New Delhi, Aug. 13 -- India's aviation regulator has issued a show-cause notice to IndiGo for using "non-qualified simulators" to train pilots operating to three challenging airports, citing scrutiny of records and email replies from the airline. The Directorate General of Civil Aviation notice, issued on Monday and seen by HT, found that "Category C (Critical) airfield training for flight crew" was conducted using simulators not approved for specific airports as required under Civil Aviation Rules. It found that about 1,700 IndiGo pilots received training on simulators that lacked the required approval to prepare them for flights to Leh, Kozhikode and Kathmandu. These three destinations are classified as "critical" airports, meaning they present special flying challenges that require specific, certified training equipment. The review showed several Full Flight Simulators used for training, testing or checking used by the airline were not qualified or approved for those specific destinations. Issues were recorded across 20 simulators nationwide - two each in Delhi, Chennai and Hyderabad, five each in Greater Noida and Gurugram, and four in Bengaluru. All were found unqualified to operate training for the three airports. "As an approved post holder (director - training) of M/s IndiGo, you were responsible for ensuring compliance with all applicable Civil Aviation Requirements. However, it has been observed that you have failed to ensure the use of appropriately qualified simulators for training related to Class III (critical) airports, in violation of the above-mentioned CAR provisions," DGCA said in the notice. The regulator has given IndiGo 14 days to respond, warning: "Therefore, you are hereby called upon to show cause within 14 days of receipt of this notice as to why action should not be taken against you for the said lapse under the applicable provisions of the Aircraft Rules and CAR." DGCA said it would presume the airline had nothing to submit in defence should it fail to respond within the deadline. "Ex parte action shall be initiated against you as per rules," the notice added. The airline confirmed the notice. "We confirm receipt of a show-cause notice issued by the DGCA pertaining to simulator training of some of our pilots. We are in process of reviewing the same and will respond to the regulator within the stipulated timeline," an IndiGo spokesperson said in a statement....