There are essentially two categories of merges: offensive and defensive. The goal of an offensive merge it to gain angles on your enemy. The goal of a defensive merge is to deny your enemy angles on you while cutting down whatever perceived advantage caused you to go defensive until you can either go offensive or disengage. The key to either type of merge is controlling flight path separation.

Flight path separation can be either horizontal or vertical. No flight path separation means that, if both planes continue to fly a straight line, they will intersect each other. See the illustrations below:

It is possible to have planes at different altitudes with no flight path separation. In the "Vertical Flight Path Separation" diagram above, just imagine the blue plane climbing directly towards the red plane and the red plane diving directly towards the blue plane.

The merges described here are for use against a single enemy. While you still must merge if you are engaging multiple enemies, you must add your SA estimate of when the second enemy can/will arrive and how it can influence the fight before deciding how or even if to engage at all. Some tactics for engaging multiple enemies will be discussed in another write-up. Keep in mind that there is a lot of information contained in the write-ups you are about to look at. You're not going to learn it all at once. Like I suggested in my Tips for Beginners write-up, pick one to learn well, master it, then move on to the next. Now for the merges.

Co-Altitude/Co-Energy Merge

This situation is the proverbial fair fight. Two bogies at the same altitude with similar energy states. How do you know the enemy's energy state? You are using your SA to estimate it! The key to a good merge in this situation is to create flight-path separation which will then allow you to turn into your opponent as you approach. By initiating the turn into your opponent, you have gained "angles" on him. The flight path separation can be either vertical or horizontal. You will find, though, that horizontal flight path separation is easily countered by your enemy with no sacrifice of advantage.

This brings us to the first merge we are going to look at: the "Immelman" merge. It is also often called an Immel merge or loop merge. The key to this merge is getting vertical flight path separation The best explanation of this merge I have seen is in

Mastering the Merge part 1 by Rocketman

Keep in mind that this write-up was written for Air Warrior, where most head-on shots were thrown out by the host and collisions didn't happen. In simulations where head-on shots and/or collisions occur, you will have to add enough horizontal separation to deny your opponent a shot.

If your opponent is in a plane which turns better than yours, don't allow yourself to get sucked into a turning fight after the merge. It is very tempting, especially if you are close to being on the enemy's 6 o'clock, but the better turning plane will win unless you can destroy it right away. Take your shot if you get it on the merge, then separate before you get caught.

Another thing mentioned by Rocketman which is very important is to watch your opponent in case he tries to get below you. Many players try to use this type of merge and it is important not get caught sleeping while your opponent starts a dive at farther than icon range. I often start a shallow dive at vis range just to be safe and pick up some extra speed. If your opponent does start his dive first, follow as closely as possible and then level and start your pull into the immelman at the appropriate range. Your opponent is often so pre-occupied with staying below you that you end up at least level on the merge while he is still diving. This leaves you with the advantage. Remember, by the time you pass the enemy, you want to be at least level and preferably starting into your immelman.

Merging With A Higher and/or Faster Enemy

While a co-alt/co-e (energy) situation for every fight would be nice, the reality of the situation in the arena is that you are often going to be jumped by an enemy with more energy than you. This energy may be in the form of more altitude but it can also be in the form of higher speed. Your goal in this situation must be to equalize your energy states without giving the enemy an advantage or at least one that you can't recover from. While different planes benefit from different tactics, the key in all of them is forcing the enemy to give up his energy while you conserve, or better yet, gain energy in the form of altitude or speed until you are equal with the enemy. Piece of Cake!

The second write-up by Rocketman is on merging with a higher and/or faster enemy. This write-up is much more Air Warrior specific than the first one, but it still has many useful points. The most important difference again is that Rocketman recommends using a nose-to-nose pass when the enemy dives on you. This worked in Air Warrior, but you need some flight path separation to keep from taking a head-on or colliding with the enemy if those things are possible in your simulation.

Mastering the Merge Part 2 by Rocketman

Merging With A Lower and/or Slower Enemy

The third situation you find yourself in is the one that everybody likes to start out in. You have an altitude and/or speed advantage on your opponent. Many on-line pilots go into this situation with way too much confidence and way too little thought. The next thing you know they suddenly find themselves with no advantage left. The third and last in Rocketman's series deals with how to handle this situation.

Mastering the Merge Part 3 by Rocketman

Other Write-Ups About Merging

A couple more write-ups on the subject.

Lead Turns - by SB (?)

Opening Moves - by Rapier