PA-28R Cherokee Arrow All Series
Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 16.8; Flight Crew Total 624.2; Flight Crew Type 368.6
Human-Machine Interface; Situational Awareness
Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Aircraft; Human Factors
I was practicing instrument approaches with my instructor. The aircraft has a new Garmin GTN-650 and the touch screen was new to both of us. We did a missed approach from Sacramento and contacted Approach control for another. We were given vectors by ATC. We did not hear from ATC for about 8 minutes then got a call from the Tower to contact ATC. Somehow the VHF frequency was swapped; perhaps by an inadvertent touch of the screen; and the radio was actually receiving Tower frequency again. There were towers in the area ATC was concerned about; but in actuality it was VFR and my instructor had them in sight so there was no real safety issue. It is important to get familiar with new equipment and what problems may occur with it (that is part of why we were training). One needs to be careful not to touch the touch screen inadvertently; check radio communication if nothing is heard for a suspicious length of time; and visually verify the frequency display of the receiver.
PA28 pilot on a practice missed approach with instructor experiences lost communications with ATC. A new Garmin GTN-650 touch screen was being used and it is believed that an inadvertent touch caused the departure frequency to be swapped to the Tower frequency.