The alleged terrorist plot in London will mean increased security and longer lines on interisland flights.

Authorities are asking passengers to arrive at the airport at least 1 1/2 hours in advance for interisland flights. Travelers will have to go through added inspections as officials search for newly banned liquids and gels.

The added inconveniences come just as interisland travel was beginning to look more attractive, with one-way prices as low as $29 and more flights.

Airline executives said yesterday the heightened security hasn't resulted in cancellations of reservations and caused few, if any, flight delays.

Hawaiian Airlines, the largest Hawai'i-based carrier, said four of its 100 daily interisland flights experienced delays related to the enhanced security. The longest delay was 28 minutes.

Aloha Airlines said its interisland flights were on time, but its three Orange County-to-Honolulu flights were delayed because of gate availability at John Wayne Airport.

Go!, which began flying on June 9, said all of its planes were on time yesterday.

Jonathan Ornstein, chief executive of Phoenix-based Mesa Air Group, owner of go!, said the London terror threat may deter trans-Atlantic travel over the short term but won't have much impact on local flying habits.

Unlike the Sept. 11 tragedy, the terrorist plot occurred outside the U.S., and for that reason is not expected to discourage domestic travel, he said.

Ornstein likened the Atlantic bombing attempt to terrorist Richard Reid's unsuccessful attempt in 2001 to set off a bomb concealed in his shoes on a Miami-bound flight. Ornstein said the Reid incident did little to deter travel.

"If history is our guide, these have a tendency to pass quickly," Ornstein said. "I don't see it as having a big impact on the Hawai'i flights for any period of time."

After the London plot was foiled, federal officials increased security measures at U.S. airports and raised the threat level to its highest since Sept. 11, 2001.

Yesterday, thousands of interisland travelers stood in lines as long as 45 minutes at Hawai'i's airports as security officials checked carry-on baggage for water bottles, suntan lotion and other liquid containers, which are banned under the new security rules.

Duke Ah Moo, staff vice president of Pleasant Holidays' Hawai'i operations, said his company received hundreds of calls from travelers who wanted to find out more about what they could take on planes and what they couldn't. But he said none of the company's customers canceled travel plans.

Ah Moo said he believes travelers eventually will adjust to the new security.

Peter Forman, a former airline pilot who recently wrote a history of the interisland airline market, said he expects the delays to shorten as airport officials get a better handle on the new security requirements and as passengers get a better understanding of the new policies.

"In the short run, it will be a hassle as lines get longer, but I don't anticipate a change in travel patterns," Forman said.

Reach Rick Daysog at rdaysog@honoluluadvertiser.com.