Any disappointed passenger who's ever tried to fly stand-by can sympathize with the plight of Humbug, Sweden's entry in Saturday's Washington, D.C. International.

The 3-year-old filly was originally scheduled to leave Sweden Tuesday, and would have arrived yesterday. But according to Laurel Vice Chairman Frank Brady, the horse was bumped from her Scandinavian Airlines (SAS) flight.

"They have what are called 'combi' (combination) planes, with passengers and freight," he said. "If there are enough passengers, they can shorten the amount of freight. They shortened it so much they left all of it, including the horse, behind. I understand the Swedish press is all upset over it."

A Scandinavian Airlines spokesman, Ray Chambers, said yesterday that Humbug remained in Sweden because of a change in aircraft.

Chambers said the 747 combi has a convertible flight deck that has the flexibility to provide additional passenger space, if necessary. Horses, or other animals traveling, are secured in an area behind the passenger section, with their own handlers, as well as one from the airline, seated in the last row.

"Humbug was scrubbed because of a change in aircraft," he said. "We used a 747-B, which is the passengers-only version of the other plane, and is not the type of aircraft to accommodate horses."

That plane, said Chambers, does not have a pressurized cargo cabin, necessary for carrying live freight.

"It's entirely possible the aircraft was switched because of heavy demand from passengers flying over," Chambers said. Asked if Humbug would be compensated for the inconvenience, much as two-legged passengers are, he quipped, "We might give her an extra cocktail."

Laurel officials were notified yesterday that Humbug was scheduled for a flight at 8 a.m. today Swedish time and should arrive in New York by late afternoon. "Yes, Humbug is definitely scheduled on flight SK-911, which should be in here by 4 p.m.," Chambers said. "It'll be the only horse running with jet lag."

Brady said Humbug will have blood samples drawn upon her arrival, then will be taken by van immediately to Laurel, and should be on the grounds tonight.

"The blood will be sent immediately to Ames, Iowa (a testing lab), but the testing takes time," Brady said. "If everything goes well, we could get her out of quarantine by noon Saturday."

Brady said a representative of the horse's owner, Bengt Bockman, "realizes the risk" -- that if things go less than smoothly, Humbug could arrive and not be eligible to race--and is going ahead.

Shipping horses worldwide is slightly more complicated than sending a package by express mail.

"Oh, there've been some times," Brady said. "Probably the worst troubles were when we were trying to get Japanese horses here when there were no flights across the Pacific."

None of the other international entries experienced airline hassles similar to Humbug's but poor weather -- on both ends -- delayed England's Awaasif and Diamond Shoal and Italy's Friendswood.

Awaasif and Diamond Shoal were held up more than two hours in London and nearly four more in New York. Friendswood's flight was delayed a total of nearly 12 hours by fog and, according to Frank Turner, son of the horse's trainer, Luigi Turner, the 3-year-old filly "has lost some weight" through her travels.

France's April Run, runner-up in last year's International and probable favorite Saturday, arrived at Laurel yesterday without difficulty. She is expected to gallop this morning.

Of the five U.S. entries, Pair of Deuces was shipped in yesterday with the others -- Royal Roberto, Thunder Puddles, Majesty's Prince and Sprink -- due in from New York later today or Friday.