National Airlines Flight 2511 was a United States domestic passenger flight from New York City to Miami, Florida. On January 6, 1960, the Douglas DC-6 serving the flight exploded in midair. The National Airlines aircraft was carrying 5 crew members and 29 passengers, all of whom perished. The Civil Aeronautics Board investigation concluded that the plane was brought down by a bomb made of dynamite. No criminal charges were ever filed, nor was the blame for the bombing ever determined, though a suicide bombing is suspected. The investigation remains open. One of the victims was retired U.S. Navy Vice Admiral Edward Orrick McDonnell, a Medal of Honor recipient and veteran of both World Wars. Flight history National Airlines' New York-Miami route was usually flown by a Boeing 707 as Flight 601. On January 5, 1960, the 707 aircraft scheduled to fly to Miami was grounded due to cracks that were discovered in the cockpit windshield. The windshield replacement procedure would take eight hours to perform, so National Airlines transferred the passengers of Flight 601 to two propliner aircraft it had in reserve. Passengers were boarded on these two replacement planes on a first-come, first-served basis. Seventy-six passengers boarded a Lockheed L-188 Electra. This aircraft flew to Miami and arrived safely. The remaining 29 passengers boarded a Douglas DC-6B, which departed Idlewild Airport for Miami as Flight 2511. They were accompanied by two stewardesses, pilot Dale Southard (45), copilot Richard L. Hentzel (31), and flight engineer Robert R. Halleckson (34). The plane departed New York at 11:52 p.m. and was scheduled to arrive in Miami at 4:36 a.m. on January 6. The aircraft, registration was described as being in good condition. It had four Pratt and Whitney R-2800 CB-16 engines and had accumulated 24,836 hours of flight time. 2511's flight plan called for it to fly south from New York to Wilmington, North Carolina, where it would continue south over the Atlantic Ocean. It would fly south over the ocean to Palm Beach, Florida. The crew maintained radio contact with National Airlines' radio controllers and air traffic control, reporting clouds and instrument flying conditions. The crew checked in with Wilmington Airport at 2:07 a.m., and later reported flying over the Carolina Beach radio beacon at 2:31 a.m. This was the last radio contact with the airplane. Crash and recovery After losing contact with the DC-6 aircraft, National Airlines, the United States