julesmusician
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Avoiding Bad Weather On Radar And ATC

Sat Oct 29, 2005 1:52 am

A question always wanted to know - if you are flying down on a set course and want to avoid nasty weather showing up on radar can you turn to avoid it without informing ATC or do you have to tell them everytime you do a slight turn to avoid bad weather?



Jules
African Civil Aviation Commission president "You don't want to fly out as a passenger and come back as cargo."
 
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HAWK21M
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RE: Avoiding Bad Weather On Radar And ATC

Sat Oct 29, 2005 2:43 am

Out here,Any Deviation from flight plan has to be with ATC Knowledge,Even if its weather related.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Woodreau
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RE: Avoiding Bad Weather On Radar And ATC

Sat Oct 29, 2005 3:10 am

"Center, United 235, Request 20 degrees right for weather (or buildups.)"

"United 235, Minneapolis Center, Approved as requested, report returning to course."

"United 235 Roger."
Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.
 
SlamClick
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RE: Avoiding Bad Weather On Radar And ATC

Sat Oct 29, 2005 3:27 am

US Domestic, you are in radar contact pretty much all the time. Ultimately you can use your emergency authority to avoid flying through a thunderstorm but as a practical matter, ATC is kept very much in the loop and is the practical solution to all the problems.

Normally there is no problem, as they fully understand your need not to fly through the stuff. I've only had one actual conflict and it went like this: We were southeast bound, approaching the Coaldale VOR to join J-92 down over Las Vegas and there was a giant thunderstorm on that airway. By the time we turned the corner at OAL it was apparent that this monster was going to crowd us off the airway to the east and it was too late to turn back and circumnavigate it to the west and south sides. There was no way to avoid the red and purple areas of the cell without going into Tonopah Test Range airspace.

The captain was flying and he had me advise center that we had to deviate to the east. They said they could not approve that and to stay on the airway. The problem was that the testing of the F-117 fighters was being conducted then, out of the Tonopah Test Range and it was active at that moment. They could not see these stealth aircraft on their radar and could not guarantee our separation. The captain got on the radio and re-stated that he was going about ten miles east of the airway centerline.

Again the controller said he could not approve that. The captain again said that was what he was going to do. A different voice came up as "center" and said: "Immediate right turn, heading 240!" or some similar direction out of TTR airspace. The captain said: "Negative."

A few miles further on, we were clear of the cell and I told them we could accept a right turn. They gave us a vector back to rejoin J-92 and that was the end of it. Never heard anything more about it. We expected the letters to come in about six months alleging a violation but nothing ever happened.

I think everyone involved thought as we did. The risk of collision with one little fighter in a thousand cubic miles of air was one factor, the certainty of flying into a level 5 or 6 thunderstorm at 33000' was another. While it was kind of a bad deal for all of us to be in, we went with the vastly better odds. Someone agreed.

The big deal on thunderstorm avoidance in the continental US is probably when the Marfa line is really active; you can get a line of monster cells from west Texas all the way to the Canadian border near Lake Erie. Every east/west flight has to deal with these lines of thunderstorms and hundreds of us end up slipping through the same couple of holes. The talk is about where the soft spots are and the traffic does get bunched up in them. Under these conditions I really admire the guys in the ARTCCs. They do a fabulous job of getting us through without running a bunch of us together.
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modesto2
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RE: Avoiding Bad Weather On Radar And ATC

Sat Oct 29, 2005 11:32 pm

Some people may argue that you can deviate for weather without notifying ATC as long as you stay within the 8nm width of an airway (4nm on each side). I always notify the controller so he/she knows what's going on. Additionally, it's almost a psuedo PIREP that could help other pilots flying through the same airspace. If your deviation extends beyond the lateral boundaries of the airway, then you must definitely notify. Atlanta Approach once yelled at us for deviating without giving him a call.

My personal policy? I always give them a call.
 
julesmusician
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RE: Avoiding Bad Weather On Radar And ATC

Tue Nov 01, 2005 7:40 am

So can a pilot answer how do ATC deal with nasty thunderstorms over the airport - are they likely to place you in a hold while it clears or just clear you into the airport approach and let you make your mind up when you get there? or is it the pilot that will tell ATC what he is going to do?!
African Civil Aviation Commission president "You don't want to fly out as a passenger and come back as cargo."
 
Woodreau
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RE: Avoiding Bad Weather On Radar And ATC

Tue Nov 01, 2005 2:27 pm

Nope but an air traffic controller might.  Wink

But at DFW today, when the squall line moved through, ATC just shut the airport down until it passed. All the arrivals were put in a hold, all departures were held on the ground.

What's up with the sixty questions in 3 days?
Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.
 
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HAWK21M
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RE: Avoiding Bad Weather On Radar And ATC

Tue Nov 01, 2005 5:12 pm

Quoting Julesmusician (Reply 5):
or is it the pilot that will tell ATC what he is going to do?!

ATC Will Advice/Caution if needed in case of bad weather.Final Responsibility lies with the PIC.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
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TripleDelta
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RE: Avoiding Bad Weather On Radar And ATC

Tue Nov 01, 2005 6:22 pm

In normal situations (i.e. not emergency ones or those imminently threatening the safety of the aircraft), the pilot cannot act without the approval of ATC. In almost all cases, ATC will either already be aware of bad weather (through pilot PIREPs mentioned by Modesto2) and will take action to steer aircraft away from the area at an early stage, or the pilot will inform ATC of bad weather and ask for a vector to avoid it - preferably adding the best solution for him/her.

In many cases, even in high-density traffic areas, vectoring can be easily accomplished, since the aircraft's wx radar gives enough advance warning to enable both the pilots enough time to warn ATC and prepare for a course/altitude change, and ATC enough time to coordinate and clear a section of airspace into which the incoming aircraft can be vectored.
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