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-   -   Weather avoidance and ATC (https://www.pprune.org/tech-log/425540-weather-avoidance-atc.html)

cortilla 28th Aug 2010 01:49

Weather avoidance and ATC
 
Earlier today i was flying into a busy airport where there was alot of weather in the TMA. Also it was very busy at the time.

Now some aircraft were telling ATC, i'm heading xxx to avoid. Other aircraft were requesting xxx due weather and waiting for clearance. At the same time some departing aircraft were constantly requesting further climb/descent as they were levelling off (no weather avoidance so as far as i'm concerned these guys/gals went to the back of the que). However alot of aircraft and ATC were stepping all over each other and there were many many garbled transmisions. Was a bit of a mess and the service provided by the guy on approach was absolutely fantastic. I can imagine he's since gone home and collapsed on his bed in an exhausted heap.

However my question is when cb's and other aircraft are a factor, what do you do. Request and wait for approval or just tell atc what you're doing. (remember TMA not enroute)

For those wondering what we did. We told ATC we're doing xxx because the red on the radar screen was getting very close and there was very little space to manouver. clouds to the left of me clouds to the right of me stuck in the middle for all you steelers wheel fans.

Sky Wave 28th Aug 2010 09:11

Having been to a NATS TRUCE day the answer in the UK is most definitely wait for a clearance.

One of their closest "Near Misses" of last year was caused by just the situation you are describing. A very busy London TMA, lots of wx avoidance and lots of stepping on each other. A Biz Jet decided to avoid without getting a clearance and they caused a serious loss of separation with an Air Lingus on departure from Heathrow. (And of course someone saying TCAS RA is yet more talking and confusion on the frequency)!

The word from NATS is that if you can't get a word in, and you MUST turn to avoid WX, you should squawk 7700. This will cause you to show red on their screens. They will stop all other communication and ask you what the problem is. You can then tell them you are turning due to weather.

Your target going red will also immediately draw their attention to you and enable them to move aircraft out of your way. Controllers operating the sectors above or below the sector that you are in will automatically stop any aircraft climbing or descending through your level when they see a 7700.

I admit it does seem strange squawking 7700 when you are not on a Mayday, but this is what NATS want us to do.

I'd also highly recommend going to a TRUCE day. It's a real eye opener and very interesting.

SW

cortilla 28th Aug 2010 09:25

Okay so what happens when several aircraft start squaking 7700. There were alot of a/c needing avoidance at the same time.

Agree on the TRUCE, went on one a few years back at the new prestwck centre before it opened. Very informative for both us and the new contollers. Unfortunately weather never came up. No of the aircrew or ATC bods thought to think of it. (big D'oh moment on my front)

rudderrudderrat 28th Aug 2010 09:52

Hi,

Is it not possible for ATC to anticipate weather problems by allowing CBs to be painted on their screens? In anticipation of the extra work load, an additional frequency and controller could be allocated.

westinghouse 28th Aug 2010 11:14

hey,

where you flying into indra gandhi international airport - delhi? ( vidp)

your description sounds so much like that place. ATC has no idea whats going on and the pilots are doing their own diversions. just one big recipe for disaster.

cortilla 28th Aug 2010 11:38

No not india. If you read my initial post I state that the controller did an excellent job in trying to sort out the mess that all these cb's were creating. As to the weather on controllers radar screens, I'm lead to believe these are filtered out. ?

Sky Wave 28th Aug 2010 17:07

Cortilla is correct.

UK radar screens filter out the weather.

Max Angle 28th Aug 2010 17:30

Whereas 30 mins. flying time East in the Amsterdam FIR the controllers can see the weather and just vector traffic around it without being asked. Guess which is the best system. :ugh:

Aviophage 28th Aug 2010 18:47

You do NOT squawk 7700 if you are turning to avoid wx and require ATC attention. That is the most ridiculous piece of advice I have read on this forum.

:ugh::ugh::ugh:

Sygyzy 28th Aug 2010 21:02

Aviophage
 
Have you ever been to a TRUCE day, do you read what other people post. But then you probably don't need to given your superior knowledge.:rolleyes: Under 50 posts and it a shame it's not 5000 cos the whole of the aviation world would've been changed by now. That is if anyone had agreed with you.

I've read quite a bit on various threads here but not so many bits of dogmatic :mad:' in so few posts. Nonsense here about the squawk with no source to back it up (nonsense somewhere else too about anti col/strobe lights).

We all have so much to learn. You especially it would seem.

S

FLEXPWR 28th Aug 2010 21:16

I have been vectored around weather in Ireland and in the USA, with an amazing precision. Dunno about the UK, but with todays toys for controllers, most places you can get an overlay of the weather on the radar screen. It makes of course the airplanes more difficult to see...

