posted 4/22/2008 by Dave Gamble
other articles by Dave Gamble
A well-known and easily observable hallmark of things in life that inspire passion in people is that they nearly always have some form or another of a never-ending debate. An obvious example would be religion, of course, given that throughout history epic wars have been fought over differences in fundamental tenets of belief. Other examples? How about professional sports: have you ever heard of a soccer riot? Formula 1 racing drivers have received death threats. Even at the collegiate football level, you don’t have to live in Columbus, Ohio for very long to realize that it is the absolute last place in the world where you want to wear a University of Michigan sweatshirt in November.

Unless you suffer from it yourself, you may not realize that aviation can (and does) rise to the level of passion in many, many people. Personally, I was diagnosed at a very early age as having a nearly terminal (slight pun there – did you get it?) case of aviation passion. If you spend any appreciable amount of time hanging around in areas where the infected gather, you will no doubt learn that there are debates within the clique that well never, ever be resolved. High-wing or low-wing? Fixed-gear or retractable? Those are the high-level arguments, but as you dig deeper into the cult you will find ever more granular and esoteric bones of contention. In the case of my personal airplane, a Van’s RV-6, the argument as to whether the tip-up canopy or the slider canopy is to be preferred can go on-and-on for days on end in some of the Web forums. And please, don’t ever mention the topic of overhead break approaches: that’s 100% guaranteed to start a flame war.

The thing about a passion for aviation is that it cannot always be pacified. It’s no secret that flying is expensive. Strike that: flying is damned expensive. The thing about a passion, though, is that people will do whatever they can to feed it. In aviation, it is often the case that the closest one can get to actual flying is the PC-based flight simulator. It’s no accident that Microsoft Flight Simulator is perennially one of the top selling software titles each and every year. It is a very approachable simulation, and doesn’t require extensive learning or effort to use. It is eminently suitable for everyone, whether they are passionate or not about flying. There are those sim users, however, that are, in fact, very passionate about flight simulators. And because there is passion involved, there is also almost by definition an unanswerable question: Microsoft Flight Sim, or X-Plane.

How that question is answered is, as is often the case in aviation where the only way to address all needs is by owning at least two (but no more than five) airplanes, very dependent on the user’s primary mission. When you think back to the high-wing vs. low-wing question, consider the pilot that stores his airplane outside in a rainy area: he appreciates the high-wing when it shelters him from the rain when he’s getting in and out of the plane. Even the hangared high-wing has benefits over the low-wing if the owner is one of those folks that uses the excess space in the hangar for the storage of boats, motorcycles, or whatever won’t fit in the home garage. There’s much more empty and useable space below a high-wing than there is under a low-wing. Is that the deciding factor for a lot of airplane owners? Maybe it is, maybe not, but it is most assuredly a consideration.

When the decision has to be made between Microsoft Flight Sim and X-Plane, a number of factors come into play. As this essay is intended to be a review of X-Plane Version 9, I will try to concentrate primarily on telling you as much as I can about it in particular, but to provide a fuller picture of its abilities and efficacy to your personal mission, I will have to lean very heavily on comparisons with the much better known standard of Microsoft’s offering. One of the more obvious examples is whether the sim pilot intends to “fly” IFR or VFR. Both sims will allow for both modes of flight, but they each have relative strengths and weaknesses. Microsoft Flight Sim X (hereafter referred to as ‘FSX’) concentrates primarily on VFR flight in that it provides a much richer visual world for sightseeing and navigation via pilotage. Depart from McCarran airport in Las Vegas and fly for just a few miles, for example, and you will be able to fly up “the strip” and see the fountains in front of the Bellagio. Make the same flight in X-Plane and you will see only generic buildings and, oddly enough, a lot of oil tanks in peoples back yards. Because of this, for the casual sim pilot FSX is probably going to be the winner in the sightseeing category. While X-Plane provides the ability to have global scenery, out-of-the-box (in other words, without installing custom add-on scenery) this means only that the ground beneath you will be topographically correct, all navaids will be available for use, and all airports will be where you expect (and need!) them to be. This is not to say that the default X-Plane scenery is not attractive; nothing could be further from the truth. Mountainous areas, in particular, are quite striking. It’s just that you shouldn’t plan on a whole lot of aerial tourism.

