- perform enroute navigation on a world-wide basis. 
- fly nine or more three-hundred-mile flight lines while 
maintaining accurate sidelap control 
- compute latitude and longitude with input from navi 
gation viewfinder or the electronic distance measuring 
equipment to an accuracy of 0. 1 minute. 
- Monitor the operation and credibility of the inertial 
reference unit. 
- read out the pitch and roll of the aircraft. 
- read out drift angle, ground track, ground speed, true 
heading, altitude track error, latitude or longitude and 
range to go. 
- program the airborne digital computer so that the air 
craft will automatically pass over selected ground 
points. 
It should be pointed out that the navigation system of the 
AN/USQ-28 does not attempt to position the aircraft with the same 
accuracies required for horizontal control. The basic navigation 
mode programs the aircraft along parallel flight paths, with accur 
ate control of sidelap. The location of nadir points is accomplished 
after the fact, during photo reduction. 
Navigator's Viewfinder: 
Figure 3 illustrates the navigator's viewfinder, that part 
extending into the navigator's station. Table 1 presents the primary 
specifications of the viewfinder: 
TABLE 1 
Search Field . . . 
Field of View . . 
Magnification . . 
Resolution . . . 
Sighting Accuracy 
Tracking Rate . . 
Drift 
pitch+100°, -35°, roll t 50° 
60° 
2X, 4X 
1 minute of arc 
3 minutes (1 ) 
^2 degrees /sec. 
- 20 minutes (accuracy 8 min. 
1 )