Hyderabad, Sept 4 :
The exact reason for Wednesday's crash that killed Andhra Pradesh Chief Minister Dr Y S Rajasekhara Reddy and four others could lie in the black box if it survived the accident and can be found.
The black box is located in the tail of a helicopter, away from the fuel-holding part of the aircraft. Though a helicopter can fly in bad weather, if it is caught in clouds, heavy rain and strong winds in a mountainous terrain, it risks the danger of going out of control. The absence of a visual reference can also lead to disorientation.
Bad weather, low visibility compounded by hilly terrain poses one of the greatest risks to flying. Pilots have to constantly veer past bad weather patches and often have to deviate from a stipulated flight path to bypass inclement weather and cloud cover.
And another reason is an aircraft can also go out of control when its instruments start misbehaving --pressure, speed, rate of climb etc. At an average a helicopter can fly up to 400 to 500 kms at a stretch. Though it can climb up to much higher altitudes, it flies at an average altitude of 2,000 to 3,000 feet to maintain visual ground contact.
Investigations may reveal the cause of the accident, but initial reasons why the Emergency Location Transmitter (ELT) did not transmit any signal could either be because the ELT, which emits signals on impact, could have burnt out in the crash or malfunctioned due to a technical problem. If the rotor hits a hill or a tree, the helicopter explodes or disintegrates.