Any pilot can imagine a "worst case scenario" on any flight. A pilot who never flies isn't really a pilot is he? If you can't fly a plane without TCAS then it is because A. you're too lazy to be bothered to look out the window for traffic, or B. you're incompetent.
I would not have fired the pilot. I would have brought him in for additional training. That said, if I was a GIA Chief Pilot in this situation then I would fire every single pilot on the list and then quit.
As for mid air collisions...
29 September 2006; Gol Linhas Aereas 737-800; near Peixoto de Azevedo, Brazil
The aircraft was on a scheduled domestic flight from Manaus to Brasilia when it had a midair collision in the area of São Félix do Xingu with an Embraer ERJ135 Legacy 600 executive jet operated by ExcelAire. The ExcelAire Legacy 600 jet had been on a flight from São José dos Campos to Manaus. After the collision, which damaged the left wing, left stabilizer, and left elevator of the executive jet, the crew of the damaged ExcelAire aircraft was able to land at a nearby military airfield at Cachimbo, Brazil. The 737 subsequently crashed 30 kilometers (19 miles) north of the Peixoto de Azevedo municipality. The Legacy 600 was on the first leg of a delivery flight to the U.S. The 737 aircraft was also relatively new, having come into service with the airline less than three weeks before the crash.
All six crew members and 148 passengers on the 737 were killed. The two crew members and five passengers on the Legacy 600 were not injured.
1 July 2002; Bashkirian Airlines Tupolev 154; near Ueberlingen, Germany
The aircraft was involved in a midair collision involving a DHL 757 while both aircraft were flying at about 36,000 feet (about 11,000 meters). Debris from both aircraft fell in an area near Lake Constance on the German-Swiss border. Both crew members on the DHL 757 and the 57 passengers and 12 crew members on the Tupolev 154 were killed. The 57 passengers on the Tupolev 154 included 44 children. The 757 departed Bahrain and was continuing on to Brussels after a stop in Bergamo in northern Italy. The Tupolev 154 was on a trip from Moscow to Barcelona and had made a stopover in Munich shortly before the accident.
12 November 1996; Saudia 747-100; near New Delhi, India
22 December 1992; Libyan Arab Airlines 727-200; Near Tripoli, Libya
31 August 1986; Aeromexico DC9-32; Cerritos, CA
The DC9 collided with a single engine Piper Archer which had made an unauthorized penetration of controlled airspace. All 6 crew members and 58 passengers were killed. The three occupants of the Piper and 18 people on the ground were also killed.
25 September 1978; Pacific Southwest 727-200; San Diego, CA
The aircraft had a midair collision with a single engine Cessna and crashed. All seven crew members, all 128 passengers, both occupants of the second aircraft, and 13 others on the ground were killed.
1 March 1978; Nigeria Airways F28-1000; Lagos, Nigeria
10 September 1976; Inex Adria DC9-32; Near Zagreb, Yugoslavia
5 March 1973; Iberia DC9-32; Nantes, France
30 July 1971; All Nippon Airways 727-200; northern Honshu, Japan, CA
6 June 1971; Hughes Airwest DC9-31; Near Duarte, CA
9 September 1969; Allegheny DC9-31; Near Fairland, IN
19 July 1967; Piedmont 727; Hendersonville, NC
The 727 was climbing away from the Asheville airport when it hit a Cessna 310 about eight miles (13 km) from the airport. All five crew members and 74 passengers were killed. The three occupants of the Cessna were also killed.
9 March 1967; TWA DC9-14; Near Urbana, OH
The aircraft crashed after an in flight collision with a Beech Baron. All four crew members and 21 passengers on the DC9 were killed. The sole occupant of the Baron was also killed.
16 December 1960, United Air Lines DC8 and Lockheed Constellation, New York, NY
The two aircraft collided over New York with the Constellation crashing in Staten Island and the DC8 crashing in Brooklyn. All seven crew members and 76 passengers on the DC8 were killed. All 50 occupants of the Constellation were also killed.