Naval ships and combatant military aircraft but that threat, too, is serious." (IO Exhibit 136).
4. Environmental Data.
a. (U) At 030400Z Jul 88, the following environmental data existed:
(1) Wind Speed/Direction: 10Kts/340 degrees T
(2) Sea Temp: 30 degrees C
(3) Air temp: 28.3 degrees C
(4) Relative Humidity: 62%
(5) Evaporation Duct Height: 78.5 ft
(6) Surface Pressure: 998.0 MB
(7) Visibility estimate was 8-10 miles
(8) Ceiling: approximately 200 ft/scattered
(I.O. Exhibit 177).
b. (U) Predicated on the environmental data provided from USS Vincennes on 3 July 1988, which is summarized in I.O. Exhibit 177, Joint Electronic Warfare Center (JEWC) San Antonio, Texas, concluded the following as regards ducting:
C U) Atmospheric conditions suggest USS Vincennes was operating with a strong surface based duct (extending up to approximately 485 ft) and also within an evaporation duct extending up to approximately 78 ft. (IO Exhibit 179).
S U) AN/SPY-1 (AEGIS radar), AN/AWG-9 (F-14 radar) and AN/UPX-29 (IFF) emitters show strong coupling with these ducts greatly enhancing detection ranges. (IO Exhibits 179).
S U) The data provided by NSWC Dahlgren also validates that, in fact, SPY radar was ducting, resulting in greatly enhanced detection ranges. (IO Exhibits 86, 87, 88, and 184)
5. Commercial Air