Garmin G1000 Manual

190-00709-04  Rev. AGarmin G1000 Pilot’s Guide for the Socata TBM 850377
HAZARD AVOIDANCE
NEXRAD AND AIRBORNE WEATHER  RADAR 
Both	Airborne	 Weather	Radar	and	NEXRAD	 measure	weather	reflectivity	 in	decibels	 (dB).		A	decibel	 is	a	
logarithmic	 expression	of	the	 ratio	 of	two	 quantities.		 Airborne	Weather	Radar	measures	 the	ratio	 of	power	
against	 the	gain	 of	the	 antenna,	 while	NEXRAD	 measures	the	energy	 reflected	 back	to	the	 radar,	 or	the	 radar	
reflectivity ratio.
Both	 systems	 use...

Garmin G1000 Pilot’s Guide for the Socata TBM 850190-00709-04  Rev. A378
HAZARD AVOIDANCE
RADAR SIGNAL ATTENUATION
The	phenomenon	 of	radar	 signal	 attenuation	 affects	the	operation	 of	weather	 radar.		When	the	radar	 signal	
is	transmitted,	 it	is	 progressively	 absorbed	and	scattered,	 making	the	signal	 weaker.	 	 This	weakening,	 or	
attenuation,	is	caused	by	two	primary	sources,	distance	and	precipitation.
Attenuation	 because	of	distance	 is	due	 to	the	 fact	 that	 the	radar	 energy	 leaving...

190-00709-04  Rev. AGarmin G1000 Pilot’s Guide for the Socata TBM 850379
HAZARD AVOIDANCE
Figure 6-96  Precipitation Type and Reflectivity
gROUnD RetURns
The	intensity	 of	ground	 target	returns	 depends	 upon	the	angle	 at	which	 the	radar	 beam	 strikes	 the	
ground	 target	(Angle	 of	Incidence)	 and	the	reflective	 properties	 of	that	 target.		 The	gain	 can	be	adjusted	 so	
shorelines,	 rivers,	lakes,	and	cities	 are	well-defined.		 Increasing	the	gain	 too	much	 causes	 the	display	 to	fill	
in...

Garmin G1000 Pilot’s Guide for the Socata TBM 850190-00709-04  Rev. A380
HAZARD AVOIDANCE
Figure 6-97  Angle of Incidence
A	smaller	 incident	 angle	gives	the	radar	 a	larger	 detectable	 range	of	operation	 and	the	target	 display	 shows	
a	higher	 intensity.		 Since	more	radar	 energy	 is	reflected	 back	to	the	 antenna	 with	a	low	 incident	 angle,	the	
resulting	detectable	range	is	increased	for	mountainous	terrain.
SAFE OPERATING DISTANCE
The	following	 information	 establishes	a	minimum	 safe...

190-00709-04  Rev. AGarmin G1000 Pilot’s Guide for the Socata TBM 850381
HAZARD AVOIDANCE
 
MPEL
B ou ndary
9.16 f t. for 1 0”  
antenna
Figure 6-98  MPEL Boundary
BASIC ANTENNA TILT SETUP
The following discussion is a simple method for setting up the weather r\
adar antenna tilt for most situations.  
It	 is	 not	 to	be	 considered	 an	all	encompassing	 setup	that	works	 in	all	 situations,	 but	this	 method	 does	provide	
good	 overall	 parameters	 for	the	 monitoring	 of	threats.		 Ultimately,	 it	is...

Garmin G1000 Pilot’s Guide for the Socata TBM 850190-00709-04  Rev. A382
HAZARD AVOIDANCE
PRACTICAL APPLICATION  USING THE  BASIC TILT  SETUP
With	the	antenna	 tilt	set	as	previously	 described,	any	displayed	 target	return	 should	 be	scrutinized	 when	
flying	at	altitudes	 between	2,000	and	30,000	 feet	AGL.	 	 If	the	 displayed	 target	advances	 on	the	 screen	 to	
within	5	nautical	 miles	of	the	 aircraft,	 avoid	it.		This	 may	be	either	 weather	 or	ground	 returns	that	are	2,000	
feet	 or	less...

190-00709-04  Rev. AGarmin G1000 Pilot’s Guide for the Socata TBM 850383
HAZARD AVOIDANCE
WEATHER MAPPING AND INTERPRETATION
WEATHER DISPLAY INTERPRETATION
When	evaluating	 various	target	returns	 on	the	 weather	 radar	display,	 the	colors	 denote	 precipitation	
intensity	and	rates	shown	in	the	table.
Weather Mode ColorIntensity
Approximate
Precipitation Rate 
(in/hr.)
Black< 23 dBZ< .01.
Green23 dBZ  to < 32 dBZ.01 - 0.1.
Yellow32 dBZ to < 41 dBZ0.1 - 0.5
Red41 dBZ to < 50 dBZ0.5 - 2
Magenta50 dBZ and...

Garmin G1000 Pilot’s Guide for the Socata TBM 850190-00709-04  Rev. A384
HAZARD AVOIDANCE
Along	squall	lines	(multiple	 cells	or	clusters	 of	cells	 in	a	line)	 individual	 cells	may	be	in	different	 stages	
of	development.		 Areas	between	 closely	spaced,	 intense	targets	may	contain	 developing	 clouds	not	having	
enough	 moisture	 to	produce	 a	return.	 	 However,	 these	areas	could	 have	strong	 updrafts	 or	downdrafts.		
Targets	showing	wide	areas	of	green	are	generally	precipitation	without	severe...

190-00709-04  Rev. AGarmin G1000 Pilot’s Guide for the Socata TBM 850385
HAZARD AVOIDANCE
In	areas	 of	multiple	 heavy	cells,	use	the	Vertical	 Scan	feature	 along	with	antenna	 tilt	management	 to	
examine	the	areas.		Remember	to	avoid	shadowed	areas	behind	targets.
Figure 6-102  The Blind Alley
The Blind Alley at Close Range The Large Storm Behind
tORnaDOes
There	are	no	conclusive	 radar	target	 return	 characteristics	 which	identify	 a	tornado.		 However,	 tornadoes	
may	be	present	if	the	following...

Garmin G1000 Pilot’s Guide for the Socata TBM 850190-00709-04  Rev. A386
HAZARD AVOIDANCE
Hail	shafts	 are	associated	 with	the	same	 radar	 target	 return	 characteristics	 as	tornados.		 U-shaped	cloud	
edges	three	to	seven	 miles	across	 can	also	 indicate	 hail.		These	 target	returns	 appear	quite	suddenly	 along	
any	edge	 of	the	 cell	 outline.		 They	also	change	 in	intensity	 and	shape	 in	a	matter	 of	seconds,	 making	vigilant	
monitoring essential.
OPERATION IN WEATHER MODE
 WARNING:  Begin...