Monday, January 11, 2016

ADS-B For Cheapskates

Never say I never give you anything, dear readers. I'm about to show you how to make a homebuilt 978MHz ADS-B receiver in 30 minutes and for under $100. I built this a month and a half ago in preparation for a major trip with the Pacer that I'll be writing about shortly, and it has worked flawlessly and been an invaluable addition to the flight bag. I used it with an iPad 2 running WingX Pro7, but it purportedly works just as well with ForeFlight and various other EFB apps on a wide variety of platforms. The commercial versions of this box (Stratus, Garmin GDL39, etc) retail for $500-800. The original parts list, assembly instructions, and code were put together by a pilot whiz named Christopher Young, who posted it to Reddit. I've just expanded, simplified and illustrated his instructions using my own recent stratux build.

Stratux is based on the Raspberry Pi, an ultra-cheap miniturized Linux computer designed for student experimentation. Don't let that scare you; you won't be dealing with the Linux OS at all. A number of Raspberry Pi kits are now offered online, such as this $70 one from Amazon; it comes with everything needed for the stratux build except for a DC power source (AC power cord is included). We'll cover that at the end. The other piece of the puzzle is a USB Software Defined Radio (SDR) dongle with antenna; stratux uses the $22 NooElec NESDR Mini2. Here's everything as it came from Amazon:

Here's everything unwrapped. You can set aside the HDMI cord and the SDR remote control, you won't be using them. 

Making sure you've grounded yourself first, remove the motherboard and the two small metal heat sinks from their packages. Remove the adhesive backing from the heat sinks and apply them to the appropriate chips on the motherboard (see below). Separate the two halves of the clear plastic case, insert the motherboard, and mate the case halves again until you hear a definite click.


Take the tiny Edimax wifi dongle out of its package and plug it into one of the four USB ports. Plug the NooElec SDR dongle into another USB port, and connect the antenna. The assembled computer should look like this:


Next, take the microSD card, use the full-size SD adapter if necessary, and put it into a computer with a SD card reader (if you don't have one, USB readers can be had for $6). Next, download the most recent release of the stratux software from this page (I used v0.4r4) and decompress the ZIP file. The resultant image file includes both the Raspbian (neé Linux) operating system as well as the stratux code. You'll need a way to flash the IMG onto the SD card, such as Win32DiskImager for Windows or PiFiller for Mac. Once complete, eject the microSD card and insert it into the microSD slot on the Raspberry Pi.

That's it. Plug the Raspberry Pi in using the wall adapter and fire up the tablet computer that houses our EFB app. Go to Wifi settings and select the Wifi network "stratux," which will appear as soon as the Pi has finished its short bootup sequence. From here the procedure will vary by EFB app; WingX automatically connects and you'll see "stratux" in a green field on the lower right of the screen when in Moving Map mode. Note that you won't actually be receiving ADS-B data unless you live right next to one of the FAA's transmitters.


Time to go flying. Here's where you have to figure out a 12V power source. If your plane has a cigarette lighter and you don't mind a little power cord spaghetti, use a 12V USB adapter and a 5v/1.2A USB-to-microUSB cord like the one that comes with practically every non-Apple phone these days. If you don't have a cigarette lighter or want a cleaner out-of-the-way setup, a lithium ion battery pack like this one is a cheap option. I normally use the cigarette lighter and keep two battery packs handy as backups (for both the iPad and stratux). You can experiment with mounting options using velcro or zipties; so far I've just left mine sitting on the glareshield (on the right side, below pic was while testing).


So far I've found that the antenna works best in its retracted position; orientation doesn't seem to make a difference. I start receiving ADS-B data somewhere between 500 and 3000 feet depending on how close I am to a transmitter. The text weather is very quick; it only takes a second or two to update every airport within a 250 mile radius of the transmitter. The radar takes a little longer, sometimes doesn't load at all if ADS-B signal strength is weak, and of course there are the well-known latency issues, but its still a valuable resource for making strategic decisions.

