High time this mystery is unwrapped

WHY would the report on a plane crash be classified?

For almost half a century, no one has known what exactly happened on June 6, 1976, to cause an aircraft on a flight from (what is now the Federal Territory of) Labuan to Kota Kinabalu International Airport to crash, killing 11 people, including Sabah chief minister Tun Fuad Stephens and practically half his Cabinet.