Actually nobody wants to make a disastrous movie and the movies that you have mentioned above are not that bad. They were an attempt to try something different and there is always a risk in doing so. Yash Chopra who is mainly known for his romantic musical movies also tried his hand in the thriller genre with Itefaq starring Rajesh Khanna which did not had a single song.
He tried something different with Kala Pathar. A lesser known fact is that Kala Pathar was based on a real incident Chasnala mining disaster that took place in 1975 in Dhanbad, Bihar (now known as Jharkhand.)
There was an explosion in the mine followed by flooding which killed more than 300 miners. The film did average business at the box office but was critically acclaimed and received several nominations at the Filmfare Awards.
It attained a cult status and is considered a classic in Indian cinema. Besides this the IMDb rating of the film is 7.7 which is quite good so it will not be fair to call it a disaster.
Similarly Ravi Chopra tried something different in 1980 by making The Burning Train which was inspired by a Japanese disaster film The Bullet Train. Though the film is considered a flop it was the seventh highest grosser of 1980. It can be said that the movie was some 5 to 10 years ahead of its time.
The Burning Train shows the struggle to live when you are trapped in the clutches of death. It was a different movie which did not work at that time probably might have done better if released later because the special effects in the film were quite normal.
The length of the film is a matter of concern still the film has a good repeat value. The IMDb rating of the film is 6.8 which is not that bad. Therefore these two films cannot be given the tag of being the most disastrous film of Hindi cinema.
Its my personal opinion that trying something different should not be termed as a disaster because it requires a lot of courage to go against the wind and try something different rather than follow the trend. If IMDb rating is considered as the parameter then Sadak 2 is the most disastrous film which has a rating of 1.1 otherwise it is very difficult to pick out one film and term it as the most disastrous movie of Hindi cinema.
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