Documents / Report
UK Airprox Board report 2013085 examines a 22 July 2013 conflict near Daventry between an A320 inbound to Heathrow and a DH8D inbound to Birmingham, both deviating around thunderstorms. Both crews received TCAS resolution advisories and controllers issued avoiding action, with recorded separation of 1400ft vertical and 2.3nm horizontal. The Board found the Welin controller allowed the DH8D to come into conflict with the A320 by not monitoring its slow descent, and assessed the risk as Category C, with no collision risk.
“TCAS”5 pages
3 Figure 1 At 1906:00 the two aircraft were 10nm apart with the A320 descending through FL204 for FL200 and the DH8D was passing FL198 for FL90. The Welin controller instructed the DH8D to expedite descent due to traffic above. Low level STCA activated. At 1906:05 High level STCA activated. The Cowly controller issued avoiding action to the A320 to turn left heading 095°. The Welin controller issued avoiding action to the DH8D to turn left heading 290°. At 1906:20 the A320 reported receiving a TCAS RA (Figure 2). Figure 2 At 1906:22 the two aircraft were 4.1nm and 1000ft apart (Figure 3).
Report, cited by the archive. The PDF is mirrored here; the original link is under it. 5 pages are in the text index: search them above, or from the library's search.