The sky itself has been a successful surface on which to advertise in unique ways. Two of these methods are banner ads and skywriting. A banner ad is a streamer or billboard that is pulled behind an airplane or helicopter over a mass of people. Skywriting contains no printed material but is a message written in smoke against the sky.

How does Skywriting work? A paraffin oil is injected into the exhaust of the airplane at controlled times, causing a white smoke to form. As the plane flies in various formations turning on the oil spray, letters of a message are formed. The letters are formed from 7000 to 17,000 feet up, and are at times a mile tall.

A unique form of skywriting is called, among other things, skytyping. Five or six planes fly in unison over the selected area. A computer on the lead plane decides when each plane is to make smoke and for how long. The result is a series of dashes in a straight line. When viewed from the ground, these dots or dashes of smoke together form parts of letters and eventually an entire word or sentence, much like the dots on a computer screen form a word or picture.

There are advantages and disadvantages to each technique. The advantages to skytyping are as follows: The message is made much quicker and thus can be longer. While it takes a plane 60 to 90 seconds to form one letter in skywriting, the letters are formed in a few seconds with skytyping. This means the entire message is still visible when it is finished. With skywriting, a long message will mean the first letters have drifted away by the time the message is finished.

Also skywriting requires extra skill to maneuver a plane to form letters. He is somewhat of an artist making the message uniform and attractive. On the other hand, the skytyping pilots only need to fly in a straight line. The computer decides when to make the white smoke that will form into letters.

Because skywriting only needs one or two planes, the cost is less than hiring a whole fleet of planes to make one message. Geico insurance has made the skytyping their name against the sky famous.

Both methods have things in common. First, the preparation is simple. No need for printing or color design is necessary. The skywriting pilot plans how to write his message backwards so the people below see it frontwards. The skytyping pilots simply enter the message in the computer and let it do the work. Second, the message in both cases is environmentally friendly. The paraffin smoke is harmless to nature.