London, England (CNN) -- Baggage handlers and check-in staff at Heathrow Airport threatened Wednesday to strike during the week of Christmas, as British Airways went to court to try to stop a strike called by its cabin crews.
The planned industrial action looked set to throw one of the world's busiest airports into chaos over Christmas -- while United Kingdom-based drivers of the Eurostar train announced they would go on strike at the same time.
British Airways hopes a London court will order cabin crews to stay on the job, despite a vote by 92 percent of members of the Unite union to walk out.
The strike could threaten 1 million passengers' holiday travel plans.
BA made its case before Judge Laura Cox at London's High Court Wednesday. Unite also is expected to present its views Thursday and the judge could rule the same day.
The airline held emergency talks with union leaders even as it sought the court order to block the 12-day walkout. The two sides talked for about four hours on Wednesday afternoon, a BA spokeswoman told CNN, without disclosing the contents of the discussions. She declined to be named.
BA is challenging the Unite union's ballot of its 12,500 cabin crew members, arguing that some workers who had taken voluntary redundancy -- or buyouts -- took part in the voting even though they would have left the airline by the time the strike took place.
Unite, which said British Airways cabin crews will strike from December 22 to January 2, also announced the threat of the second air travel strike as BA fought its case in court.
Baggage handlers and check-in staff at Heathrow and at Aberdeen airport in Scotland will strike next week unless there is movement on resolving a pay dispute, Unite announced.
The strike is not related to the BA dispute. The baggage handlers and check-in staff are employed by SAS Ground Services UK Ltd.
Unite said the strike would affect travelers on Turkish, Emirates and Thai airlines at Heathrow and passengers on KLM, Air France, Wideroe and Atlantic at Aberdeen. The walkout, which is over pay and pensions, is scheduled for December 22 to 24, December 26 to 27 and January 3 to 4, 2010.
SAS said it was preparing a statement in response.
Opening the British Airways hearing at London's High Court, the airline's legal counsel, Bruce Carr, told the presiding justice that the balloting process contained "serious and substantial irregularities." He called the union's action in choosing to strike over Christmas "willfully disproportionate and clearly unlawful."
Carr referred several times to the serious disruption that will be felt by the airline's passengers, saying some "ordinary people will find it very difficult to understand."
Meanwhile the Unite union said it had accepted an offer from British Airways to meet for talks Wednesday afternoon. "We are pleased the company has seen sense and will meet with us to seek an opportunity to get the talks back on track," union spokeswoman Pauline Doyle told CNN.
Those talks do not affect the airline's attempt to seek an injunction to prevent the strike.
Unite union members voted in November to walk out because of planned changes to cabin crew conditions. The union's Deputy General Secretary Len McCluskey announced the result of the ballot Monday.
The strike vote came after the airline introduced cost-cutting measures, including a two-year pay freeze and reducing the numbers of cabin-crew members on long-haul flights.
British Airways says the changes, introduced in the wake of a record pre-tax loss of more than $485 million for the six months from April to September, will save the airline $665 million.
Meanwhile, Eurostar train drivers based in the United Kingdom announced Wednesday they will strike Friday and Saturday, and again December 26 and 27. Eurostar, however, said service would not be affected, because drivers from France and Belgium would be used. The train line provides service between London and both Paris, France, and Brussels, Belgium.
Talks between the Associated Society of Locomotive Engineers and Firemen and Eurostar "concerning international allowances" broke down, the union said. The dispute is over how much drivers' meal allowances should be when they are in Paris and Brussels.
A Eurostar spokeswoman said it offered the drivers what it believes is a reasonable amount, but the drivers rejected the offer. She would not divulge specifics of the offer, saying only that it was "enough for a good meal."
Separately, the International Air Transport Association, an umbrella group for the air travel industry, predicted Tuesday that the world's airlines will lose $5.6 billion in 2010. That's more than the group's previous prediction of a $3.8 billion loss in 2010, but still only half as much as it expects the industry to lose this year.
"The world's airlines will lose $11 billion in 2009," said Giovanni Bisignani, the association's director general and CEO, in a statement. "Between 2000 and 2009, airlines lost $49.1 billion, which is an average of $5 billion per year."
If the BA strike goes forward, passengers will find themselves unable to take their flights or be stranded at their destinations, unable to return home, said travel expert Simon Calder of The Independent newspaper on CNN's "Quest Means Business" Tuesday.
British Airways has said passengers holding tickets for the strike period may rebook for any date in the next 12 months with no penalty, but ticketholders still hoping to fly over the holidays are faced with a dilemma.
The airline has said it will refund a passenger's ticket only if their flight is canceled, and so far it has not canceled any flights because of the strike. Passengers not willing to wait to see whether their flight will be canceled can try to rebook on another airline, but British Airways has said it will not reimburse them for the cost of that ticket if their original flight goes ahead as planned.
There is little availability on other airlines, and any tickets are likely to be expensive, Calder said. Follow news of strike on Twitter
CNN's Alysen Miller contributed to this report.