SLAB aircraft at desired altitude while the 

 regular reconnaissance aircraft provided surface 

 verification flying routine search tracks and in- 

 vestigating all SLAB targets. Missions were 

 flown over the open water iceberg areas of the. 

 Grand Banks and into the pack ice area upstream 

 along the Labrador coast. Various adjustments 

 to the system were made with a wealth of good 

 data. Results were basically as expected. The 

 systems provided greatly increased coverage and 

 effectiveness, obtained all targets including whales 

 and debris, easily detected icebergs in sea ice and 

 penetrated all weather except heavy rain. Small 

 bergs were consistently detected to 48 kilometers 

 with a signal to noise ratio of at least 2. The 

 basic problem continued to be target identifica- 

 tion. Other problems were : slow target geo- 

 graphical location by manual plotting, sea return 

 interference, and antenna fade. The Moving 

 Target Indicator mode provided unsatisfactory 

 results mostly due to equipment performance and 

 slow target movements in azimuth. The Ice 

 Batrol and NASA Lewis plan to continue experi- 

 mental SLAB flights during the 1976 ice season 

 attempting to solve the target discrimination and 

 data handling problems. Additional modifica- 

 tions will include : a moving window display with 

 automatic target designation, several approaches 

 to automatic target recognition and identification, 

 better amplitude-time discrimination, and de- 

 polarization of echoes. 



The future looks promising. The Coast Guard 

 prototype Airborne Oil Surveillance System 

 (AOSS) has been flight evaluated and will soon 

 be installed in a service C-130 aircraft. This 

 system includes an AN/APS-94D SLAB, a 

 37-GHz passive microwave imager, a multi- 

 spectral line scanner and a low light television 

 system with position reference and real-time 

 processor/display console. AOSS was originally 

 developed for marine pollution detection and 

 cleanup support, but will be used in other Coast 

 Guard mission areas, particularly the Interna- 



tional Ice Patrol. A multisensor system with 

 separate detection and interrogation functions is 

 another approach to be evaluated. Other ad- 

 vances with good potential of target identification 

 are the use of synthetic aperture systems and a 

 dual mode operation with low resolution, broad 

 swath search and narrow width, high resolution 

 scrutiny. But these are presently beyond Ice 

 Patrol's limited funding scheme. Ice Patrol is 

 also well represented on the SEASAT user work- 

 ing group and, in the long-term, envisions such a 

 satellite to continuously monitor the area of re- 

 sponsibility, not only detecting sea ice and ice- 

 bergs, but also providing needed surface 

 environmental data. 



But that is in the future. Today Ice Patrol is 

 still plagued by its old nemesis, fog, while con- 

 tinuing to guard the Grand Banks against an- 

 other TITANIC disaster. 



References 



Dinsmore, B. P. "Ice and Its Drift in the North 

 Atlantic Ocean" 1972. ICNAF Special Publi- 

 cation No. 8, 1972. 



Edgerton, A. T., Bommarito, J. J., Schwantje, 

 B. S. and Meeks, D. C. Development of a 

 Prototype Oil Surveillance System, Final Be- 

 port May 1975, Beport No. CG-D-90-75. 



Farmer, U. L. Iceberg Classification Using Side- 

 Looking Airborne Radar 1972, U.S. Coast 

 Guard Office of Besearch and Development 

 Beport. 



Ice Detection by Radar, Consolidated and 

 Abridged Report 194-5 and 191^6 Studies, Inter- 

 national Ice Patrol May 1959. 



Osmer, S. E. "ERTS-A Evaluated" 1975, CG- 

 188-29, Bui. No. 60. 



Osmer, S. B. "The Aviation History of the 

 International Ice Patrol" 1975, In preparation. 



U.S. Coast Guard Report of the International 

 Ice Patrol Service in the North Atlantic Ocean 

 Annually 1914 to 1973, CG-188 Series. 



58 



