scholarly journals Correlated Bayesian Model of Aircraft Encounters in the Terminal Area Given a Straight Takeoff or Landing

Author(s):  
Andrew Weinert ◽  
Ngaire Underhill ◽  
Christine Serres ◽  
Randal Guendel

The incorporation of unmanned aircraft terminal operations into the scope of Detect and Avoid systems necessitates analysis of the safety performance of those systems—principally, an assessment of how well those systems prevent loss of well clear from and collision with other aircraft. This type of analysis has typically been conducted by Monte Carlo simulation with synthetic, statistically representative encounters between aircraft drawn from an appropriate encounter model. While existing encounter models include terminal airspace classes, none explicitly represents the structure expected while engaged in terminal operations, e.g., aircraft in a traffic pattern. The work described herein is an initial model of such operations, scoped at this time specifically for assessment of unmanned aircraft landings and encounters with other aircraft either landing or taking off. The model shares the Bayesian network foundation of other MIT Lincoln Laboratory encounter models but tailors those networks to address structured terminal operations, i.e., correlations between trajectories and the airfield and each other. This initial model release is intended to elicit feedback from the standards-writing community.

Drones ◽  
2019 ◽  
Vol 3 (4) ◽  
pp. 84 ◽  
Author(s):  
Peter J. Burke

Using data from an Automatic Dependent Surveillance-Broadcast (ADSB) aggregator, a custom data-mining program was developed to identify all manned aircraft below 500′ AGL within 5 miles of the KSNA airport on six specific days in 2018–2019. The data (a spot check) show that several of the zero-foot grids are well outside of the traffic pattern, with no manned aircraft below 500′ AGL for at least a mile. Detailed maps showing all the traffic on those days are overlaid on the KSNA UAS facility map for comparison. This data-driven safety analysis is outlined as a new paradigm for drone safety near airports, which can be applied worldwide.


Author(s):  
S.K. Bailey ◽  
I.M. Davies ◽  
M.J.C. Harding

SynopsisCommon dogwhelks (Nucella lapillus) show a characteristic response to exposure to tributyltin compounds. Females develop male sexual characteristics, a phenomenon termed imposex. Dogwhelks have been collected for assesment of imposex from sites throughout Sullom Voe and Yell Sound in 1987, 1990 and 1991.Results of the 1991 survey have indicated that dogwhelks were completely absent from the terminal area, on the promontory of Calback Ness. The degree of imposex was highest in the population from Kames, the site closest to the terminal. Juveniles were completely absent from this site. Incidence of imposex was high in populations throughout the Voe and 91% of the females examined from within the Voe were reproductively unviable due to blockage of their reproductive tracts with vas deferens tissue. Outside the Voe, in the well flushed waters of Yell Sound, imposex was much lower, but only fell to levels associated with populations from areas distant from tributyltin (TBT) contamination in the two most northerly sites surveyed.Results of the survey have indicated that activities associated with the oil terminal are the source of TBT contamination to the area, and that contamination arising from the terminal operations has not only affected dogwhelks in Sullom Voe, but populations throughout Yell Sound.Comparison of the imposex levels from 1987 and 1990 data indicates that the reproductive capacity of females has progressively declined and that populations within the Voe are gradually being eliminated. Forty-six percent of females sampled from populations within the Voe were sterile in 1987, compared to 65% in 1990, and 91% in 1991. In 1987, both adult and juvenile dogwhelks were present in the jetty area, although 94.5% of the females were sterile. In 1990, juveniles were absent from this area, and all females were sterile. No dogwhelks were found in the terminal area during the 1991 survey and, at Kames, the next closest site, juveniles were absent.


2020 ◽  
Author(s):  
Devin P. Jack ◽  
Keith D. Hoffler ◽  
Roy D. Roper ◽  
Anna Trujillo ◽  
Tod Lewis ◽  
...  

1978 ◽  
Author(s):  
Gary L. Orkin ◽  
Richard L. Folck ◽  
Richard A. Startzman

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