{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T20:50:58Z","timestamp":1777668658046,"version":"3.51.4"},"reference-count":7,"publisher":"SAGE Publications","issue":"1","license":[{"start":{"date-parts":[[1998,3,1]],"date-time":"1998-03-01T00:00:00Z","timestamp":888710400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Hum Factors"],"published-print":{"date-parts":[[1998,3]]},"abstract":"<jats:p>The risk of a collision between aircraft is rising as the density of commercial air traffic increases. This trend, together with the overwhelming need to upgrade the National Airspace System, has motivated the Federal Aviation Administration to sponsor the development of metrics to evaluate \u201cdynamic density\u201d\u2014a proxy for the likelihood of collision risk. Here we propose and evaluate a mathematical index of dynamic density, D, that describes collision risk. Although our domain of investigation is aviation, the logic of D is applicable whenever objects move in limited spaces. A series of sensitivity analyses illustrate how D responds to frequently encountered air traffic conflict situations. We illustrate a use of D that characterizes pilot performance and efficiency in experimental simulations of free flight and suggest other human factors applications. This research could be applied immediately by the traffic management units of en-route air traffic control centers to reformulate the criterion for the critical capacity of sectors.<\/jats:p>","DOI":"10.1518\/001872098779480604","type":"journal-article","created":{"date-parts":[[2007,1,13]],"date-time":"2007-01-13T10:25:31Z","timestamp":1168683931000},"page":"69-78","source":"Crossref","is-referenced-by-count":15,"title":["An Index of Dynamic Density"],"prefix":"10.1177","volume":"40","author":[{"given":"Kip","family":"Smith","sequence":"first","affiliation":[{"name":"University of Minnesota, Minneapolis, Minnesota"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Stephen F.","family":"Scallen","sequence":"additional","affiliation":[{"name":"University of Minnesota, Minneapolis, Minnesota"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"William","family":"Knecht","sequence":"additional","affiliation":[{"name":"University of Minnesota, Minneapolis, Minnesota"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Peter A.","family":"Hancock","sequence":"additional","affiliation":[{"name":"University of Minnesota, Minneapolis, Minnesota"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"179","published-online":{"date-parts":[[1998,3,1]]},"reference":[{"key":"atypb1","volume-title":"National plan for civil aviation human factors: An initiative for research and application","author":"Federal Aviation Administration. (FAA).","year":"1995"},{"key":"atypb2","doi-asserted-by":"publisher","DOI":"10.1007\/BF01405730"},{"key":"atypb3","volume-title":"Baseline assessment of the national airspace system: An approach toward modeling operational errors","author":"Rodgers, M. D.","year":"1995"},{"key":"atypb4","doi-asserted-by":"crossref","unstructured":"Rodgers, M. D., Manning, C. A. & Kerr, C. S. (1994). Demonstration of POWER: Performance and objective workload evaluation research. In Proceedings of the Human Factors and Ergonomics Society 38th Annual Meeting (p. 941). Santa Monica, CA: Human Factors and Ergonomics Society.","DOI":"10.1177\/154193129403801502"},{"key":"atypb5","volume-title":"Report of the RTCA board of directors' select committee on free flight","author":"Radio Technical Commission for Aeronautics. (RTCA).","year":"1995"},{"key":"atypb6","doi-asserted-by":"crossref","unstructured":"Scallen, S. F., Smith, K. & Hancock, P. A. (1996). Pilot actions during traffic situations in a free-flight airspace structure. In Proceedings of the Human Factors and Ergonomics Society 40th Annual Meeting (pp. 111\u2013115). Santa Monica, CA: Human Factors and Ergonomics Society.","DOI":"10.1177\/154193129604000223"},{"key":"atypb7","doi-asserted-by":"publisher","DOI":"10.1177\/106480469700500105"}],"container-title":["Human Factors: The Journal of the Human Factors and Ergonomics Society"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1518\/001872098779480604","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1518\/001872098779480604","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T07:50:46Z","timestamp":1777449046000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.sagepub.com\/doi\/10.1518\/001872098779480604"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1998,3]]},"references-count":7,"journal-issue":{"issue":"1","published-print":{"date-parts":[[1998,3]]}},"alternative-id":["10.1518\/001872098779480604"],"URL":"https:\/\/doi.org\/10.1518\/001872098779480604","relation":{},"ISSN":["0018-7208","1547-8181"],"issn-type":[{"value":"0018-7208","type":"print"},{"value":"1547-8181","type":"electronic"}],"subject":[],"published":{"date-parts":[[1998,3]]}}}