Table 5.

Regression of heading r-value against flight altitude.

Period	df	F	r2	p
Daytime	15,807	504.40	0.080	<0.0001
Sunset	12,014	376.10	0.157	<0.0001
Night	1397	36.38	0.082	<0.0001
Total	18,222	724.90	0.081	<0.0001