Thursday, August 6, 2009

Fickle Charlotte

Although I’m commuting home on the 06:40 AM NWA flight after getting four hours light sleep in the same crashpad bedroom as our new resident, a real snorer (and I should know about snoring), I’m going to replay the adventure we had yesterday evening while it’s still fresh in my mind. We had climbed out from Harrisburg, PA and turned south toward Charlotte, knowing that at the very least we would have to deviate around thunderstorms we had already seen up close on the way from Charlotte to MDT two and a half hours previously. The forecast for Charlotte was a general one for garden variety thunderstorms in the Charlotte area, and according to it the most likely time for a storm at CLT would end just when we were climbing out from Harrisburg.

Soon enough later, cruising at FL320 (32,000 ft MSL), on my suggestion my good FO requested a safe heading for a deviation in the wide gap between a scattered line of big ones. The weather radar displayed them as colorful on the MFD screen, like shiny pebbles in a tropical stream, but the view out the office windows was entirely different. Clean air in the upper atmosphere and blue sky was a great backdrop to present these immense, puffed up giants in the sky against us. They were clearly head and shoulders taller than we were, with tops of 48,000 feet. It’s almost football season, and this bright white defensive line of monsters in opposition to us were in full summer drills. The good news was they were moving slowly, that was also the bad news.

After passing the first couple of linebackers, Center (ATC) told us that CLT approach wasn’t accepting any more arrivals because a thunderstorm had the airport shut down. That was logical, the activity seemed to stretch that way, 150 miles ahead. Pretty flexibly, center let us virtually plan our own holding fix near a point on our arrival route, close to Greensboro, our alternate airport. At FL240 now, we programmed the FMS and slowed down, checking out the weather around us.

Once in the hold we took scope of the situation. One storm to our left wouldn’t drift toward us, but we had a huge mass of gray from previous leftover cells right in front of us, with towering cumulus below and in front of it, threatening to become big players as it all came toward us at 20 knots groundspeed. After doing the normal routine of notifying everyone, we waited for our Dispatcher to give us our bingo fuel. We had 4800 lbs of fuel, our bingo fuel give was 3900. At our rate of fuel burn we had 30 minutes till we bugged out to Greensboro (GSO), which still had good weather at that point. I didn’t know if my bladder or the weather would last that long, however. It looked like GSO might become thunderstormed in by the weather we saw in front of us, and we could only hold so long where we were. The towering ‘cumes’ were coming closer.

ATC started offering us alternate routings to get in better position for the arrival to CLT, once they started taking aircraft in again. Quick messages to Dispatch over our electronic box, asking him to check these routes and fuel burn for us, went unanswered for long periods, it seemed at least. I know he was busy, though. I turned the engine anti-ice and continuous ignition on, because in the holding pattern a few of these spires in the sky drifting over were climbing up to meet us. If we punched any of them they were sure to have good icing potential and guaranteed turbulence, so we locked down the peeps in back and updated them on what we might encounter.

The first route they offered looked the best. We would have to fly through the big gray area, which was only painting green returns on the radar; it would be light turbulence at most, probably. We had checked the weather in GSP (Greer, SC, serving Greenville and Spartanburg) and it was fine. GSP, where the storms had already passed by, would be our new alternate if we took this routing. Impatient with dispatch, but with good fuel burn numbers indicated by our FMS, using GSP as a new alternate, we accepted the new routing from center. It was a smooth ride when a few minutes later they cleared us to hold again, at the fix we were cleared to in the first place. This was entirely expected, of course, we assumed that the storm over the airport at CLT was still closing things down and there were a few aircraft holding in front of us as well, all true. These days, in these times, you don’t want to try to land while tangling with a moderate thunderstorm producing heavy rain in two miles visibility. Too many lessons have been learned and too many lives have been lost in the past.

Programming the second holding pattern produced yellow fuel numbers on our FMS, meaning that if we held the entire time CLT approach told us we would, we would be unable to arrive at GSP with legal minimum IFR reserve fuel, 1900 lbs for our jet. Our way out was GSP as our alternate airport, and we couldn’t give it up. The storms seemed to be moving slowly out of CLT, but we didn’t have the complete big picture.

Urgency in our voices to approach control seemed to get him to respond to help us as best he could. We could see, or imagine victorious end of our fight, but it was still seemingly far away. The storms were starting to clear from the CLT airport, but there were six aircraft in front of us, , and the wind shifted to require landings from the south toward the north, necessitating a still longer flight for us. This battle had already hard fought, and I and my very capable partner were weary and fatigued from it. Dispatches new bingo fuel number for us was 3300 lbs, received after one and half turns in this second holding pattern. We had 3400, so in black and white terms we had 100 lbs left till diverting to GSP.

