Based on the serious nature of the allegations, AVSIM Editorial Board Chairman Chuck Boudreaux; Senior Managing Editor Maury Pratt; Associate Publisher and AVSIM Inc. COO Robert Kirkland; and Publisher and AVSIM Inc. President Tom Allensworth immediately launched an independent investigation into the Carenado C-172 release and any similarities it may have to the freeware Dreamfleet version of the aircraft released months before. An analysis of the AVSIM Online Editorial Policy dealing with such matters was also ordered to ensure the policy meets the needs of today's development environment.

The initial Carenado investigation centered on the alleged similarities in the airfiles as this is one of the easiest component to verify quickly and with a high degree of accuracy. AVSIM Senior Staff Reviewer Steve "Bear" Cartwright was asked to examine the two files in question along with the default Cessna 182 provided by Microsoft. Using state-of-the-art airfile analysis tools, Cartwright discovered key sections of the Carenado C-172 airfile were exactly the same as those in the file created by Small for the Dreamfleet version. Yet when Cartwright compared the Microsoft version with that from Carenado there were significant differences in all the places one would expect to find them.

In the first example we will look at, Cartwright compared the graphic representation of the airfoil centerline vs. the angle of attack in the three aircraft. As the graph labeled Image 2 shows, there is a noticeable difference between the Microsoft versions and those by Small/Dreamfleet and Carenado. However, the Small/Dreamfleet version and the Carenado version are obviously similar. If you will note the values for X and Y in the graphs, you will see the accuracy of this representation is significant to six decimal places, or millionths of a radian.

[Editors Note: In order to provide this information for the widest possible audience, we have provided three levels of resolution in the photos. Those within the story itself are obviously thumbnails to provide a quick loading article. If you click on the thumbnail, you will see an image at a resolution suited for 800 X 600 display. For the highest resolution, click on the "Hi Res" link and your will get the image at a resolution suitable for 1152 X 864 display ]

Graphic Depiction of Airfoil Cl vs. AoA in the three aircraft. Hi Res Image

If you have any doubts as to the similarity between the Small/Dreamfleet version of the C-172 and the Carenado version, Image 2A should dispel them. The top graph overlays the Microsoft version with the Small/Dreamfleet version and the differences are quite obvious. Panel two overlays the Small/Dreamfleet version with the Carenado C-172 N. It is impossible, even at the highest resolution to see any difference between the two. Considering accuracy to millionths of a radian, it is virtually impossible using the design tools available today to coincidentally have two different airfiles match to this degree of accuracy.

Overlay of the Airfoil Cl vs. AoA graphics for the three aircraft. Hi Res Image

Small in cooperating with the AVSIM investigation also provided what he classed as "digital watermarks" or digital fingerprints to look for in his airfile. The digital watermarks are a way for developers to positively identify their work, by stealthily manipulating code or figures associated with variables in certain parts of the airfile that would naturally be different even among versions of the same aircraft. Because current analysis programs allow accuracy to five and six significant figures beyond the decimal point, a developer can alter values ever so slightly so that it does not effect the performance of the aircraft but provides for positive identification in the case of copyright violations.

In this image, Cartwright shows the tabular information from the three aircraft for the Record 301 Fuselage Center of Gravity (COG) information. This is one of the areas indicated by Small as including a digital fingerprint. As these files represent proprietary information, AVSIM has blurred all but the relevant areas. While the Microsoft and Small/Dreamfleet files agree where they should, they also differ where one would expect each individual aircraft to differ. Yet the Small/Dreamfleet file and Carenado file are identical, despite Small noting this area contains a digital watermark thus precluding coincidental similarity of values.

Record 301 - Fuselage CoG information. Hi Res Image

"The height above ground should be the same on all three, which it is, but the remaining numbers will vary from aircraft to aircraft," Cartwright notes. "With the direct comparison of the Cockpit view CoGs between these three airfiles, (it) reveals that Carenado has indeed copied Steve Small's airfile or they are the victims of an extraordinary coincidence!"

Considering these values are dealing in most cases with variations of ten-thousandths of an inch and the evidence from Small that this area contains digital watermarks, it makes the probability of coincidental similarity extremely remote.. However, it does not totally exclude the possibility. Yet this was not the only digital watermark Small provided to AVSIM. In Record 404 Airfoil, which the above images graphically depict, the values are once again identical when comparing the Small/Dreamfleet airfile to the Carenado one, though those differ from the Microsoft version.

And once again, in Record 507 Fuel Mixture Control the same is true. The values in the Small/Dreamfleet airfile and those in the Carenado airfile are identical. And it is this instance, which Small considers proof positive Carenado used his airfile without permission.

"This table, which controls fuel leaning and engine response to mixture change - is unique to the FSD Cessna 172 aircraft AND OTHERS that I have programmed," Small wrote in an email to Carenado and provided to AVSIM. "It is absolutely unique."

In light of the multiple instances noted where the two airfiles are identical, and specifically in relation to those areas Small digitally watermarked for just such an incident, the probability of coincidental similarity grows very remote. When you consider extremely high degree of accuracy available in the Cartwright analysis, the evidence is overwhelming and conclusive in the minds of AVSIM investigators.

"I have observed the use of many of my unique developments in other Carenado aircraft, and it appears that you have been using my Freeware flight models regularly as templates when you create your own aircraft," Small writes to Carenado. "This cannot be an accident, it is not acceptable, and I would like to better understand how this could be possibly happen. So, I hope you can help me shed some light on this matter."

Despite this specific new evidence, Carenado has issued no new statement. Instead they stand by their original contention that any similarities are purely coincidental. This position was conveyed to AVSIM COO and Associate Publisher in an email from Carenado team member Fernando Herrera. The following is taken directly from that email:

"Related to some mails and comments going around about our aircraft, saying that we are copying FDE from another planes we want to say:

1. All our aircrafts are 100% made by Carenado (except the sounds, we use the default ones).
2. If someone find some Carenado's FDE similar to other FDE of the same model, it probably because the aircrafts are the same.
3. Our team is composed by 4 professionals. 2 civil engineers and 2 designers, all of us bigger that 30 years old. Thereby we are not playing.
4. We are dedicated to make the best models on Internet, and we are working very hard for that.
5. We don't want to spend time responding mails or comments attacking our work. Our best guarantee and support is the thousands of customer who are logged into our site and buy our products.
6. We don't want to attack anybody, we believe that the only way to be successfully is working hard and not decrying the competence."

As other developers have become alerted to this situation, new evidence is coming to light to support additional allegations. Dreamfleet's Lou Betti has provided substantial evidence that gauge files in the Carenado C-172 panel are also the wok of others. AVSIM is examining this latest evidence in hopes of independently verifying it as well. That analysis was not complete when this story was published.

We will continue to investigate that claim and others related to the Carenado release and report any other allegations, which are substantiated by independently verifiable evidence. In the meantime we have removed our earlier Carenado "Piper Saratoga II TC, Warrior I — Warrior II" review, until such time as copyright issues have been resolved by the parties involved.

As for the impact of the allegations related to the airfile and now the gauges, that depends on whether Small and any other aggrieved developers wish to exercise their rights as outlined clearly in the freeware licenses accompanying their products, as well as any change in the Carenado position. Only law enforcement and judicial officials can make any type of final determinations of fact. Until then, readers must make up their own minds based on the allegations and evidence thus far released.