Though the concept of "off-course navigation" (steering to one side so you know which way the error is) is probably as old as navigation, Chichester was the first to use it in a methodical manner in an aircraft. His only method of fixing his position was to take sun sights with a sextant. As a solo pilot, this was a difficult thing to do in a moving aircraft, as he needed to fly the aircraft at the same time. After the sun sight was taken, he had to make calculations by long-hand. As all this could be unreliable, Chichester needed an alternative. When he reached a point at which the sun was at a calculated altitude above the horizon, the pilot then made a 90-degree turn to the left (or right as calculated) and then flew along this line until the destination was reached. Since he did not know in advance when he would arrive at a line of position passing through his destination, he calculated a table or graph of the Sun's altitude and azimuth at his destination for a range of times bracketing his ETA. The advantage of this method was that the effects of drift were reduced to errors in distance travelled, usually much smaller. Since Chichester arrived at Lord Howe Island in the afternoon, the Sun was to his north-west when he made his turn. Some hours before making his turn, close to local noon when the Sun was to his north, Chichester made two observations with his sextant to check his dead-reckoning course.