ZAVENTEM, Belgium — Thirteen dots looked just right to designer Ronane Hoet.

Together they had the perfect balance to form a stylized "b" for the new Belgian carrier Brussels Airlines and the number also matched the airline's destinations in Africa, a key market. "It was harmony," she said, wistfully.

This week, however, Brussels Airlines was busy changing the 13-ball logo on the tail and sides of one of its Airbus jets and adding a 14th one in response to complaints from superstitious customers in the United States and Italy.

The airline, the successor to the merged SN Brussels and Virgin Express, won't start flying until March 25 and had only painted one of its planes with the new logo.

"They said they were not pleased with an aircraft with a logo with 13 balls because they think it brings them bad luck," said Brussels Airlines spokesman Geert Sciot.

Hoet was baffled.

"We are never surprised by reactions — but that it was that bad? It really took us aback," said Hoet.

But superstition remains firmly ensconced in modern society.

Try looking for a 13th floor in some buildings, or a 13th row on some planes. On the stock exchange, some amateur traders pick shares based on lucky number combinations.

"There are many examples in business where people make decisions based on intuitive reasoning which are in fact woefully incorrect, in fact very irrational," said psychology professor Bruce Hood of Bristol University.

Tammy Karplus of Portland, Ore., said she understood Brussels Airlines' decision as she prepared to board a Geneva-bound Lufthansa flight at Germany's Frankfurt-Main airport.

"That is just a business decision," she said.

Hood agrees that catering to the irrational can be a rational choice.

"Why make a decision which flies in the face of what everyone else perceives to be real forces," he said. "Why buck the trend?"

Brussels Airlines had the choice to go to 12 dots or 14. It chose 14 because of the religious connotations of the 12 disciples.

Luckily, Brussels Airlines is not flying to China, where 14 is a definite no-no. Fourteen, or one-four, in Mandarin, sounds like the phrase "to want to die."

"The Chinese are notoriously superstitious. Certain numbers are very lucky and their business decisions are very much shaped by their cultural superstitions," Hood said.

Karplus felt pretty relaxed about flying when the gates opened for her flight to Geneva. Then she noticed the flight number "LH3666" — and the last three digits gave her reason for pause.

"The sign of the devil," she said, eyes wide. "But I'm still flying."