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Lightning vs. the Weather Radar.

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Lightning vs. the Weather Radar.

Old 22nd Oct 2015, 09:52
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Lightning vs. the Weather Radar.

Recently, an A320 on a sister airline was struck by lightning and had its weather radar knocked out. Luckily they had system 2 to fall back on and operations were unaffected.

At this point I realized that our fleet of A320s only has one weather radar system available as management was too cheap to install two when ordering the aircraft from Airbus. Minimum Equipment List says that one weather radar system is all you need, even when dispatching for an ETOPS flight.

Now the scary bit... You're flying ETOPS over the Ocean on a particularly cloudy and moonless night and your one weather radar fails. By the weather report at dispatch, it's supposed to be a right mess with build ups all over the place that you now cannot see. Nearest airport is hundreds of miles away. What would you do?

Has anyone had this experience or faced something simliar? Care to shed some light on what a company procedure for this might look like? And please don't say avoid the flashes.
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Old 23rd Oct 2015, 20:14
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High vlsrotate,

Welcome to PPRuNe! Good question, and sorry no one has yet risen to the challenge. Afraid I'm not going to be much help either.

However, just want to point out that, even when the a/c is fitted with two radar transceivers (as mine were), they are in close proximity and there's only one dish antenna. I once got struck bang on the nose on an approach into Bilbao (no, that wasn't the co-pilot losing his temper ). The result was a fist-sized hole in the radome and the failure of both TRx boxes.** I can't remember if the dish itself was damaged, but if the airspeed had been higher I suspect it would have been.

So maybe the case in your sister airline was fortunate. Perhaps one of our resident engineers will comment.

I don't know the probability of a TRx failing spontaneously after despatch. Being equipped with two obviously reduces the probability of the a/c being unable to despatch because one TRx has failed when away from a suitable maintenance base - assuming your MEL is representative.

** EDIT
On reflection (it's been many years...), the non-operating TRx may not have been damaged. A new radome was sent by road from Madrid (my having declined the ground engineer's offer to repair the rain-soaked damage to its honeycomb-type material with speed tape ). But I think we may have despatched the following day with one serviceable TRx, and I don't recall a replacement TRx being fitted.

(BTW, FWIW the a/c was an A320 and no other systems had been affected by the lightning strike, so the approach had been continued without further incident. EFIS, FMGC and EFCS continued operating without interruption.)

Last edited by Chris Scott; 24th Oct 2015 at 11:05. Reason: "EDIT" paragraphs added.
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Old 24th Oct 2015, 06:53
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Originally Posted by vlsrotate View Post
Now the scary bit... You're flying ETOPS over the Ocean on a particularly cloudy and moonless night and your one weather radar fails. By the weather report at dispatch, it's supposed to be a right mess with build ups all over the place that you now cannot see. Nearest airport is hundreds of miles away. What would you do?
Speaking as self loading freight, I wouldn't mind if the pilot popped out of the cockpit, told the passengers that it was going to be rough and possibly perilous, and conducted a poll on whether they would prefer a pleasure flight round the local scenery instead. To be honest I think I'd opt for the sight seeing! If that means a diversion to somewhere sunny and tropical so much the better!

Is it possible to get basic weather data via ground support?

From a purely technical point of view it would be possible to feed a whole lot of real time meteorological data to an aircraft. It would be gathered from satellites, ground stations, etc. Most of the earth's surface is continually monitored these days especially the oceans. I guess running a weather radar on the plane is a lot cheaper and simpler, but with some development effort a data feed could be made into a viable backup.

Last edited by msbbarratt; 24th Oct 2015 at 07:05.
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Old 24th Oct 2015, 09:20
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vlsrotate: When I operated the B707 for Zambian Airways we had a "rogue" aircraft which would regularily lose its wx radar after take-off. Always tested OK on the ground - suspect an earthing fault.
These flights were about 11 hours at night and always passed through the ITCZ.
The tactic was to always maintain VMC conditions for the ITCZ transit. ie. never fly into cloud. It is surprising how easy it is to do this if you are prepared to deviate extensively. Usually it is quite easy to see the active cells with the cockpit light down low. Even with no moon, the active cells give off their own light!!
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Old 24th Oct 2015, 09:32
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You're flying ETOPS over the Ocean

Is it possible to get basic weather data via ground support? [...]with some development effort a data feed could be made into a viable backup.

...like, building a network of weather radars in the middle of the North atlantic? msbbarratt, that's not going to happen.

What would you do?

try asking for nearby aircraft who could provide some guidance? phone home and ask meteorologists for the best and most current data and advice they have? and as Meikleour said, deviate extensively.
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Old 24th Oct 2015, 14:37
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Well, if you had a weather radar but got struck by lightning anyway then the weather radar wasn't doing you much good was it? You may as well have had it off in the first place.

