Pelican’s Perch #70:
Gulfstream IV Part 2

Last month, AVweb's John Deakin told us what it was like to live the life of an itinerant Gulfstream IV pilot. This month he digs into the actual operations in the cockpit and, guess what? It's a good thing he likes computers and can read computer screens.


I‘ve always liked Grumman airplanes. They range from the funky (the Duck and the Widgeon) to the awesome (Bearcat). What does that have to do with the Gulfstream? The lineage, and history. Grumman built the first Gulfstream, a Gulfstream I (a twin turboprop). Over the last 40 years the company has gone through the now-common American corporate transmogrifications that obliterate the history and give rise to those long, hyphenated names that eventually end up as acronyms that contain the initial letters of some of the companies previously absorbed or discarded. Then the acronyms get merged, and hyphenated, and the process repeats.We lose a lot of history, that way.The name today is Gulfstream Aerospace Corporation, and while no trace of the original manufacturer remains, I could swear I hear a soft whisper in my ear (“Grumman”) anytime I see one, and I still flashback to “Grumman Gulfstream.” There is more than a little of the famous Grumman solidity and “feel” to the airplane, too. One common nickname in bygone years was “Grumman Ironworks,” intended to convey strength and ruggedness. Others took that to mean “overbuilt,” or “unsophisticated,” and perhaps that had something to do with the name changes.

The Digital Cockpit

Gulfstream IV Cockpit
Gulfstream Cockpit (click for larger version)

For those with no “glass cockpit” experience, the front office looks like something straight out of “Star Wars,” and at first, it’s just about as mysterious. The front panel is dominated by six, very large, TV-like screens called “Display Units,” or “DUs” for short: two in front of each pilot, and two in the center. With no power on the airplane (or in some failure modes), they stare out as if they are large, square, dull black eyes, giving no information at all. They look downright hostile when they go dead in-flight! Properly powered, they are capable of displaying more information than you ever dreamed of, with more lights than Times Square. With automatic and manual switching, most information can be displayed on any of them, and a large part of training is learning how to control them, and what they are trying to tell you. My favorite comment was, “I feel like a dog, watching TV.”

The “outboard” DU (properly called the “PFD,” for “Primary Flight Display”) in front of each pilot contains all the old flight instruments, but in electronic form; nothing more than electrons dancing on a screen. These include the horizon, heading navigation display, altitude, speed, vertical speed, angle of attack, and a whole host of little bits of data sprinkled all over, showing the modes and status of the autopilots and autothrottles, distances to go, etc. Many of them change automatically, so if you look away, and then come back, something has probably changed.

PFD Details (93 Kb)
PFD Details (click for larger version)

For example, the airspeed is shown on a vertical tape at the left edge of the upper half, and displays knots at low altitude, Mach at high altitude. Beneath that is a tiny number that shows “the other speed,” so if you’re showing knots on the main tape, the little number will show Mach. If the main tape is working with Mach, the little number shows knots.Five “Headlines” across the top of the instrument come and go, change color, and show borders (or not) to display the status of the speed controls, nav switching, altitude selection and capture, and so on. At first, I tended to try and focus on one thing at a time, moving from item to item, as in the old aircraft. I think there’s a different technique that emerges with practice. The key is that all the information is presented in a much smaller area on this nine-inch screen, so the eyes don’t have to jump back and forth from the horizon to the speed, to the horizon, the altitude, back to the horizon to the heading, to the horizon, or however we used to scan in the old days. I don’t even know how I used to scan — I just did — but I think I scan very differently with the “glass.”For one example, take the altitude selector. In my old 747, it was a series of mechanical drums, driven by gears, turned by a knob, all mounted in the glareshield. The pilot not flying (PNF) would get a new altitude or flight level from ATC, dial it in, and keep pointing to it until the pilot flying (PF) indicated that he understood the new altitude. Anytime either pilot wondered what the setting was in the “ALT SEL” window, he’d look at it directly.Not so in the “glass cockpit.” The knob is still there, but now there’s an electronic display of the altitude selected right next to it. This is much more complex than it sounds at first, because the knob is now nothing more than a potentiometer, which probably adjusts a voltage that is converted to a digital signal, which is then placed on a “bus” that runs all over the airplane (The “ASCB,” for “Avionics Standard Communications Bus.”) Virtually everything electronic on the airplane “rides” on this bus, so if the nav light in the left wingtip needs to know the number dialed into the altitude preselect, it just looks for the right signal on the bus. Silly example, of course: The nav light would never need to know that (I think).

ACBS Block Diagram (153 Kb)
Avionics Standard Communications Bus (click for larger version)

What does need to know that number? Well, for one thing, that little window does, along with the FMS (Flight Management System), which drives the flight directors and autopilot. Do the pilots ever look at that little window? Only to set it, because that number will be repeated (via the ASCB, of course) in the upper right corner of the outboard DUs. When a new altitude comes in, the PNF now sets it on the glareshield, and the PF looks at (and often points to) the DU right in front of him, saying, “I see Flight Level 210.” Presumably, once the little numbers show up in the DU, they have also made their way via the ASCB to everything that may need them. But there’s no direct connection between the knob and the DU! The knob sends an electronic signal to various computers, and one of them feeds the binary data to another device called a “signal generator.” This is the device that receives the stream of ones and zeros, and converts that to show on a video screen. That’s a long way from the knob that used to drive little gears!

