An increasing threat to commercial aircraft is the availability of portable surface to air missiles. It is estimated that there are more than 200,000 unfired SA-7 Missiles in the world today. There are more than several hundred unfired U.S.-made Stingers remaining from the Soviet-Afghan war, which are more accurate than the SA-7s. The SA-7 and Stinger missiles are shoulder launched and are effective up to an altitude of 20,000 feet. They can be fired from the ground, from rooftops, boats, and vehicles anywhere in the landing or takeoff pattern of an aircraft.
The SA-7 and Stingers incorporate an infrared (IR) radiation guidance system that “sees” (or senses) the IR radiation signature (or pattern) of the target aircraft. The hot metal surfaces on a jet engine (or turbo-prop engine), and associated hot gas plume, are typically the major contributors of the radiation signature. Once a radiation signature is placed within its field of view and the missile guidance system is initiated, it locks onto the radiation signature and communicates guidance instructions to the missile flight control system. Well-developed algorithms in the guidance systems provide a continuously updated lead angle for the missile trajectory based on sensed changes in direction and rate of the changes in the relative position of the target aircraft, or more precisely, its radiation signature.
IR radiation countermeasure systems for aircraft have been developed to thwart these types of seeker missiles and other types of threat vehicles. Generally, an IR countermeasure system works by first detecting a missile launch, then initiating a spurious radiation signature substantially more intense than that produced by the aircraft's engines, from a location displaced from the aircraft. The source of the spurious radiation is typically ejected (or otherwise physically removed or displaced) from the immediate vicinity of the host aircraft (e.g., firing flares or towing a decoy). Thus, the IR guided missile is attracted towards the source of the spurious radiation signature, away from the target aircraft.
Flares used in such systems typically have as much as twenty (or more) times higher intensity than the emissions that are being masked (i.e., the IR signature from the aircraft). Unfortunately, some missiles (or other threat vehicles) are programmed to detect and reject a radiation signature having a large difference in intensity.
One available countermeasure system uses a missile launch detector, detecting the missile exhaust plume, and directional IR sources (or lasers). This type of countermeasure system is very expensive (i.e., between two and three million dollars). Another countermeasure system employs an onboard transmitter in conjunction with the threat detection and identification system to send a command signal directly to the incoming missile to redirect it. This “electric brick” or “hot brick” type system modulates an electrical (or fuel heated) IR source to spoil the aim of the IR missile.
Another countermeasure system is disclosed in U.S. Pat. No. 4,990,920 (hereinafter “the '920 patent”) to Royden C. Sanders, Jr. The '920 patent disclosed a missile detection system and a RF transponder onboard an aircraft and a towed decoy to separate the transponder. The system has been used with a decoy towed at 300 feet behind the aircraft. The system has induced missile misses of 150-feet behind the towed decoy, protecting both the host aircraft and the towed decoy.
Another countermeasure system is disclosed in U.S. Pat. No. 6,825,791 (hereafter “the '791 patent”) to Sanders et al. The '791 patent discloses a deceptive signature broadcast system for an aircraft (or other emissions generating asset). The system generates an emissions pattern that masks the normal emissions signature of the aircraft or asset. The system protects it from emissions tracking intercept vehicles, such as IR tracking missiles. The system includes at least two beacons mounted in a spaced apart arrangement orthogonal to the desired zone of protection, and bracketing the asset, such as on opposite wingtips of the aircraft for fore and aft protection. The beacon set is modulated from one end to the other with a sweeping pattern of emission intensity, deceptively indicating to the intercepting vehicle a lateral component of motion of the aircraft away from its true relative position within the intercept vehicle's field of view, thereby inducing the intercept vehicle to adopt an erroneous and exaggerated lead angle and course correction that results in a missed intercept trajectory. Unfortunately, the '791 patent requires many expensive additional components for providing the synchronized, multi-source radiation broadcast system.
Visual detection and recognition of an approaching hazard by means of warning signals, such as external alerting lights, play a major role in avoiding collisions between transportation vehicles. The United States Department of Transportation (DOT) requires two lighting systems for certain mass transportation vehicles; an “aid to navigation” lighting system and an “anti-collision” lighting system. “Aid to navigation” lighting systems consist of steady burn lights and landing lights, including red, green, and white position lights See 14 CFR Part 25, subparts 25.1383-1395 for specific requirements. “Anti-collision” lighting systems consist of flashing lights to illuminate the vital areas around the airplane. The system of flashing lights must give an effective flash frequency of not less than 40 cycles per minute (cpm) and nor more than 100 cpm. See 14 CFR Part 25, Subpart 25.1401.
The FAA procedures require that an “anti-collision” lighting system be operated during take off and landing to make the aircraft visible to other aircraft and to those on the ground. The existing lighting systems on aircraft emit visible light to meet the requirements of the FAA. Current sources utilized in countermeasure systems allow only for IR to be emitted. As is well understood in the art, jet engine IR signatures of the engine metal at the inlet, or outlet, fall generally in the region of Band 1 (i.e., about 1.8 microns to about 2.8 microns), which is the reason that threat missile guidance systems operate in this region. However, the jet engine plume is of greatest intensity in the region of Band 4 (i.e., about 3.8 microns to about 5 microns), and some guidance systems utilize a Band 4 or a dual-band sensor system to provide for greater reliability of the tracking system. Unfortunately, current countermeasure system sources do not pass a significant percentage of the Band 4 spectra.
Existing countermeasure systems require the deceptive (or jammer) emissions from a countermeasure system to have greater power than the host asset's inherent emission signature. These deceptive emissions require a large amount of power in order to draw the missile away from the host asset. This requirement often renders the prior art countermeasure systems impractical and expensive.
What is needed in the art is a low-cost, low-power solution that utilizes existing components of an aircraft (or asset) with a specialized lighting assembly, which emits both visible light and IR in the appropriate ranges, so as to integrate a missile countermeasure system based on a synchronized, multi-source radiation broadcast system with visible lighting procedures.