The United States Grand Prix began in bizarre circumstances as fog and a mechanical fault with the medical helicopter caused delays.
Despite the city of Austin bathed in sunshine in the early morning, the Circuit of the Americas – based 10 miles away – was shrouded in fog.
With the first 90-minute practice session poised to get under way, FIA race director Charlie Whiting was forced to call a number of delays as the medical helicopter was unable to fly given the conditions.
The run finally started after a 40-minute stoppage, with the session cut to an hour.
However, after just 14 minutes of on-track action Whiting was forced to bring proceedings to a halt due to a message that read ’further problems with the medical helicopter’.
It is understood the pilot discovered a technical issue, leaving organisers to locate another helicopter before the session could be restarted.
That resulted in a further 34-minute wait prior to the cars returning to the track to complete a session topped by Fernando Alonso in his Ferrari.
After being given the all-clear to race despite an issue with his back sustained during the last grand prix in Abu Dhabi, Alonso was fractionally ahead of McLaren’s Jenson Button by just 0.028secs.
The 32-year-old Spaniard, pushing for second place in the drivers’ standings, posted a lap time of one minute 38.343secs.
Behind Button was Williams’ Valtteri Bottas in a shake up of the order as four-time champion Sebastian Vettel was down in 18th in his Red Bull, 2.3secs behind Alonso.
But with times largely irrelevant in opening sessions, Vettel will be unconcerned as he still completed 21 laps, doing a high-fuel run.
Sauber’s Esteban Gutierrez was fourth on the timesheet, which will have pleased his fans from Mexico – just across the border – here to see him and Sergio Perez in action, with the second McLaren driver down in 12th.
The Mercedes duo of Nico Rosberg and Lewis Hamilton were fifth and sixth quickest, 0.314secs and 0.636secs adrift respectively.
Ferrari’s Felipe Massa and Mark Webber in his Red Bull were up next closely behind Hamilton, with Sauber’s Nico Hulkenberg and Williams’ Pastor Maldonado completing the top 10.
Force India’s Paul Di Resta was 15th, 1.493secs adrift and right behind his team-mate Adrian Sutil.
Heikki Kovalainen, as replacement for Kimi Raikkonen who on Thursday underwent successful back surgery, was 13th and just 0.2secs adrift of Lotus team-mate Romain Grosjean on his first outing for the team.
Toro Rosso’s Daniil Kvyat, the 19-year-old Russian rookie who gained his superlicence recently ahead of his maiden campaign for the team in 2014, was 1.722secs down, and just 0.2secs behind team-mate Daniel Ricciardo.
American Alexander Rossi, as reserve for Caterham, enjoyed a strong showing in front of his home crowd as he was 19th, 0.7secs ahead of team-mate Charles Pic.