In Africa, I had the opposite, where only primary radar would get us lost in bad wx, and ATC comes up and says...:"ah, no more vectors, can't see you, so self position for the approach..." :}

Most of times, I just ask ATC, but when the time comes and you can't step in to talk, I just avoid and notify later. Rather have a well flown TCAS RA, than an aircraft pitted with hail stones... :ouch:

Flex

Sky Wave 28th Aug 2010 22:06


You do NOT squawk 7700 if you are turning to avoid wx and require ATC attention. That is the most ridiculous piece of advice I have read on this forum.

lol, thanks for your input.

You obviously think it's ok to deviate from an ATC clearance without telling anyone then?

You'd best have a chat with the people at the NATS training centre if you think that they are giving out ridiculous advice.

They went to great lengths to try and persuade us pilots not to be afraid of using 7700.

They also went to great lengths to persuade their controllers to get aircraft to squawk 7700 if unable to comply with a clearance for any reason.

In another case explored at the TRUCE session an Easyjet aircraft was unwilling to climb and take certain vectors after receiving a huge lightning strike. The aircraft was not on a PAN or a MAYDAY, but they'd just received a massive strike, lost a couple of minor systems and wanted to divert back to LGW without going near to any other weather. The controller was very obliging, but in doing so became extremely overloaded since other aircraft kept entering his sector and this EZY was in the way. The trainer impressed upon the controllers that amongst other things the EZY should have been made to wear 7700. This one action would have stopped other aircraft entering his sector and allowed him to deal with the difficult aircraft.

Not my rules and I'm not making this up for the fun of it.

If you don't like it, don't do it. (that assumes you're a pilot)

But before spouting off on here I suggest you speak to the NATS training department to get their opinion.

SW

Sky Wave 28th Aug 2010 22:13


Rather have a well flown TCAS RA, than an aircraft pitted with hail stones...
I do agree with that statement, however

TCAS is the last line of defence and we should never let it get to that stage.

Secondly an RA can cause further loss of separation against other aircraft in a busy TMA

squawking 7700 would add another line of defence and hopefully prevent it getting to a TCAS RA.

babotika 29th Aug 2010 04:00

Really wondering why all radar controllers don't have some sort of weather representation these days... The technology must exist as some have it, and it makes life much easier for everyone involved.

Back to the original question, I will request heading xxx when I have the time and/or I would like to avoid, and this only if the situation allows. I will state that I require heading xxx when continuing is completely unacceptable, but never turn before I get a reply.

S.

Slasher 29th Aug 2010 07:02


You do NOT squawk 7700 if you are turning to avoid wx and require ATC attention. That is the most ridiculous piece of advice I have read on this forum.
I agree. 7700 is saying "I am in deep sh!t!" (and usualy
acompanyed by a mayday call). Your not in deep sh!t by
avoiding weather cleared or uncleared. Sqawking ident is
the best way to draw ATC to your blip if theres too much
bloodey racket on the radio.

Just as 121.5 has degraded to a chatter freq (esp in SE
Asia) 7700 will be degraded to nusance value if the wolf
is cryed too often.

AerocatS2A 29th Aug 2010 09:55

Cortilla, what does your AIP say to do? ours (Australia) says, request clearance, if a clearance can't be given broadcast a PAN PAN and do what you have to do to stay safe.

spin_doctor 29th Aug 2010 16:04


I agree. 7700 is saying "I am in deep sh!t!" (and usualy
acompanyed by a mayday call). Your not in deep sh!t by
avoiding weather cleared or uncleared.
I don't fly through Cb's. They are dangerous. If the frequency is too congested to request avoidance, and deviating from my clearance could result in a loss of separation, then on the contrary I am in deep sh!t.

Slasher 29th Aug 2010 16:48


I don't fly through Cb's. They are dangerous
I agree Spin. So what will you do when your confronted with
a thick line of nastey 45,000 footers and have no choice but
to plow through em? Your infering you have no experience. :bored:

BTW "deep sh!t" refers to the posibility of losing your life.
If you cause a reduction of separation your not in deep
sh!t. A loss of separation is a different storey and between
you and the authority who issues your licence. Personaly I
batten down the hatches and plow through the muck till I
can get safely clear than risk plowing into another aircraft.

Max Angle 29th Aug 2010 20:37


So what will you do when your confronted with
a thick line of nastey 45,000 footers and have no choice but
to plow through em?
You always have a choice, at least you should have. If you literally have no choice but to fly through a line of 45000 footers then you have well and truly blown it somewhere back along the route. What circumstances do you have in mind that would tempt you in?.

Teddy Robinson 29th Aug 2010 21:00

sometimes there is another option ...
 
plan a route that avoids the area of severe weather, (severe TS walls over the Alps is a reasonably frequent example).
not always possible, but when it is, take the safest option and explain your extra fuel requirement and routing to ops, if not be prepared to sit it out until more information is available: don't get airborne and "hope" for the best.

Have seen lemming like behaviour on STAR's resulting in several lightning strikes to several planes within a few minutes , end result : several AOG pending engineering attention, when all they had to do was to request a routing to another STAR entry point.

If it is there, and you know it is there, try and deal with the problem at the planning/ briefing stage.


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