Monday, October 05, 2009

Construction

"NewCo fifty-seven fourteen, holding instructions for you, advise ready to copy."

My First Officer looks up from the FOM he is studying in preparation for an upcoming training event and gives me a quizzical look. "Was that for us?" he asks.

"NewCo 5714, you copy Minneapolis Center?"

Well shoot, it was for us. NewCo recently switched their flight numbers from the 1800-2099 range to the 5700-5999 range, and I'm not quite used to listening for the new numbers. I grab the release and a pen. "Center, NewCo 5714, sorry 'bout that. Ready to copy."

"Minneapolis Center clears NewCo 5714 to SKETR intersection, hold southwest as published, twenty mile legs approved, expect further clearance two two five five zulu, time now two one five niner zulu."

I read back the clearance and begin entering the hold into the Flight Management System by selecting "Hold" from the NAV page, then entering it over SKETR on the Flight Plan page. This brings up a form where I enter the inbound course, leg length, holding airspeed and altitude, and expect further clearance (EFC) time. Punching the 6R line select key inserts the hold into the flight plan, displaying the proposed route in white dashes on my MFD's map display. My FO looks over to verify that the hold looks correct, gives me a thumbs up, and I hit 6R again to activate the flight plan. The FMS takes about ten seconds to recompute everything - I've become so used to it that I no longer make 286 processor jokes - and then displays the hold in solid white on the map display, signifying that it is indeed active. At this point, the FMS will automatically choose the correct holding entry, enter the hold, and continue until we tell it to do otherwise. It's a mockery of all that holding practice over NDBs in 30 knot crosswinds that I did as a young pup.

"Wonder what's going on in Minneapolis?" my FO muses. I shrug and request a new D-ATIS from the FMS' ACARS menu. It takes about thirty seconds to pop up; it's still the same ATIS I pulled up about 30 minutes ago. The weather isn't too bad: 2100 foot ceiling, eight miles visibility, winds out of the north at 15 knots. That last item is likely the cause of the delays. Runway 12L/30R is under construction, and Minneapolis is down to three runways that all intersect or nearly intersect each other: 30R/12L, 35/17, and 4/22. So long as the weather is nice and the winds are light or from the south, ATC can keep things humming along smoothly with approaches to runways 17 and 22 (land and hold short of 17) while they fire departures off 12R in quick succession. Meanwhile ground control lines up all the crossing traffic on each side of 12R and crosses them en masse whenever departures pause for an arrival to 22. It's a thing of beauty to watch when everything is running smoothly.

It doesn't take much to mess up the plan, though. Marginal weather takes away Land and Hold Short Operations (LAHSO) so that the arrivals must be staggered, or else ATC will use 17 as the sole arrival runway. If the ceiling gets much lower, it takes away both 22 and 17 for arrivals since those runways are served only by localizer approaches with fairly high minimums. In this case arrivals use 12R and departures use 17, which really gums up the works. Winds from the north, while not as problematic as a low ceiling, do also slow things down. Since the construction began in early September, ATC has become very good at predicting how the weather will affect the maximum arrival rate and issuing ground holds accordingly to make sure the arrival banks don't all arrive at once. This is only the second time I've had to hold so far.

Entering the hold into the FMS automatically changed the Estimated Time of Arrival and Estimated Fuel at Arrival display to reflect the extra 45 minutes of holding at FL240 and 230 knots. It's a nice feature that can make a captain lazy. However, I'm rather mistrusting of machines in general and of the JungleBus' Flight Management System in particular. If there's anything I've learned in two years of flying the JungleBus, it's to not believe a thing its computers tell me. Every software patch that fixes one bug seems to introduce two new ones. It's very reliable for navigating from point A to point B, it's just the theoretically labor-saving features like VNAV and fuel management that give us plenty of "what's it doing now?" moments.

Therefore I pick up a pen and paper to do some quick and dirty figuring. I conclude that this time the airplane is not lying to me and we will indeed land right at what I consider to be our minimum arrival fuel - 5200 lbs, enough to go to our alternate of Rochester plus 3000 pounds of reserve fuel. This is slightly more than the minimum fuel shown on the release, because their reserve is based upon 45 minutes of long-range cruise at 10,000 feet and is generally 2200-2400 pounds. I don't ever want to land with that little fuel in the tanks so I use a more conservative number. I add the fuel burn from SKETR to the airport to that minimum arrival fuel, throw in a few extra hundred pounds for vectoring, and write down our "Bingo" fuel number on the release after discussing it with the FO. We will reach it right at our current EFC time. Fortunately our dispatchers have been very liberal with holding fuel throughout the construction.

It's time to let our dispatcher know what's going on. I text him our holding point, EFC, altitude, fuel on board, and my calculated bingo fuel. A few minutes later he texts back an acknowledgement along with his own calculated bingo fuel, which of course is 800 lbs less than my number. We enter the hold and I make a short PA to the passengers about the delay.

After about twenty minutes in the hold, I start hearing Minneapolis Center extending other flights' EFC times. Several divert to their alternate airports. I query whether our 2255Z EFC is still holding up, and Center replies that it is - for now. I check the Minneapolis weather again. It's still good. The reality is that my bingo fuel number is a little more conservative than it needs to be, because it assumes that I'll be vectored for the approach, fly it to minimums, go missed approach, and then fly to Rochester. Diverting from SKETR - or even from any part of the downwind or base leg for Runway 35 - will require a lot less fuel. My FO and I discuss the fact that an alternate isn't legally required; we could have our dispatcher remove it and hold for a while longer, but still divert once we got down to 3000 lbs plus the fuel needed to reach Rochester. In the end, I decide not to officially remove the alternate, but to use our dispatcher's bingo fuel number instead of mine. The reality is that once we get past SKETR, the likelihood of a diversion drops to near zero and some 4600 pounds of fuel in the tanks on landing in MSP is plenty in this situation. The difference gives us almost twenty extra minutes of holding.

