8.33 kHz Channel Spacing

New channel spacing for radio communication for aviation due to the increasing demand for radio frequencies in aviation. The channel spacing of the radio frequencies in the range of 118 kHz to 138 kHz are subdivided from 25 kHz to 8.33 kHz. As a result, further radio frequency ranges are available for radio traffic. Since the older types of radios cannot display these intermediate frequencies. They must be replaced by 31.12.2017 in order to continue to participate in air traffic.


Classic data bus for information transmission for commercial aircrafts. A distinction is made between a high-speed and a low-speed bus. For a high-speed bus, the maximum data transmission rate is 100 kbit/s, with low-speed 12.5 kbit/s. ARINC 429 is also available in a light version in commercial and sports aircrafts. In military aviation and space travel, the MIL-STD-1553 bus is preferably used instead of the ARINC bus

Advisory Circular (AC)

The FAA or EASA publishes Advisory Circulars for the approval of systems in aviation. It presents accepted procedures on how to prove compliance in the field of certification, operation, maintenance and instructions for continued airworthiness of aircrafts and their environment.

Airworthiness Directive (AD)

Airworthiness directive are information issued by the Agency for the safe operation of aircrafts. This information are issued for aircrafts which, due to a possible defect or malfunction, no longer fulfil the requirements for airworthiness. The AD shall provide measures which must be implemented within a time limit or for a specific hour of operation of the aircraft. Only when all the measures described in the AD have been carried out on the aircraft that it can be released into operation again.

Aural Message Box (AMB)

Digital multi-channel storage and playback unit for audio files in the aircraft. Playback of audio files by selective selection via the display for the crew or the passengers. Playing of checklists for post-flight and pre-flight checks. Output of music and audio books for the passengers. Easy storage and playback of the audio files via SD card. Audio output via the intercom system to the headsets or speakers. The compact design allows a high degree of versatility for all required application spectra. The AMB is a product of SPAES.

More information on this may be found on page Products of our homepage.

Aural Warning and Information System (AWIS)

Digital multichannel memory and playback unit for audio signals or warning information in the aircraft. Warnings and information can be output to the headphones or speakers in the aircraft via the audio system to warn or inform the crew or passengers. Various variants allow a high application diversity for all required application spectra. Own product of SPAES.

More information on this may be found on page Products of our homepage.

Automatic Deployable Emergency Locater Transmitter (AD-ELT)

The AD-ELT can be ejected in an emergency situation, during operation water or during offshore operation. The ELT is connected to a water activated switch. If the switch has contact with water, it releases the emergency transmitter from the helicopter and floats on the water surface. The last position of the aircraft with further aircraft information is sent to the rescue coordinating center. The AD-ELT is required for the operation of helicopters over water by EASA.


Avionics is a portmanteau word (keyword) of aviation and electronics. The term comes from the aerospace industry and refers to the entirety of the electrical and electronic equipment and systems including the flight instruments in an aircraft.

Certification Specification large Airplanes (CS-25)

Approval requirements for the construction of aircrafts with a take-off weight of 5.7 tons and higher. The design of the aircraft must be designed in such a way that the required regulations are demonstrated by tests and verifications to the authorities. SPAES offers CS-25 training courses for aviation companies and their interfaces to other departments.

Certification Specification large Helicopter (CS-29)

Approval regulations which must be complied with so that a large helicopter can be operated with an MTOW of more than of 3.175 tons. The construction of the helicopter must be designed in such a way that the required regulations are met by tests and verifications. SPAES offers CS-29 training for design organizations and their interfaces to other departments of an aviation company.

Certification Specification small Airplanes (CS-23)

Approval regulations which must be complied with so that a large helicopter can be operated with an MTOW of more than of 3.175 tons. The construction of the helicopter must be designed in such a way that the required regulations are met by tests and verifications against the authorities. SPAES offers CS-29 training for design organizations and their interfaces to other departments of an aviation company.

