You use your MOBIB card in 2 simple steps:

1. Scan your card every time you board and with every transfer: wave your card in front of the blue circle at the bottom of the scanner. Using the card for the first time? Hold it in front of the scanner for slightly longer (5 to 10 seconds).
2. A check mark is displayed as soon as the MOBIB scanner recognises your card. This means your travel pass has been validated. Only then can you pass. You don't have to scan your card again when you get off.

Do you get a cross on a red field? Check if your card is defect.