A merged US Airways and American Airlines will overtake Delta as the world’s biggest airline when the deal completes today – here’s what you need to know.

1. The combined airline, the biggest in the world, will have more than 1,000 aircraft, flying nearly 6,700 daily flights to 330 destinations across 54 countries.

2.Together, the airlines took a total of $38bn in revenues and flew 190m passengers in 2012.

3. American Airlines and US Airways expect to save $1bn a year by 2015 thanks to the merger.

4. The new airline will employ around 24,500 flight attendants and 12,500 pilots.

But you can’t merge two giant airlines just like that:

Today is the legal ‘marriage’ of the two airlines. But it will take months, even a couple of years, for the two to truly become one operation.

5. The merged airline will spend the next two years re-configuring its fleet of aircraft to ensure that all planes of a particular model use the controls for the same functions.

A pilot flying a US Airways Airbus A330 will need to flick a switch in a particular direction to get the plane to go into taxi mode. The same model owned by American Airlines might be configured so the instruction to taxi requires the switch to be flicked the opposite way.

Over the next 24 months, the merged airline will bring all aircraft into line, so that just one instruction manual is needed for any particular model.

6. The combined airline is also going to renew its flight attendant uniform. A spokesman for American Airlines said both employee groups have had “a lot of input” into the new get-up, which will be designed by Kaufman Franco and unveiled next year.