By Jung Sung-ki
Staff Reporter

Most Air Force fighter jets were temporarily grounded for safety checks Wednesday, following crashes Tuesday that killed three pilots, the service said.

A single-seat F-5E and twin-seat F-5F crashed into a mountain near Gangneung, Gangwon Province during a training mission.

``Flight missions by most fighter aircraft were suspended for safety checks, but unless new problems emerge, missions will resume in a phased manner beginning Thursday,'' an Air Force spokesman said.

The fleet of F-5 aircraft, however, will be grounded until the cause of the accident is confirmed.

Fighter jets deployed near the inter-Korean border will continue their missions so as not to harm the defense posture, he said.

A fact-finding team is investigating the cause of the accident, the spokesman continued, adding it was possible that the pilots lost their bearings and the two jets may have collided.

Investigators are also looking at the possibility of problems with the older aircraft deployed in South Korea since the 1970s.

Tuesday's accident was the first jet crash in almost a year after a KF-16 fighter crashed off the west coast on March 31 last year. The last F-5 crash occurred in November 2008.

Under a military modernization program, South Korea has purchased 60 F-15k fighter jets and will buy 60 more to replace the country's aging fighter aircraft.

In particular, the Air Force plans to introduce 60 F/A-50 light attack aircraft, a modified variant of the T-50 supersonic trainer jet, in coming years to replace the older F-4/5 jets, most of which will retire between 2105 and 2018.

The Air Force currently operates about 250 F-4/5 aircraft, which have been in operation for almost 30 years.

gallantjung@koreatimes.co.kr