We were practically resigned to our fate, GSP, then were teased more by the controller. I appreciated it but was irritated at the same time, not by him personally though, he was just trying to help. It is frustrating battling the temptation to take the bait, to shave off a little integrity, safety, and legality, in order to arrive at the planned destination. And I hate inconveniencing passengers by diverting; connecting flights are missed, expletives come out in the cabin, and the stress level is tasted by everyone. But pushing (and exceeding) the legal limits in this way is a slippery slope on which I am not comfortable traversing. Any number of things could have conspired against us to make us fly to GSP after we attempted an approach at CLT.

We were inbound to the holding fix, about to tell approach we would like to divert to GSP, when he said “cleared to CLT airport via radar vectors, fly the outbound heading” (in the hold, to the northwest, away from CLT). So we did so, looked at our fuel, and a voice of experience (a little experience albeit) and caution spoke inside me. In the turn outbound we had 3250 lbs. I asked the controller ‘how far would he take us out’? “20 miles”. Twenty up and twenty back, just to get back the holding fix, then inbound on the arrival route to CLT. At about 2000 pph (lbs/hr) and 4 miles/minute ground speed that’s 10 minutes, or about 0.2 hour, or about 400 lbs of fuel we didn’t have to play with. No deal. We’d be landing at CLT with 2300, not 2700 if we had left the hold right at bingo fuel. If we had actually tried to land at CLT, then had to divert to GSP, we’d have landed with 1600 lbs, due to the 700 lb estimated fuel burn from CLT to GSP. It’s a lot of numbers, I know, but the boilerplate in the minds of airline pilots when it comes to fuel is don’t ever plan the possibility of landing at your destination or alternate with less than your legal reserve, in our case, 1900 lbs and 45 minutes of fuel.

My good FO, who actually was doing a great job, had already sent the message to dispatch that we were diverting to GSP anyway. I told approach we were going to continue to GSP, which we were cleared to then. A moment later, he asked if we could proceed direct to another fix, slightly southwest of CLT, to get on the approach corridor that way. Still no dice, we were committed to GSP, and had lost all confidence in our fuel situation. I appreciated the offer, but it was time to stick to our guns.

Greenville airport was close by, and we were high, descending at our maximum practical rate with the flight spoilers (panels on top of the wings) deployed at maximum. I kept my hand on the handle, a reminder to one that the spoilers are still extended, although the airframe buffet from the spoilers was a readily apparent clue. I spied the long runway almost below the nose, and joked with my FO “Chris” about whether we could make it straight in, or whether we should try to. Maybe with landing gear down and a sideslip we could. That would only be called for if the plane had a fire or smoke we couldn’t put out, or if an angry nest of wasps stormed the flight deck (I hate wasps).

The tower controller gave us a vector around the green area below Greenville so we could lose more altitude and get on a proper, normal approach path, three degrees to be exact. Parking on the large ramp at Greenville-Spartanburg next to the two mainline Airbuses helped to show our 50 inconvenienced passengers that we weren’t the only one in this predicament. The GSP station is used to having CLT bound aircraft divert, and I was impressed at how quickly we got fuel and new paperwork to head to CLT with. We even made one particular GSP bound passenger happy, the ramp agent escorted him and his carry on bags inside; fate had smiled on him to not require a connecting flight on this journey.

The short flight east to CLT was punctuated with diversions between a dozen rapidly developing towering cumulus clouds with tops high above our low altitude. They were already painting as red and pink exclamation points on our radar. We got a few good jolts of moderate turbulence on the way in, just for good measure. The pax were told there were thunderstorms about, after all! Have to ‘keep it real’, you know. Charlotte, fickle Charlotte, had cleared up well; it had an orange streak visible from the sun lowering behind a gap in the blue and gray tinted sky, and the express ramp welcomed us as usual with a friendly chaos.

This was perhaps weather diversion number ten for me in nine years of airline flying, but who’s counting? They never get easier; well they get a little easier every time, I suppose. Experience teaches, as things I and my crew could’ve done better are brought to light each time in a mental review.

BTW if you want to see our MDT-GSP diversion flight, click the highlighted portion. Flight aware is a very cool flight tracking website. You can see our route, holding patterns, and an overlay of the weather at that time, even zoom in on a portion.

Till next time, thanks for stopping by.


Shannon said...

Had to laugh at that part about your bladder holding out...remember Dodge City, KS? Bwahahaha! Glad you are err on the side of cautious and safe while you are on the job honey!

Flying Kites Mom said...

Captain Craig- I'm delighted to have found your blog. I've just read Fickle Charlotte-loved it- and look forward to catching up on the rest of your postings and sharing in your future crossings. lhspf

'Captain Craig' said...

SGB: Oh yea I do, and you telling me 'no that's not the airport you think it is!' That's defitely bloggable. Someday!

Flying Kites Mom, thanks for the compliment! It helps motivate me to keep at it and improve the blog.