Section 3 (q) of administrative tribunal act defines service matters as
"(q) "service matters", in relation to a person, means all matters relating to the conditions of his service in connection with the affairs of the Union or of any State or of any local or other authority within the territory of India or under the control of the Government of India, or, as the case may be, of any corporation or society owned or controlled by the Government, as respects -
(i) remuneration (including allowances), pension and other retirement benefits;
(ii) tenure including confirmation, seniority, promotion, reversion, premature retirement and superannuation;
(iii) leave of any kind;
(iv) disciplinary matters; or
(v) any other matter whatsoever."
2) HAL termination of your service would fall within ambit of CAT
3) you have not remained absent unauthorisedly. You have resigned from service and company did not reject your resignation for over 2 months . You served the notice period of 3 months