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NASA's Deep Space Network (DSN) uses high-power transmitters on its large antennas to communicate with spacecraft of NASA and its partner agencies. The prime reflectors of the DSN antennas are parabolic, at 34m and 70m in diameter. The DSN transmitters radiate Continuous Wave (CW) signals at 20 kW - 500 kW at X-band and S-band frequencies. The combination of antenna reflector size and high frequency results in a very narrow beam with extensive oscillating near-field pattern. Another unique feature of the DSN antennas is that they (and the radiated beam) move mostly at very slow sidereal rate, essentially identical in magnitude and at the opposite direction of Earth rotation.

Recent changes in DoD procurement directives have encouraged the purchase of civilian products for use in certain military applications. One such application is the upgrade of avionics suites with the Global Positioning System (GPS) in military air transport aircraft to meet joint civil-military operational requirements. This paper reviews the Commercial Off-the-Shelf (COTS) concept and the proper use of TSOs, ACs, and FARs in both the design and integration process.

This paper describes the recently established Commercial Aviation Alternative Fuel Initiative (CAAFI), including its goals and objectives, as well as presents an alternate fuel roadmap that was originally generated by industry and refined by the CAAFI stakeholders. CAAFI is designed to coordinate the development and commercialization of “drop-in” alternate fuels (i.e. fuels that can directly supplement or replace crude oil derived jet fuels), as well as exploring the long-term potential of other fuel options. The ultimate goal is to ensure an affordable and stable supply of environmentally progressive aviation fuels that will enable continued growth of commercial aviation. This initiative is organized into four sub-groups: Research and Development (R&D), certification, environment, and economics & business. The R&D group seeks to identify promising new drop-in alternate fuels, and to foster coordination of development efforts.

Many of the certification regulations in 14 CFR Part 25 are by design, broad and as such, can be subject to large differences in the interpretation of what constitutes adequate compliance. Advisory Circulars (AC's) were developed for many of the regulations to assist industry, as well as certification personnel, with what is considered an acceptable, but not the only means, of compliance. However, there are many regulations where no advisory material is available. In these cases, the “acceptable means” of compliance can vary to a greater degree among the various aircraft certification offices. This difficulty is aggravated as new applicants and regulatory personnel enter the certification field. Recent discussions and interpretations on the usage of an avionic unit's mean time between failure or MTBF for its detectable faults as the basic repair rate for undetected or latent faults, is a subject area where no significant advisory material exists.

The issues involved in certifying head-up displays for civil aircraft are reviewed and proposed guidelines for the certification of head-up displays are presented. These guidelines are based on experience with civil and military head-up displays and follow the intent of the existing rules.

The advent of digital electronics for use in civil aircraft, particularly the new technology represented by central processor and microprocessor controlled systems, represents a major challenge to the aviation industry. The Federal Aviation Administration (FAA) is charged with the responsibility of evaluating these systems to determine if they can be used safely. The complexity of these systems as compared to their analog counterparts in use today makes their evaluation difficult. This paper outlines the major concerns of the FAA with the use of software controlled digital systems for airborne applications. The methods which can be used by members of the aviation industry to obtain FAA certification of these systems are also discussed. The proposal of Special Committee SC-145 of the Radio Technical Commission for Aeronautics (RTCA) form the basis of the design methodology which is described for the successful development of the computer programs (software) to be used by these systems.

The Federal Aviation Administration has placed increasing emphasis on modern information systems to achieve safety improvements. The ASAS (Aviation Safety Analysis System) is a comprehensive new system to upgrade significantly the agency's ability to collect process and disseminate safety-related information.

This paper will discuss some considerations regarding man-machine interface during helicopter instrument flight. Several misconceptions have existed regarding FAA helicopter IFR certification. In response to some concerns pertaining to “excessive workload considerations,” designers have responded with several configurations. Some of these configurations have highlighted the need to educate the designer and the pilot population that the pilot must have the option to “actively participate” in the flight activity during helicopter IFR operations. “Active participation” includes the option of flying the vehicle through the normal flight controls. In addition, there has been some confusion regarding the terms “stability augmentation systems” and “autopilot.” Some individuals use the terms interchangeably. This paper will discuss the various lessons learned during FAA certification of helicopters for IFR flight from a certification test pilot's viewpoint.

The rapid growth in digital computer technology and display systems has impacted most aerospace disciplines. The designer manufacturer operator and even airplane passengers are all affected by this technology boom. The FAA in its role of certifying new aerospace products is no exception. This paper will emphasize the changing methodology of the FAA certification process with some specific examples of recent flight test programs.

Federal Aviation Administration philosophy regarding simulator use in the airman certification system is stated. Airman certification requirements, specified in the Federal Aviation Regulations, are expressed in behavioral terms. Distinctions between simulator uses for training, evaluation, and gaining operational experience are discussed. A methodology for determining systematically and objectively how simulators may be used for pilot performance evaluation is derived from instructional system design. An experimental design, appropriate for validation studies of pilot performance evaluations in simulators, is referenced.