When it comes to flying IFR, the question becomes much more nuanced. There is one area where I think FSX has an advantage over X-Plane in flying IFR, and that is in the ATC voice communications. In FSX, the ATC controllers vectoring you around and providing you with the required clearances sound more or less human. In X-Plane, the voices are clearly machine-generated and somewhat grating. Again, FSX wins in the category of fidelity to the real world in the aesthetic realm, but where X-Plane wins the trophy in IFR flight is in the response of the instruments (which, obviously, play a very critical role in instrument flight) used to fly and navigate when the view out the window simply isn’t there to help. The response of the flight instruments in X-Plane is the smoothest I have ever seen in a PC-based flight sim; there is no jerkiness or lag at all in their motions. This is an absolutely critical factor in simulated (and real, for that matter) IFR flight, and is quite possibly one of the reasons that X-Plane can be (NOTE: this capability requires significant hardware upgrades, but the underlying software ‘engine’ at the core of such a system is X-Plane) used to actually log FAA-approved flight time.

Another aspect of X-Plane that enables it to provide a realistic enough flight environment to be used for actual flight training is its physics engine. If all you are going to do is try to immerse yourself in the illusion of flight ala FSX (and don’t get me wrong, there is nothing at all wrong with that), you don’t need a whole lot of fidelity to actual flight physics. In fact, too much realism would be detrimental in that it would make it much harder for novices to successfully fly (witness my experience with trying to fly helicopters!) and it could also have a negative impact on system performance. Calculating physics takes CPU time, as does animating the fountains at the Bellagio. These operations are quite likely to be handled by separate sub-systems in the modern gaming PC, but then again, maybe not completely. In any event, if you want (or have the need for) the most accurate flight physics available, X-Plane is the proper choice for you.

I’m not an aeronautical engineer by any stretch of the imagination, so I’ll borrow heavily from X-Plane’s web site to provide an explanation as to why X-Plane is the more accurate flight model. First and foremost, “X-Plane reads in the geometric shape of any aircraft and then figures out how that aircraft will fly. It does this by an engineering process called ‘blade element theory’, which involves breaking the aircraft down into many small elements and then finding the forces on each little element many times per second. These forces are then converted into accelerations which are then integrated to velocities and positions.” Wow, sounds complicated! Fortunately, it’s a lot like a heart defibrillator – you really don’t care how it works, as long as it works when you need it to! It’s important to note the part that says that it ‘finds the forces on each element many times per second’ because that is what allows the flight characteristics to respond correctly to ever-changing conditions ranging from up and down drafts, angle of attack on the wing (a complex calculation that involves a whole heck of a lot of things), control inputs, drag from the air on the airplane itself, momentum, and a host of even more complex things.

That’s a heck of a lot of math going on, but the net result has both positive and negative outcomes. On the positive side, real-world pilots or pilots-in-training are going to find a simulated airplane that behaves similarly to a real airplane, which will in turn make their simulated flight more beneficial to their competency level. On the negative side, it can cause somewhat exotic behavior if a ham-handed pilot gets the airplane into a situation where the math gets into boundary conditions. It is possible to get the airplane into modes of flight that don’t exist in the real world, and at that point the staunch adherence to the math and physics of the flight model no longer has any grounding in the real world and, in a word, gets a bit wacky. In essence, X-Plane flight physics adhere to a fundamental and immutable computing tenet: Garbage in, garbage out. Fly it like you’d fly a real plane and it will respond like a real plane. Throw it into conditions in which a real airplane cannot and will not fly, and all bets are off. It’s standard medical advice that I offer here: if it hurts to do it, stop doing it. Treat X-Plane like the professional tool that it is, and you will get professional results. Treat it like a toy, and a toy is what you will have.

