73 Years ago today: On 1 November 1949 an Eastern Airlines Douglas C-54 collided with a Bolivian Air Force P-38 on approach to Washington-National, killing all 55 occupants.

Date:Tuesday 1 November 1949
Time:11:46
Type:Silhouette image of generic DC4 model; specific model in this crash may look slightly different
Douglas C-54B-10-DO (DC-4)
Operator:Eastern Air Lines
Registration:N88727
MSN:18365
First flight:1944
Total airframe hrs:12161
Crew:Fatalities: 4 / Occupants: 4
Passengers:Fatalities: 51 / Occupants: 51
Total:Fatalities: 55 / Occupants: 55
Aircraft damage:Damaged beyond repair
Location:0,8 km (0.5 mls) SW of Washington-National Airport, DC (DCA) (https://cdn.aviation-safety.net/database/country/flags_15/N.gif   United States of America)
Phase:Approach (APR)
Nature:Domestic Scheduled Passenger
Departure airport:New York-La Guardia Airport, NY (LGA/KLGA), United States of America
Destination airport:Washington-National Airport, DC (DCA/KDCA), United States of America
Flightnumber:EA537

Narrative:
At 11:37 A Bolivian Air Force Lockheed P-38 Lightning fighter (NX26927) took off from runway 03 at Washington-National Airport, DC (DCA). The pilot was carrying out an acceptance test flight. Because of erratic operation of the right hand engine, the pilot decided to land as soon as possible.
When abeam runway 36 the pilot transmitted, “Washington Tower, this is Bolivian P-38. I got engine trouble request landing instructions.” Waiting for instructions he circled the field. When he was between Bolling Field and the National Airport and at about 3,500 feet altitude, the tower asked, “Bolivian P-38, you were asking landing instructions?” The Bolivian pilot answered, “Yes, I have engine trouble. I am in a hurry,” and that the tower at that time responded, “Bolivian P-38 cleared to land number two on runway 3.”
Number one on the approach was Eastern Air Lines flight 537, a Douglas C-54. Because the P-38 was descending above and behind the C-54, it was then told to enter the left traffic pattern and to land behind the C-54. This message was never confirmed, nor complied with. The tower then switched to the Eastern aircraft and told it to turn left. When turning left, half a mile short of the runway at an altitude of 300 feet, both aircraft collided and crashed. The pilot of the P-38 survived with serious injuries.
Probable Cause:

PROBABLE CAUSE: “The execution of a straight-in final approach by the P-38 pilot without obtaining proper clearance to land and without exercising necessary vigilance.”