I'm at 36,000 ft and on the way home after the first F1 test of the 2013 season in Jerez, Spain.
Approximately half the flight is what we call petrol, people who work in F1, all heading back to the UK after a gruelling start to the year that saw the 11 teams who will compete in the 2013 Championship accumulate more 10,000kms of test laps between them.
The tests are a crucial part of the year, giving the teams the chance to iron out all the technical issues that may befall their cars before the season starts in Melbourne in mid-March.
In the past, testing was allowed throughout the season and all the F1 teams had dedicated test teams that would work through thousands of laps away from the cameras and fans, all in search of those elusive tenths of seconds that are the difference between winning and losing in F1.
In the modern era testing is banned, mainly to reduce costs, but every season now starts with all the teams decamping to Spain for most of February, running three four-day tests in the sunshine and warm weather of Jerez and Barcelona.
The February tests are a tough re-introduction to life on track for the whole team.
Every day on track we work two shifts of mechanics, engineers and truckies (what we call the lads who do all the setting up, packing down and maintenance of the garage and trucks on track): a night crew who start at around 1800 and will work through to around 0800 the next day, and the day crew who run the car while the sun is up, but start and finish their days in the dark.
Right across the team the hours are hardcore. We have a motorhome on track that is our base, our track home, where we eat during the day and where the drivers have their private rooms to prepare and relax after their work is done.
The motorhome's kitchen team are usually in by 0530 to prepare breakfast, and they bring with them the front-of-house people and the motorhome 'technicians', the guys who make sure everything works as it is supposed to in our track home.
Having started at 0530 and prepared, served and cleaned away a range of breakfast options that would grace the menu of any hotel, they then kick straight into lunch and dinner, all for a team of around 50 people who also need constant supplies of drinks and food to stay hydrated and energised. Leave time for the motorhome crew at the end of their shift is often past ten pm, just enough time to head back to the hotel for one beer and six hours sleep before it all starts again.
For the mechanics, truckies and engineers the day is no less tough. Streams of bleary-eyed men and women walk into the paddock as the clock ticks past 7am and head straight for the coffee machines and kettles before going to work. At 9am the peaceful Spanish air is ripped apart by the screaming sounds of F1 V8s propelling their drivers around the track and, barring technical issues, the drivers will be required to run up to 150 laps per day, around three full race distances for every day of the test.
When the track is officially shut, usually around 5pm, the cars are stripped down to the bare minimum so every minute detail can be checked for damage, parts replaced and everything cleaned up to F1 standards.
The engineers, many of whom are never seen on TV or by the fans as they are hidden away in their track offices in the pop-up sections of the trucks in the paddock, will spend the day analysing the data that is constantly coming from the car. At night they will analyse every last detail of that data to give themselves the car setup options they will run the next day, all in search of the elusive goal - time.
Having completed the first test relatively successfully our team will now have a week in the UK before heading to the second test in Barcelona.
The mechanics and truckies will have a day off to recuperate and then they will be back in the factory for four days of work before the flight to Spain. The engineers will have Sunday to recover and then they have a full week in the office ahead of them before it all starts again in just over seven days.
This is the side of F1 that the fans don't see.
It's hard work, carried out in often freezing conditions and with little visible results to motivate a tired workforce. It's not glamorous and it can be very tough, but without the February tests the F1 season would kick off with cars that stand a very good chance of grinding to a halt early in the opening races of the season, so it's vital.
Follow Tom Webb on Twitter: www.twitter.com/TWCaterhamF1