Switching Off weather radar

[naveedriaz69]

V have a trend in our airlines of switching off the weather radar when the weather is clear and then putting it back ON when a weather is expected. And there a an argument also going on weather it does increase the radar's life or does it actually reduce its life by affecting the MTBF. Those in favour of switching off say that why leave the radar scanning when its not required and those who oppose say that MTBF is, apart from some other factors, also dependent on the number of times a radar is switched ON and OFF. So what do u guys say? Pl avoid guessing.
Regards

[galaxy flyer]

Honeywell says that if not in use, best to have it switched off as regards to MTBF. And not Standby, either.

GF

[411A]

Honeywell says that if not in use, best to have it switched off as regards to MTBF. And not Standby, either.


RCA and Bendix, likewise.
Then, there are those that proclaim...it repels birds.
Sorry, not supported with facts
Switch it ON when needed, otherwise, OFF....just as you might with engine anti-icing.
Now, having said this, our weather RADAR sets are a twenty five year old design, nevertheless, they work just like a weather RADAR should, superbly....might be different with new(er) models.
Others might like to comment about these new(er) units.

[A Comfy Chair]

A lot of airspace now want you to have it on to aid in identification of civilian airlines by the military... so best keep it on in that airspace ;)

[galaxy flyer]

A Comfy Chair

Quite correct, the US has a NOTAM out for operations in the Persian Gulf region that wx radars should be on for id

GF

[SE7EN]

Here in the tropics, I always encourage leaving it on at all times. Some have the habit of switching it off when on approach even when significant weather is obvious in the go around area. You can bet that during a go around followed by a serious malfunction the radar would be the last thing on anyone's mind. I don't want to fly into an active cell at the best of times but imagine doing it by mistake on one engine!

[A Comfy Chair]

I guess it depends on model, but if you have yours switched off do you still get the predictive windshear alerts? I'm guessing you dont (but it may not be installed on the radars you use anyway).

[GlueBall]

Keep off in clear weather; except when overflying Afghan airspace. :eek:

[TheGorrilla]

And Iraq... Funny you should bring this subject up. Our shorthaul fleets have a habit of turning it off when not in use, where the longhaul ones leave it on (even when nowhere near afghan or iraqi airspace).

P.s. What is MBTF? Is that the phsical sweeping of the radar dish? In which case I can understand it wearing out.

[CR2]

Mean Time Between Failure.

[TopBunk]

Scenario: you are flying in clear weather with radar off. You then enter a thin haze layer that starts to slightly obscure the horizon. You then lose sight of the ground but can just about still see the horizon and the sky above.

Question: at what point before hitting the enbedded CB you can't see do you switch on the radar?

The radar should be on at all times in flight, or at least until path to touchdown and go around paths confirmed clear.

Do none of you remember the UK-bound charter flight a few years ago that flew into an embedded CB with resultant major damage to windscreens and leading edges? Learn the lesson folks, leave it on. MTBF is for others to worry about.:ouch:

[757operator]

And that was 2 training captains flying together!

[411A]

You then enter a thin haze layer that starts to slightly obscure the horizon. You then lose sight of the ground but can just about still see the horizon and the sky above.


In this scenario, switch radar ON.
Severe clear, leave OFF/standby.

Our standard ops.
We are a small operator, and MTBF is everyones business, pilots included.

[Skyworker]

The WX radar antenna if switched on near the TS cell will be the 1st thing that the lightning will strike.Proven fact.

Also consider what those beams make to the most essential part of your body...Your wife/GF will tell you what to do with the switch.

[forget]

I don't happen to like a major Electromagnetic transmission source a couple of feet in front of my toes going on for hours.....

Modern Wx radars are streets ahead of the old stuff. You're at more risk in your kitchen. :)

The (Collins) WXR-2100 power density is half or less than that of the microwave oven standard.

HERE (http://www.smartcockpit.com/data/pdfs/flightops/aircraft/Collins_WXR-2100_Operator's_Guide.pdf)

[TopBunk]

The WX radar antenna if switched on near the TS cell will be the 1st thing that the lightning will strike.Proven fact.

Ok, so you suggest leaving it switched off near TS now in case it gets you a strike:ugh:

Jeez, you guys:yuk:

Rainboe - when did you EVER switch off the wx radar flying the BA 747's- remember, I've flown with you?

Folks, severe CAVOK for local flights maybe fine, but you cannot see more than about 120nm at altitude. Strategic avoidance on longer flights starts before then - you need a picture (and a plan) for about 20 minutes out.

The wx radar is an in-flight tool in the same way as the rad alt/gpws - maybe you suggest switching them off also?

From my A32x experience, it was not uncommon (say 1 in 50 sectors) to get a 'wx radar' ECAM that required a CB reset. This never happened in the air - but maybe because the radar was already on. Not something you would want when trying to avoid a cell close in!

If I'm in the minority then I am happily there - and safely so....

