Error Propagation Concepts Including Flight Dynamics for Total System Performance Analysis During GBAS based Initial CAT-III Approach and Landing

In order to assess the integrity risk for GBAS based automatic approach and landing, we investigated a total performance concept of a combined system consisting of an ILS look-a-like GBAS landing system (GLS) and a DeHavilland Dash-2 Beaver aircraft. We propagated four basic pseudorange errors to a position error distribution, which was then the source of position uncertainties for the GLS installed in the aircraft. Results show that the vertical total system error (TSE) in the steady state final approach lags behind the vertical navigation system error (NSE). The TSE is smoothed and preserves the general temporal sequence of the error. A reduction of 30\% of the TSE standard deviation with respect to the NSE only occurs during a period of glide slope overshoot, where the autopilot uses large and steadily declining elevator deflections to return to the desired glide path. With minor adaptations this concept can be refined and a possible error reduction may be achieved

Vertices in Total Dominating Sets.

Fricke, Haynes, Hedetniemi, Hedetniemi, and Laskar introduced the following concept. For a graph G = (V,E), let rho denote a property of interest concerning sets of vertices. A vertex u is rho-good if u is contained in a {minimum, maximum} rho-set in G and rho-bad if u is not contained in a rho-set. Let g denote the number of rho-good vertices and b denote the number of rho-bad vertices. A graph G is called rho-excellent if every vertex in V is rho-good, rho-commendable if g \u3e b \u3e 0, rho-fair if g = b, and rho-poor if g \u3c b. In this thesis the property of interest is total domination. The total domination number, gammat, is the cardinality of a smallest total dominating set in a graph. We investigate gammat-excellent, gammat-commendable, gammat-fair, and gammat-poor graphs

Flight Testing GLS Approaches Enabled by Wide Area Corrections in Kerkyra, Greece

Many airports with a high value to commercial air traffic have spatial or budgetary constraints which prevent the installation of a precision approach system. We previously designed a low-cost precision approach system which combines the advantages of both ground-based and satellite-based augmentation systems by using a converter between them in order to allow GAST-A approach types. We installed, operated, and flight-tested such a system at Kerkyra Airport using an A320 aircraft. During these, we recorded data from a commercial multimode receiver as well as GPS raw data in order to prove the feasibility of the system. Data were analyzed using the Pegasus toolset as well as a highly precise reference trajectory computed from postprocessed carrier phase data. The data recorded show excellent performance for approach guidance that is no different from that of the more expensive GPS landing system GLS and provides guidance in accordance with the localizer performance with vertical guidance standards. Our low-cost precision approach system can provide precision approach-like guidance to appropriately equipped transport aircraft. Kerkyra Airport is extremely limited in availability of usable surface area, such that conventional precision landing aids cannot be placed on airport property. The system provides the ground-based augmentation system approach service type A, a category defined in Annex 10 to the convention of Chicago. This category has not seen any operational use until now but offers an opportunity to provide precision approaches based on GLS where guidance down to a certain altitude will be sufficient

Software Safety Assurance in Non-Airborne GPS Based Landing Aids

This paper investigates the software standard DO-278A from the RTCA according to assurance level 3 to provide a concept for approving software of ground-based navigation aids. For this purpose, related literature and standards were reviewed and evaluated for their applicability for proposing such a concept. The resulting approval concept shows our approach for conducting the development process according to DO-278A based on a traditional one and focusing on an activity schedule. Therefore, the paper offers preliminary considerations at first to show the relation between system and software development. In addition, corresponding standards that are related to the development are presented as well. The concept is segmented in three main phases for software planning, realization, and verification, which are subdivided and scheduled in specific activities. Each activity consists of an outline describing the contents expected by DO-278A and our approach to organizing them. This paper shows our conceptional approach to obtain an approval for software according to DO-278A. This concept is prepared to approve a radio navigation aid

