Ok, I have a thought experiment; a visual model.

 

I used to run daily. I would run down the trail at an 8-minute mile. Somehow a fly that has a maximum speed of 5 mph lands on my neck. I swat the fly and it leaves my neck. Accordingly, I increase my speed to a 6-minute mile. The same fly somehow lands on me again. Every time it leaves my body from my swat in comes right back.

 

The thing to ponder is that the fly moves slower than me yet can intercept me and after intercepting me leaves my body only to intercept me again. What are some physical properties behind this?

 

I would like to get a variety of answers. But to show what I was thinking: suppose drones were set up to intercept a jet aircraft or missile. They don’t have the speed to match the missile or time to acquire exact coordinates. Could a drone intercept a missile as the fly has intercepted me (multiple times)? And would being able to intercept multiple times solve the problem of finding exact coordinates of the missile?

You carry air with you in some short distance. The fly's maximum is with respect to the wind, not the ground.  Also (and related), you don't have the same air resistance when following a large body. In cycling and car racing this is known as drafting.  

Since missiles have an exhaust that propels them, this tactic does not work with them. And for any body, it will likely be less effective as the atmosphere gets thinner.

A fly can not only travel in your wake, but choose (or happen upon)the more favourable part of it to catch up.

Did you identify the fly? There are many types of flies which fly faster than 5 mph. Many biting flies are particularly fast. A deer fly can fly at 25 mph.