ji1 chang3 means airport. It literally means “machine threshing-field”. Let’s break it down!
On the left we have the tree determinant 木 mu which is a picture of a tree. This character as a determinant (=concept key) designates structured, patterned, and/or wooden things. 木 is next to ji 几 the table character. 几 is a picture of a table seen from the side (2 legs and flat table top).
How does wood+table= machine? Well, the first machines were made of wood! And tended to be weapons. This particular machine is a crossbow, particularly its trigger. The crossbow is depicted here disassembled – unlike 尔 er, which is a picture of an assembled crossbow. Why? Because the idea of ji 机 here isn’t the weapon itself but rather the idea of a machine: a thing with parts which can be assembled and disassembled. So why “machine” for airplane? Basically it’s an abbreviation of 飞机 fei ji which means flying machine. 飞机 is a picture of a flying bird on the left (2 wings head on top tail below) next to machine. What kind of machine flies? An airplane! Well, you might know that German for airplane is “flying man-made thing”: Flugzeug. Chinese and German here are similar, just like the Flugzeug is the Germany flying machine so also is fei ji the Chinese flying machine.
Ok, what about 场? The plus on the left which looks like a grave marker means “dirt clump, dirt wall, DIRT. It’s pronounced tu3. 土 On the right is yi 易 which means easy amiable, and is the image of the sun and moon in their mutual orbital relation which conveys the idea of mutuality and amity and also the exchange (of light of positions). The top part is the sun the lower vertical lines are the shadows or rays of sunlight cast onto the surface of the moon.
Why does it sound like Chang and nothing like tu or yi? Because this is an associative idea character NOT a phono-semantic character. It’s an associative idea character: earth (indicating field)+exchanging changing (of wheat from chaff): two ideas are brought together to express a third different idea.
Why chang? Well, Chang E is the Chinese Goddess of the moon so perhaps that may help us remember the yi 易 amiable easy orbital exchang component of chang
From the idea of “threshing floor, threshing field” 场 the word chang extended its meaning to indicate fields and open spaces generally.
THRESHING FLOOR, THRESHING FIELD, FIELD