There is an interesting reason why the Coastal Artillery and AAA shared the same training establishment. The tradition dates back to World War I when US Coast Artillery Corps (CAC) served as the foundation of its AA Branch. There were two reasons for this1 .
First, with reduced threat to coasts during the World War I, CAC had the trained manpower which could be used for raising of AAA units and establishments.
Second, the CAC was the only branch that had any experience at all in firing at moving targets.
Indian AAA also followed the same tradition when it established AA and Coast Defence Wings in July 1940 at Karachi for training of Indian Officers, JCOs and NCOs in the AA techniques2.
The coastal batteries were the responsibility of the Army till 1963 when the responsibility for Seaward Defence was entrusted to the Navy and the Coast Batteries were taken over by the Navy3. Right from the beginning, AAA and Coastal artillery have had an umbilical relationship, with a common training establishment (Coastal and AA Artillery School at Karachi). This change in responsibility was another break from the past and was to put AAA on an independent trajectory.
1. ‘History of Air Defence and Early Weapon systems’ at Globalsecurity.org at http://www.globalsecurity.org/military/library/policy/army/accp/ad0699/lesson1.htm#less1
2. History of Army Air Defence http://indianarmy.nic.in/Site/FormTemplete/frmTempSimple.aspx?MnId=4Fm+GZejNPYci/u/KMAV7g==&ParentID=M/DOGn6JXk49a1ugLTlLfA==History
3. Hiranandani GM Vice Admiral Transition to Triumph Indian Navy 1965-1975 Page 16 https://www.indiannavy.nic.in/content/transition-triumph