In the dark Cliff would not know the difference between one thousand feet and five thousand, and Johnny wanted to save his gas.

He even shut off his motor and glided down to one thousand before he had passed the line, and picked up again and held the Thunder Bird steady, regardless of the droning hum, that would shout its passing to those below.
"Isn't this rather low ?" Cliff turned his head to shout.
Johnny did not read suspicion in his voice, but vague uneasiness lest the trip be brought to a sudden halt.
"It's all right.

They can't do anything but listen to us go past.
I've got to keep my landmarks." Cliff leaned and peered below, evidently satisfied with the explanation.

A minute later he was fussing with the flare he meant to set off for a signal, and Johnny was left free to handle the plane and do a little more of that thinking for which he was not paid.
The night sky was wonderful, a deep translucent purple studded with stars that seemed closer, more humanly intimate than when seen from earth even in the higher altitudes.

The earth was shadowy, remote, with now a growing brightness as the moon slid up into sight.