Douglas DC-3 accident at Miami, Florida, 28 Dec 1948 (NC-16002)

Accident narrative

On December 28, 1948, a Douglas DC-3 operated by Airborne Transport, Inc., disappeared while en route from San Juan, Puerto Rico, to Miami, Florida. The aircraft, registered NC-16002, was carrying 29 passengers and a crew of three. Despite an extensive six-day search, no trace of the aircraft or its occupants was ever found.

### The flight

The crew consisted of Captain Robert E. Linquist, Copilot E. E. Hill, and Stewardess Mary Burke. Captain Linquist had 3,265 flying hours; he had flown the route for other companies and as a copilot for Airborne Transport, but this was his first trip as captain for the company. Copilot Hill had 197 flying hours.

The aircraft had arrived in San Juan at 1940 on December 27. Upon landing, the captain reported that the landing gear warning light system was malfunctioning. A mechanic examined the aircraft's batteries and found them discharged with a low water level. Advised that recharging would take several hours, the captain asked the mechanic to add water and return the batteries to the aircraft without charging them. The warning light system was not repaired.

At 2030, the crew filed an instrument flight rules (IFR) flight plan to Miami. One hour later, the flight advised that they were experiencing battery trouble and would be delayed, which invalidated the flight plan. At approximately 2245, the DC-3 taxied to the runway, but the control tower was unable to contact it by radio. The Chief of Aviation proceeded to the aircraft, where the crew advised that the radio receiver was working, but the transmitter was not functioning due to the weak batteries.

The Chief of Aviation authorized a visual flight rules (VFR) takeoff. It was agreed that the flight would remain in the vicinity of San Juan until the generators produced enough power to transmit. Once contact was established with the tower, a new IFR plan would be filed; if this proved impossible, the flight was to return to San Juan. Contradictory weight and balance and passenger manifests indicated the aircraft was 113 pounds overweight at departure.

### Disappearance

The DC-3 departed at 2303. Eleven minutes later, the flight called the control tower. The tower did not receive the call, but it was intercepted by CAA Communications at San Juan. The flight reported that it was unable to contact the tower and was proceeding to Miami on an IFR plan.

At 2323, the Overseas Foreign Air Route Traffic Control Center at Miami received a radio communication from the flight, stating it was flying at 8,500 feet and estimating its arrival over South Caicos at 0033 and Miami at 0405. The final known contact occurred at 0413 on December 28, when the New Orleans center intercepted a position report stating the aircraft was 50 miles south of Miami. Subsequent attempts to contact the flight were unsuccessful.

When the aircraft was determined to be missing, an extensive search was launched involving the U.S. Coast Guard, Navy, Air Force, civil aircraft, and international agencies. The search covered the route, the Florida coast, the Gulf of Mexico, Cuba, Hispaniola, and the Bahamas. Over 1,300 plane hours were flown before the search was terminated on January 3, 1949.

### What the investigation found

Because the aircraft was never located, the Civil Aeronautics Board could not examine the wreckage. A review of company records showed the aircraft had received a partial overhaul the previous month, but the maintenance records were incomplete, missing entries for recent engine installations and a prior repair in San Juan.

The Board found that at the time of takeoff, the aircraft did not meet the requirements of its operating certificate due to the malfunctioning electrical system. Although the original IFR plan had been cancelled, the Board believed the pilot thought it was or could be reinstated, as evidenced by his radio message eleven minutes after takeoff.

Investigators noted that the aircraft had fuel for seven and a half hours of flight. Because the final intercepted message occurred approximately six hours and ten minutes after takeoff, the Board noted that any error in the pilot's reported position would be critical. While the transmitter was working at 0413, the Board stated it was possible that a subsequent electrical failure rendered the radio and automatic compass inoperative.

A weather analysis revealed an unpredicted wind change along the route. As the flight neared Miami, the wind shifted from the northwest to the northeast. This information was broadcast from Miami at 0015, but it was unknown if the flight received it. The Board noted that without knowledge of this change, the aircraft could have drifted 40 to 60 miles to the left of its course.

### Probable cause

The Civil Aeronautics Board concluded: "The Board lacks sufficient information in this case to determine the probable cause."