To me this is a question about a scenario that is unlikely enough that I wouldn't lose too much sleep over it, and if it did happen I'd just play it by ear. Do I think I can transit the weather safely using visual techniques or help from another aircraft? If not, go land somewhere and have the thing fixed.
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Old 25th Oct 2015, 08:23
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...like, building a network of weather radars in the middle of the North atlantic? msbbarratt, that's not going to happen.
Actually, that is not that far fetched, simply datalink all aircraft wx radar returns and build a composite real time picture. Now, the only thing preventing that at the moment is cost and datalink capacity, but it is possible right now.
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Old 25th Oct 2015, 11:44
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What's ETOPS got to do with it?
You're flying into an area of weather and your radar fails! To continue is basically Russian roulette!
Good Airmanship would dictate you follow the least path of resistance and land asap, preferably without flying into a CB!
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Old 25th Oct 2015, 18:31
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Well if you're ETOPS it probably means you're a couple hours from being able to land and will have to deal with what you see or don't see out the window.
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Old 25th Oct 2015, 19:20
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A320 radar

Happened to me flying an A320. Domestic flying and lightning struck the radome knocking out the radar. Late afternoon in Asia during the monsoon and trying to revive the radar didn't work. Ended up following a higher flying aircraft using TCAS as a guide. We still got a few thumps though.

Destination TAF was typical TS and our ETA was well after sunset. I diverted and landed at a nearby airport, wrote up the strike and the busted radar. Engineers fixed the radar quickly by simply resetting the breaker on 121VU. It never popped but the reset worked.

That's one breaker or CB (no pun intended) location worth knowing about. Right behind the FO's seat. I'd had strikes on the Boeing but never had the radar fail unlike this experience.
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Old 26th Oct 2015, 02:00
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Originally Posted by deptrai View Post
What would you do?

try asking for nearby aircraft who could provide some guidance? phone home and ask meteorologists for the best and most current data and advice they have? and as Meikleour said, deviate extensively.
Qantas and ANZ held hands across the pacific a few years ago after exactly this kind of occurrence.

A good use of available options and professional courtesy, if you ask me...
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Old 26th Oct 2015, 03:24
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Qantas and ANZ held hands across the pacific a few years ago after exactly this kind of occurrence.
That's a great option, but not generally available on the South Atlantic routes from the U.S. to JNB or back.

Avoid going Popeye is about your only recourse along with a possible routing change courtesy of flight control.

Last edited by wanabee777; 27th Oct 2015 at 07:45.
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Old 26th Oct 2015, 09:52
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Actually, that is not that far fetched, simply datalink all aircraft wx radar returns and build a composite real time picture. Now, the only thing preventing that at the moment is cost and datalink capacity, but it is possible right now.
There are systems out there that link aircraft measurements, and transmit between aircraft. So far, it is the basic winds aloft and a few other parameters.

AMDAR data is sent from most widebodies, and other ac equipped. It is just a matter of uplink, which is becoming much easier these days due to the IFE and Ku band transmission capabilities.

Several services offer the winds aloft direct to the flightdeck, pilot just has to accept. The winds are broadcast directly from the aircraft, and frequently. This information is then uploaded to the other aircraft on the route.
Southwest Airlines in the US has the system active, and the drivers love it.
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Old 26th Oct 2015, 20:16
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simply datalink all aircraft wx radar returns and build a composite real time picture. Now, the only thing preventing that at the moment is cost and datalink capacity
Fascinating idea. simply datalink...the word datalink also made me think of peer-to-peer networking, to overcome current satellite bandwidth cost, data could (theoretically) be transmitted from aircraft to aircraft. Frequencies suitable for line of sight, automated, buffered if there are "gaps". Aggregated into a composite picture, and made available to all.
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Old 27th Oct 2015, 07:29
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It's time we caught up with the Americans, and all got XM weather.
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Old 27th Oct 2015, 13:29
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Doesn't Lufthansa also flog its real-time in-flight met data back to the forecasters? That's the best kind of safety enhancement, one that also makes money...
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Old 27th Oct 2015, 13:33
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There sure were times that I would've liked to have streamed what I was seeing on my radar screen back to my dispatcher.
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Old 27th Oct 2015, 13:41
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Training partner story from years ago - soda can dropped into center console = no radar and no comm. Used TCAS to follow a plane ahead of them. Comm eventually came back nearing land. Radar never did.
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Old 27th Oct 2015, 20:42
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The best idea would be to take assistance from other aircraft on the same route and at different flight level or in the vicinity and you can also take some assistance from ATC.Once you are of the weather then depending upon the forecast and current scenario either divert or continue to your destintion
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