FSX/Prepar3D Scenery--MGRT-Retalhuleu Airport. Retalhuleu Airport or Base Aerea del Sur (IATA: RER, ICAO: MGRT) is an airport located in Retalhuleu, a city in the department of Retalhuleu in Guatemala. The Retalhuleu airport began operations in March, 2014. This airport has a 1.5 km landing strip, which should provide aircraft of up to 70 passengers to land. Photo-terrain area improved with autogen files. By Fernando Angel Gonzalez.