d E 
1 
17 
After the calibration of the systems have been completed, the results 
will be published. 
4C. Comparison between the accuracies and performances of integrated 
survey flight systems 
The two most relevant differences in accuracy between the ITC PHOTNAV 
system and the Fokker F-27 integrated inertial system are: 
(i) that — basically — the errors of the doppler-equipped ITC PHOTNAV 
system depend on the square root of the distance, and on the number 
of turns (i.e. number of flight lines), whereas the errors of the inertial- 
equipped F-27 system depend on the elapsed time, and 
(ii) the doppler-equipped system is intended to produce perfect pre- 
programmed survey navigation whereas the inertial-equipped system 
produces excellent general navigation, without the Symphotblock 
possibility, but with additional sensing and recording of the attitude 
angles of the camera at each exposure station, with very high accuracy. 
The graphs in figures 5, 6, 7, 8, 9 and 10, illustrate the comparison 
between Doppler performance and INS performance. 
Performances are compared for two different aircraft speeds: 
150 Kts (being typical for propeller-driven aircraft) and 
400 Kts (being typical for jet-propelled aircraft). 
Figures 5 and 6 show absolute lateral performances for a number of 
parallel flight lines. This is of importance if the flight lines have to be 
positioned at well defined latitude/longitude values (map sheet arrangements). 
Figures 7 and 8 are to be considered where the relative lateral performance 
and accuracy between two strips is important (i.e. to obtain gap-free 
coverage). 
Figure 9 and 10 show the longitudinal performances as a function of 
the distance from the last fix. Longitudinal performance might be the limiting 
factor for the production of pin-pointed photography.