SCP-XXXX, as it was contained by the Foundation at Armed Site-21.
Special Containment Procedures: Following the events of Incident XXXX-02, containment of SCP-XXXX itself is currently unnecessary.
Archived Containment Procedures: SCP-XXXX is secured on-site at Armed Site-21 under standard Site asset security protocol, and is to be monitored for any alterations in its reporting pattern. A log of all aircraft contacted and identified by SCP-XXXX-1's computers is to be maintained in Armed Site-21's combat information center. SCP-XXXX-2 is to be inspected for any damage or wear on an annual basis, and all deficiencies shall be repaired promptly. Testing is only to be done with approval of Armed Site-21 Tower and under supervision of the Project Lead.
As per standard Veil protocols, the location of SCP-XXXX on FAA Sectional Charts has been scrubbed, and local air traffic controllers have been notified to instruct military and civil aircraft equipped with TACAN avionics to steer clear of Armed Site-21's airspace and avoid channel 777.
Description: SCP-XXXX was a TACAN1 installation located within Armed Site-21's boundaries, approximately 3 kilometers north of the Site's primary runway. The installation consisted of two primary segments: a control room located inside of a small building (designated SCP-XXXX-1), and a paratechnologically-enhanced TACAN antenna (designated SCP-XXXX-2), which was located adjacent to SCP-XXXX-1.
Most of the interior and exterior of SCP-XXXX-1 was non-anomalous and was constructed in a fashion consistent with mundane TACAN installations, with a few noteworthy differences. The computers and instruments within SCP-XXXX-1 were capable of automatically transmitting accurate positional and navigational information to aircraft operating within the station's range, so long as the aircraft's radio transponder was set to channel 777. These computers were additionally capable of receiving data containing the make and model, airspeed, bearing, and intended destination of all aircraft operating within range of the station, even if the aircraft in question was not equipped with TACAN avionics or locked on to the installation.
SCP-XXXX-2 was a paratechnologically enhanced TACAN antenna that stood at a height of approximately 27 meters. SCP-XXXX-2 operated in a frequency band which commonly fluctuated between 300 MHz and 3 GHz, making the data produced significantly more precise than a standard civilian VOR2 or ordinary TACAN site. SCP-XXXX-2 was capable of providing accurate positional and navigational information to multiple aircraft at once from distances of up to 360 nautical miles.
SCP-XXXX's primary anomalous function was its ability to receive and transmit SCP-XXXX-3, an anomalous form of electromagnetic radiation originating from an as of yet inaccessible higher dimension. SCP-XXXX-3 transmissions typically contained an average wavelength of 300 EHz3, and contained noteworthy amounts of Aspect Radiation. Additionally, SCP-XXXX-3 transmissions would always contain a sophisticated form of encryption, which made reading the transmissions without using SCP-XXXX-1's instruments effectively impossible.
When SCP-XXXX received a SCP-XXXX-3 transmission, it was capable of decrypting the signal as an audio message, which would summarily be presented on a terminal within SCP-XXXX-1 as a text message. Responses could be sent through a computer within SCP-XXXX-1 via a standard QWERTY keyboard, though these messages contained a 40 character limit.
Given SCP-XXXX's apparent autonomy in formulating responses and transmitting data to aircraft operating within its effective range (See Addendum XXXX.1), responses were ultimately optional. The majority of these transmissions, when not directed to any aircraft in the baseline reality, consisted of an automated voice providing erratic, often nonsensical information to nonexistent aircraft operating in the area. (See Transmission Event #XXXX-02)
The exact nature of SCP-XXXX-3 is currently unknown to the Foundation. According to the computers within SCP-XXXX-1, trace amounts of SCP-XXXX-3 can be detected within the baseline reality, though the majority of SCP-XXXX-3 transmissions that have been received by SCP-XXXX appear to originate from the same inaccessible higher dimension they were broadcasted from.
History & Discovery: SCP-XXXX was first built in 197█, under stringent U.S. FAA specifications, where it saw infrequent usage by the U.S. Air Force since. Given its rather coincidental proximity to Armed Site-21, Foundation aircraft operating within the region began using SCP-XXXX to aid in navigation and non-precision approaches to the Site's airfield. By 1985, 96% of all aircraft which used SCP-XXXX were identified as being owned by the Foundation or a Foundation front organization.
In 1986, Armed Site-21 began experimenting with upgrading the then-aging SCP-XXXX with paratechnology, in hopes of using the assumedly mundane installation as a means to allow Foundation aircraft to covertly navigate in the region far beyond the installation's then-effective range of 100 nautical miles. Additional modifications were also implemented by Armed Site-21 SIGINT teams to monitor the testing of Lockheed Martin's Skunk Works, which had begun test flights of anomalously-modified prototype aircraft in the region.
After Foundation technicians fitted an anomalously-enhanced AESA antenna onto SCP-XXXX-2, SCP-XXXX-3 was detected for the first time, and the installation's anomalous functions were identified. By 1987, amid ongoing efforts at détente with the U.S. Government, SCP-XXXX was officially transferred to Foundation custody for further study, though the installation remained in regular operation by both parties until its neutralization in 1998.
Addendum XXXX.1:
SCP-XXXX Transmission Event Excerpts
SCP-XXXX operated autonomously and required little to no human input. However, the installation would, on occasion, transmit personalized data and navigational instructions to aircraft which were tuned in to transponder channel 777 on its own accord. Below is a list of archived transmission events from SCP-XXXX which are considered to be of significance to the project.
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