Sunday, May 16, 2010

An Adventure in Three Acts

Act One of Friday evening's trip from Bridgeport down to the DC area provided a lovely tour (green track, left) of Connecticut and southeastern New York. This is what they called "radar vectors to Sparta". I have to assume that the controller had sequencing issues but it was making me nervous because I knew there was a lot of convective weather approaching from the west. It would greatly behoove N631S and I to turn the corner and start heading south with minimum delay.
After finally getting "cleared direct Sparta," I was able to negotiate an early turn toward Solberg (SBJ), making the run to the south just in time to turn the corner at SBJ without anything more than moderate rain and light turbulence. If you look at that screen-shot, however, you'll note that there is a patch of serious "red stuff" garnished with yellow lightning-thingies, in the Allentown (KABE) Airspace, obscured in part by the top right data block. That led to Act Two.
Looking at the weather over Allentown I knew I couldn't go there. Given the movement of the cells, it didn't even seem like the usual "cleared direct FLOAT" (which shifts the track a few miles to the south) would suffice to keep me out of trouble. I would need a fairly serious diversion to the south. So I checked in with Allentown Approach, prepared to request a change, and the response to my check-in call was, "Skylane 631 Sierra, Allentown altimeter 29.97, and if you can stay on the airway for a couple of miles we're working on a better routing for you."

I imagine my smile in response to that was pretty wide! I said, "Allentown, 31 Sierra, that sounds great, something that starts with direct Pottstown (PTW) would be nice." And that brought, "31 Sierra, cleared direct Pottstown and I'll be back to you in a few minutes with the rest of your re-route."

The screen-shot at left was taken at 2216Z and shows the clearance I received: PTW MXE V378 BAL direct. It nicely set up a divergent track for me away from the weather. I have to say, too, I've heard that Philly Approach has a reputation for being prickly but they were as helpful as I could have asked for.

Having avoided the weather approaching from the west, it was time to look ahead at what was going on in the area of KVKX, our destination. Which brings us to Act Three.

I'd been aware of a fairly isolated cell that was working over Dulles (KIAD) and Manassas (KHEF) and had thought to myself, "It'll be just my luck to have that get to VKX the same time I do." Guess what? (Note: The weather depicted above at left (click to enlarge) was as of 22Z. That big cell had moved fairly fast in the succeeding hour.)

But again, I drew an outstanding controller. Just before reaching Martin State Airport (KMTN) he said, "Skylane 31 Sierra, there is some severe weather near Andrews at this time so fly a 180 heading and we'll take you south to around Nottingham (OTT) and figure out how we're going to get you in."

On the way down toward the OTT VOR he asked me, "31 Sierra how are you on fuel? Can you accept a delay of 45 minutes or an hour?" A glance at the Shadin fuel totalizer said I had about 40 gallons to spare - again, the best safety feature on N631S is 75 gallons of AvGas in the long-range tanks. I replied, "631 Sierra can accept an hour delay with no difficulty."

As you can see from the track, the controller had me carry on to the south for a while, then turn west when I was clear of the cell. All along, I was watching occasional strikes of cloud-to-ground lighting four or five miles beyond my right wingtip.

From about fifteen miles due south of the field, the controller suggested a turn for home. I had some turbulence on the descent to the airport (moderate; actually, the worst of the whole trip) but the visual approach and landing on a wet Runway 24 was routine.

Here, with a hat tip to the folks at FlightAware.com, is the track for all three acts stitched together:


Royski said...

Good one

Keith Smith said...

Outstanding post! As I start doing more and more XC IFR flights, it's becoming clear that it might be wise to get a handheld with some sort of weather capability. That said, it seemed like the controllers were already working hard on your behalf. I guess I should ask you, how would you feel about doing these trips without your 396, in terms of weather avoidance?

Do you find that ATC keeps an eye out for you, and offers you re-routes without you having to solicit them?

Frank Van Haste said...

Royski, thanks for stopping by!

Keith, for me on a night like Friday, the Garmin 396 with XM weather is a no-go item. The controllers, bless their hearts, do work hard on your behalf but their vision goes only as far as their radar sector.

For example, I was very serious about getting an early turn south whilst headed over to Sparta 'cause I could see the line of wx stretching east from Allentown to be avoided. The EWR controller could only see that I'd asked for a route into some Level 1 wx - that confused him a bit but he worked with me. If all I'd had going for me was the controllers' wx displays, I believe I'd have wound up in a box with the only exit to the north and no good way back across the line.

Conversely, working in to KVKX at the end of the flight, the Potomac Approach controller had better data than I did with sufficient scope and (key point) no latency. When he said it was good to turn for the airport I could trust that. Working off the XM I'd need to be very conservative with that kind of decision. (Of course, the Mark I eyeball factors into all this.)

As to re-routes, most often if I wanted one I've had to solicit it. Friday was different - Allentown Approach initiated a re-route without my asking. They knew they had a problem. In contrast to re-routes, it is not uncommon for a controller to offer a deviation left or right to avoid an area of weather without being asked. But don't hesitate to ask for what you need to stay safe.

If you plan to get serious about XC IFR a Garmin handheld with XM wx is the best investment you can make. The 396 is old but meets all my needs. And, it's a backup GPS in case the 530W ever goes toes up.

Thanks for reading, and fly safe...


Greg said...

Great post! I am controller at Potomac approach and talk to you often, including that Friday night. That was definitely an interesting evening to say the least! It's great to see the pilots' side of situations like this, and I appreciate your time and effort to write these posts.

I agree that on board weather radar and XM weather are invaluable tools for pilots. As you said, controllers can only see as far as the sector they are working. While we can help you navigate around the weather in our sector, we often don't have the big picture. That's where we
rely on pilot's to tell us what they need and then we can make it happen.

One of the biggest limitations of our weather radar is that its a composite image, showing the heaviest returns at any altitude. We can't filter to show one altitude or a specific block of altitudes. Pilot reports are the best way for us to translate those yellows and reds on our radar into the actual flying conditions in a particular area at a particular altitude.

Thanks for the post. Be safe out there!


Frank Van Haste said...


Have I mentioned that I love you guys(and gals)?

Thanks for your comment. The XM weather display is also a composite, so at night or if working embedded wx, we both have to assume that the baddest stuff is at MY altitude. But if we can get some additional data from the Mark I eyeball it will help to "layer" the flight conditions.

I'm neither a user of nor expert in on-board radar but I believe folks with that capability can use the tilt feature to find the best altitude.

See you on the freq.