[Skyworker]

I suggest you do it if you`re alredy in deep **** (sometimes it happens on all-haul-flights regardless of experience). Cell is not the TS itself (compare it with ass and you`ll understand what I mean).

[Stan Woolley]

A growing minority perhaps?

I completely agree with Topbunk.

[TopBunk]

Stan

Thanks - happy to fly behind you as SLF anytime:D

[Conan The Barber]

At our lot the radar goes on when entering the runway and off again when vacating.

Everybody seems quite happy with that.

[tom775257]

At the previous airline I worked at, on line up WX radar on; exit active WXR off. Interestingly even at an airline which had moved onto multiscan weather radar, there were many pilots who didn't understand it / didn't know how to use it, therefore didn't trust it. We also used to test the weather radar as part of the pre-flight scan (med based airline).

At the airline I work for now, we switch the radar on and off as necessary. I still meet captains who think that the reflected beam off another aircraft will be enough to fry your nuts - power output has gone down so much on modern units that you could theoretically quite safely (as far as we are told) stand more than a few feet away from the business end of the WX radar while it is on. I suspect WX radar is a poorly understood area for many pilots - myself included, although at least I read the manual.

I know a crew who using my latest airlines cultural approach to WX radar flew into a CB while not monitoring things outside of the window; but monitoring EFIS without WXR on...

[Reimers]

Situational awareness is the key. During winter in Europe, the convective activity can be zero over a vast area. Why turn on the radar, when cruizing 35900' over a 100' layer of fog for two hours?

When in doubt, it definitely should be switched on! And there are tropical locations where it has to be used every single day.

[doubleu-anker]

With the old type of WX radar, the dish was stabilised when switched to stdby or on. However it was not stabilised when switched off.

There was a lot of wear and tear to the dish mounts etc.,on taxi, etc., with the dish flopping up and down and around. IIRC.

[Doug E Style]

If I can SEE there is nothing to avoid, it remains off. If I can't see if there's anything to avoid it goes on.

[Lou Scannon]

Having started long distance flights before radar was fitted, perhaps I appreciate it's benefits more than most.

I generally kept it on crossing the pond and the Med even though the sky was clear of cloud, to detectional gross navigational errors.

I remember the story of the captain who picked up what he thought must be a large ice mass floating in the atlantic. When pushed the navigator suggested checking a VOR station that "couldn't possibly be in range".

It was.

...and the lage ice mass was for real. The one that covers Greenland!

[411A]

...to detectional gross navigational errors.



Or, to stay on track in the first place, when only Bendix Doppler was fitted for overwater navigation on some sectors....known and charted small islands being the most accurate.

[forget]

I remember the story of the captain who picked up what he thought must be a large ice mass floating in the atlantic. When pushed the navigator suggested checking a VOR station that "couldn't possibly be in range".

That'll be THIS (http://www.vc10.net/History/incidents_and_accidents.html#Navigation_error_over_the_North _Atlantic) one. Remember it well, from seat number ......... I forget.

[SNS3Guppy]

From a maintenance perspective, weather radar formerly needed to be operated regularly to protect the magnetron; failure to operate em the radar regularly would result in the loss and replacement of the most expensive component.

Today with solid state systems that do not have those problems, turning off the radar won't harm the system with respect to not energizing the magnetron. However, gyro stabilization and power to the gyro platform does extend life. It's hard on the motor, gimbal mount, and other components to bounce along in turbulence without being stabilized and protected with the system energized...wear is minimized by having power to the radar unit (at least in standby).

So far as mean time between failures, the life of a radar unit is so extensive that failures are rare anyway; the most common failure points aren't in the radar, but in the mechanical components...and these are protected when the system is on...not worn out or brought closer to failure.

This may seem counter-intuitive. However, with a gyrostabilized radar platform, you can think of it in a similiar manner to a simple air-driven gyro on a light airplane. Sitting in the tie-downs on the ramp is harder on the airplane, and does more to damage the instruments, than flying with the gyro spinning. Why? Because as the airplane bounces and rocks in the wind on the ground, the ruby bearings and needles in the instrument wear concentric patterns, and lead to precession over time...a gyro can wear out just sitting on the ramp not turning. In the case of the radar unit, when it's not stabilized and protected by an energized system, wear increases, and the frequency with which mechanical problems will develop, increases.

True enough, the mean time between failures for the radar systems in general, with respect to the electronics, may increase, but the trouble components, particularly dish hardware, decreases...and this is the highest maintenance item. While it's no longer necessary with modern systems to energize the magnetron to keep it from permenantly failing, it's still benificial to run the radar.

With older radar, of course, failure to run the radar will result in a drastically reduced life of the magnetron.

[Pugilistic Animus]

And that was 2 training captains flying together!


that's the worst:\

[Old Smokey]

1 Training Captain + 1 Training Captain = Double Trouble!:ugh:

Regards,

Old Smokey