I expected to mostly use the stratux for weather updates but I've found the traffic feature unexpectedly useful. True, it doesn't show all targets and sometimes it doesn't work at all (since I don't have ADS-B Out, another airplane that does has to be within 25nm of me) but is nevertheless a welcome aid to the Mark I eyeball. Several times already I've been alerted to potential threats before ATC called them out, and on one occasion I declined an erroneous instruction by an overwhelmed tower controller based on traffic I didn't see but ADS-B showed was there. I'm still a bit miffed at the way the FAA is handling the ADS-B Out mandate, but I can certainly see the practical upside to the system once everyone is participating. I just wish there was a VFR ADS-B Out solution as cheap and elegant as the stratux.

Monday, December 14, 2015

The Last Tour

I was originally awarded the 757/767 back in February, but this came on a fairly open-ended bid that allowed the company to converted awarded pilots more or less when they pleased (though always in seniority order). At the time the thinking was that they needed us on the line yesterday, and I assumed I'd be trained and on the line by July. As it turned out, I was dead wrong and got to enjoy another sweaty summer on the Mad Dog. I then would have been placed in training in October, except that was when I had two weeks of vacation, and in the bid preferences I had asked for the vacation to be honored. After all, that was when I was heading down to the BVI for my fourth year of sailing in the Interline Regatta. Because of the vacation, PBS only assigned me six days of flying in October, a four-day trip before the regatta and a two-day to end the month. I was subsequently assigned a 6 Nov class date, and despite my best efforts to get 1-5Nov off, PBS assigned a two-day trip on the 1st and 2nd.

I caught a lucky break and had my early October trip pulled for newhire OE, since I was paired up with a line check airman. This left me with only four days of flying to finish up my stint on the Mad Dog, 30Oct-2Nov. Coming back to any airplane after a full month off is a little uncomfortable, but once you've been on it a while it only takes a leg or two to get back into the swing of things. Of course I'd already been hard at work studying for my new airplane for a few weeks, and I had a couple minor screwups due to the negative transfer (on one takeoff roll I accidentally called "80 knots, throttle hold, thrust normal" instead of "Clamp, 80 knots, thrust normal" - which the captain thought was hilarious). Overall, though, I didn't make too many "short-timer's" mistakes.

Lord knows there was plenty of opportunity to screw the pooch. The first three days were a hilariously bad compendium of the assorted and well-known ravages of Mad Dog flying that keep senior FOs on widebody fleets long after they can hold MD captain. The weather was dogshit all up and down the east coast - low ceilings, wind, and rain - with the attendant flow programs and major delays going in and out of hub airports. We seemed to have maintenance issues on nearly every leg: a bunch of MELs, or unusual ones that required extra study, or open writeups from prior crew, breakages during preflight, and glitches enroute. We had the exact same malfunction I wrote about in my column earlier this year: the FMS spontaneously dumped all route and performance data, apparently due to a momentary power interruption. This time it happened while descending at night on a complex RNAV arrival (and getting the snot kicked out of us in heavy rain); I saw the problem right away and immediately reverted to lower automation levels while the captain coaxed a simpler clearance out of the clearly-displeased controller. That was on leg three of a long four-leg day - with two plane swaps - in and out of our largest hub. The next leg (different airplane) saw me hand-flying a no-kidding ILS approach into mountainous Asheville, NC, after the autopilot did a decidedly unsatisfactory job of tracking the localizer. We broke out about a hundred feet above minimums. Despite our late-night arrival and the driving rain, the captain accompanied me to one of my favorite Asheville watering holes for a nightcap. The brew went down easy on my last Mad Dog layover.

The last day started the same as the first three, with rain and low ceilings prompting flow delays into "Mecca." Our last leg to Minneapolis, thankfully, was blissfully smooth once we got past Nashville. The weather was decent in Minnesota, we broke out of the high overcast to see the lights of the Twin Cities stretched before us, and ATC cleared us for the visual approach quite early. I clicked off the autopilot and autothrottles at 8000 feet and enjoyed my last time handflying the old gal around the pattern to Runway 12R. My last landing wasn't perfect, but it wasn't horrible either; I'll take it. It was a little surreal to think I may have landed that plane for the last time, though I rather suspect I'll have another crack at Mad Dog wrangling at some point in my career. In the meantime, I've been advised that any misplaced nostalgia for the Mad Dog will likely disappear right about when I land the Boeing 757 for the first time!