In view of the fact that future generations of derivative or new aircraft will be faced with problems of increasing operating efficiency, new and more advanced technology will have to be introduced. To this end, the Federal Aviation Administration has been examining the certification question and has concluded that simulation may be increasingly important in the future certification activities. Through a contract with Lockheed Aircraft Company, the FAA will be able to review past use of industrial simulation in connection with certification.

This paper presents a description of several Federal Aviation Administration (FAA) incident data systems that contain information on events which result primarily from human error. These data systems include reports of near midair collisions, operational errors, pilot deviations, and events reported through the Aviation Safety Reporting System (ASRS). Over 17,000 incident reports are received and stored in these data bases annually. This paper discusses the information content of the data bases, reporting procedures, system limitations, proposed improvements, and uses of the data.

Since the first airplane was certified in 1927, the standard configuration has been with the main lifting surface or surfaces forward of the stabilizing surface. Although some of the advantages of the canard configuration were recognized quite early - by the Wright Brothers, for example - canard surfaces have been used to date only as additional control surfaces on some military airplanes, and on some amateur built airplanes. As a result, the Airworthiness Regulations of Reference 1 address only tail aft configurations. When FAA was first approached regarding certification of a canard configured small airplane, an FAA/Industry Empennage Loads Working Group was formed to develop technical proposals for the necessary rule changes and policy. The concerns addressed by this working group are discussed in the following sections.

Microprocessor technology is allowing functions in aircraft to be implemented to a greater degree by digital process control than by conventional mechanical or electromechanical means. A review of this technology indicates a need for updated certification criteria. A high level of commitment to the technology such as fly-by-wire is completely beyond the scope of existing certification criteria. This paper emphasizes the areas of software validation levels, increased concern with basic power system qualification, and increased environmental concerns for electromagnetic interference and lightning.

One Engine Inoperative takeoff climb performance of the XV-15 tilt rotor aircraft was analytically determined from level flight data and compared to the proposed powered-lift aircraft criteria. The results of this analysis can be useful in establishing the takeoff profile and highlighting potential certification issues.

Powered-lift aircraft, such as the V-22 tilt-rotor, are likely to spin-off a civil version. The present FAA airworthiness certification standards are not considered to be adequate for these unique aircraft. The FAA has drafted certification criteria and held a public conference to review the draft and identify significant technical certification issues that require further effort to establish correct standards for powered-lift aircraft. Some of those issues are discussed.

Wind tunnel tests were performed on an 8.9-percent scale semispan wing in the Wichita State University 7x10-foot wind tunnel with simulated ice accretion shapes. Simulated ice shapes from large-droplet clouds, simple-geometry ice horn shapes, and simple-geometry spanwise ridge shapes typical of runback icing were tested. Three Reynolds number and Mach number combinations were tested over a range of angles of attack. Aerodynamic forces and moments were acquired from the tunnel balance and surface pressures and oil flow visualizations were acquired. This research supplements the Swept Wing Icing Program recently concluded by NASA, FAA, ONERA, and their partners by testing new ice shapes on the same wind tunnel model. Additional surface roughness was added to simulate large-droplet ice accretion aft of the highly three-dimensional primary ice shape, and it had little effect on the wing aerodynamic performance.

The Ice Crystal Environment Modular Axial Compressor Rig (ICE-MACR) was developed by the National Research Council of Canada (NRC) with support from the Federal Aviation Administration (FAA) in response to the need to understand ice crystal icing of aircraft engines at high altitudes. Icing wind tunnel tests on static hardware lack some of the real physics of turbofan compressor such as centrifuging and fracturing of particles, and melting of particles due to compression heating, heat transfer through a casing wall, as well as annular geometry effects. Since the commissioning of ICE-MACR in 2019 new insights have been gained on the physics behind ice crystal icing of turbofan engines. Additionally, the results of various test campaigns have been used to validate engine ice accretion numerical codes. This paper summarizes the key insights into ICI of turbofans gained from the ICE-MACR to date.

In 2021 the Federal Aviation Administration in collaboration with the National Research Council of Canada performed research on altitude ice crystal icing of aircraft engines using the modular compressor rig, ICE-MACR, in an altitude wind tunnel. The aim of the research campaign was to address research needs related to ice crystal icing of aircraft engines outlined in FAA publication Engine Ice Crystal Icing Technology Plan with Research Needs. This paper reports the findings on ice accretion from a configuration of ICE-MACR with two compression stages. Inherent in two-stage operation is not just additional fracturing and heating by the second stage but also higher axial velocity and potentially greater centrifuging of particles. These factors influence the accretion behavior in the test article compared to single stage accretion.