I have seen the @ symbol in some flight plans. How is it used and what does it do?

What it does is force the aircraft to arrive at the set time.
You see it most often in airliner flightplans. What it will do is override the cruise speed. I did see the consequence once when I was following a BA 777 once and it got over taken by another airlines 777 crossing the atlantic.

It was the quick and dirty method to get airliners to arrive on time, Most people nowadays use the cruise speed and use tools like AIFP to work out when the aircraft should arrive.

It is also more realistic not to use the @ symbol because airliners do not always leave on time and due to head winds tail winds or ATC route issues they may arrive early or late compared to the stated arrival time. Just look at the departure and arrivals board at any airport and you will see this.
Like Steve said better to leave the @ symbol out and make flightplans with AIFP that uses the cruise speed to work ou arrivals.
Steve P

Thanks.

I had some issues with @ symbol. some AI airliners weren't shown in Traffic Toolbox. After removing the symbol it worked correctly.

Bernard

If I remember correctly the "@" flight plan symbol is a carryover from FS2002 and can and does cause problems when used in FS2004.

The Biggest problem I had when I started using the AIG flightplans, was that AI Aircraft never seemed
to land at the destination airport at the time specified in the flightplan but just respawned at the gate
after 20 minutes or so. I spent a whole day de-compiling Traffic bgl's and deleting those little "@" things.
Just make sure you have the correct speed set in the "Aircraft.txt"