Another thing that you absolutely have to be aware of is another application of the ‘garbage in, garbage out’ principle: the quality of your controller(s) will have a very large influence on the performance of X-Plane. You will not be able to fly it with a mouse and/or keyboard. I’m not sure you would even be very satisfied with a cheapy joystick. I’m using two different control set-ups, depending on the type of plane I’m flying. For fighters and other stick-controlled aircraft, I’m using the Saitek X52 Pro Flight System. For the yoke-controlled planes, I’m using the Saitek Pro Flight Yoke System with an additional quadrant. For both types, I use the Saitek rudder pedals.

These are quality controllers, but even so they exhibit a few inherent weaknesses with a high-fidelity program like X-Plane. Like all controllers, they have to have centering springs. In almost all flight, but especially in high-response airplanes such as my RV-6, the majority of control inputs happen in a very small area around the center of the control. Unfortunately, this is exactly the area where the breakout forces of the controller centering springs are the highest. This is noticeable in both pitch and roll on the joystick airplanes, but it is at its absolute worst in the pitch axis of the yoke-controlled airplanes. Note that this is not unique to X-Plane; I have the same problem with FSX. It ends up causing over-controlling, which often results to PIO, or ‘Pilot Induced Oscillations.’

Both X-Plane and FSX provide configuration screens to help address control customization issues like this, though, and it possible to mitigate these problems to some degree. This does bring to light a significant difference between X-Plane and FSX, however: configuring X-Plane requires quite a bit more attention to detail and willingness to learn the system than FSX does. In a word, configuring X-Plane is complicated. A lot of power is put in your hands when it comes to setting every facet of X-Plane, including display parameters, weather conditions, control configuration, possible simulated system failures, etc. With that power comes, in the words of Peter Parker’s very dead Uncle Ben, great responsibility. Expect to devote some time to learning how to set up X-Plane for your mission. The first few times you bring up configuration screens can be somewhat daunting, but once you learn your way around you will appreciate the level of control you have over the environment. Even fundamental things like setting the action associated with a button or keyboard key are completely different from what you may be used to. In FSX, for example, you select the action and then press the button you want to trigger that action. In X-Plane it’s the exact opposite: you click the button then select the action it should perform. Neither way is better or worse; they’re just different. You’ll run into a lot of that.

It won’t (or shouldn’t, anyway) come as much of a surprise to you when I say that a fairly important component of a flight simulator is the quantity and quality of airplanes that it simulates. Flight models and scenery are very important, but without airplanes to fly, well, they become somewhat moot, do they not? But here we are, more than 2000 words into this review and I haven’t said a word about them. What’s up with that? Well, it’s become a bit of a grey area for me, to be honest. The thing is, X-Plane can simulate just about any flying vehicle ever built, and many that have not. Because of the flexibility of the flight model, you can fly anything from a Piper Cub to the Space Shuttle, and if that’s not a wide enough continuum for you, you can even fly an airplane on Mars! And, as with FSX, the airplanes that come with the initial installation of the program are nothing more than a good place to start. There is a healthy market in third-party expansion planes, both commercial and free downloads. Granted, the free ones are often worth exactly what you paid for them, but that is by no means always the case. Very sophisticated and accurate airplanes can be found for the price of only the time it takes to download them. In fact, you can build your own if you have the desire and diligence to learn how. X-Plane includes all of the tools required to create your own airplanes, up to and including the use of your own airfoils. Oh, you want your own private airport? Well, so do I, but we’re not talking about me. X-Plane also includes the tools needed to build your own scenery, and if you want to use it to build a pyramid in your back yard, have at it.

