Singapore Airlines passed the Pyongyang FIRs on the first day.North Korea last month officially opened its airspace to Western airlines, as well as South Korea's two national-flag carriers, according to the Ministry of Construction and Transportation.
US air transport firms Delta Air Lines and United Airlines, along with Singapore Airlines, passed through the Pyongyang flight information regions (FIRs) on the first day, ministry officials said.
Five other airlines, including Korean Air (KAL) and Asiana Airlines, have reported to the ministry that they will be flying through the Pyongyang FIRs, according to the officials.
A country with an FIR under its control is required to provide aircraft flying inside the zone with flight information.
When an accident takes place in the zone, the country is responsible for co-ordinating subsequent searches, rescues and investigations.
The eight airlines have reported to the ministry that they are scheduling a combined total of 43 flights a week flying over North Korean airspace, the officials said.
The opening of Pyongyang FIRs to western airlines is expected to help South Korean and other airlines save time and fuel.
Ministry officials said that the opening of the Pyongyang FIRs will shorten flight times by between 30 and 60 minutes on routes between Seoul and North American cities, while it will shorten flights for the Seoul-Khabarovsk and Seoul-Vladivostok routes by about 30 minutes.
Last October, South and North Korea, which have prohibited each other's national flag carriers from passing through their skies since the Peninsula's division in 1945, agreed to open their FIRs to each other.