Ryanair has a 40-minute rule that could see passengers forking out an extra £100. It's common knowledge among travellers that arriving at the airport well ahead of your flight's departure time is a wise move, given the potential for check-in delays and security queues.

The general guideline suggests getting to the airport at least two hours before your flight is scheduled to take off, but some risk-takers opt to arrive less than an hour prior. However, if you're planning to fly with Ryanair, it's advisable not to cut it too close.

The airline has a policy, which might be unknown to many, that allows them to impose a 'missed departure fee' of £100 per person on passengers who show up at the airport less than 40 minutes before their flight. Those arriving up to an hour before the flight's departure time may also face charges.

Determining the right time to arrive can be tricky - eager passengers who turn up more than three hours early expecting long queues often breeze through security and then have to wait around the airport for hours. Conversely, those who leave it late are sure to encounter delays, reports Bristol Live.

Instructions regarding Ryanair's missed departure fee policy read: "Only available at less than 40 mins before and up to one hour after flight departure time. Also available to customers who arrive at the ticket desk up to an hour after their flight departure to move to the next available flight. The fee is charged per passenger per sector."

According to the airline's terms and conditions, fliers with Ryanair opting to check in at the airport as opposed to doing so online ahead of time will be subject to an additional cost of £55. The airline says: "If you do not check in online up to two hours before your scheduled departure time, you may check-in at the airport up to 40 minutes before departure, but you will be charged an airport check-in fee."

Furthermore, the airline urges passengers to utilise its online check-in system before reaching the airport to avoid these charges. It adds: "We urge all passengers to check in online before arriving at the airport so these fees can be avoided."

It's important to note that Ryanair isn't alone in imposing penalties for late attendees.