Deviate around thunderstorm?

[tireman]

Situation...you're on a IFR flight plan with a big old storm cell painting red on your radar. How exactly does ATC usually clear you around these things? With vectors or are you usually just cleared to deviate as you see fit until you can resume your original navigation? Have you ever not been able to get a clearance to deviate around a storm and if so what then (get clearance to alternate?). I'm interested in hearing all your more difficult experiences with managing your way around thunderstorms.

[Rockie]

You tell ATC where you need to go and for how long. They will do their best to accommodate but may need to impose some limits and/or discuss other options in a busy terminal area. They probably already have good intel on the best routes based on their own radar and other traffic, and could preemptively reroute you. They are very good. If for some reason though they are unable to clear you then you declare an emergency and do what you must.

But under no circumstance do you ever - ever - fly through a thunderstorm.

[PilotDAR]

Deviate around thunderstorm

Yes.

Do the most logical thing, notify ATC as much as you are able, and they'll work it out. They should be aware of your proximity anyway. You are responsible for the safety of the flight.

[rookiepilot]

Assuming this is referring to a light single, (or I suppose anything really) a few caveats about ATC deviations:

1. They may not always have good primary radar of cell development. Trust but verify applies. Make sure the deviation looks good to you visually or via aircraft tools, and be quick to question. Not a time for passivity. Be especially careful IMC of embedded cells. VFR is really better, as can actually see the cells.

2. ATC is very good. Ask for what you need. Well yes usually, Not always. I've been pressured to get back on course which would have meant turning right into an active line. Don't assume anything from a vector that ATC can vouch for its safety. Trust, but verify. Be prepared to say unable or even cancel IFR as required. I've had to do this once as ATC was insistent to have me join a long ILS queue with numerous rotor clouds present, not recognizing the difference between a group of twin turbines and a light single. Nope. Remember It's your butt up there not theirs.

All said most of the time ATC if they have good coverage is outstanding and will go backwards to help out.

[Rupert_Pupkin]

There is a huge difference between flying around storms in the USA and Canada. In the US they will vector you around in a good fashion (especially true in the south). In Canada its more on you. I've never been turned down an option to deviate when you say its for storm avoidance. There is always options.

[Zaibatsu]

Ask for deviations left or right of track. They may limit you or you may feel prudent to ask for a specific heading. Another option if your aircraft is capable is to go over the storms.

Finally, turn around or hold. Sometimes there is a line of storms even the best equipped aircraft can't get through. Don't take chances. Also don't rely only anything other than wx radar to get you through embedded storms. Ground based radar sources have lag and poor coverage and not all storms will produce lightning.

[photofly]

On the few occasions I've asked Canadian ATC for information about weather ahead they've always told me they have very poor weather information displayed on radar and that they couldn't provide me any operationally useful information. I get the idea that US air traffic control facilities have much more information available and/or are more willing to share it. In one of Rod Machado's books he goes into great details about the fabulous radar facilities available to ATCOs in the US and how to ask them to adjust their displays and tell you what you need to know.

[Black_Tusk]

Most of the time it's "Center, request deviations N,S,E,W for weather" they will say "deviations N,S,E,W approved, direct XXXX when able."

[bradley]

There are plenty of ways to do it, request vectors, request a heading, request X miles left or right of course (useful oceanic), or simply request a deviation in a direction.

I've never been denied in North America or Europe, but I have been denied once for thunderstorm avoidance while in busy terminal airspace in Asia. I was being vectored directly into a massive area of magenta returns, and after telling ATC multiple times I needed to turn NOW and still being denied, I eventually just said "XXXX turning right heading X for thunderstorm avoidance". ATC stuttered out a few shocked words, then two or three airplanes behind me heard what I did and did the exact same thing. I didn't get violated, and I've never heard a word about it since. An IFR ticket isn't worth my life.

[Lotro]

I get the idea that US air traffic control facilities have much more information available and/or are more willing to share it.

In Canada ATC has VERY limited weather information on the Radar display. So limited, it's basically useless.

No one holding out on you.

[Braun]

On the few occasions I've asked Canadian ATC for information about weather ahead they've always told me they have very poor weather information displayed on radar and that they couldn't provide me any operationally useful information. I get the idea that US air traffic control facilities have much more information available and/or are more willing to share it. In one of Rod Machado's books he goes into great details about the fabulous radar facilities available to ATCOs in the US and how to ask them to adjust their displays and tell you what you need to know.

