Falcon 4.0 represents the current state of the art in military flight simulations for the PC. New, more authentic levels of realism were achieved in almost every area of modeling: flight, weapons, ground war, radar and detection systems, communications and campaign dynamics.

Inevitably, ground-breaking simulations of this caliber present even the most experienced of virtual pilots with never-before-seen, often mystifying, events. Usually, these types of events are expected and even welcomed in new sims; however, weird, frustrating, mission-killing events are instantly branded as bugs and the programmers burned in effigy. For example, many simmers were ready to revolt over the annoying frequency of the "Mission Aborted" call: bug or accurately modeled feature?

At first, many thought it was a bug. Upon closer observation, however, we all learned that Falcon 4.0's campaign engine simply models the annoying frequency of aborted missions with painful authenticity. In Falcon 4.0 every event impacts subsequent events: A SEAD mission preceding your flight fails---"Mission Aborted" comes the call; AWACS redirects you to a higher priority threat---"Mission Aborted". Annoying to be sure, but not a bug; rather, the correct decision by the game's AI given all the events leading up to the "Mission Aborted" call. So just how far does this sort of realistic, interdependent, cause-and-effect modeling go in Falcon 4.0? We spoke to Leon Rosenshein, Lead Engineer for Falcon 4.0, about the intelligence behind, and factors that impact, this sim's weapon guidance and detection systems.

COMBATSIM: In Robert Shaw's classic Fighter Combat, he discusses the various methods employed to guide missiles from the launching aircraft (the shooter) to the target. From that discussion we learned that proportional navigation is the cause of that characteristic 'wiggle' one sees as a Sidewinder streaks toward its target. Is this form of guidance modeled in Falcon 4?

L.R.: The first missile I modeled was the Sidewinder. As in real life, the Sidewinder's control surfaces steer either right or left, with no in-between. As a result, it does adjust its course proportionally and you will see this "wiggle."

COMBATSIM: What other factors impact missile targeting?

L.R.: Missile modeling is broken into four components: flight model, seeker, guidance, and warhead. The flight model for the missiles, like the aircraft, has a full 6 degrees of freedom, and its flight path is affected by the same forces that act on the aircraft. Seeker sensitivity and fuel load also play a role as to whether a missile will reach its target. In some circumstances, a missile may fail to achieve a kill because its battery life is exhausted. The AIM9 has only about 30 seconds of battery life, but the AMRAAM has about two minutes of battery life. These realities were taken into account when we modeled Falcon 4.0's missiles.

L.R.: Other than these considerations of fuel and battery power, a multiband infrared seeker is influenced by the strength of the IR signature it detects. So the target's speed, aspect and current throttle setting are all considered by the missile's detection algorithim. A missile launched nose-on will have a lower PK [Ed. Probability of Kill]. If the target aircraft has its afterburners lit, the PK is much higher.

We also took pains to model aerodynamic heating and atmospheric issues. For instance, if your aircraft is travelling at Mach 1.5 on a clear, cloudless day, you will present an enemy's missile seeker with a very large, and very easy to track IR cross section. If you are above clouds and the IR seeker modeled inside the missle that wants to kill you is below the clouds, we've programmed it so the clouds mask your heat signature. In the same way, we've modeled it so that anti-aircraft systems that use optical guidance won't be much use against you either if you are shielded by clouds.

COMBATSIM: Some players believe the Archer missiles travel too fast in Falcon 4. Is there any merit to this allegation?

L.R.: I'm looking at this at the moment and so far I haven't found any strange behaviors in any of my tests. The general complaint as I understand it is that a player hears the call, "Archer inbound" and then there is the explosion. The only explanation I can offer at this time, is that the bandits are probably taking very close-range shots. If the shooter is a mile or so distant, you'll have very little reaction time. We're going to keep looking into it though.

L.R.: Two other types are modeled: Beam Riders like the AIM 7 guide on a radar reflection. We also model Command Guided systems like the AMRAAM. During the early stages of its flight, the AMRAAM is guided by the shooter or launching aircraft; near the end of its flight, when the missle gets close to the target, it switches to active guidance using its own onboard radar. This whole process of initial remote guidance then onboard guidance is precisely modeled in Falcon.

COMBATSIM: What AI factors influence a missile's PK?

L.R.: The amount of damage any missile can do depends on how close it can get to the target before it detonates. In Falcon, when the missile's AI determines it's as close to the target as its gonna get, the warhead detonates. If the explosion happens at the rear of the target aircraft, there is a good chance of engine damage. If at the front, there is a high probability of radar damage. Of course, there's always the chance that the closest point calculated by the missle AI for detonation ends up being just too far away to do any real damage at all.