Wednesday, December 02, 2015

Ode to Mad Dog

Long before I was assigned the Mad Dog, I knew I was destined to fly her. My company assigns seniority within new-hire classes according to the last four digits of your social security number, and with a sub-0300 SSN I was guaranteed to be one of the most junior in my class and assigned by default to the most junior seat at the airline: New York Mad Dog FO. I was at peace with that, and after six plus years of the stultifyingly automated JungleBus I was honestly ready for a challenge and a change of pace. The Mad Dog’s rugged design and old-school cockpit held a certain attraction for me, and my only real regret was that I never got a chance to fly the DC-9 before it was retired.

That said, I wasn’t quite prepared for just how busy the Mad Dog is, particularly in the right seat during ground operations. The preflight, pushback, after engine start, taxi, before takeoff, after takeoff, descent, approach, before landing, after landing, and shutdown flow patterns and checklists are all considerably longer than on the JungleBus (a couple of those nearly three times as long). Engine starts just about require three hands. Quite a few switches on the right side of the cockpit belong to the FO even while Pilot Flying with the autopilot off. The airplane has VNAV and autothrottles, but both are glitchy enough to require close attention and frequent intervention to smooth out their operation and ensure compliance with restrictions. The relatively small wing means that very careful attention must be paid to speed and maneuvering margins both after takeoff and at cruise altitude, which seldom exceeds FL330. The brakes are by turns pitifully weak and unpredictably grabby, and it’s nigh impossible to symmetrically deploy and spool up the thrust reversers. This is an airplane with a fairly steep learning curve; I did well in training only by studying my ass off (it also helped to have a sharp training partner with experience on the airplane).

Coming to the line as a brand new FO was an eye-opening workout. Many of the captains I initially flew with on reserve had been on the airplane for years and were used to an experienced FO’s pace of operations. I sometimes had to remind them that I was new and needed a little more time. Every trip I made mistakes, found more gotchas, learned new tips and tricks, and saw more unfamiliar glitches and failure modes. There’s a lot of tribal knowledge among Mad Dog drivers, much of it not written down anywhere. And then, after a couple months, I was able to hold a junior line and often flew with captains who were themselves brand new to both the airplane and the left seat. With only a couple hundred hours in the airplane, I was occasionally the “experienced guy” passing on my scant slice of the tribal knowledge.

I passed the magic 400-hour mark, releasing me from probation, after only five months of line flying. Remarkably, I found myself getting comfortable with the airplane. Actually, that’s not exactly the right way to put it, because I continued watching the Mad Dog as closely as ever, if not more so. Perhaps it is better to say that I got comfortable with being uncomfortable. Relaxed preflights, clean uncluttered cockpits, flawlessly smooth autopilots and autothrottles, and trying to stay awake as we blithely cruised across the country at FL370 all faded from memory until they seemed like distant, fanciful dreams. I came to simply accept the Mad Dog’s flaws and quirks as just the way life is. I didn’t pine for a more relaxed, more sophisticated airplane. The hardest part of coming to the Mad Dog is coming to the Mad Dog, and that was already done.

And in fact, once I accepted the plane’s busyness and quirkiness, I actually found quite a few things about it that I really liked. For starters, it’s built like a brick shithouse. The systems are simple and robust, and while there’s not a great deal of redundancy the plane doesn’t really need it as it’s not horribly dependent on hydraulics, electric, etc. The primary flight controls are all manual, with control cables driving servo tabs. It hand flies pretty well for being a notorious truck; though control forces are fairly high, it’s easy to put the plane right where you want it and keep it there. Near-centerline thrust makes single-engine work a cakewalk. The extension speeds on the very draggy flaps are ridiculously high (starting at 280 kts) so it’s easy to get down when you find yourself high. The pilots are so far forward of the engines that even on the JT8D model it’s really quiet, and though the cockpit looks like the bridge of a Russian submarine, it's actually laid out pretty logically. The Flight Mode Annunciator may look like a 1980s football scoreboard but it’s large and visible in any lighting conditions. And once you figure out the myriad controls for the cockpit lighting, it’s almost infinitely customizable which makes for a very comfortable nighttime environment.

