United Technologies Corporation (UTC) is a provider of high technology products and services to the building systems and aerospace industries. It operates in four segments: Otis, Carrier, Pratt & Whitney, and Collins Aerospace Systems. Otis manufactures, sells and installs passenger and freight elevators, escalators, and moving walkways. Carrier provides heating, ventilating, air conditioning (HVAC), refrigeration, fire, security, and building automation products, solutions, and services. Pratt & Whitney supplies aircraft engines for the commercial, military, business jet and general aviation markets. Collins Aerospace Systems offers technologically advanced aerospace products and aftermarket service solutions. The company merged with Raytheon to form Raytheon Technologies.