COMBATSIM: Tell us more about visual detection in Falcon 4.

L.R.: Visual detection is a factor for both ground based weapons and AI aircraft. Visual detection ability varies by the type of platform: The MiG23, a single seat fighter, can only see in front. The bombers, on the other hand, have the advantage of human eyeballs in the rear and we have modeled this in the AI.

COMBATSIM: Tell us about countermeasures.

L.R.: There are two levels of counter measure for the game: level one is your on-board self-protection jammer, which we modeled after the ALQ-131, and level two is area jamming. For area jamming we have EA6Bs and some bombers. Two important factors affect your ALQ's ability to protect you: your enemy's radar strength and your range from the transmitter. The type of radar also plays a factor in its ability to burn through to a lock, and we model five or six different levels of ability.

Su27 Kill. Click for larger.

The radar range equation includes a variety of factors including power output, antenna size, pulse repetition rate, signal to noise ratio, and so forth. Detection ability is also influenced by jamming, doppler notches, and ground clutter. [Ed. This is why it's wise not to fly in a straight line for very long in Falcon 4.]

Su27 Kill. Click for larger.

L.R.: The air defense network in the game breaks down like this: there are a handful of long-range search radars plus some local SAMs radars. The long-range radars are the ones that will normally track you, while the local SAMs, unless they want to distract your attention, keep their radars switched off.

The long-range radars tell the SAMs where to look. If you manage to take out enough area long-range radars the SAM sites will then be forced to use their own search radars. But these small search radars are not as effective for detection.

Communication is two-way. If you manage to evade the long-range radar but are picked up by a local radar, your position is immediately communicated throughout the entire network. You will also find that the ground stations are capable of playing radar games. The game, if you want to call it that, requires that each ground radar take a turn at lighting up your aircraft for just a few moments at a time. [Ed. For a more detailed explanation of this tactic, see the Games People Play extract below.]

Strike Mission. Click for larger.

COMBATSIM: After the 1.04 patch many players noticed that enemies would rarely launch radar missiles beyond visual range. Can you tell us if this has been corrected?

L.R.: Yes, there was a problem there but it's been fixed.

COMBATSIM: We've noticed that when we allow the Combat Autopilot to take over the duties of flying and fighting our aircraft, many of the aircraft maneuvers executed pull G's beyond the limits of human endurance. Are the enemy planes run by the same AI that runs the combat autopilot feature? If so, doesn't this put those of us who fly at full realism settings at a disadvantage?

L.R.: The Combat AP is somehow detached from the general G limit model. It's a bug. But enemy AI does have the same limits as the virtual pilot. Of course, this will vary somewhat with the skill rating of the particular AI pilot. Your readers may be interested to know that enemy pilot skill is plotted along a bell curve. Because of this, even if you have Ace AI selected, you will still encounter a range of skill levels in your opponents, including an occasional novice pilot.

Strike Mission. Click for larger.

L.R.: Even though I know how everything is designed to work, I'm always intrigued when I watch a scenario unfolding on a monitor in real-time. Even I can't know what will happen next because of the highly organic, dynamic nature of the AI. It never fails to surprise me and that's fun.

COMBATSIM: What's your next challenge with respect to AI development?

L.R.: The concept of Master Tactics. Right now there is a concept of a four ship picking a maneuver and executing it as a four ship. It has some connection to its package but not a lot. It knows where its package is, and it knows what it's supposed to defend, but the communication between flights in the package is still limited---we wanted to do more. That's the next big thing on the AI side. You will see a four ship in a particular formation, you'll change formation to counter it, and they, having seen your change, will react accordingly.

COMBATSIM: When will we see this?

L.R.: Falcon 4.0 is an ongoing product, so you shouldn't have to wait for an add-on to see this. However, I dont want to give your readers the impression that they'll see Master Tactics in the next patch. That'll come later.

COMBATSIM: What can you tell our readers about the patch?

L.R.: 1.05 has become 1.06, and the emphasis on 1.06 is stability. It primarily addresses crash problems, memory problems, and fixes the frame rate slowdown with the 2d cockpit. 1.06 has been tested internally and was recently turned over to external testers. We plan to start addressing specific gameplay, bug, and multi-play issues with the 1.07 patch. The code for that is already in small scale testing as is the networking patch. Once it's out, the art patch should be ready.

COMBATSIM: What details can you give us about the art patch?

L.R.: Basically, the art patch contains new vehicles and cleans up the air bases. You will see better texture maps around the air bases, increased object detail, and more objects around the base. You'll also see new aircraft; but, for the moment, the specific types will have to remain a secret.