IAG airlines British Airways, Iberia, Aer Lingus and Vueling are poised to make personalised fare offers to customers

But IAG chief executive Willie Walsh warned data “needs to be handled carefully”, saying: “There is a lot you can get wrong.”

Walsh told the CAPA Airline Leader Summit in Dublin: “We carried just over 100 million passengers last year. We have sufficient data on 53 million people to personalise an approach to them.

“That already contributes about €170 million to our business. It is less than 1% of passenger revenue, but within two years it could be 40% of passenger revenue.

“We haven’t fully exploited it yet, but we will.”

Walsh said: “It will contribute to a better customer experience, to improved cost control and improve revenue and therefore profitability.”

However, Walsh told the summit: “It needs to be handled carefully. We need to ensure it doesn’t turn off the customer.

“That is probably holding the process up at the moment. There are a lot of things you can get wrong.”

For example, he said: “You can call people the wrong name. I receive emails which get my name wrong or my company wrong. You can make the wrong kind of offer.”

Toni Raurich Marcet, Booking.com group director of strategy and network for Europe, agreed. He told the summit: “It’s better not to do anything than to get it wrong. It can cause a huge problem.”

Walsh said: “We’ve collected data for years, but we didn’t know what to do with it. We’re at an early stage now, but it is critical for us.

“We’re on the cusp of exploiting the data more explicitly. But we need to tread carefully and be sure to get it right.”