Experienced air traffic controllers and naïve college students participated in 2 experiments we conducted to test a hypothesis that controllers evaluate potential conflicts between aircraft in a hierarchical manner, comparing altitudes first for vertical separation, then extrapolating aircraft trajectories for lateral separation, and finally performing speed-distance computations for longitudinal separation. The results clearly support the hypothesis and imply that controller workload in terms of time pressure could be determined by momentary conflict geometries between aircraft pairs in a sector. Similarity of results between the groups has implications on both our understanding of controller expertise and on experimental research on air traffic control-related issues.

A safety driver sits behind the wheel during a test of a self-driving taxi in Yokohama, Japan. 1 2 A P R I L 2 0 1 8 | V O L 5 5 6 | N A T U R E | 1 6 9 COMMENT KIYOSHI OTA/BLOOMBERG/GETTY © 2 0 1 8 M a c m i l l a n P u b l i s h e r s L i m i t e d , p a r t o f S p r i n g e r N a t u r e . A l l r i g h t s r e s e r v e d . 1 7 0 | N A T U R E | V O L 5 5 6 | 1 2 A P R I L 2 0 1 8 COMMENT A driverless bus shuttles passengers across Southeast University's Jiulonghu campus in Nanjing, China. VCG/GETTY

Fourteen pilots flew a synthetic vision system (SVS) display, through a terrain and traffic-rich environment in a high fidelity flight simulator. Traffic information was hosted on the SVS display. In a 2x2 factorial design, the SVS display hosted a highway-in-the-sky in half the conditions, and hosted an instrument panel overlay in the other half. We examined the effects of the resulting clutter from overlay (but reduced scanning) on routine flight performance, SVS traffic detection, and response to off-normal events, as these were mediated by visual scanning measures of attention allocation. The tunnel greatly improved flight path tracking and traffic detection, but slightly disrupted the detection of unexpected outside world traffic. The instrument panel overlay provided no benefits to tracking and a clutter-related time cost to SVS traffic detection. Visual attention was focused on the SVS display over half the time, and rarely on the outside world, even in visual meteorological conditions (VMC), a source of possible cognitive tunneling.

No abstract

Procurement incentives are a widely leveraged policy lever to stimulate electric vehicle (EV) sales. However, their effectiveness in reducing transportation emissions depends on the behavioural characteristics of EV adopters. When an EV is used, under what conditions and by whom dictates whether or not these vehicles can deliver emissions reductions. Here, we document that replacing gasoline powered vehicles with EVs may—depending on behavioural characteristics—increase, not decrease, emissions. We further show that counterfactual vehicle inventory—how many vehicles a household would own absent an EV purchase—is an important influencer of these effects. We conclude that achieving emissions reductions using EVs requires redesigning procurement incentive programmes in a manner that (re)distributes incentives towards the second-hand EV market. Doing so would not only facilitate emissions reductions but also address fiscal prudency and regressivity concerns associated with these programmes.