An Operational Concept Flying GLS Approaches Using SBAS

A new converter technology allows suitably equipped aircraft to use data provided by the satellite-based augmentation system in receivers originally designed for the ground-based augmentation landing system. For these aircraft, that system enables a lower decision altitude and, hence, improved access to airports. To make this technology usable, air crews require an operational concept and the flight crew has to be presented with the appropriate information in the form of approach charts. Two different possibilities for an operational concept were developed and the corresponding approach charts created. One option is a modified area navigation approach chart, to which the specific information is added. The other chart is an entirely separate procedure for the approach. These two options were tested with airline pilots in an Airbus A320 full-flight training simulator. During the simulator flights, aircraft performance data was recorded and the participants filled in questionnaires regarding workload and quality of the operational concept. The results show different behavior during the intercept of the final course, but all approaches remained within the required limits. The questionnaires revealed that the workload is higher during the area navigation variant and that all participants prefer the separate ground-based augmentation landing system variant

Enabling LPV for GLS Equipped Aircraft Using a SBAS to GBAS Converter

We build a prototype system intended to bring together the advantages of both the ground based and satellite based augmentation systems (GBAS, SBAS). It combines an SBAS-capable global navigation satellite systems receiver with a database and a GBAS-compatible data link. The correction and integrity data received from the SBAS satellite are automatically translated into GBAS-compatible structures and sent to the airborne multi-mode receiver using the final approach segment data block. As commercial air transport aircraft are rarely equipped with SBAS capable receivers but are increasingly fitted with GBAS receivers our System adds the SBAS capability to a GBAS equipped aircraft. Here, we present data collected during airline trials in the summer of 2022

An algal enzyme required for biosynthesis of the most abundant marine carotenoids.

Fucoxanthin and its derivatives are the main light-harvesting pigments in the photosynthetic apparatus of many chromalveolate algae and represent the most abundant carotenoids in the world's oceans, thus being major facilitators of marine primary production. A central step in fucoxanthin biosynthesis that has been elusive so far is the conversion of violaxanthin to neoxanthin. Here, we show that in chromalveolates, this reaction is catalyzed by violaxanthin de-epoxidase-like (VDL) proteins and that VDL is also involved in the formation of other light-harvesting carotenoids such as peridinin or vaucheriaxanthin. VDL is closely related to the photoprotective enzyme violaxanthin de-epoxidase that operates in plants and most algae, revealing that in major phyla of marine algae, an ancient gene duplication triggered the evolution of carotenoid functions beyond photoprotection toward light harvesting

Impact of GNSS-band radio interference on operational avionics

GNSS outages due to intentional jamming affecting the airspace over the Eastern Mediterranean have received significant attention in recent years. In an effort to better understand the phenomenon and its impact on aviation hardware, DLR sent a data collection flight to the area. The flight was conducted in an Airbus 320, which allowed a study of the behavior of regular avionics and aviation-grade GNSS receivers under jamming conditions. Part of the experimental instrumentation included a high-definition radio-frequency recording device, which allows in-depth pre-correlation analysis of the radio spectrum around the main GPS and Galileo carrier frequencies. The results confirm that the observed outages likely stem from man-made radio interference. They also provide an in-situ opportunity to study the behavior of commercial avionics under GNSS interference conditions

GNSS Double Differences used as Beacon Landing System for Aircraft Instrument Approach

When using GNSS navigation for final approach guidance of aircraft to a landing site, the only systems currently available are differential GNSS with additional integrity data called augmentation systems. These work well when the landing site is fixed in space and well surveyed. In all other cases, augmentation systems are difficult to use. Here, we propose relative navigation based on GNSS double difference measurement to accomplish the same task, but also onto moving landing platforms or at unsurveyed locations. We call this the Beacon Landing System. Furthermore, we show long term measurement data confirming the sub-meter accuracy and results from flight tests. During the flight test we successfully used the relative navigation for aircraft guidance