Certification Specification small Helicopters (CS-27)

Approval regulations which must be complied with, so that a small helicopter can be operated up to a max. take-off weight (MTOW) of 3.175 tons. The construction of the helicopter must be designed in such a way that the required regulations are met by tests and verifications. SPAES offers CS-27 training for design organizations and their interfaces to other departments of an aviation company.

Compliance Verification Engineer (CVE)

A CVE checks the prepared documentation, which were carried out for changes and repairs on aircrafts. CVEs release design documents and compliance documents within the scope of approval of the Part 21J design organization to issue approved design data. A CVE must have special qualifications and experience in the subject areas. EASA will check and accept CVE‘s for their suitability.

Continuing Airworthiness (Part M)

Part M stands for “Continuing Airworthiness Management Organization” (CAMO) and is responsible for maintaining the airworthiness of aircrafts as a whole. This facility ensures that the maintenance requirements of aircraft are complied with. In addition, it verifie that the installation of new systems does not affect the airworthiness of the aircraft.

Design Organization (Part 21J)

An approved Part 21J design organization may carry out changes and repairs on aircrafts in their scope of approval. The approval is carried out by the Agency (EASA). The EASA audits the Part 21J design organization in periodical intervals. The scope of approval of SPAES covers small and large helicopters (CS-27/29) as well as small aircraft (CS-23) in the field of avionics, electrical systems, structure and cabin interior.

European Aviation Safety Agency (EASA)

European Aviation Safety Agency based in Cologne. EASA has the task to create and monitor uniform and high safety and environmental standards for aviation at European level. It monitors, among other things, Part 21J design organizations, Part 21G production organizations, and is controlled by the European Parliament.

For more information see http://www.easa.europa.eu/.

European Military Aviation Requirements (EMAR)

Military requirements for operation, instructions for continued airworthiness, maintenance, training of personnel and production and design of aircrafts. In addition to EMAR M (requirements for continued airworthiness), EMAR 145 (requirements for maintenance organization), EMAR 21 (design and manufacturing), EMAR 147 which is relevant for the approval of training facilities for maintenance personnel, will also be implemented in conjunction with EMAR 66 (aeronautical and release to service personal). The targets are increasingly aligned with the EASA requirements and are currently being implemented by the national military organizations.

See also: http://eda.europa.eu.

European Technical Standard Order (ETSO)

An ETSO states that a component, equipment or an appliance meets the minimum requirements set out in the CS-ETSO. The minimum requirements are determined by further specifications such as e.g. RTCA DO-160 or ED-14 (environmental standards) or RTCA DO-178 or ED-12 (software).

Federal Aviation Administration (FAA)

The FAA of the United States is a national authority which regulates all aspects of civil aviation. These include the construction and operation of airports, the management of air traffic, the certification of personnel and aircraft.

See also https://www.faa.gov/.

Federal Office of Civil Aviation (FOCA)

The Federal Office of Civil Aviation is responsible for aviation development and the supervision of civil aviation activities in Switzerland. The FOCA is part of the Federal Department of the Environment, Transport, Energy and Communications (DETEC) and is commissioned with ensuring that the high safety standards in civil aviation in Switzerland are maintained, and with pursuing a policy of sustainable development.

Form 1

A Form 1 is an authorized release certificate from a Part 21G production organization. This means, that a product, part or appliance of an aircraft is regular manufactured according to approved design data of a design organization in a Part 21G production organization.

Head of Office of Airworthiness (HoOA)

A HoOA is the leader of the Office of Airworthiness in a Part 21J design organization. The HoOA is responsible for all aspects of airworthiness related to changes and repairs which were performed in the design organization. He/ She is the interface between the design organization and EASA in all aspects of airworthiness.

Helicopter Emergency Egress Lighting System (HEEL)

A HEEL system is an emergency lighting system for helicopters for offshore or for operation over water which will be activated manually or by water switch in an emergency water landing. The system illuminates the doors and emergency exits in the helicopter and facilitates to escape easier out of the helicopter for the crew and the passenger. A HEEL system is an EASA requirement for operation of helicopters over water.

