Passenger Numbers

Is there some way of know how full a flight is?

You can get a feel of how busy a flight is by searching for 9 seats and seeing what fares are offered.
However most booking engines only allow you to check a maximum of 9 seats per flight - and that can mean 9 seats left or 199 seats!

Expert Flyer displays availability by fare bucket - but again up to a maximum of 9 seats, therefore when you see figures below that you can estimate that the flight is getting busy.

Try a dummy booking for you flight on orbitz.com. You will be able to see availabilty on the seat maps for economy and upper class. It doesn't give a booking option for PE.

[Neil]

Try a dummy booking for you flight on orbitz.com. You will be able to see availabilty on the seat maps for economy and upper class. It doesn't give a booking option for PE.

Just a quick warning, while the seat map will show which seats are currently available, don't forget a certain % of pax won't have selected any seats, so it won't really tell you how many seats are still available.

The seat map could show 20 seats but there might be only 5 left for sale as 15 pax might not have selected their seats yet.