Since the time I was on an airplane forced to make a bomb-threat landing at an abandoned Air Force base in Kansas, my unswerving loyalty and devotion to the Fourth Amendment clearly swerves on those days I am about to board an airplane.

While civil libertarians tend to object to most searches at airports, whether by electronics device or by a police officer, even the most jaded police officer would probably find my airport standards unconstitutional. I view every person who approaches the terminal as a suspicious person worthy of further checking. Criminality is plainly written across the face of everyone waiting to board the plane that I am about to take.

Before the installation of electronic arches through which everyone must pass before allowed near the gates, airlines used a "profile" to determine whom to stop, question, and possibly search. That "profile" was a set of characteristics intended to point out the likely hijacker, bomber or person otherwise carrying a weapon.

Naturally, the profile was kept secret because if it were made known, the potential hijacker would simply camouflage his characteristics and avoid detection. The profile has been recently resurrected during the rash of hijackings by disgruntled Cuban refugees.

I am fairly certain that I psyched out the authorities, but I would not disclose that "profile" even now in the event it is ever needed again. I never quite understood why the toddler carrying a stuffed toy was not frisked by airport authorities. I was certain that he fit the profile. At least he fit mine, which included every man, woman and child in the airport.

It is understandable, then, why I cheered last spring when the five conservative justices on the Supreme Court approved the practice of federal drug enforcement agents' stopping, questioning and sometimes searching passengers who show drug smuggler "characteristics," even though I rarely agree with those five gentlemen on any search issue that does not take place 30,000 feet in the air.

Sylvia Mendenhall was the defendant who fit the Drug Enforcement Administration's "profile." She appeared nervous, claimed no luggage and abruptly changed airlines in Detroit after getting off a flight from Los Angeles. The court said the "profile" identifies passengers who display "characteristics and behavioral traits" that tend to distinguish drug courriers from other passengers.

Keep in mind that Mendenhall fit my profile simply by being in the airport. More importantly, she fit the DEA's profile. A search turned up two bags of heroin in her under-garments. The Supreme Court concluded that the warrantless intrusion met the Fourth Amendment standard of reasonableness and did not violate Mendenhall's right of privacy. The court stressed that she was not involuntarily detained and could have avoided the search by walking away. The justices left in doubt whether the drug agents could have detained her against her will and without a warrant in order to make the search.

The problem with profiles such as the one used by the DEA at 20 airports is that cases reach the courts when a search of a person who fits the "profile" turns up contraband and results in prosecution. We are left to wonder how often persons who fit the "profile" are searched and no contraband is found.

Even the conservatives on the court struck down a drug conviction after the Mendenhall case, where the original detention was based upon innocuous elements of the profile. The justices pointed out that the characteristics that alerted the airport police "described a very large category of presumably innocent travelers."

We only hear about the cases where the profile works and not those cases where an innocent person has been stopped and searched. It again highlights the point made several years ago by the late Justice William O. Douglas that the problem with the Fourth Amendment is that its advocates in court are always guilty.

The innocent, whose rights have been violated by unreasonable searches, are not charged with crimes and are not in court. It hardly enhances the popularity of the Fourth Amendment with the general public that it protects the guilty as well as the innocent.

As for those of us who do not fit the profile utilized by DEA, the intrusion into our privacy at airports is generally limited to passing through the magnetometer. The intrusion is minor, and the inconvenience slight if at all. Since the Fourth Amendment protects against unreasonable searches and seizures, passage through the arches raises no constitutional issues. The monitoring of all boarding passengers by the magnetometer reduces the possibilities of police harassment and enhances the reasonableness and constitutionality of the practice.

When the magnetometer sounds, it indicates that a person is carrying a metallic object. Airport authorities will go one step further by requesting that the person who set off the machine completely empty his pockets onto a tray and retrace his steps through the magnetometer. The indication that the passenger had a metallic object on his person renders the greater intrusion by the police reasonable by constitutional standards.

Continued buzzing by the magnetometer provides the reasonable cause for deeper intrusions into the passenger's privacy, starting with a pat-down for weapons and eventually even a full search if the cause of the buzzing is not uncovered. The great threat to the lives of people in the airport as well as the other passengers on the plane provides the constitutional justification for the warrantless search.

A person cannot simply withdraw from the process and avoid discovery of the metal object by announcing that he has changed his mind and decided to take a bus. Hasty retreat from the magnetometer provides reasonable cause for the police to follow that person in order to protect all the people in the airport.

The constitutional standard of reasonableness is a varying one, and a person's suspicious behavior will justify police action that would not be allowed without the suspicious conduct.

In the meantime, airport police can be certain that the white-knuckle flyers are there to help them. We are on the lookout for suspicious persons who try to avoid the magnetometer. We only wish that the airport police would talk less amongst themselves and pay greater attention to all those suspicious persons entering the concourse.