This is an earlier experiment. Read the amendments below before treating its findings as current.
The question
Before changing the controller, reviewers wanted to know what state a wing is in when it drops to its minimum speed.
What was tested
We recorded the situation at each slow moment and 4 s before, which rule pushes forward or backward, and the angle between flown and commanded direction.
What was found then
Traffic is rarely close: another craft is in a close call at only 1.6 % (5 m/s wing) to 3.1 % (3 m/s) of these moments; few are near a crossing. The controller never asks for a slow speed, and no single rule is the main brake on half the slow moments. At 5 m/s the held wing is typically 37° off its commanded direction (fleet 20°), read then as turning not being the cause; at 3 m/s it is mostly mid-turn. The cause stayed unknown.
What we learned later
'Turning is not the cause' was narrowed to: most held moments are within 45° of the command, and turning's share is unknown.
research/reviews/brief-c29.md
Switching off the rule that makes craft match their neighbours' speed and direction removed most of the slow time, naming it as the main cause.
research/reviews/brief-c29.md
What changed
Nothing. A recorder of each rule's push was added, off by default.
Corrections retained in the record
Earlier wording: which I read as the aircraft flying 50 to 90 degrees away from where it is told to go
Record correction: the derived figures were ~50° (5 m/s) and ~86° (3 m/s)
research/reviews/brief-c27.md
Numbers and source references
- 1.6 % / 3.1 %
- slow moments with another craft inside one standard, 5 / 3 m/s wingresearch/reviews/brief-c26.md
- 4.0 %
- same over the preceding 4 s, 5 m/s floorresearch/reviews/brief-c27.md
- 12 %
- slow moments within 100 m of a crossingresearch/reviews/brief-c26.md
- 7.9 m/s
- mean commanded speed at slow momentsresearch/reviews/brief-c27.md
- 37° vs 20°
- median heading error of held wing vs whole fleet, 5 m/s floorresearch/reviews/brief-c28.md
- 44 %
- held moments more than 90° from command, 3 m/s floorresearch/reviews/brief-c28.md
- ~50° / ~86°
- withdrawn derived heading figures, 5 / 3 m/sresearch/reviews/brief-c27.md