The pilot involved in the deadly helicopter crash at a Midtown skyscraper Monday had told air traffic controllers he was having problems as he flew through heavy fog and rain, law enforcement sources told The Post.

The pilot — identified as Tim McCormack — had just dropped off his boss at the 34th Street heliport on the east side prior to the crash-landing, sources said.

Police have said they believe his chopper was headed back to an airport in Linden, New Jersey, while conducting executive travel.

The pilot contacted the West 30th Street heliport to say he was experiencing some kind of problem and needed to land there, sources said.

Investigators believe he may have gotten lost on the way, possibly due to the fog, sources said.

Police say the craft was in the air for 11 minutes when it made a “hard landing” at around 1:45 p.m. on the top of the 54-floor AXA Equitable Center building at 787 Seventh Avenue.

One person, believed to be the pilot, died, officials said.

The chopper is registered to a company called American Continental Properties Inc., which was founded by real estate honcho Daniele Bodini — a former ambassador of San Marino to the United Nations, sources said.

“We are mourning the loss of Tim McCormack who has flown for us for the past five years. Our hearts are with his family and friends,” the company said in a statement to ABC News.

The East Clinton Volunteer Fire Department in upstate New York paid tribute to McCormack, saying he served as chief for a decade.

“Tim was a dedicated, highly professional and extremely well trained firefighter,” it said on Facebook.

“Tim will be exceptionally missed by this department’s members, not only for his leadership but for his wonderful sense of humor.”