CARLSBAD -- People who live in homes near McClellan-Palomar Airport said they hope that Tuesday's early morning plane crash leads to a ban on takeoffs and landings prior to 7 a.m., when the control tower opens.

If pilots weren't permitted to use the county-owned airport prior to the tower's opening, the 6:40 a.m. crash that killed four people might not have happened, they said.

"I think this points out the 'quiet hours' issue," said Gail Carroll, a real estate agent who has been leading a campaign to get the airport to be more "friendly" toward its neighbors. "I don't want to make hay over somebody's demise, but it does point to the 'quiet hours' issue."

The "quiet hours" at Palomar stretch from 11 p.m. to 7 a.m. During that period, pilots are encouraged not to take off or land at the airport. It's a voluntary requirement, not mandatory measure. Neighbors would love for that to change.

Airport officials said there is no indication so far that the crash -- one of the worst in the airport's history of more than 40 years --- was in any way related to the lack of staffing at the control tower prior to 7 a.m.

"It would not have made any difference whatsoever in the incident we had today," said Bill Polick, a San Diego County spokesman who handles airport issues.

Stressing that the investigation is being handled by the National Transportation Safety Board, Polick said early indications are that the plane was not hampered by the lack of air traffic controllers, nor did weather conditions play a part. Others said the plane was fairly new and "some other factor" must have been at work.

Polick said the airport has navigation equipment allowing it to be used by pilots 24 hours a day. When there are no air traffic controllers on duty, pilots announce on a set radio frequency what position they are at and notify others in the area that they are coming in for a landing.

Even if investigators find that the lack of control tower staffing was a factor in the crash, a Federal Aviation Administration spokesman said it's "extremely highly unlikely" that Palomar's voluntary nighttime operating regulations would change because they are based on a different set of standards relating to noise issues rather than crash data.

Much to the ire of nearby homeowners, the federally established noise guidelines are not mandatory. Unlike San Diego's Lindbergh Field, Palomar isn't considered noisy enough to warrant mandatory requirements.

Carroll, who lives about two miles southwest of the airport in one of a series of housing developments south of Palomar Airport Road, said she usually hears about seven to 10 planes flying over her home during the period of quiet hours. Between 6 a.m. and the crash at 6:40 a.m., she heard three, she said.

Maureen Kube, who lives near Carroll, said she hopes that the crash brings "more attention and sensitivity" to airport issues, but a consultant studying conditions at Palomar said the crash may have no effect on her nearly completed noise study.

Produced by the Florida-based consulting firm URS Corp., the document assesses the airport's impacts on surrounding neighborhoods and recommends changes to the FAA. Paid for by the county, the study is in its final public comment period before going to the federal agency for its review.

Its recommendations include expanding the voluntary nighttime flight ban to include all planes, not just jet traffic. However, the federal agency is free not to accept that recommendation, consultant Deborah Murphy Lagos said.

Tuesday's crash probably will have no effect on the agency's decision on the recommendations because different departments within the agency handle crash issues and noise problems, she added.

"I hate to say it, but they're almost like different companies," she said.

FAA spokesman Mike Fergus confirmed this, saying "they're divorced from each other."

Lagos added that Tuesday's crash won't be mentioned in her new noise report because the document doesn't contain crash statistics. However, if people want their comments incorporated into the report, there is still a week left before the deadline, Lagos said.

Send comments to deborah_murphy@urscorp.com.

Contact staff writer Barbara Henry at (760) 901-4072 or bhenry@nctimes.com.