(CNN) — North Korea's aviation industry has long been a source of intrigue and fascination for travelers from around the world, even when the country's diplomatic hostilities aren't in the news.
Some of this curiosity is focused on Air Koryo, the state-owned national airline of the communist Democratic People's Republic of Korea. It's the country's only commercial airline and only flies to just two international destinations -- China and Russia.
Tours dedicated to North Korean aviation that arrange charter flights on some of Air Koryo's planes quickly fill up, the chance to fly in its rare Soviet-era aircraft -- some dating back to the 1960s -- too tempting for plane spotters to miss.
Among those fascinated by Air Koryo's fleet of classic Antonovs, Ilyushins and Tupolevs is photographer Arthur Mebius.
It features photographs taken during three North Korea visits.
We interviewed Mebius to find out more about his experiences creating this book.
CNN: What inspired you to create 'Dear Sky'?
Mebius: I am an aviation lover and a professional photographer. I am always working on a project to put this love for aviation in a photographic project.
After a couple of days flying and shooting, it became clear to me I wanted to capture the story in a photo book. I returned two more times to North Korea to complete the series.
Due to international sanctions and environmental restrictions, this fleet of older Russian jetliners of Air Koryo rarely fly abroad. Nevertheless these aircraft and their crews are kept ready for operation.
Occasional domestic flights are all the more important for the flight attendants and pilots to practice and keep up their knowledge and skills.
It was the dedication and pride of the crew that caught my interest for the series.
Tell us a bit about Air Koryo's fleet
The fleet of Air Koryo has a total of, I believe, 15 airplanes.
Four of them are newer planes (from 90's and younger). These four -- two Tupolev 204s and two Antonov 148s -- are used for the regular international flights.
The newer planes are far more modern than the heritage ones and equivalent to what Western airlines fly today.
What are some of the most surprising things you discovered about the airline?
Given its Skytrax "one star" rating and that the heritage fleet is activated for enthusiast charters, people are led to expect poor service and old planes.
In fact, on a regular flight from Beijing, the aircraft is a new-build Tupolev or Antonov, indistinguishable from a contemporary Airbus or Boeing.
Even though the flight time is only 90 minutes, a complimentary meal is served along with hot and cold drinks (and a first taste of excellent North Korea beer) by incredibly polite and polished cabin crew.
There are some eccentric touches, such as showing variety stage performances of North Korean musical bands, complete with backdrop of military maneuvers, with the soundtrack playing through the aircraft PA. The crossing of the Yalu River into North Korean airspace is announced over the PA.
Why are aviation fans are so intrigued by Air Koryo?
North Korea is an unusual country that is fascinating to many people, and I think people are curious to see what an airline might look like in such a strange context.
Also it is famous for being the earlier mentioned "one star airline," mostly because it doesn't qualify for a rating with many key criteria such as a frequent flier program not fulfilled at all. It's nothing to do with the service or safety record, both of which are of a very high standard.
How did you gain permission to take the photographs?
During my flights in the DPRK I was part of a group of tourists with common interest in the planes.
We were allowed to take photographs of the planes. I took this opportunity carefully to take photographs of the pilots and stewardesses as well.
Have you received a reaction from North Korea?
No word from North Korea. The book is not intended to be negative in any way. It's a different aesthetic to what they're used to, so it's hard to know what they will make of it.
I showed it to someone who works as a tour guide there. They said the North Korean authorities will be like, "why aren't the people looking the camera? Why is the flight attendant so blurry?"
In light of recent events, critics say travelers are taking a big risk by heading to North Korea. Thoughts?
My experience is the North Koreans want you to come and see what they want you to see, have a good time, spend a few euros, and leave with a positive impression of their country.
They are very sensitive about how the world sees them. Visitors are briefed before the trip about do's and don'ts, like don't take pictures of locals without asking first, don't take pictures of soldiers, don't make fun of the leaders.
As it's nominally at least a communist country, there is no advertising or international brands. The cities are clean and uncongested.
For the visitor, the lack of Internet and phone signal means the group form a tight bond, without distractions from social media and smart phones buzzing on the table.
The locals I met are very kind and curious, and due to a lack of other entertainment options, they all play music and sing. It's a unique destination, and I hope to be able to go back one day.