The Federal Aviation Administration issued a new rule Tuesday, loosening medical certification requirements but adding training for general aviation pilots, who cruise the skies in small planes made by manufacturers such as Cessna, Piper, and Beechcraft.

Until now, private, recreational, and student pilots and flight instructors had to renew their FAA medical certificate every five years for those under 40 and every two years for pilots 40 and older. If certain medical conditions were found, the FAA stepped in -- often grounding the aviator and ordering more tests.

Starting May 1, pilots of small aircraft up to 6,000 pounds, with up to six seats and carrying up to five passengers and at altitudes below 18,000 feet, will have a medical exam every four years, and complete a mandatory online education course every two years.

Dennis Tajer, spokesman for the Allied Pilots Association, representing 15,000 American Airlines pilots, said, "We're glad this legislation and these rule changes have finally reached reality." The changes "deepen the education and professional training of general aviation pilots" and will free up private pilots to get experience flying because they won't be bogged down renewing the FAA medical certificate.

Under the new rule, valid FAA medical certificates issued after July 15, 2006 will continue in effect. Pilots will no longer have to get physical exams from a FAA-designated doctor. If a family doctor signs off, that will suffice.

More than 300,000 recreational fliers, members of the Aircraft Owners and Pilots Association, lobbied for the change, and last summer Congress approved and President Obama signed the rule into law as part of an FAA authorization extension.

Pilots whose medical certificate was revoked, suspended, withdrawn, or denied will need to get a new medical certificate. Pilots who never had an FAA medical certificate, including student pilots, will still need to go through the process.

In a conference call with reporters, FAA administrator Michael Huerta said the reforms will make it ''more efficient" to become a private pilot, simplify regulations, and "keep general aviation flying affordable."

Jim Coon, a senior vice president of the Aircraft Owners and Pilots Association, said the former medical requirements were expensive and burdensome, and discouraged pilots from general aviation. The medical certification exams cost pilots collectively $20 million annually.

The National Transportation Safety Board, which did not have an official response to the new rule on Tuesday, said in a 2014 study that an "increasing number" of general aviation pilots were "flying without a medical certificate" and some were making decisions about "medical fitness to fly, including use of drugs while flying."

The NTSB report found an association between fatally injured pilots flying without a medical certificate, and increased drug use, but the agency found no increase in the "proportion of accidents" in which drug impairment was the cause.

Coon, of the AOPC, said while some autopsies showed an increase in certain medications that pilots had in their body, "it didn't correlate to the cause of the accident. General aviation fatalities are on the decline. There are more people who fall out of bed and die than there are G.A. accidents every year." Previous FAA medical certification requirements "discouraged pilots from disclosing their health conditions,'' he said.

The Air Line Pilots Association, the union representing 54,000 pilots at 31 commercial airlines, said the new rule ensures "an adequate level of safety" in the national airspace and "serves the needs of the general aviation community well. We will oppose any attempts to weaken it."