Sir: The Bhoja Air crash is a colossal national tragedy. According to reports, aviation experts believed that the disaster was caused due to Cumulonimbus (Cb) clouds. The pilot of the ill-fated plane may have tried to fly under the clouds, charged with a hailstorm and lightning. This is one of the logical reasons behind this disaster. Cumulonimbus clouds are towering vertical clouds, dense in nature, full of thunderstorms and other inclement elements. Cumulonimbus clouds originate from atmospheric instability. They can create lightning, severe thunderstorms and erratic air movements. The most surprising element of this whole episode is why the pilot was not warned of the presence of cumulonimbus clouds. There days all airports are equipped with two types of radar. One is for monitoring positions of airplanes; the traffic controllers guide planes in their designated air corridors through these radars. The other radar does weather surveillance and is used by airport meteorologists for monitoring weather conditions around an airport. The data from the Weather Surveillance Radar (WSR) is linked with the radars of Air Traffic Controllers (ATCs), who can then guide the planes accordingly. WSR can very easily pick up the presence of towering cumulonimbus clouds in the vicinity of an airport with zero percent doubt. There is a big question on the efficiency of ground radars and people operating them now.In my opinion, the Civil Aviation Authority (CAA) should investigate this disaster from this perspective and I am sure, unlike in the past, the findings of this air crash will be made public, especially for the sake of those people who have lost their loved ones in the crash. NASIR RIAZOman