Download of KIAD for FS9 1.2.1 was on the developer's website when we last checked. We cannot confirm if there is a free download of this software available. The most popular versions among KIAD for FS9 users are 2.1 and 1.2. The actual developer of the program is OnDuty Support Systems, LLC. According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. The program is categorized as Games.
From the developer:
BluePrint Simulations’ KIAD scenery depicts Washington-Dulles International Airport as it exists in 2011. It includes the main terminal and four concourses as well as all relevant cargo maintenance and general aviation facilities. A detailed model of the National Aerospace Museum located under the runway 1R approach path is also included.
You may want to check out more software, such as Republic XP-47J Escort Experimental FSX & P3D & FS9, Microleve ML-400 FSX & P3D & FS9 or Los Angeles LAX for FSX and FS9, which might be similar to KIAD for FS9.