T.A.S. on APR runs 
Drift on APR runs 
Maximum variation of T.A.8. 
on any 1 APR run 
Maximum variation of drift 
on any 1 APR run 
Winds 
Hypsometer warming-up 
period 
Nearest met. station 
Pressure conditions 
Diurnal change 
Velocity of propogation 
of beam 
Lengths of APR lines 
Drift rate between 
datum points 
Survey Camera exposure 
interval (1/40, 000 cover) 
35mm exposure interval 
Maximum lateral tilt 
Maximum F & A tilt 
Maximum inclination of 
airbase 
Maximum change of flying 
height between two 
exposures 
121 - 154 knots 
119P - 103° S 
5 knots 
Of the order of 29 - 39 
Generally 10-15 knots at 20, 000" 
Always 1% hours (during transit from base at Kaduna) 
Kano 
Constant over any 100 miles distance 
At Kaduna airfield level, +120! between 
0600-1200 GMT 
Different from U.K., but insignificently so 
Lines 2/3 - 9/10 
Lines 15/16 and 16/17 
Lines PR15 and PR17 
Line PRN3 
Tie runs 1, 2,3, and N1 
17 - 28ft. per hour, in negative 
90 miles each 
30 miles each 
30 miles each 
15 miles 
45 miles each 
direction (agrees with typical 
diurnal barometric changes). 
Same drift rates apply at both 
20,000! and at 6, 000! - 8, 000' 
c.45 secs. 
c.7 secs. 
14° 
14° 
48 minutes 
160! 
17