I found myself growing downright fond of the airplane. More than one friend suggested that my newfound appreciation for the Mad Dog was nothing more than Stockholm Syndrome. Perhaps. The reality is that, much like taildraggers, a certain amount of the Mad Dog’s cachet comes not despite its flaws but because of them. It’s frequently stated to be a “real man’s airplane” (though I hasten to add that several female friends have flown it for years and claim to love it). Airbus pilots, like Cherokee drivers, are considered perhaps a little suspect for no other reason than that their airplanes can camouflage weak flying skills, while Mad Dog wranglers, like tailwheel pilots, get a (sometimes undeserved!) presumption of competence. In 757/767 training, each instructor has asked what fleet I’m coming from and, informed of my Mad Dog status, to a man they’ve given a relieved little wave and assured me I’d do great on the Boeing.

Given all this, I wasn’t planning on leaving the Mad Dog anytime soon. I enjoyed the fruits of its juniority, spending a mere six weeks on reserve in New York, soon thereafter holding weekends-off regular lines, and then getting back to Minneapolis after eight months of commuting. Of the other aircraft in my base, the Airbus has remained improbably senior (nobody wants to leave it!) and the 757/767 category was slowly shrinking. But then pending aircraft retirements were cancelled, the category got additional flying, there was movement from senior FOs upgrading to captain, and suddenly there was a bid out for fifty (!) MSP 757/767 FOs. I ran the numbers and concluded I’d have about the same seniority in either airplane. The Boeing paid more and had better trips, though I might not be able to hold international flying. I was still undecided when I had lunch with (now-former) Flying editor Robert Goyer on an Austin layover. I mentioned the possibility of bidding the Boeing but noted I’d have to spend a month at training. “Don’t you like training for new airplanes?” prodded Goyer. He had a point, I actually do, and I've wanted to fly the 757 since I was ten years old. That decided it; I put the bid in that night.

I was awarded the Boeing in February and didn’t start training until November 5th, so I had plenty of extra time to appreciate the Mad Dog. The last four days on the plane were so hilariously Maddogish that they merit their own separate post. Meanwhile I wrap up training on the Boeing in a couple days and will be enjoying some paid time off over the holidays while I wait to be assigned OE/TOE. 


Saturday, November 28, 2015

Across the Sea

(Originally written back in August)

"So, you're an airline pilot, huh? Do you fly the big planes?"

"Eh, more medium-ish. 149 to 160 passengers."

"I see. What's your route?"

"It changes from week to week. I go all over the U.S., but probably 75% East Coast."

"Oh. Any overseas routes?"

"No, the plane I fly is pretty range limited. I do a little close-in international."

"Like South America?"

"No. Like Nassau."

Such is cocktail party conversation as a Mad Dog pilot. My 757/767 friends talk of Paris and Palau and Rio, and such exotic ports of call may well beckon in my near future, but for now I mostly ply my trade to places like Huntsville, Buffalo, and Columbus. I have not yet landed in the Great White North with my new company. I have flown turns to Nassau several times, but was rerouted out of my one overnight there. I've laid over in Kingston, Jamaica; a tropical paradise it is not. Atlanta-based Mad Dog driver friends report dreamy wanderings to Providenciales (Turks and Caicos), Montego Bay, and Grand Cayman, but I do not believe any MSP Mad Dog wrangler has ever laid eyes on those bejeweled realms. We do, however, fly to Cancun, Mexico, and in fact I have gone there twice, most recently this past week.

Cancun is actually about as International as our humble fleet gets, for it involves legitimate "offshore" flying. Our other Caribbean destinations involve going "feet wet" (our New York-Florida routes also go offshore more often than not), but always within 162nm of land. This is as far as we can go without life rafts, with which only a handful of the Mad Dogs are equipped. The Cancun route nearly always goes further out and thus requires the raft-equipped aircraft. I'm not sure how 162nm came to be the magic number, as it seems somewhat arbitrary, but I surmise it must somehow relate to the offshore capability of rescue helicopters. I'm not certain that I would want to be 161nm from land with nothing but a life vest keeping me afloat and marginally visible to would-be rescuers, but don't ever plan on testing this scenario in depth.

