Safety Investigation Report 2018:1 Factual Information/1.9/1.9.2 VHF
SAFETY INVESTIGATION REPORT MH370 (9M-MRO)
1.9.2 Very High Frequency System
This aircraft was installed with Collins VHF-900B VHF System. The very high frequency (VHF) communication system permits voice and data communication over line-of-sight distances. It permits communication between aircraft or between ground stations and aircraft. The VHF system operates in the VHF aeronautical frequency range of 118.000 MHz to 136.992 MHz.
The VHF communication system on this aircraft uses three VHF systems. Each VHF system has a VHF antenna and a VHF communication transceiver.
The VHF communication system connects with Selective Calling Equipment (SELCAL) decoder that starts an alert when a call comes in for that aircraft.
The captain’s flight instrument bus sends 28V DC to the Left VHF communication transceiver and the Left Radio Tuning Panel (RTP). The Left Main DC bus sends 28V DC to the centre VHF communication transceiver and the centre RTP.
The Right Main DC bus sends 28V DC to the right VHF communication transceiver and the right RTP.