All that being said, it is still the case that a number of airplanes are included in the initial installation. As with the planes that you can buy or download, there is a spectrum of quality across the fleet. For example, I was super excited to see an RV-6 in the list, but it is unfortunately not one of the better planes in the package. It flies ok, but the instrument panel is bland, and it is not one of the planes that includes a full 3D cockpit – an essential thing to have if, like me, you are using a head-tracking system such as TrackIR. On the other hand, the F-4 Phantom has a wonderful panel which not only includes a full 3D cockpit but also has the only accurate F-4 attitude indicator I’ve seen in a simulator. I worked on F-4s when I was in the military, and the coolest thing on the panel as far as I was concerned was the “full ball” attitude indicator that would also spin on its vertical axis to act as a directional indicator. It’s hard to describe, but it gives the pilot everything he needs to know about attitude and heading on one instrument. Very slick. Another of the airplanes that has the more modern full 3D cockpit is the Cirrus Jet, an airplane that is not yet in actual production. It’s kind of neat to be flying one of those around before the millionaires that will eventually fly the real thing have gotten their hands on them. It’s enough to send me out for a handful of lottery tickets.

While I wish all of the planes had the 3D cockpit, the 2D panels still work pretty well. Some of the other airplanes that I’ve found to be both challenging and enjoyable to fly are the V-22 Osprey and the Canadair CL-415. The V-22 is one of the included VTOL aircraft, and it is very cool to spool up those huge propellers in order to lift off vertically and ease them from the upward-facing position into the forward-facing position to make the change from helicopter mode to airplane mode. The transition back to helicopter mode has been a more daunting task, though, and I’m still not very good at it. I enjoy the Canadair for a different type of flying. The CL-415 is used for aerial water drops on forest fires. While X-Plane doesn’t have the formal ‘missions’ available in FSX, it does have what are called ‘Situations.’ For example, you can load a ‘Aircraft Carrier Cat Launch’ or a ‘Space Shuttle Full Approach’ situation. For the Canadair, I load a forest fire situation and try to drop water on the fire. I suck at skimming the lake to fill the water tanks without either crashing or getting so bogged down in the water that I can’t take off again, though, so it’s been challenging enough to keep my interest in trying to get better at it. Other favorite situations for are ‘Formation Flying’ and ‘Tanker Refuel’, both of which require the challenge of performing precise formation flying.

One thing to be aware of regarding the airplanes, though, is that the avionics (the autopilot in particular) can have steep-ish learning curves. Being the type that uses documentation only as a last resort, I struggled with even getting the autopilot turned on, and oddly enough also had occasions where I couldn’t figure out how to turn it off. X-Plane requires your full investment in learning how to use the equipment properly, but once you do make the effort, you will be rewarded with realistic and gratifying behavior. This is not to say that all of the navigation equipment is 100% capable of real-world performance, though; the FMS and GPS systems are somewhat dumbed down, but are sufficient to the tasks at hand.

You really want to get good at managing the equipment before trying your hand at flying in some of the weather conditions you can create using the weather settings because you can put yourself in weather conditions that cause ducks to choose walking over flying. For additional challenge, you can configure X-Plane to provide random equipment failures of dangerous meteorological conditions such as wing icing to keep things exciting. The degree to which this kind of thing can be taken is staggering; forget to set the cabin pressurization to an appropriate altitude in a high-altitude flight, for example, and see how long you last before blacking out. Flying an IFR approach to minimums is challenging enough, particularly if you have set up a healthy dose of turbulence, but try to do it partial-panel to really test your mettle. Or, you can do what I do: let X-Plane download real-world weather on those inevitable days when the Weather-out-the-Window ™ forecast shows that it’s far too cruddy to fly the RV and see how you do.

I can’t decide for you whether or not X-Plane is right for you. Just know going in that it is far more of a simulator than it is a game, and as such requires at least some measure of the devotion to practice and learning that real-world flying does. Aviation is not known for being a pastime or occupation that is forgiving to those that will not put forth the effort to do it correctly and safely, and in that, X-Plane is very similar. But, as with real-world aviation, the effort put into doing it right will be rewarded with immense satisfaction.

X-Plane may not be for everybody because of its focus on accuracy and its sometimes steep learning curve, but it will reward the diligent user with a simulation worthy of the word. It is not a game, nor is it intended to be. Use it as a professional grade flight simulator, and you will be rewarded with professional grade flight simulation.