This is a common tactic used in PvE primarily. This tactic allows you to keep a high transversal velocity, making it difficult for ships with large calibre guns from hitting you.

It should NOT be confused with corkscrewing.

<image spiraling>

<image corkscrewing>

The commands to issue the ship to achieve this is as follows:

1. Orbit at 30km
2. Orbit at 20km
3. Orbit at 15km
4. Orbit at 10km
5. Orbit at 500m

You basically start off with a really wide orbit, then gradually shrink down as you get closer to the enemy.You can also manually pilot at the beginnning to get a better balance of transverse velocity and actually approaching the target faster.