Chandigarh, May 12 :    Chandigarh, May 12:  A Delhi-based Directorate of Flight Safety report has said a large number of crashes occur due to inadequate and improper communication between the pilot and agencies directly involved with flying activity. The report, shown to this correspondent by defence sources after the Ambala crash on May 9, refers to communication failure not as a failure in the overall system but as a 'serious breakdown in communication between the pilots in the air as well as between the pilots and ground-based controllers'. It also states that analysis of radio transmission scripts recovered from aircraft involved in crashes reveals 'huge gaps' in communication. This could be because pilots, as the report published last year pointed out, concentrate on mastering flight controls and learning safety measures rather than absorbing the correct jargon of radio transmissions and educating themselves on the finer aspects of communication. Ground engineers and air traffic control (ATC) officers recall the number of times pilots read back incorrect information on flight, altimeter settings and even the runway. These errors are either not reported or are overlooked due to their increasing frequency. Sources, however, point out that improving communication was not given priority. 'The practise of junior pilots utilising spare time at the ATC listening to radio transmissions to educate themselves and learn from the mistakes of other pilots should be made mandatory,' an officer said. According to the study, which sources said, had not been implemented fully, there is either not enough communication between the pilot and the ground staff or, at times, no communication whatsoever. Worse, the communication is often not accurate. Even terms and phrases used in routine communication have deviated from their original meaning. For instance, 'Roger' conveys 'I have received and understood your transmission'. But it is being increasingly replaced with 'yes' or 'I will comply with your instructions'. The correct usage for the two expressions is 'affirmative' and 'wilco' respectively. While the IAF, over the years, has developed an in-house jargon for communication, the standard transmission in use worldwide has somewhat got lost. This has resulted in a large number of near mishaps because of wrong interpretation. The study recommends that pilots and ground crew make efforts to master aviation terms as stipulated in the standard service manual. It also states that IAF personnel should not digress from the manual.