British Airways boss Willie Walsh has urged passengers to make Christmas bookings with the airline, despite the growing threat of a crippling cabin crew strike during the festive season.

Willie Walsh said trade union warnings of industrial action were premature and the airline was still prepared to hold discussions despite the carrier’s largest union, Unite, launching a strike ballot.

Asked if potential customers should buy British Airways tickets for Christmas travel, he said: “Yes. Talk of a strike is premature and there is a long way to go. Unite has indicated that it wants to work with British Airways, cabin crew have indicated that they recognise change is necessary. We should be sitting down and talking.” Walsh added that Unite had yet to serve formal notice that it is holding a ballot, as it is required to do.

Speaking as British Airways announced a record first-half pre-tax loss of £292m – during what is normally its most profitable trading period – Walsh said he had sent a letter to the joint heads of Unite seeking further talks on cost-cutting measures. British Airway’s track record of negotiations with cabin crew indicates that Christmas will be fraught with financial and PR risks for the airline. Heathrow airport’s largest carrier lost £80m in 2007 after a dispute over cabin crew pay was called off at the 11th hour, too late to reinstate thousands of bookings that had been refunded or switched to other airlines.

However, Walsh said this morning that the situation was much more serious, with the airline still far from stemming a series of huge losses including a pre-tax loss of £401m last year. “The circumstances behind the discussions are very different this time round. British Airways is a company reporting significant losses that are not sustainable. Cabin crew job security can only be achieved if BA is profitable.”