Luftfahrtbundesamt (LBA)

LBA is the national civil aviation authority of Germany. The LBA is responsible for developing and maintaining aviation safety standards, as well as certifying airlines, airports and training devices such a simulators and Flight Training Devices (FTDs). Some of these tasks are fulfilled on behalf of the European Aviation Safety Agency (EASA) e.g. surveillance of aviation companies (e.g. Part 21, Part 145, Part 147). Furthermore, licensing for commercial aircraft operators, aviation navigators and flight engineers as well as the surveillance of flight training schools is also a task of the LBA.

Maintenance Organization (Part 145)

A maintenance organization is responsible for the inspection and maintenance of the aircraft. It has the task to maintain systems and components in the aircraft or to carry out modifications and repairs on an aircraft. The Part 145 organization must carry out all work and activities in accordance with approved documents, such as the maintenance manual. The maintenance organization and its approval is supervised by the LBA on behalf of EASA.

Minor Change (MC)

A Minor Change is a change to an aircraft, which has no appreciable effect on the airworthiness of the aircraft. The change may be carried out by the Part 21J design organization without the Agencies involvement within the scope of approval. The content of the documentation includes the installation information and all necessary compliance documentation for the minor change.
The installation is carried out by a Part 145 maintenance organization or a Part 21G production organization.

Minor Repair

Repairs on an aircraft are used to restore the airworthiness of an aircraft. First, it must be determined whether it is a major or minor repair by a classification. Subsequently, a design organization prepare and approve all the necessary installation documents and proofs, so that the maintenance organization (Part 145) can carry out the repair.

Night Vision Imaging System (NVIS)

System for the operation of helicopters or airplanes at night. Consisting of a night vision goggle attached to the helmet of the pilot and the cockpit or the passenger compartment which fulfill special lighting requirements in order to reduce the brightness to the required light intensity and avoid dazzling the crew.

Pressurized Cabin

Aircrafts, which are operated at higher altitudes require a pressurized cabin with increasing altitude due to the lower oxygen partial pressure (lower oxygen content per m3). In the cabin, a pressure of about 2500 m MSL is generated by compressing air, which allows normal operation for the passengers and the crew.

Production Organization (Part 21G)

Part 21G describes an organization that carries out the production and manufacturing of aerospace products and parts. Therefore, the company must demonstrate that the resources and procedures used for this, are in accordance with the EASA regulations. A production organization may produce products only in accordance with approved design data of a design organization. Design of products and subsequent production may not be carried out in a production organization without the necessary approval as an EASA Part 21 design organization.

Standard Changes (CS-STAN)

Standard changes are modifications to an aircraft, which may be carried out and approved by a Part 145 maintenance organization. These changes are merely the replacement of an already installed system for a new system (exchange) with the same characteristics. For the implementation of CS-STAN, special requirements may be required for Part 145 organization which were checked by the Agency (EASA).

Supplement Type Certificate (STC)

A STC is a major change to an aircraft which is approved by a Type Certificate Data Sheet (TCDS). For an STC, an application has to be send to EASA. The Agency monitors the design and certification process during the implementation. All relevant design and test documents as well as tests are prepared by a Part 21J design organization and are checked and accepted by EASA. They have specifically trained Project Certification Manager (PCMs) in the respective areas, who are responsible for verifying the created documents. If required, EASA would like to be present during tests or test flights in order to verify the documentation carried out. The issuing of the STC certificate is carried out by EASA.

Terms of Approval

The Terms of Approval is the conclusion of the types of aircrafts and areas which are approved by the Agency (EASA) of a Part 21 design organization, for e.g. large and small helicopters in the field of avionics, structure, cabin interior, etc.

Type Certificate Data Sheet (TCDS)

A TCDS certifies the airworthiness of an aircraft, engine, propeller, etc. The type certificate holder must demonstrate proof of compliance with aviation requirements. EASA issue the type certificate after a successful fulfilment of the requirements.

SPAES explains important aviation terms of the working environment of the entire company.

For questions or suggestions according to further terms, do not hesitate to contact us by E-Mail info@spaes.de or call us +49 (0)721-96317750.