sheet prior to departure, to obtain updated weather reports enroute, to report delays to dispatch or even request updated flight plans (for example if a planned cruising altitude is unavailable). ACARS also provides a way of instantly updating dispatch in the event of a diversion or emergency. The AOC function also includes automatic reporting of engine health and any ECAM warnings to the airline maintenance department, reporting of flight times (OOOI), gate assignments etc. 3. Airline Administrative Control (AAC) – The AAC functions to provide relevant admin information such as the PIL (Passenger Information List) which contains information such as passenger connections, available seats etc. Normally when a message is received on the flight deck its automatically printed out on a printer on the center console. Pilots can then used the FMS (Boeing) or MCDU (Airbus) to type a reply or request further information. How to Receive ACARS On a typical flight,send and receive messages through the MCDU or FMS, but it’s also possible to receive ACARS messages on a regular PC or Raspberry Pi mini computer. Although more of an “intermediate level project” than something for a beginner it’s relatively straightforward to do with a Software Defined Radio (SDR) usb dongle and some software. The cheap RTL-SDR dongle was originally intended for people to receive TV broadcasts onto their computers, clever people have adapted its use. It has a wide frequency spectrum and covers the aviation frequencies necessary to receive ACARS. In addition to the dongle, decoding software such as Plane Plotter or Acarsdeco2 is used to decode the received messages. Combining the software defined radio mentioned above with software such as SDR# (“SDR Sharp”) can even allow you to listen in to aircraft voice communications. AN EXAMPLE OF ACARS USE ON A FLIGHT During the preflight phase the ACARS will be used to request the latest ATIS (D-ATIS) to plan the expected departure and calculate the take-off performance. Often a request for the latest weather at the destination is also made for the public address With the latest ATIS in hand a Pre Departure Clearance (PDC) request will be sent to ATC with our aircraft type, the ATIS received and our gate number. Once decided on final fuel a request will be sent to the load planning department with our figures requesting a load sheet, which will print out automatically once it arrives (usually STD-10 i.e. 10 minutes before our departure time). Throughout the flight various automated messages (such as OOOI messages, automated reports to maintenance control etc.) will be sent to the airline’s operations department. Airborne, apart from the routine requests for enroute and destination weather, ACARS will be busy sending dispatch updates of position and ETA at destination, and keeping maintenance informed about any ECAM/EICAS warnings or cautions that will be received. Approaching ocean crossing point we’ll send our OCX (Oceanic Clearance Request) with our requested cruising flight level (depending on forecast turbulence and aircraft weight). Learn how pilots try to avoid turbulence during flight. Approaching to destination, sending updates to dispatch and requesting expected parking position, and also sending any information about passenger assistance requirements for PRMs (Passengers with Reduced Mobility).  HISTORY OF ACARS Prior to the implementation of digital communication in aircraft, all communication was down by voice over VHF or HF (long range) radio. As many things in aviation depended on accurate timings (including pilot pay!), airlines identified the need for accurate, up to date digital communications from aircraft and so, in 1978, ACARS was introduced by the engineering department in ARINC. ARINC (Aeronautical Radio, Incorporated) which was a major provider of transportation communications systems (ARINC was sold in 2013 to Rockwell Collins). ACARS originally stood for “Arinc Communications Addressing and Reporting System” but this was later changed to what we now know as “Aircraft Communications, Addressing and Reporting System” WHAT FREQUENCIES DOES ACARS USE? Datalink Service Provider (DSP) Frequency ARINC America 131.550 MHz SITA North America 136.850 MHz SITA Latin America 131.725 MHz ARINC Europe 136.925 MHz SITA Europe 131.725 MHz ARINC Africa 126.900 MHz ARINC Asia 131.450 MHz ARINC Korea 131.725 MHz SITA Pacific 131.550 MHz DEPV Brazil 131.550 MHz AVICOM Japan 131.450 MHz ACARS Frequencies COMMUNICATION FAILURE: GUIDANCE FOR CONTROLLERS Description This provides guidance for controllers on what to expect and how to act when dealing with onboard radio communication failure (RCF) situations. There are some considerations which will enable the controller, not only to provide as much support as possible to the aircraft concerned, but also to maintain the safety of other aircraft in the vicinity and of the ATC service provision in general. Useful to Know RCF is an eventuality that pilots, as well as air traffic controllers, are well prepared to manage. Although the complete loss of communication is an extremely rare event due to duplication of equipment, there are several areas which contribute most commonly to full or partial communication breakdown: 1. Airborne or ground radio equipment malfunction; 2. Sleeping Receiver; 3. Stuck microphone selector. It is important to note that the applicable RCF procedures are