Our jaunt across the Gulf of Mexico also exposes us to the world of Class II navigation, meaning outside of the reception area of most VORs. Not to worry, the Mad Dog's modern navigation equipment frees it from dependence on obsolescent land-based navaids. No, not GPS, silly! A $50 burner flip phone may have GPS accurate to within a couple feet, but not the Mad Dog! We use Inertial Navigation System, or INS, for long-range navigation. We have to do a full realignment before such a long flight, and then check it against a trusty ground-based NavAid before launching out into the trackless ether.

We also fly outside of the reach of radar for a short stretch, right around the changeover from Houston Center to Merida Center. Thus, we get a little practice in making position reports, usually on first contract with Merida southbound or Houston northbound. This still takes place within voice VHF communications range - we don't have HF radios installed, much less the CPDLC datalink systems now commonly used for trans-oceanic communications. The only communications challenges on Mad Dog international flights are of the linguistic variety: Mexican and Cuban controllers converse with local pilots in Spanish, making it a bit harder to keep track of who's doing what (my high-school/traveler smattering of Spanglish helps); their accents when speaking English also vary considerably, from slight to barely comprehensible. You just have to listen carefully and make inquiries if anything isn't perfectly clear. Recording the ATIS usually takes a few loops, and you definitely want the captain listening in before attempting to transcribe your clearance.

On my next fleet, of course, there will be far more opportunities to do overwater flying. This is an airplane that we operate to five continents, and I see all five represented in the MSP bid packet. Of course I'll be fairly junior so it's likely the majority of my flying will be domestic, but I think I'll be able to occasionally sample trips that take me further afield. The variety of flying was one of the reasons I bid the new category. Dawn and I have traveled to many of the places that the Boeing flies, so it's not necessarily the attraction of visiting new places, but moreso the appeal of doing something completely different than I've been doing for the last twelve years. I'm both a night-owl and able to sleep almost on command, so I think I'll be able to adjust well to the schedules (fingers crossed). And, of course, far-flung flying adventures always make good fodder for blogging!

Monday, November 16, 2015

Not Quite Dead

Well, uh, sorry bout that folks - I went NORDO for a couple months, which had readers wondering and querying whether the blog was dead. Nope, it's not dead - it's just restin'! But I think its rest is just about over.

Here's the long and short of it. You may have heard that my airline had a minor labor kurkuffle this summer when our pilots - for the first time ever - turned down a tentative agreement (65%-35%) and subsequently pretty much overturned the apple cart at our chapter of ALPA. I took an active and somewhat visible role in the fight against the TA, heard through the grapevine that my name had come up in high places, and decided I'd better lower my profile for a little while. I wasn't about to stop writing for Flying, but figured I could take a little break from blogging until things settled down. Well, now that the dust has cleared, we have a new MEC Chairman, a new Negotiating Committee, and a lot of new reps - all this a full month before our current contract becomes amendable. I suspect the more traditional contract negotiation process we're about to enter will drag on for several years, as it has at other companies. I'm not going to refrain from blogging that long. Writing has a certain intertia to it. Start writing, and you'll tend to keep going. Stop writing, and you tend to stay inert. In reality I probably could have resumed blogging a month or two ago.

The good news is that I have a bit of a backlog of things to write about. I actually have a few already-written posts that I'll release over the next couple days, and then I'll reflect on my last days on the Mad Dog and the preparation for and first several weeks of 757/767 training (I'm about halfway through right now). In the meantime, you should definitely check out Flying's December issue. Besides my usual column, I have a six-page feature about the flying/sailing trip to the Bahamas that I think turned out really well. Enjoy!


Monday, July 27, 2015

If Every Day Were Like Oshkosh...

You'd awake every morning at 6:30am to the beautiful music of Merlin V12s at full power as half a dozen P-51s roar overhead to embark on the dawn patrol....

You'd cheerfully chat with perfect strangers while standing in line for a lukewarm shower in a portable shower block....

You'd plan every day over eggs & pancakes at Tall Pines Cafe, deciding who you want to hear speak more that afternoon: Burt Rutan or Bob Hoover....

You'd forget that air conditioning exists, spend every day gloriously bathed in sweat, thank heaven for every little wisp of wind, and find yourself pausing in the shadows of DC-3s, B-17s, and A350s....

You'd come to find farmer's tans incredibly sexy...and your standards for attractiveness in the opposite sex would ease considerably....

