This week Indianapolis Motor Speedway has had something of the look of a small airport, with several cars getting airborne after very similar single car accidents. As a result the rule makers have implemented a set of emergency regulation changes to slow the cars and reduce incidence of rear end breakaway that seems to be causing the accidents.
The problem for Indycar is that running at these sorts of speeds on ovals with ground effect underbodies a car that ends up going backwards ends up going up too. F1 killed ground effect cars for exactly this reason. In 1982 the fatal accident of Gilles Villeneuve, the career ending accident of Didier Pironi, and the miraculous escape of Jochen Mass and hundreds of spectators at Paul Ricard persuaded the FIA that underbody aerodynamics introduced to much risk.
Indycar has retained these ground effect floors, which allows the cars to run with less wing and produce higher headline lap speeds. However when tied to the rear end instability that the new 2015 aero kit appears to be causing, the end result can be spectacular.
Hopefully by changing the car's aerodynamic setup and reducing the amount of turbo boost Indycar has done enough to stop cars spinning into the wall and getting airborne.