The pilot of a hot air balloon that went down in a fiery crash in Texas last summer — killing him and 15 sightseers — had binged on a cocktail of drugs before takeoff, Bloomberg News reported Friday.

Alfred “Skip” Nichols, 49, had ingested seven drugs, including the opiate painkiller oxycodone and Valium, according to a toxicology report. The pills are forbidden by the FAA because they impair a pilot’s judgment and motor skills.

He was able to continue flying passengers despite five convictions for driving while intoxicated and three for drug offenses, according to National Transportation Safety Board documents obtained by Bloomberg.

Nichols suffered from type II diabetes, depression and chronic pain from fibromyalgia, among other ailments. Some of those conditions should have prohibited him from operating an aircraft, officials said.

He was taking 13 prescription drugs, many of which are prohibited for pilots, the feds said.

A toxicology test found that Nichols’ blood and urine contained seven drugs that were prohibited by the FAA, including oxycodone and the sedative diazepam, also known as Valium.

While pilots are prohibited from flying after taking those medications, balloon pilots are exempt from having to receive the periodic medical checkups required for other commercial flight crews.

The disaster revealed lax regulations on balloon operators and a regulatory loophole that allowed Nichols to avoid enforcement action, the documents said.

Authorities say the balloon, which was operated by Heart of Texas Hot Air Balloon Rides, hit high-tension power lines before crashing into a pasture on July 30 near Lockhart, about 60 miles northeast of San Antonio.

The death toll was the highest in a single US aviation accident since 50 people perished in a 2009 commuter plane crash in upstate New York near Buffalo.

Victims included a professor with the US Army Institute of Surgical Research and his wife, and a mother and daughter aboard as part of a Mother’s Day gift.

“The ultimate goal of this investigation is to learn from this tragedy so that we can keep it from happening again,” NTSB member Robert Sumwalt said at Friday’s hearing.

The agency will examine safety issues raised by the tragedy, including why Nichols took off in spite of a report of questionable weather, Bloomberg reported.

It also will consider how Nichols slipped through the cracks after serving two prison terms for drug and alcohol violations, and while being treated for medical conditions that should have prohibited him from flying.

The NTSB recommended in 2014 to give balloon passengers “a similar level of safety oversight as passengers of air tour airplane and helicopter operations.”

But the Federal Aviation Administration has so far declined to add tighter rules on balloon flights.

The FAA spends less time conducting inspections and oversight on balloons because it has determined they were a lower risk than other areas of aviation, John Duncan, head of the agency’s flight standards division, told the NTSB.

The agency is working with the balloon industry on voluntary measures rather than trying to adopt new regulations, he said.

“Changing the rules is very cumbersome,” he said. “A more effective and more timely way to deal with that is what these gentlemen had been describing, and that is the community, recognizing that they would choose to operate with higher standards and require those standards.”

The NTSB documents also shed light on why the FAA said it was unable to take punitive action against him after learning in 2013 of his driving convictions.

The rules of the agency — which oversees appeals of FAA enforcement cases — prohibit the FAA from taking certain actions on infractions more than six months old.

As a result, an FAA official investigating the violations notified Nichols in 2013 that the agency wouldn’t pursue any actions related to his convictions. The most recent conviction was in 2010.

Nichols’ actions related to weather also are under scrutiny. The balloon was supposed to fly only in clear conditions, but photos taken shortly before the accident showed clouds obscuring the ground.

In a recorded phone call with an FAA weather station, he was advised, “Those clouds may be a problem for you.”

“Well, we just fly in between them,” Nichols replied. “We find a hole and we go.”