Weather Radar operation. Help!?!
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Join Date: May 2005
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Weather Radar operation. Help!?!
More and more recently I have been flying with guys who switch on the radar whilst taxiing, more often than not behind other aircraft. When I suggest turning it off until we are lining up the answers I receive are becoming more and more baffling. From the aircraft fuselage will protect people inside to it doesn't affect people further away than 17ft!!!!! One left it on on the basis that he must have been zapped before so he's just doing the same as payback. Mindnumbing stuff. 
I always thought and was taught that you don't turn on your Wx radar until you are lining up and never when there is any person, building or aircraft in front of you. Am I causing myself undue stress or am I correct in asking these guys to switch off the radar for the sake of the crew and pax in the aircraft ahead??
I always thought and was taught that you don't turn on your Wx radar until you are lining up and never when there is any person, building or aircraft in front of you. Am I causing myself undue stress or am I correct in asking these guys to switch off the radar for the sake of the crew and pax in the aircraft ahead??
Join Date: Jun 2004
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The people in the aircraft ahead will be perfectly safe.
The danger is to your own radar, which, with a large metallic reflector directly ahead, which may return radar energy far in excess of the capability of your receiver.
Regards,
Old Smokey
The danger is to your own radar, which, with a large metallic reflector directly ahead, which may return radar energy far in excess of the capability of your receiver.
Regards,
Old Smokey
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I must admit that I often switch the radar on when taxiing out, but only when I am pointing in the direction of the SID routeing, when that part of the route will be not visible when lined up on the runway for departure. Otherwise I leave it off until lined up.
Having said that, I was led to believe that modern radar emission levels are very much less than on older radar installations, and are therefore much less harmful.
Having said that, I was led to believe that modern radar emission levels are very much less than on older radar installations, and are therefore much less harmful.
Radio man here !
Modern Wx Radar runs quite low peak power typically 150w Peak, this compares with older radars which ran power in the order of Kilowatts Peak. Conversly using modern receiver technology the have sensitivities up to 10Db better than older receivers, so the power budget remains broadly similar. While, correctly, an older radar was best given a wide berth when operating on the ground, modern radars are much more approachable as the average power, taking into account the Pulse Repetition Frequency is quite low. However the close in object / big reflection hazard to the equipment remains.
There a couple of rules of thumb to enable you to determine the power catagory of equipment fitted to your a/c.
1. Colour display - nearly always low power.
2. Monochrome display - usually old enough to be high power.
3. Observe your Avionics man getting a TR out of his van - just picking up a unit with no great effort - low power, about to get a hernia - high power.
And finally from the A330 AMM
WARNING: OBEY THESE SAFETY PRECAUTIONS WHEN THE WEATHER RADAR IS IN OPERATION. MAKE SURE THAT:
- ALL PERSONS ARE MORE THAN 5 METERS (16.4 FT) FROM THE ANTENNA.
- NO PERSON IS IN THE AREA MADE BY AN ARC OF 135 DEG. ON EACH SIDE OF THE AIRCRAFT CENTERLINE.
- THERE IS A MINIMUM SAFETY DISTANCE OF 60 METERS (200FT) BETWEEN THE ANTENNA AND ALL REFUELING OPERATIONS.
- THERE IS A MINIMUM SAFETY DISTANCE OF 5 METERS (16.4 FT) BETWEEN THE AIRCRAFT AND ANY OBSTACLE IN THE AREA MADE BY AN ARC OF 90 ON EACH SIDE OF THE AIRCRAFT CENTERLINE
Modern Wx Radar runs quite low peak power typically 150w Peak, this compares with older radars which ran power in the order of Kilowatts Peak. Conversly using modern receiver technology the have sensitivities up to 10Db better than older receivers, so the power budget remains broadly similar. While, correctly, an older radar was best given a wide berth when operating on the ground, modern radars are much more approachable as the average power, taking into account the Pulse Repetition Frequency is quite low. However the close in object / big reflection hazard to the equipment remains.
There a couple of rules of thumb to enable you to determine the power catagory of equipment fitted to your a/c.
1. Colour display - nearly always low power.
2. Monochrome display - usually old enough to be high power.
3. Observe your Avionics man getting a TR out of his van - just picking up a unit with no great effort - low power, about to get a hernia - high power.
And finally from the A330 AMM
WARNING: OBEY THESE SAFETY PRECAUTIONS WHEN THE WEATHER RADAR IS IN OPERATION. MAKE SURE THAT:
- ALL PERSONS ARE MORE THAN 5 METERS (16.4 FT) FROM THE ANTENNA.
- NO PERSON IS IN THE AREA MADE BY AN ARC OF 135 DEG. ON EACH SIDE OF THE AIRCRAFT CENTERLINE.
- THERE IS A MINIMUM SAFETY DISTANCE OF 60 METERS (200FT) BETWEEN THE ANTENNA AND ALL REFUELING OPERATIONS.
- THERE IS A MINIMUM SAFETY DISTANCE OF 5 METERS (16.4 FT) BETWEEN THE AIRCRAFT AND ANY OBSTACLE IN THE AREA MADE BY AN ARC OF 90 ON EACH SIDE OF THE AIRCRAFT CENTERLINE
