Esther:

The easiest way to find a passenger is to simply put in their last name in one search field, add another search field and type in the word "PASAJERO". That will bring up both licensias and passenger lists that have that name. This was easy enough with a name as rare as ARREDONDO. Obviously once you get to more common surnames, you would get hundreds of hits so you have to narrow down more. You can then either add yet a third field and add the first name or instead of using just their last name, type their whole name in quotes, i.e. "Juan de Arredondo." This last method is problematic because the match has to be exact. If you leave out the "de" or the name is "Joan" and not "Juan" nothing will come up. Of course you can try every variation possible as it will probably not take longer than having to go through thousands of records.

Unfortunately, the date fields have never worked for me so you have to sift through hundreds of years worth of data.

Another tip... when the scan of the record is available, click on the red version of the camera. While you are not supposed to be able to right-click to save or print, if you are using Firefox, the code they have put into the page does not work and you will get an error message, but Firefox will let you save the image nevertheless. That is how I got yours.