In the world of diplomacy, symbolism is everything, and Kim Jong-un just sent quite a set of messages by his choice of airplane to fly to the most important meeting of his life.  He seems to have just acknowledged his tributary state relationship with China, among other messages.  His use of an American-made Boeing 747 in the livery of Air China for his trip to Singapore is remarkable. Here is a picture of his arrival from the Singapore government making clear that his ride (and important parts of his anatomy) belongs to China:

Photo credit: Terence Tan/Ministry of Communications and Information, Republic of Singapore

The choice of airplane was not a matter of Kim not having an aircraft capable of the trip. His own executive transport plane, a Soviet-era IL-62 built around 1985 in the livery of Air Koryo, took off from Pyongyang for the trip shortly before the Air China carrying him did. This is the same airplane he used for his visit to Dalien, China for consultations with Xi Jin-ping prior to meeting Trump:

Photo: KCNA

According to South Korea’s Yonhap News Agency, a total of 3 airplanes left Pyongyang for Singapore  today:

North Korea sent three planes to Singapore on Sunday with one likely carrying its leader who is set to hold the first-ever summit talks with the president of the United States this week, the South's government and a flight route-tracking website said.

According to Flightradar24 and official sources here, the Chammae-1 -- an Ilyushin-62M passenger jet -- which is the North Korean leader's private jet, departed Pyongyang Sunan International Airport at 9:30 a.m. and is flying in a southeastward direction without revealing its flight number.

The website earlier detected a separate takeoff by an Air China airplane heading for the same destination at 8:30 a.m., after it discreetly landed in North Korea for a brief stop that last about an hour.

The departures of the two planes come shortly after Pyongyang sent an Ilyushin-76 cargo plane to Singapore, according to the sources.

Here is a video screen grab of the IL-76 landing at Paya Lebar Singapore Air Force Base, which used to be Singapore’s International airport, then (and sometimes now) known as “Changi Airport.” The IL 76 model cargo plane first took to the air in 1971.

The day before Kim’s arrival, another Air China plane, an Airbus A-330, carried his advance party, presumably including many of the elite ruling circle of North Korea. That plane flew from Beijing to Pyongyang, picking up North Koreans, then on to Singapore, and back to China.  

So, why would Kim fly Air China for the biggest trip of his life?

I have to believe that security was uppermost in his mind. Here is the actual flight path used by A-330 advance party, which, while sticking to Chinese airspace as long as it could, was exposed to potential enemies over international waters.

My guess is that he figured those who might be tempted to shoot down a North Korean airpoane might be more circumspect attacking a Chinese airplane.

A second theoretical reason is a desire to fly on the same aircraft type that President Donald Trump is currently using, a Boeing 747-400.  Arriving on an ancient and noisy IL-62 would denote inferiority. The particular plane that he used, with registration number B-2447:

…is quite special. B-2447 is used by the top rungs of the Chinese government, predominantly President Xi Jinping and his entourage, when traveling abroad. It is capable of being specially outfitted with a VIP interior and has special interfaces for secure satellite communications among other modifications. 

Of course, China’s leadership would be able to listen to anything said on that airplane.

In a sense, the use of Chinese aircraft for his trip shows Kim acknowledging the need to internationalize Pyongyang’s economy, a goal that President Trump is holding out for him, citing the bright future ahead for North Korea if it gives up its nuclear arsenal. Kim is a notable aviation buff, and claims to be able to pilot an airliner. His government released video of him (with an actual pilot sitting next to him) supposedly at the controls of a small airliner that is art of the small fleet of Air Koryo: