TDR is the ratio of the number of flights delayed due to technical faults to the total number of flights, expressed as a percentage.
Minister of State for Civil Aviation Mahesh Sharma said in a reply to a query, "There have been technical delays on account of snags in Dreamliner aircraft. The technical dispatch reliability for Boeing B787 (Dreamliner) aircraft has been lower than the average for the carrier's total Boeing fleet, including B777 and B747-400 type of aircraft."
As against 97.90 per cent average TDR for six B787-800s in 2012 (the year Air India started inducting these planes in the fleet), the wide-body fleet had a 99.11 per cent average TDR that year, according to the data presented by Sharma.
In 2013, when the Dreamliner fleet size grew to 11, the average TDR for these planes stood at 96.52 per cent as compared with 98.54 per cent that of the total Boeing planes fleet.
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Last year, the average TDR for 18 B787-800s in the national carrier's fleet was reported at 97.29 per cent as against 97.73 for the wide body.
However, Sharma refused to divulge details of delays and losses incurred by the state-run carrier on account of such dealys.
"The information with regard to losses incurred is commercially confidential in nature and cannot be revealed," Sharma said in a reply to a question on the issue.
In reply to another query, the minister said that Air India has taken up the reliability issue with the aircraft maker, Boeing Co and the suppliers, who have provided on-site support to the airline.