It turns out that we don't need it; as if to mock all my contingency planning, Minneapolis Center clears us past SKETR twenty minutes before our EFC, and we land with 6200 pounds of fuel remaining. It takes us a while to reach our gate on the G concourse because the departure lineup for 30L extends all the way to Runway 22! Thankfully, the backlog has mostly cleared out by the time we leave an hour later. I smile as we climb westward into the setting sun. We're going to Montana, where the beer is good, the gate agents are friendly, and even airports under construction are blissfully delay-free.

13 comments:

Mark Richards said...

"We're going to Montana, where the beer is good, the gate agents are friendly, and even airports under construction are blissfully delay-free."

Surely, you were not inspired by Garrison Keillor:

"Welcome to Lake Wobegon, where all the women are strong, all the men are good-looking, and all the children are above average. "

Wayne Farmer said...

Sam, your distrust of avionics software is understandable. It's those rarely-used features of the software that are most likely to have unreported bugs. Software developers like myself try to test all the features, but it's nearly impossible to test all the possible combinations and sequences of events, especially those events which shouldn't have anything to do with each other, but somehow do.

Like the Flight Level 390 blog, you provide a revealing look into the cockpit for those of us in the cabin. Prior to these posts, I thought that the pilot's job would be fairly routine, but I'm learning that coping with regulations, paperwork, equipment, and weather can make each flight an unexpected event for the crew.

Sarah said...

Interesting post!

Last week's weather was interesting in MSP. Wednesday, I think it was, I noticed a midday thunderstorm out my window and pulled up MSP's "flightaware" display. ( Yes, I can too do my job with such a screen saver. :) )

The weather went from fairly calm with light rain to heavy rain and wind suddenly. I think there was a windshear alert, or sudden wind shift at any rate, as I noticed the conga line of arrivals down 12R each peel out to the right and enter holds in place.

This in addition to a half-dozen already holding SW of MSP ... hey, that must have been SKEETR. Maybe one of them was you. Arrivals returned to 12R after about 20 minutes.

It does sound like holds on FMS ( or for us GA types, Garmins ) are effortless compared to hand-flown NDB/VOR holds. I guess you earned it - and so will I, as the airplane I will take my checkride in still has an ADF, and still has no autopilot.

GreenPilot said...

awesome new post. holding patterns are currently giving me and my classmates night terrors-but you describe a mastery of what seems so complex for us.

wondering if the EFC time is par for how long you're usually instructed to hold for. to a fairly new instrument pilot like myself, holding for anything longer than 10 minutes seems like an eternity.

also: at what point does your remaining fuel become an issue as to potentially have to depart for the alternate?

Tim G in MN said...

Sam,
I listen to KMSP ATC and Tower in the internet at my desk while I work (which is better than crusing Facebook, which my boss calls "Social Not-working")and as you point out, those folks really have their hands full some days with the runway situation. Very professional and patient. Passengers need to be too as it feels like you're driving all the way to Chicago instead of flying with the long taxi routes and runway crossing holds!
Hang in there, Winter Will Come!

Tim G in MN

Tim G in MN said...

PS: I just got my newly converted from Perks to Skymiles number via email... made me think about your post today and wonder: "Why don't I get extra miles credited for holding patterns?" Hmmmm...

Tim G in MN

Aluwings said...

It's nice to hear flights ahead having to "bug out" for their alternate because I figure that should move me up in line (as seems to have happened for you here). But then, I don't know how many bugged out ahead of them, and they still didn't have enough fuel to make it.

Some days I can't help thinking, there's gotta be a better way to coordinate all this.

Thanks for writing. Always enjoyable reading.

Portable Storage said...

Thanks for the article.Your article was pretty informative and i hope that in future also i get these kind of article.

Thanks,
Portable Storage,
www.moveablecubicle.com

zb said...

Like Mark Richards, I was also expecting the last words to be something like "above average". As in: We're going to Montana, where the beer is good, the gate agents are friendly, and even airports under construction have controllers that are faster than average. The Prairie Home Companion is soooo nice!

Sam said...

Being in Montana at the moment, I can certainly say the temperatures are below average! Got down to 1F last night.

GreenPilot: Normally if we already have an alternate and the weather still requires it, I'll hold until we have enough fuel to get to the destination, fly an approach and go missed, fly to the alternate, land, and still have 3000 lbs (45 mins-1hr) remaining in the tanks.

If we don't have an alternate, I'll pick a potential diversion airport as soon as we begin holding. Not just any airport with a 5000' runway will do: it should be in our op specs, preferably served by RedCo/Widget or one of their regionals, and better yet with a JungleBus towbar or airstairs handy. I calculate the fuel required to go to that airport from the holding fix, and will divert if my fuel falls to that number plus 3000 lbs OR the fuel required to go to the destination plus 3000 lbs - whichever is greater.

Portable Storage said...

Thanks for the article.Your article was pretty informative and i hope that in future also i get these kind of article.

Thanks,
Portable Storage,
www.moveablecubicle.com

Tim G in MN said...

Runway 12L/30R is now open!

mukesh said...

it's a really nice blog thanks for add my comment...

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