Final answer:
When departing Portland International Airport to the north, the proper frequency for departure control is 134.225 MHz.
Step-by-step explanation:
When departing Portland International Airport to the north, the proper frequency for departure control is 134.225 MHz. This frequency is used to communicate with the departure control center, which guides planes during the initial phase of their flight after takeoff.
The proper frequency for departure control when departing Portland International Airport (PDX) to the north would typically depend on the specific procedures and air traffic control (ATC) frequencies assigned by the Federal Aviation Administration (FAA) or relevant aviation authorities at the time of departure.
The departure control frequency for PDX's northbound departures might fall within the range of frequencies dedicated to departure control for the airspace surrounding the airport. The exact frequency can vary based on factors such as airspace configuration, current traffic conditions, and any temporary changes or instructions issued by ATC.