Air-traffic control staffing issues and technology failures at the Newark Airport have resulted in some close collision calls and flight disruptions. In an exclusive interview with WSJ, one veteran air-traffic controller breaks down how tough the job is, how he deals with radar outages, why he is taking a stress-related trauma leave and more. Chapters: 0:00 Newark-area disruptions 1:30 The day-to-day job and why Stewart enjoys it 3:30 What ATC’s do in aviation safety 6:30 The biggest challenges