Date:	Thursday 14 August 1958
Time:	03:50
Type:	Lockheed L-1049H-01-06-162 Super Constellation
Owner/operator:	KLM Royal Dutch Airlines
Registration:	PH-LKM
MSN:	4841
Year of manufacture:	1958
Total airframe hrs:	886 hours
Engine model:	Wright R-3350 (988TC18EA6)
Fatalities:	Fatalities: 99 / Occupants: 99
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	180 km W off Shannon, Ireland -   Atlantic Ocean
Phase:	En route
Nature:	Passenger - Scheduled
Departure airport:	Shannon Airport (SNN/EINN)
Destination airport:	Gander Airport, NL (YQX/CYQX)
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
The Lockheed L-1049H Super Constellation, named "Hugo de Groot", impacted the water of the Atlantic Ocean 180 kilometers west off Shannon, Ireland. All 91 passengers and eight crew members were killed.
The aircraft was operated by KLM as flight 607E and had departed Amsterdam-Schiphol Airport in the Netherlands on a service to New York-Idlewild Airport, USA, with refueling stops at Shannon, Ireland. and Gander, Canada.
The aircraft departed Shannon at 03:05 GMT. Last radio contact with the aircraft was at 03:40 GMT. Nothing more was heard from the flight. Pieces wreckage were found 110 miles north-northwest off the Irish coast.
According to investigators the wreckage gave the impression that the slope of the flight path was not very great at the moment of impact.

PROBABLE CAUSE: "On the basis if the evidence available and the investigation of possible serious threats to safety, the Board cannot establish the cause of the accident with certainty. Moreover, investigation of the possibility that the cause of the accident may have been a bomb explosion has yielded no conclusive facts to support such a hypothesis. The statements in the press to this effect have either been based on misunderstandings or else were tendentious. On the other hand, the Board attributes a high degree of probability to hypothesis that the cause of the accident is related to 'overspeeding' of one of the outboard propellers resulting from oil polution after a gear had been damaged when the supercharger of the corresponding engine was accelerated (shifted). This probably took place close to the time of the accident. The overspeeding of the propeller, owing to the obstruction of metal particles in the regulator valves may have been such as to cause the propeller pitch to decrease and the propeller could not be feathered. The condition might provoke a flight disturbance which could be corrected only by prompt and powerful handling of aileron and rudder controls. in view of the rapidity with which this defect develops and taking into account that recognition of the nature of this malfunction requires a certain time, it is not always possible for the crew to intervene early enough to restore conditions of controlled flight. With respect to the presumed cause of the accident the Board has no grounds to suppose that the occurrence of the presumed malfunction might be attributable to neglect on the part of maintenance personnel or to incorrect measures taken by the crew or that the crew had been at fault in piloting the aircraft after the malfunction had occurred."

ICAO Circular 64-AN/58 (23-30)
Nederlandse Constallations / H.Dekker

photo (c) via Anefo; Amsterdam-Schiphol International Airport (AMS/EHAM); 1958; (publicdomain)

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