expected to conform to the established ICAO Standards and Recommended Practices (SARPS) and Procedures Anticipated Impact on Crew A wide range of practical problems could arise following RCF: 1. Crew may not be immediately aware of the communication loss; 2. Increased workload in the cockpit - crew must determine the time the RCF occurred and act accordingly by: 3. attempting to establish radio telephony (RT) contact on the last frequency and other radio frequencies established for the flight route; 4. attempting to establish RT contact with other aeronautical stations or aircraft or attempting to establish communication with the relevant ATC unit by any alternate available means; 5. if RT contact cannot be established with the responsible ATC, the crew will follow procedures for RCF failure as described by their operational manual and all other applicable documents; 6. adherence to the appropriate RCF emergency procedures depending on the flight conditions - VMC or IMC. WHAT TO EXPECT The aircraft shall comply with the voice communication failure procedures of Annex 10, Volume II, and with those of the following procedures as are appropriate. The aircraft shall attempt to establish communications with the appropriate air traffic control unit using all other available means. In addition, the aircraft, when forming part of the aerodrome traffic at a controlled aerodrome, shall keep a watch for such instructions as may be issued by visual signals. An aircraft equipped with an SSR transponder is expected to operate the transponder on Mode A Code 7600 to indicate that it has experienced air-ground communication failure. An ADS-B equipped aircraft experiencing radio communication failure may transmit the appropriate ADS-B emergency and/or urgency mode. An aircraft equipped with other surveillance system transmitters, including ADS-C, might indicate the loss of air-ground communication by all of the available means. If the aircraft fails to indicate that it is able to receive and acknowledge transmissions, separation shall be maintained between the aircraft having the communication failure and other aircraft, based on the assumption that the aircraft will: In VMC: 1. Continue to fly in visual meteorological conditions; 2. Land at the nearest suitable aerodrome; and 3. Report the arrival by the most expeditious means to the appropriate air traffic control unit IN IMC 1.In IMC or when conditions are such that it does not appear likely that the pilot will complete the flight in accordance with the prescribed VMC RCF procedures above: 2.Unless otherwise prescribed on the basis of a regional air navigation agreement, in airspace where procedural separation is being applied, maintain the last assigned speed and level, or minimum flight altitude if higher, for a period of 20 minutes following the aircraft’s failure to report its position over a compulsory reporting point and thereafter adjust level and speed in accordance with the filed flight plan; or In airspace where an ATS surveillance system is used in the provision of air traffic control, maintain the last assigned speed and level, or minimum flight altitude if higher, for a period of 7 minutes following: i) The time the last assigned level or minimum flight altitude is reached; or ii) Time the transponder is set to Code 7600 or the ADS-B transmitter is set to indicate the loss of air-ground communications; or iii) The aircraft’s failure to report its position over a compulsory reporting point; whichever is later and thereafter adjust level and speed in accordance with the filed flight plan; 3.When being vectored or having been directed by ATC to proceed offset using RNAV without a specified limit, proceed in the most direct manner possible to rejoin the current flight plan route no later than the next significant point, taking into consideration the applicable minimum flight altitude; 4.Proceed according to the current flight plan route to the appropriate designated navigation aid or fix serving the destination aerodrome and, when required to ensure compliance with hold over this aid or fix until commencement of descent; 5.Commence descent from the navigation aid or fix specified in 4) at, or as close as possible to, the expected approach time last received and acknowledged; or, if no expected approach time has been received and acknowledged, at, or as close as possible to, the estimated time of arrival resulting from the current flight plan; Complete a normal instrument approach procedure as specified for the designated navigation aid or fix; and 6.Land, if possible, within 30 minutes after the estimated time of arrival specified in 5) or the last acknowledged expected approach time, whichever is later. A note concerning departing aircraft experiencing RCF: If the aircraft has been vectored away from the route specified in the flight plan then the flight crew is expected to comply with the procedures published in the appropriate regional air navigation agreement and included in the SID description or published in the AIP. REFERENCES https://www.aviationmatters.co/what-is-acars/#google_vignette https://skybrary.aero/search/google?keys=VISUAL+COMMUNICATION https://skybrary.aero/articles/communication-failure-guidance-controllers ENRICHMENT ACTIVITY _________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ FORMATIVE ASSESSMENT _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________