The historic airplane Tante Ju will no longer be taking off. To make them airworthy again, more than a million francs would have to be invested and ticket prices could no longer be offered to the general public. The last Tante-Ju-52 can now be viewed and climbed at the Dübendorf Aviation Museum.
On August 4, 2018, a Ju-52 crashed on Piz Segnas near Flims GR. All 20 people on board died. The Tante Ju crashed vertically into the rocky ground at 202 kilometers per hour. The final report on the incident states that the crash of the Ju-52 was due to errors on the part of the two pilots. However, technical defects were also identified, with the aircraft no longer achieving the proven flight performance.
I read the full accident report for work some years ago. It’s part of “statistics”.
The pilots decided to give passengers a special view of the mountains, but the flight had no safety margin in terms of elevation above ground level. They entered a canyon, at some point found out that they had not enough elevation to go above mountain tops, tried to turn around but not enough speed or space to accomplish the 180° turn. Air close to mountains is known to be extremely turbulent, sometimes there’s a strong downdraft on one side on the mountain that neutralizes the climbing rate of the airplane. Commercial operations (air carriers) have internal manuals that tell “keep a minimum of xxx thousand feet above mountains”. But this flight was in a very gray area between hobby and commercial operation. If it were a new airplane, it would need a black box (flight recorder). But it is an old one so modern laws don’t apply, no black box, and most of the investigation data came from photos, videos and declarations from people hiking in the area that day.
There’s also the legal issue of carrying paying passengers. The “two-tier system” idea has been floating around in the last days and it may apply to this event. 2 people die in a bus crash and there’s a long legal process to determine liability. 20 people die in a plane crash and… 
Positive outcome: until this accident it was easier to keep an old airplane flying than an old car on the road, but this was fixed and that’s the reason the airplane will stay on the ground.
