If anyone else is having problems with broken links in that documentation then here, as far as I can see, are the correct links in four languages EN, DE, FR, IT where available:
Quoted from
https://www.sust.admin.ch/inhalte/AV.../HB-HOT_EN.pdf :
"Publications (EN) on the investigation of the accident involving the Junkers Ju 52 HB-HOT air- craft on 4 August 2018
The following links can be used to view or download the STSB’s publications on the safety investigation of the accident involving the Junkers Ju 52 HB-HOT aircraft on 4 August 2018. Not all publications are available in English (EN). If a publication is not available in English, reference is made to a version in German (DE).
..."
Media release:
EN:
https://www.sust.admin.ch/inhalte/AV..._Release_E.pdf
DE:
https://www.sust.admin.ch/inhalte/AV...tteilung_D.pdf
FR:
https://www.sust.admin.ch/inhalte/AV...e_presse_F.pdf
IT:
https://www.sust.admin.ch/inhalte/AV...o_stampa_I.pdf
Main part of the final report (EN, DE, FR, IT)
EN:
https://www.sust.admin.ch/inhalte/AV...B_HB-HOT_E.pdf
DE:
https://www.sust.admin.ch/inhalte/AV...B_HB-HOT_D.pdf
FR:
https://www.sust.admin.ch/inhalte/AV...B_HB-HOT_F.pdf
IT:
https://www.sust.admin.ch/inhalte/AV...B_HB-HOT_I.pdf
Glossary (EN, DE, FR, IT)
EN:
https://www.sust.admin.ch/inhalte/AV..._Glossar_E.pdf
DE:
https://www.sust.admin.ch/inhalte/AV..._Glossar_D.pdf
FR:
https://www.sust.admin.ch/inhalte/AV..._Glossar_F.pdf
IT:
https://www.sust.admin.ch/inhalte/AV..._Glossar_I.pdf
Annex A1.1 (EN)
https://www.sust.admin.ch/inhalte/AV...OT_A1-01_E.pdf
Annex A1.5 (EN)
https://www.sust.admin.ch/inhalte/AV...OT_A1-05_E.pdf
Annex A1.6 (EN)
https://www.sust.admin.ch/inhalte/AV...OT_A1-06_E.pdf
Annex A1.7 (EN)
https://www.sust.admin.ch/inhalte/AV...OT_A1-07_E.pdf
Annex A1.12 (EN)
https://www.sust.admin.ch/inhalte/AV...OT_A1-12_E.pdf
Annex A1.16 (EN)
https://www.sust.admin.ch/inhalte/AV...OT_A1-16_E.pdf
Annex A1.17 (EN)
https://www.sust.admin.ch/inhalte/AV...OT_A1-17_E.pdf
Annex A1.18 (EN)
https://www.sust.admin.ch/inhalte/AV...OT_A1-18_E.pdf
Annex A1.19 (EN)
https://www.sust.admin.ch/inhalte/AV...OT_A1-19_E.pdf
Download a copy of the final report including all annexes:
ZIP file of the final report (EN) including all annexes (EN) (93 MB)
https://www.sust.admin.ch/inhalte/AV...Version__E.zip
Explanatory video:
MP4 file (EN, DE, FR, IT) (840 MB)
EN:
https://www.sust.admin.ch/inhalte/AV...FINAL%20EN.mp4
DE:
https://www.sust.admin.ch/inhalte/AV...FINAL%20DE.mp4
FR:
https://www.sust.admin.ch/inhalte/AV...FINAL%20FR.mp4
IT:
https://www.sust.admin.ch/inhalte/AV...FINAL%20IT.mp4
Watch the video on Youtube (EN)
EN:
DE:
https://www.youtube.com/watch?v=PKnb...ature=youtu.be
FR:
https://www.youtube.com/watch?v=q_Hs...ature=youtu.be
IT:
https://www.youtube.com/watch?v=gv-r...ature=youtu.be
Illustrations for prevention awareness:
ZIP file containing illustrations from the final report (EN) and the annexes (EN) (300 MB)
EN:
https://www.sust.admin.ch/inhalte/AV...EN/Mappe_E.zip
DE:
https://www.sust.admin.ch/inhalte/AV...DE/Mappe_D.zip
FR:
https://www.sust.admin.ch/inhalte/AV...FR/Mappe_F.zip
IT:
https://www.sust.admin.ch/inhalte/AV...IT/Mappe_I.zip
Earlier publications:
Status report as of 3 August 2020 (EN)
EN:
https://www.sust.admin.ch/inhalte/AV..._StatB_E_2.pdf
DE:
https://www.sust.admin.ch/inhalte/AV..._StatB_D_2.pdf
FR:
https://www.sust.admin.ch/inhalte/AV..._StatB_F_2.pdf
IT:
https://www.sust.admin.ch/inhalte/AV..._StatB_I_2.pdf
Status report as of 2 August 2019 (EN)
EN:
https://www.sust.admin.ch/inhalte/AV...OT_StatB_E.pdf
DE:
https://www.sust.admin.ch/inhalte/AV...OT_StatB_D.pdf
FR:
https://www.sust.admin.ch/inhalte/AV...OT_StatB_F.pdf
IT:
https://www.sust.admin.ch/inhalte/AV...OT_StatB_I.pdf
Interim report from 20 November 2018 (DE)
https://www.sust.admin.ch/inhalte/AV...B-HOT_ZB_D.pdf
Preliminary report from 15 August 2018 (DE)
https://www.sust.admin.ch/inhalte/AV...B-HOT_VB_D.pdf