Garmin GNC 255 GNC255A/255B Pilot's Guide - Page 14

1-2

Garmin GNC 255A/255B Pilot’s Guide

190-01182-01

Rev. A

1.2

Pilot Controls

The GNC 255 controls have been designed to simplify operation of the

system and minimize workload and the time required to access sophisticated

functionality. Controls are comprised of dual concentric knobs for frequency

tuning, Com volume/squelch knob, Nav volume/ID knob, and bezel keys.

1.2.1

Power/Com Volume/Squelch Knob

The

Power/Com

Volume/Squelch

knob located in the top left

corner of the bezel controls audio volume for the Com radio.

Rotating the knob clockwise past the detent turns power on

and counter-clockwise turns power off. When the Com radio is

active, press the

Power/Com

Volume/Squelch

knob to toggle

automatic squelch control On/Off for the Com radio.

Squelch, TX, or RX

Annunciator

Com Volume Bar Graph

Active Frequency

Annunciator

Com Mode

Annunciator

Active Nav

Frequency

Standby Frequency

Annunciator

Figure 1-2

Com Volume and Squelch Display Description

The Com radio features an automatic squelch to reject many localized noise

sources. You may override the squelch function by pressing the

Power/Com

Volume/Squelch

knob. This facilitates listening to a distant station or setting

the desired volume level.

To override the automatic squelch, press the

Power/Com

Volume/Squelch

knob momentarily. Press the

Power/Com

Volume/Squelch

knob again to

return to automatic squelch operation. A “SQ” indication appears to the left of

the active Com frequency window in the upper left corner of the display when

automatic squelch is overridden.

1.2.2

Nav Volume/ID Knob

The

Nav

Volume/ID

knob located in the bottom left corner

of the bezel controls audio volume for the Nav radio. Press the

Nav

Volume/ID

knob and the Morse code tones will be heard.

When Morse code tone is active, “ID” will appear to the left of

the Nav active frequency.

Section	Page
Product Registration and Support	7
1 Getting Started	13
1.1 Product Description	13
1.2 Pilot Controls	14
1.2.1 Power/Com Volume/Squelch Knob	14
1.2.2 Nav Volume/ID Knob	14
1.2.3 Tuning LARGE/SMALL Concentric (Cursor) Knobs	15
1.2.4 FLIP/FLOP Key	15
1.2.5 C/N (Com/Nav) Key	15
1.2.6 OBS Key	15
1.2.7 T/F (To/From) Key	15
1.2.8 CLR (Clear) Key	15
1.2.9 ENT (Enter) Key	15
1.2.10 FUNC (Function) Key	16
1.2.11 MON (Monitor) Key	16
1.3 USB Port	16
2 Basic Operation	17
2.1 Power On	17
2.2 Com Radio	17
2.2.1 Selecting a Com Frequency	17
2.2.2 Monitoring the Standby Com Channel	18
2.2.3 Saving a Com Channel	18
2.2.4 Com Database Look-Up	20
2.2.5 Frequency Database Reverse Look-Up	20
2.2.6 Emergency Channel	21
2.2.7 Stuck Mic	21
2.2.8 Remote Frequency Selection Control	21
2.3 Nav Radio	22
2.3.1 Selecting a Nav Frequency	22
2.3.2 Saving a Nav Channel	22
2.3.3 Listening to the Nav Audio Channel	23
2.4 OBS Mode	24
2.5 Distance/Speed/Time (DST) Display	25
3 Functions	27
3.1 Functions Description	27
3.2 Com Frequencies	28
3.2.1 Recent Com Frequencies	28
3.2.2 Com User Frequencies	29
3.2.2.1 Viewing the Com User Frequency	29
3.2.2.2 Deleting the Com User Frequency	29
3.2.2.3 Editing a Com User Frequency	30
3.2.3 Com Database Frequencies	31
3.2.4 Com Nearest Airports (APT)	32
3.2.5 Com Nearest Area Control Center (ACC) Frequencies	33
3.2.6 Com Nearest Flight Service Station (FSS) Frequencies	34
3.2.7 Com Nearest Weather (WX) Frequencies	35
3.3 Nav Frequencies	36
3.3.1 Recent Nav Frequencies	36
3.3.2 Nav User Frequencies	37
3.3.2.1 Viewing the Nav User Frequency	37
3.3.2.2 Deleting the Nav User Frequency	37
3.3.2.3 Editing a Nav User Frequency	38
3.3.3 Nav Database Frequencies	39
3.3.4 Nav Nearest VOR	40
3.4 ICS Configuration	41
3.4.1 Adjust Intercom	41
3.4.2 Aux Audio	42
3.4.3 Intercom On/Off	43
3.4.4 Speaker On/Off	43
3.5 System Configuration	44
3.5.1 Com Spacing	44
3.5.2 Display Brightness	45
3.5.3 Display Contrast	46
3.5.4 Database Info	46
3.5.5 Load Database	47
3.5.6 Software Version	48
3.5.7 Serial Number	48
3.6 Timers	49
3.6.1 Setting Up the Count Down Timer	49
3.6.2 Setting Up the Count Up Timer	50
3.6.3 Viewing Timers in the Com Display	50
4 Appendix	53
4.1 Troubleshooting	53
4.2 Updating the Frequency Database	55
4.2.1 Downloading the Frequency Database	55
4.2.2 Updating the GNC 255 Frequency Database	55
4.3 Messages	56

Garmin GNC 255 GNC255A/255B Pilot's Guide - Page 14

Pilot Controls - gnc 255a nav

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