Since we are getting the weather radar functionality in the (hopefully) near future, can someone with real world experience enlighten us on typical airline practice for using the radar?  I'm assuming that it's not on for every flight from takeoff to landing (but I could be wrong).  What are the conditions that would lead the crew to turn on the radar or turn it off mid-flight?  I'm guessing that flying into a SIGMET area would induce the crew to turn it on.  Also, keeping it on for night flight makes sense?

 

Thanks,

 

Bill Rowe

 

 

Also, keeping it on for night flight makes sense?

 

On at takeoff (or as soon are you're away from the ramp - don't want to cook rampies).

Off after landing.

 

Done.

 

 

or as soon are you're away from the ramp - don't want to cook rampies

 

Air Transat did this to us last week.

We had no idea until the ACM came up to us and told us to file a formal complaint against the airline because the pilot didn't turn it off before being put on the blocks at the gate.

 

We were a bit mad.

I refrained from using the crew room microwave for the rest of the day.

Weather radar is often (if not always) used by the pilot flying while the ground radar is used by the pilot not flying.

... while the ground radar is used by the pilot not flying.

 

Just wanted to clarify - and I don't mean to pick you out - but this is something a lot of people get mixed up with. And since SP1 will offer a raster sweep, I might as well mention it -

 

EGPWS terrain is not a radar; it is a database of terrain elevation. It is drawn onto the ND using the same raster bus as the WXR, thus rendering a sweep on the ND when drawing terrain. It looks like radar, but it's not.

 

On Boeing aircraft, the TERR's update sweep is the same as the WXR; it sweeps in from the side and it goes left to right, and back.

 

However - on an Airbus, you will notice it doesn't just sweep in from the sides; it actually sweeps from the centre outward. This is Airbus' method to differentiate non-radar and radar display.

 

Again - don't mean to pick you out; Just wanted to let other simmers know the difference.

At my airline we leave the weather radar on all the time! It gets switched on just after the after start procedure and switched off during the after landing flow when the runway has been vacated!

 

The PF will always have weather radar displayed and the piot monitoring will have TERR displayed on his MFD when operating bellow or cleared bellow the relevant MSA for the aerodrome that we are operating at

 

 

(or as soon are you're away from the ramp - don't want to cook rampies).

 

How could it "cook the rampies"? Could someone explain?

How could it "cook the rampies"? Could someone explain?

 

Weather radar uses radio waves in the microwave wavelength.

 

...there's another appliance in many households that use this same principle to heat food, except it only uses about 1200 watts.  Some weather radar applications use about 60000 watts.

 

Heat food to rather hot: 1200w

What happens when you pass up to 60000 (that's very high - I think most modern systems are down in the 10000 range as a max) through a person?  That damages tissue (specifically nerve tissue).

How could it "cook the rampies"? Could someone explain?

 

Since the radar uses radio waves to detect the precipitation(if you don't know how this works, youtube it), it emits electromagnetic radiation. If it isn't turned off, the electromagnetic radiation will "cook the rampies" in a similar way to a microwave cooking food.

 

 

And Kyle was quicker....

Microwave ovens heat food by the resonant frequency of water, however sufficient focussed energy will burn.

While most weather radar systems can be powered up (in standby mode) on the ground, and placed into "test" mode for pre-flight ops checks, the transmitter section is normally activated through the weight-on-wheels system, so that the radar does not actually radiate any energy until the aircraft is airborne. Likewise, the transmitter is disengaged upon landing.

 

There ARE means to put the system in full transmit mode on the ground - the specific method varies depending on the manufacturer and type of cockpit control head. It usually involves pressing a specific sequence of buttons on the control head within "x" number of seconds.

 

A typical situation where this override would be used would be on line-up for takeoff with active thunderstorms in the area - the crew may want to manually tilt the antenna up to get a look at cells that might affect them during departure, before actually beginning the takeoff roll.

 

A typical aircraft weather radar system really doesn't have enough power to "cook" ground crew standing in front of the antenna, unless they stood just a couple of feet I n front of the radiating antenna for a protracted amount of time. There is, however, a very real potential for causing damage to the eyes - specifically the lens and cornea. One would not want to look directly at a radiating antenna system from much less than 50 to 100 feet away There is medical research showing that individuals can experience premature development of cataracts from prolonged exposure to even quite low levels of microwave energy.

Can be bad. We had a component on test, and some group were being shown round the labs. One stayed to have a closer look when the others moved onto the next lab, went under a barrier all cordoned off and DANGER and looked into a waveguide. Similar eye problems ensued.

We turn it on during taxi out when we receive the cabin ready and turn it off again when vacating the runway after landing. There is no rule who has it on but it tends to be the PF when there is weather around.

Weather radar uses radio waves in the microwave wavelength.

 

...there's another appliance in many households that use this same principle to heat food, except it only uses about 1200 watts.  Some weather radar applications use about 60000 watts.

 

Heat food to rather hot: 1200w

What happens when you pass up to 60000 (that's very high - I think most modern systems are down in the 10000 range as a max) through a person?  That damages tissue (specifically nerve tissue).

 

Very interesting... Thanks for the explanation! 

Here's what I do...

 

I'll always decide if I'm going to have Terrain or Weather radar on during the brief. Normally once I'm out of the main ramp area - I will do an FMA/PFD check, EICAS RECALL/MEMO, Flap, Confirm Cabin Ready or not & Complete Before Takeoff Checklist. After I'll turn on whichever I'm using. That's just a sanity check to make sure I've got everything set up.

 

If it's a really short taxi, say T5 to 09R - I'll do it befor requesting/beginning taxi. I've turned on the WX radar a couple times quickly during preflight to just peek at the weather above. But of course wouldn't want to do it real world for the safety reasons already mentioned!