We can see lightning strikes and precipitation (both heavy and light). Anything else we can't officially see. Obviously we have some side systems that have extra information but nothing that is translated directly onto our radar screen.

[photofly]

Out of curiosity, what can you see "unofficially"?

[hydro]

Some sectors have a separate monitor nearby that shows big picture traffic flow, and a weather radar overlay. The weather info is usually much better than what's on our CAATS radar screen, but a) the monitor may not be to close, b) unclear how recent the images are, c) don't show motion, d) the image may be zoomed out

Overall you can anticipate someone will ask for deviations soon, or do medium term planning/reroutes, but not useful to suggest headings "in close".

sample: http://www.cs.uml.edu/~pkrolak/lab5/sli ... age027.gif

[pelmet]

Situation...you're on a IFR flight plan with a big old storm cell painting red on your radar. How exactly does ATC usually clear you around these things? With vectors or are you usually just cleared to deviate as you see fit until you can resume your original navigation? Have you ever not been able to get a clearance to deviate around a storm and if so what then (get clearance to alternate?). I'm interested in hearing all your more difficult experiences with managing your way around thunderstorms.

Depending on the situation such as the size of the storm, location(such as places where hail is more likely versus tropical stuff), wind direction, ability to see the storm, etc. it is best to have a plan in advance on what you want to do. Then give yourself some extra margin as things may change such as the location after you have made your request.

Especially in areas where communication is difficult, I make my request early. Certain remote areas can take a while to give approval so waiting until closer in can make things more worriesome. Sometimes I get the deviation approaval and don't even end up needing the deviation. But I have the approval to deviate if required instead of having to explain later why I deviated without approval.

Even in the US, an earlier rather than later request is prudent. One time I was with a well known jerk of a captain on a large turboprop somewhere down in the US with medium sized storm ahead of us. I suggested that we request a deviation. His reaction was with a smirk..."Pffft, why? Are you scared" while giving his look of complete relaxation (yes he is a complete jerk). A few minutes later, we were getting close enough that we needed to deviate soon so he told me to request a deviation. By that time the frequency was so busy with non-stop chatter and we had to deviate was without a clearance which is what happened. Another guy I was with figured that it was OK to go through a cell because there was no red but then discovered close-in that it had suddenly turned red resulting in an initiation of a deviation while still requesting a clearance for one(happened twice with him).

In the last two flights, I did perhaps five deviations. One was in the US where ATC initiated the deviation quite far back with a minor re-route but it was not enough, so eventually I requested a heading. However, I find the heading less flexible in case I need further changes and have to talk to ATC again. That is why asking for X number of miles is my preferred method with some extra buffer added in. I can adjust the heading as required. I definitly stayed quite far from the one in the US.

Two deviations were in non radar airspace, one of which was at night so even though we might have been above it but I just got the clearance to deviate anyways. The final one was 60 miles off track with a large area of various colours on the radar display. Pretty sure that while in the green area(with a few yellow splotches) that we experienced Ice Crystal Icing conditions for about 5 minutes. There was a smell(not of sulpher but perhaps ozone) along with several other indicators of an encounter.

Usually in non-radar areas, they request a report "back on course" which is what you should do unless cleared to do differently. To save time, once clear, a direct to the next waypoint was requested and we were cleared to do that.

[co-joe]

A few weeks back I had a cell right between me and the IAF on an RNAV Z IAP, and I told arrivals unable direct request left of course. They suggested flying crosswind to the opposite IAF, and what followed were 3 of the most perfect deviation steers I could have asked for. I was just about to ask for a heading and they said fly that heading. Then I needed to go left around the fully contouring cell and not straight into its brother cell and surprisingly the next vector was exactly the heading I was going to ask for, and finally the intercept to final was perfectly around the cell that ATC "couldn't see".

Made me think they may have some pretty decent prime returns on that sucker after all. Funny though because direct the first IAF would have taken me straight into a pretty serious build up, but once I said no way, they became amazing...

[pelmet]

The whole point of ADS-B is to be able to get rid of radar eventually. Then you will not be able to get this kind of service, I would think.