Instead of traveling overseas, you'd take a 10-minute bus ride to the Seaplane Base and marvel at how quaint and beautiful and relaxed it is....

You'd almost never see litter on the street. On the rare occasions you did, someone would usually swoop in to pick it up before you could get to it....

You'd live off of burgers and cheese curds, and you'd still stay skinny from walking twenty miles a day....

You'd never actually talk to Air Traffic Control, only rocking your wings in reply. All air traffic controllers would be extremely proficient, calm under fire, and unfailingly friendly....

You'd think IFR stands for "I Follow Railroads...."

You'd be an ace at last-minute runway changes, short approaches, and spot landings....

You'd check your Facebook feed, see that a good friend just landed, and arrange to meet under the Brown Arch in an hour. Really good friends would insist on trekking two miles to admire your airplane parked in the South 40....

Your musical tastes would narrow to 70s rock, modern country, and Jerry's One Man Band....

You'd swear off airshows forever, declaring you've seen Sean Tucker doing enough impossibly violent things to airplanes to last a lifetime, only to spy a new act featuring something improbable, graceful, and arresting, and you'd end up right back on the flight line with every other slack-jawed, sky-gazing rube....

You'd go to an off-airport party, run into random friends and former coworkers and aviation journalists and airshow performers and aviation legends, and the most remarkable coincidence of the night would be meeting a guy whose hangar is right next to yours back home....

You'd find sitting in the bleachers of the ultralight grass strip at dusk, watching powered parachutes making endless circuits and passes just for the sheer joy of flight, a perfectly acceptable form of evening entertainment....

You'd drift off to sleep every night under the wing of your own airplane, bedded on soft grass, knowing you'll wake up to the roar of Merlin V12s and the promise of another full day in Airplane Heaven....

Alas, Oshkosh comes but once a year. Only 51 more weeks to go!

Thursday, June 18, 2015

Hot Dog!

As mentioned a while ago, I've been awarded a slot on the 757/767, but training isn't until late October and that means I get another four months on the Mad Dog. I just had lunch with a couple of guys down in Atlanta yesterday, and though they now all fly the 757/767 one noted that he had spent "five summers on the Mad Dog...because you always measure time on that airplane in summers!" I suggested that if he's ever really bored in cruise, he should attempt to calculate how many gallons of sweat he shed over those five summers. Or not - I guess that's kinda gross.

The basic problem is that as the Mad Dog was stretched from earlier airplanes, the Auxiliary Power Unit and Air Cycle Machines ("packs") were not also upgraded to accommodate the increased cabin volume. In moderate temperatures or with both engines running at high power to put out a lot of bleed air, it's not really a problem. On the ground with a high OAT, though, both the amount of airflow and output temperature are wholly inadequate. The cockpit is a bit worse than the cabin, because you have a lot of windows, the old CRTs, electronics, and incandescent lighting put out a lot of heat, and you're sitting 120 feet forward of the packs with resulting efficiency losses through the ductwork. At times it can get miserably hot in the cockpit, especially when you're busy just before pushback. In the summer you just about have to pack a new uniform shirt & undershirt for every day of the trip.


Out of my duties as a Mad Dog FO is running the AC, largely because most of the controls are on the right side of the overhead panel. There are some tips and tricks to getting the most out of the system, and most FOs get pretty good at it. The primary controls are the packs supply switches with OFF, AUTO, and HP BLEED OFF positions, and two selector knobs, one for CKPT TEMP and one for CABIN TEMP. The indicators are L and R valve position gauges and flow gauges, as well as a larger temperature gauge that indicates either cabin temp or cabin supply duct temperature, depending on the position of a TEMP SEL knob. Most of the time this is left in the CABIN SPLY position, which along with the valve indicators is a good measure of what the system is doing at any given moment; every couple of minutes I'll flip the TEMP SEL knob over to Cabin to see how we're doing overall.

We nearly always leave the Supply switches in the AUTO position except when parked at the gate with APU off and the conditioned air hose attached to the aircraft, at which point we turn them OFF. The HP BLD OFF ("High Pressure Bleed Off") position is rarely used, though there are circumstances when it can slightly increase airflow. The temp selector switches can also usually be left in the AUTO range, which commands the system to try to attain and maintain a specific cockpit and cabin temperature. The problem is that the exact temperature you're commanding is not labeled, and every airplane is different! Most airplanes have little ink marks that previous FOs have added to show a position that works, and this makes a good starting point, but there are often multiple marks as the system changes over time with wear, maintenance and repairs. Sometimes it seems to change over the course of a single flight!

