The structure Ferrari mounted to the Halo of its F1 car at the Spanish Grand Prix to incorporate rear-view mirrors has been banned.
Ferrari unveiled the most creative use of the Halo so far in Barcelona, with mirrors and an extra winglet either side of the cockpit safety device. The team said the structure was made to aid visibility for the driver, which was the condition in the regulations allowing for such designs.
The main point of disagreement is with the secondary winglet, placed above the mirror itself, which formed a curve to aid airflow to the rear of the car. The FIA, motorsport's governing body, felt it gave it too much of an aerodynamic gain.
Ferrari believed it had done enough to seek clarification on what was acceptable ahead of the Barcelona race.
"For us it's straightforward, I see better," Vettel explained after the grand prix. "That was the point of moving. We asked already at the beginning of the year, when the first seat fit was with the Halo, if we can move them on the Halo because then they would be in a better position to see what is going on behind.
"Then with the winglet, we're doing the same as everybody else with their mirrors. There's a hole in the regulations. I don't think I need to explain. Then everybody needs to change part of their mirrors if that's the case."
The team must change it in time for the Monaco Grand Prix or revert back to its previous design. F1's race director Charlie Whiting said Ferrari's original interpretation was on the wrong side of what the regulations deemed acceptable.
"I don't think there's any controversy," Whiting said. "I think it's a liberal interpretation of the word 'mounting', because that's how they be can legal because there's no bodywork allowed in the area of the upper part of that.
"The interpretation hinges on whether we think that is a mounting or not. We somehow think not, so we're going to take some action on that.
"We sent a [technical directive] a few weeks ago now in response to a number of questions from other teams about whether or not the principle of mounting a mirror on the Halo was acceptable, and we answered yes it was, and we gave a few stipulations, one that is has to be a mounting. It's just a matter of interpretation. We feel that something that is such a tenuous interpretation really is not something that we're happy with."
On Thursday the FIA released a clarification statement saying any future designs must only feature an "incidental, or at least minimal" benefit for teams. It has also stressed that any additional mountings coming from the Halo must do two things:
a) Provide a meaningful structural contribution to the mounting system. If you use more than one mounting you may be asked to satisfy us, by way of a physical test, to demonstrate this.
b) Be mounted to the lower and/or inboard surface(s) of the mirror housing.
The statement added that: "The FIA do acknowledge that the rules currently in force with regard to mirrors are not perfect, and will strive to propose a more complete set of rules in terms of mirror position, mountings, visibility, etc. in the near future, with the aim to get a unanimous support for such changes for 2019."