A lack of technical background is often a weakness in reporting on aviation issues. Helicopters are inheriently less safe than airplanes. The chances of a single mechanical failure bringing down the aircraft is higher. The aircraft are often operated under conditions where exposure to high-risk conditions are prolonged (bad weather, low altitude, night flight, nap-of-earth flying) compared to modern aircraft. Read the litany of accidents in the article. Note how many are clearly operational in nature. There has been no investigation concluded. There is no significant information in any article I have read. The type of operation allegedly being conducted, whether it was 'training' or not, involves essentially dangerous flying. Yet we have folks blaming an 'old' helicopter. ANY aircraft type which has been in service (in various versions) for almost 50 years is going to have had some issues. The CH-53-D's flown by the IAF were extensively upgraded in the Yasur 2000 program and are rigorously maintained. We do not yet know if this was an operational loss due to error, or mechanical failure. All we know is some guys had a really bad day and their families are having a hard time.
Yemen's Houthi rebels commit to peace plan in letter to UN chief, BBC reports (Haaretz)
from the article: Yasur helicopter: A history of splendid service - and deadly collisions