In July 1967 a freight train loaded with fuel crashed into a passenger train and exploded in Langenweddingen, Sachsen-Anhalt.
It was the worst train accident in East German history, killing 94 people, 44 of whom were children.
But the general public was never informed of the causes of the accident - despite the fact that a secret state report actually acknowledged that a barrier had failed to come down at a railway crossing.
A telephone cable had dangled so low that the barrier got caught in it, preventing it from closing, the report concluded.
This week public broadcaster ZDF aired a documentary that cast some light on the disastrous accident that happened nearly 50 years ago, as well as focusing on some of the other accidents that took place during the GDR era.
After the Langenweddingen accident the train conductor and an employee of the station were condemned to hefty prison sentences. But GDR leaders did not publicly investigate structural causes, fearing this could open up a can of worms for the whole political system.
Historian Henrik Bispinck told ZDF that the strategy of East German leaders was to blame individuals and make them responsible for the accident instead.
Firemen, eye-witnesses and survivors testified to the filmmakers about their personal experiences of that tragedy and others - and for many the memory was still vivid.
“The feeling of helplessness remains”, said one man whose mother died in a 1972 plane crash near Berlin.
The thin official report released at the time failed to explain why a fire broke out in the plane, causing the death of 160 people.
Again, a confidential Stasi document kept the causes of the accident secret.
In their report about the crash, Stasi officials listed severe defects: a hot air conductor had melted near electric cables, and a fire alarm in the cockpit had failed to go off.
The ZDF documentary further revealed that the soviet manufacturer of the plane rejected proposed changes to the design and won support from Moscow, which said that it was better to leave things as they were.
GDR leader Erich Honecker agreed as a favour to the USSR, claimed historian Michael Goll in the documentary.
According to Goll, East German leaders also refused offers of help from West Germany, wanting to prove that the socialist state was strong and that it could manage on its own.
The documentary explained the accidents is connection with one another and argued that there was a recurrent pattern according to which GDR leaders and Stasi officials acted.
Strict silence was often ordered after an accident and evidence was swiftly removed from the scene. The aim was to show: “socialism is never guilty”.