Avionics Systems Day 5

Section 2

RADAR

RAdio Detection And Ranging Ground based

ATC

Aircraft based Weather radar Radio altimeter

RADAR

Radar operates on the “Pulse Echo principle” A short pulse of radio energy is transmitted Receiver waits for reflected energy

ATC Radar Aircraft separation under IFR conditions UHF Controllers watch aircraft on screens and

give pilots instructions on where to fly

Aircraft Radar

Severe weather avoidance Thunderstorms Allows pilots to continue flying while

avoiding storm cells

Aircraft Radar

Clouds are invisible to radar, however ice, rain, & hail will reflect the energy

Size & intensity of moisture & radar type will effect the image displayed

Aircraft Radar

Be careful when operating radar on ground

Microwaves can be dangerous Point into sky Outside

C-BAND 5400 MHz

Used primarily by airline operations Can see through clouds better Less reflective off of small cells to reveal

larger cells behind

X-BAND 9333 MHz

Used by general aviation Greater resolution Will reflect off of smaller cells with greater

resolution but will not see behind cells

Stormscope

A lower cost storm detection system Uses an AM directional receiver that

detects lightning discharge NOT RADAR

Stormscope

Uses a loop antenna & a microprocessor to determine the direction to a lightning strike / storm cell

Displays lightning strike data on a screen

Radar Altimeter

A.K.A. Radio Altimeter or simply RAD ALT A single target radar system used to

indicate aircraft AGL (Above Ground Level) altitude

4300 MHz Measures the time it takes for a radio

pulse to go to the ground and return

Radar Altimeter

Antenna is located on belly of aircraft Usually measures no higher than 5000 ft Usually used during landing

GPWS

Ground Proximity Warning System Warns pilot of excessively low altitude “PULL UP!” “PULL UP!”

GPWS

Computer monitors several different systems Radar Altimeter Air data computer Landing gear Flaps Glideslope

Primary component is the computer

GPWS

Warnings are activated during flight Terrain avoidance (gear & flaps up)

During landing Excessive rate of descent Below glideslope Below minimums

Enhanced GPWS systems incorporate a worldwide terrain database & GPS inputs