On the ground with OATs warmer than about 60º F, we leave both selector knobs pointing at about the 9 o'clock position, which commands both valves full cold and gives you about as cold of air as you can expect (sometimes adjusting them slightly higher can increase airflow, however). After takeoff, we turn the cockpit selector knob to around the 10:30 position and the cabin selector knob to slightly below whichever ink mark we've decided to use as a reference. The idea is to get the cockpit valve slightly above full cold, and the cabin valve right around the first index mark (as shown in the picture above). You want the cabin supply temperature to come off the bottom peg (lest you freeze the passengers out before decreasing the overall cabin temp to comfortable levels); I've found an initial supply temp of 50-60ºF works well. As the cabin temp comes down to the desired level (I shoot for 68° or so), I adjust the temp knob slightly higher into auto range - usually right around the reference mark - where ideally the system will modulate the supply valve to maintain a comfortable temp on its own (80-90° supply temp works well). Any further adjustments to the temperature knob are best made slowly and in small increments, lest you drive the valve full hot or cold. I've found that in about 75% of the fleet, you'll end up turning the cabin temp selector slightly lower over the course of the flight, and the cockpit temp selector slightly higher.

Sometimes AUTO mode just isn't working no matter what you do, and then we turn the affected temp selector knob to the six-o'clock position, which puts the respective pack in manual mode. At this point you are directly driving the supply valve with momentary selections hotter or colder; however, output temperature can still vary depending on engine power / bleed output, and more than one pilot has left a pack in MANUAL mode, didn't pay attention when the throttles came back on descent, and was surprised to find that the output temperature was driven so high that it tripped the pack offline altogether. The preferred technique if MANUAL mode is needed is to get the supply valve where you want it, let output temp stabilize for a minute or two, and then switch back to AUTO mode and see if it does a better job of maintaining supply valve position.

On descent, depending on destination OAT, you'll typically once again turn both knobs to the 9 o'clock position in an attempt to cold-soak the cabin before arrival - as temps are nearly guaranteed to rise on taxi-in. If it's very warm at all, I start the APU immediately after landing and open the crossbleed valves so it can assist with airflow. We normally shut down the #2 engine three minutes after landing for fuel savings, but with OAT over 85ºF we occasionally keep both engines running to the gate (especially in an airplane that has trouble keeping up on a single idling engine + APU). Once both engines are shut down at the gate, the cabin temperature is almost guaranteed to climb on APU alone; it's basically a question of how quickly you can get the warm bodies to exit the airplane! Nearly all of our gates have large and capable air conditioning machines with supply hoses, and the better rampers get these hooked up and running very quickly. In warm weather they almost always do. The problem is that in 60º-70º weather they often don't realize that this conditioned air is still very necessary on the Mad Dog. The proactive pilot will go outside and make sure they still hook up the air. Once this is complete, you can save fuel by shutting down the APU in all but the hottest temperatures.

This all applies to the normal Mad Dog. On the Big Dog, which makes up about 30% of our fleet, the controls are the same but the actual system components are different and require a different technique. The good news is that the APU is bigger and has more bleed output, and is often able to maintain a comfortable cabin temperature on the ground all on its own or with a single engine running. The bad news is that the system is far more aggressive and volatile in AUTO mode. It will run the supply valves from full cold to full hot with a tiny movement of the temperature selector knob, or sometimes all on its own. The initial after takoff setting of the knobs requires particularly close attention for the first several minutes, meaning that at a fairly busy time I'm looking up at the overhead panel every 30 seconds or so. It's far more common to have to run for a while in manual mode on the Big Dog.

This all sounds fairly labor intensive, and it is when you're new to the system, but once you're acquainted with its quirks it becomes second nature, much like the rest of the Mad Dog. I have a feeling that once I go to the 757/767 I'm going to initially be a little restless, feeling like I ought to be doing far more than I am. I'm sure I'll get used to the reduced workload, though - not to mention skating through summer as cool as a cucumber!