Ken Dobson, a retired police officer, said he received quite a welcome when he landed his single-engine Cessna in Detroit two days after leaving his home in Palm Desert.
Five sheriff's cars surrounded the plane and deputies got out with guns drawn. Then a helicopter arrived with four federal agents and a drug-sniffing dog.
They demanded to see Dobson's pilot's license, asked about the flight and mentioned that his long trip from Southern California was suspicious.
Fearing he would lose his flight credentials if he didn't cooperate, Dobson consented to a search of his plane. But instead of uncovering a trophy-shot cache of pot or cocaine, the officers found luggage, golf clubs and an empty Thermos.
"To investigate an innocuous concern like my flight was mystifying to me," said Dobson, who flew to Detroit to visit relatives. "My wife and I travel long distances in our car to Michigan. That alone does not give the police the right to stop me, question me and search my car."
Dobson's Cessna was picked up by a U.S. Customs and Border Protection tracking system in Riverside that uses an extensive radar network to monitor flights across the nation.
Casting such a wide net has helped authorities apprehend dozens of drug smugglers. But the operation also is snaring many more law-abiding private pilots, who say federal officers working with local police are detaining them and searching their planes without legal justification.
The situation has attracted the attention of national organizations that represent about 570,000 pilots and 10,000 aviation-related businesses. Between them, the groups have logged complaints from 50 to 70 pilots whose flights were entirely within the U.S. All were let go, some with apologies.
Those pilots included business owners, retirees, a real estate financier who was detained twice in one trip, a university professor whose car — after leaving an airport — was surrounded by dozens of officers. Even retired U.S. Air Force Maj. Gen. Hank Canterbury was tracked.
Canterbury, a fighter pilot in Vietnam who now lives in Arizona, said he was stunned to learn that federal officers had inquired about him at a Texas airport where he landed.
During the last three years and five months ending in February, the tracking operation investigated 1,375 flights. Of those, authorities intercepted 212 at airports and made 39 drug-related arrests. An additional eight were referred to the Federal Aviation Administration for possible regulatory enforcement.
Officials of the Aircraft Owners and Pilots Assn. have taken their concerns to members of Congress, including Rep. Sam Graves (R-Mo.) and Sen. Pat Roberts (R-Kan.). Wanting to ensure that federal law enforcement is complying with constitutional protections against unwarranted searches and seizures, they have asked Customs and Border Protection for an explanation.
"There is no evidence of any criminal activity in the AOPA incidents," Graves said. "If law enforcement is screwing this up, they have done a huge disservice to the public. An erratic flight, a long flight or not filing a flight plan is not probable cause" to stop pilots.
Customs and Border Protection officials defend their tracking operation, saying it plays an important role in the war on drugs and protecting national security, especially since 9/11.
They say drug smugglers often rely on aircraft, and that in two acts of domestic terrorism since 2002, pilots rammed small planes into buildings, including an IRS office in Texas.
Agency officials say they dispatch officers to check flights and detain pilots based on a legal standard known as reasonable suspicion, which can be deduced from a series of facts that suggest the possibility of wrongdoing.
Planes are not searched, they say, unless pilots consent or officers have warrants based on probable cause; that is, enough evidence to indicate a crime has probably occurred. Warrants are not required for searches at the border or if evidence is in plain view, people are in imminent danger or evidence faces immediate destruction.
Determining what flights to intercept starts at the Air and Marine Operations Center at the March Air Reserve Base in Riverside. Able to tap 700 radar installations in the U.S. and neighboring countries, the center can track up to 50,000 aircraft and ships at any time.
Staff members scrutinize thousands of flights each day looking for what they consider abnormalities. Usually, one or two aircraft warrant further investigation. Out of those, only one every few days is checked out at airports by federal and local authorities.
During the initial review, trackers consider such things as aircraft type, routes, altitudes, flight distances, where flights originate, whether flight plans are filed, the use of small airports and the identities of pilots, passengers and registered owners. Tips from confidential sources also are important.
Constitutional law and civil rights attorneys say, however, that detentions of private pilots and searches of their aircraft can raise 4th Amendment issues. The amendment forbids unreasonable searches and seizures.
In drug-smuggling cases, lower courts have both thrown out and upheld the causes used by federal law enforcement to stop and search airplanes. But there are no U.S. Supreme Court decisions related to aircraft, said Erwin Chemerinsky, a constitutional law expert and dean of the UC Irvine law school.
Because the high court has given police some latitude to search cars during a legitimate vehicle stop, Chemerinsky said justices might grant similar leeway for aircraft searches if such a case came before them.
Though customs officials contend their results are reasonable, pilot association officials say arrests occurred in only 18.3% of the stops and about 3% of all the flights scrutinized.
Two AOPA pilots, one from California and one from Louisiana, said their hotel rooms were searched without warrants. Still others reported that they were confronted at gunpoint by authorities wearing SWAT gear and that officers who were not trained mechanics removed aircraft panels and engine cowlings during searches, raising safety concerns.
Other pilots said they were told their flights were intercepted because of long travel distances, frequent course changes, landings at remote airports and questionable profiles such as flying east from California — all things they considered common occurrences in general aviation.
"It's supposed to be presumed innocent until proven guilty, but here we have Big Brother watching," said AOPA President Mark Baker. "The number of arrests are laughable for all the work they do. This looks like an agency in search of a mission."