DENVER (KDVR) — Denver International Airport visitors might have seen a big surprise on one of the airport’s runways Tuesday as one of the world’s largest aircrafts touched down.

There are only 26 Antonov An-124 Ruslan planes in commercial service across the globe. One of them had a job that led it from Milan, Italy, to Goose Bay, Canada, to finally Denver International Airport in the span of a day, according to FlightAware.

According to DIA, the plane’s special load was a helicopter, which fits easily inside the massive plane. The four-engine plane has a cargo compartment that’s 20% larger than the main cargo compartment of the C-5 Galaxy, which is a large military transport plane that can carry “a payload of … up to five helicopters,” according to the manufacturer.

This particular plane model was designed in the early 1980s, according to Antonov, a Ukrainian company that manufactures the planes. The An-124 Ruslan was originally designed as a Soviet heavy strategic military transport craft, capable of carrying up to 150 tons of cargo.

The plane type then transitioned into the commercial transportation market, which is how it’s used today. As seen in the photos, the aircraft’s noses can be raised to accommodate large, inflexible loads, such as military vehicles or helicopters, as was this case. According to the aircraft manufacturer, the plane also has a “kneeling” function to allow for easier loading.

While details on where the plane is headed are unknown, aviation geeks were quick to point out the massive bird at DIA on Tuesday.

Notably, the plane type has been used to set approximately 30 world records, according to Antonov. These include an absolute payload-to-altitude record and a world record for distance flown without refueling.

The plane’s surprise appearance at DIA was noted by many aviation experts, so keep an eye out if you’re headed to the airport for July 4 or any other trip — You never know what you might see on the runway.