N3173U

N3173U is a Sikorsky S-61 operated by SILLER HELICOPTERS LLC. SkyMeter has tracked 88 flights totalling 112 hours of airtime via ADS-B across 2 callsigns. Service window in our records spans 396 days. The Sikorsky S-61 has a maximum takeoff weight of 20,500 lb, medium wake category.

About the Sikorsky S-61

The Sikorsky S-61 is the civilian variant of the legendary SH-3 Sea King, a twin-turbine heavy-lift helicopter that entered service in 1961 and became one of the most versatile rotorcraft ever built. Originally designed for the U.S. Navy as an anti-submarine warfare platform, the S-61 was adapted for commercial operations including offshore oil support, search and rescue, passenger transport, and—most visibly in North America—aerial firefighting and logging. Its twin General Electric CT58 turboshaft engines and robust airframe allow it to carry external loads exceeding 8,000 pounds, making it a workhorse for operators who need serious lifting capacity in challenging environments.

The S-61's firefighting role has given it a second career long after military Sea Kings retired from frontline service. Equipped with belly-mounted water tanks holding up to 1,000 gallons, S-61s are a common sight over wildfires in the western United States and Canada, where their ability to hover-fill from lakes and rivers makes them invaluable for initial attack and sustained suppression. Logging operators prize the type for precision long-line work in mountainous terrain, where its power margins and stability outclass smaller helicopters. The cockpit sits high above the cabin, giving pilots excellent visibility for external load operations.

Though production ended in the 1980s, the S-61 remains in active commercial service worldwide, with airframes often exceeding 15,000 flight hours through meticulous maintenance and component upgrades. Its maximum speed of around 140 knots and service ceiling near 12,000 feet are modest by modern standards, but operators value its proven reliability and parts commonality with military Sea King fleets. The type's distinctive boat-hull fuselage—a relic of its amphibious Navy origins—is rarely used for water landings in civilian service but contributes to the aircraft's unmistakable profile.

SkyMeter has tracked flights across airframes and operators, with the largest observed operator.