Simtech Aviation

Communication (COMM) Radios Setup in Airplane

Setting up the aircraft Comm radios is a critical part of workload management and is one of the items that lack standardization. Many people set up their radios in a haphazard manner, without purpose and without understanding the potential problems that can arise.

Let's go over our recommended VHF radio set up in the airplane:

Comm1: Clearance, Ground, Tower, CTAF, Dep/Arr. Center

Comm2: Weather, Clearance (optional), UNICOM, and 121.5.

This setup will work in most modern airplanes. Regardless of the antenna locations. 

The antenna location is an important consideration because VHF radios work via line of sight. On many airplanes, the antenna for Comm2 is on the underside of the airplane while Comm1 is on top of the airplane. Structurally congested areas (hangars, buildings, or equipment), can block the signal from Comm2 radios located underneath the airplane. For this reason, we recommend the above set up for your VHF radios. 

Simple, right? Yet many people overlook this issue or are unaware that it is a potential problem. By setting our frequencies the same way every time we can standardize our procedures and prevent inconsistencies from creeping into our flights. 

121.5 (commonly referred to as guard frequency), is more than just an emergency frequency. It is a common frequency continuously monitored by both ATC and commercial operators. Pilots in non-emergency situations can and do communicate on it. 121.5 is often used to relay messages from ATC to aircraft that are out of ground facility range or who have missed a handoff to the next frequency. When ATC needs to contact you but cannot reach you, they will often do so first on 121.5. Maintaining a constant “guard” on 121.5 with Comm2 is standard practice. What does this mean to you? If you screw up a frequency (which happens to all of us), ATC can get a hold of you quickly. 

Here is the correct way to set up your radios after getting your clearance (even for VFR pilots).

This is a recipe for success. Do not be tempted to get creative, you will screw it up. Keep it standardized.

Common Problems:

Main scenario:

Using Comm2 to set  Departure frequency? Many pilots obtain their clearance, write the departure frequency down and set up the departure frequency in Comm2. After takeoff, they need to adjust the Audio panel to transmit on Comm 2 because that is where they have set the departure frequency. This switching back and forth between Comms 1 and 2 is a recipe for disaster and causes errors to be made. Often setting 121.5 as a monitor only frequency is completely forgotten in this process.