Nav Displays

Nav Display & Display Controller (72 Kb)
Nav Display & Display Controller (click for larger version)

The inboard DU (“ND,” for “Nav Display”) in front of each pilot can be switched to show even more different displays than the outboard. Most often, it will be set to show the moving map, with the course shown, a wonderful tool for situational awareness. Each pilot can choose to display any range he happens to want at the moment, and much more information can be shown. The radar display will usually be shown here, and each pilot can choose to display or suppress airports and navaids, and to show the identifier, or not.The DC (“Display Controller”) is on the glareshield, and is a whole learning experience, all by itself. Each button changes something on the DUs, and with each, there are multiple pages and sub-pages. I’m not sure anyone has ever explored them all, it seems there are thousands of them.One more note about all the displays, pilots never, never, ever touch them! Doing so will draw a scream of rage from the more experienced pilot, because then he’ll have to break out the glass cleaner and a soft rag to remove the ugly fingerprints, which really do stand out. Most carry a very soft brush to knock off the dust the screens attract.

The “EGPWS” (Enhanced Ground Proximity Warning System) and weather radar (together or separately) will display on this screen, too, with the EGPWS showing the surrounding terrain in various colors to indicate “below,” “at,” and “above,” and the radar showing precipitation in full color. The EGPWS display can be suppressed, but if the airplane gets too close to the terrain, the EGPWS will impose itself automatically, and start yelling in a male voice, “TERRAIN, TERRAIN, TERRAIN.” This system will also warn the crew if they get too low without extending the gear, and for a variety of other things.If desired, the crew can also put the normal and emergency checklists on the inboard pilot’s DU, but oddly enough, few pilots seem to like this. I’ve used the feature, and I like it very much, because it highlights items already done, it leaves a box around the next item, and it frees up the hand that most use for the paper checklist. You can even defer an item, and the system will keep it in view.

Engine and EICAS

In the center of the panel are two more DUs, one mounted above the other. The left half of the upper one usually shows a graphic representation of the old-fashioned analog (round dial) engine and systems gauges, and the right side usually shows some of the same data, and some other data in digital form. If the oil pressure drops, the oil pressure digits turn yellow, then red, the digital display does the same, and for most anything, a warning message will appear on the lower of the two center DUs. That lower one will usually have a blank left half, with space for a very long list of warning messages. The right half can be used to show a diagram of the various systems, also with data, or the TCAS. Warning messages will be shown in red (“L ENG OIL PRESS LOW”), amber messages for cautionary messages (“GND SPOILERS NOT ARMED”), and blue for advisory messages (“60 Hz DC INOP”).Gulfstream uses abbreviations extensively. There are over 490 of them listed and defined in one manual I have, and many of them are non-intuitive. You will hear talk like, “The DBDI takes its signals from the DADC and the DAFCS, and via the ASCB controls the DDRMI, the DAUs, and the BCPUs, using power from the E-INV normally, or the … ” Well, you get the idea. MOM doesn’t mean yo’ momma (it means “momentary” in Gulfstreamese), and no instructor would ever refer to the display unit (DU) in front of the pilots as a “Primary Flight Display,” because it’s a PFD.

Red messages are accompanied by three loud chimes, amber by two, and blue by one, so it pays to listen when a new one pops up, and look at the display before you cancel it. New messages pop up at the top until the warning chimes are done, then they sort to the list in priority order. Really neat stuff, but during cockpit setup and shutdown, the systems go nuts, bing-bonging your ears off, with messages being added to the list at a great rate.One of the really nice things Gulfstream has done is to go to a policy of “No Memory Items.” No more check rides where the check pilot asks for a long litany of memory items to some obscure emergency. If it’s a serious problem, and if the electronic checklist function is turned on, the appropriate emergency checklist pops up automatically on the inboard DU, a VERY nice feature, and a major reason to use it, in my opinion.When one of the lesser messages pops up, the pilot in the right seat suppresses the cacophony of chimes, pulls out a quick reference book, looks up the message, and takes action, while the pilot in the left seat flies the airplane, and takes over the radio.This is a concept that many older pilots have a lot of trouble with! There’s no room here for the hero pilot, who does it all, while telling the cowering young co-pilot, “Sit on your hands, and don’t do nuthin’ unless I tell you to.” That attitude is gone, and good riddance. It never was good, and many lives have been lost because of it. There are probably many corporate (Part 91) operations that still have the old approach, but they too are going the way of the dodo. In today’s cockpit, we’re “equal partners,” with the PIC’s authority really used as a tie-breaker. In many G-IV operations, both pilots are fully PIC qualified.Manuals. Man, does this airplane come with manuals! I’ve got a shelf three feet long, crammed with the various manuals, and there are even more than that on the airplane. Gulfstream publishes a Jeppesen-sized, four-binder airplane manual, plus a “QRH” (Quick Reference Handbook); Honeywell publishes a manual for the FMS (Flight Management System), one for the autopilot/flight director system, one for the Lightning Sensor System, and one for the TCAS (Traffic Alert and Collision Avoidance) system. Allied Signal has one on the EGPWS (“Gyp-Whiz,” for short, really “Enhanced Ground Proximity Warning System). I’ve seen others, but I don’t want to know about them.

Flying By Keyboard

It’s not a simple task to get the airplane ready for flight. Normal setup takes me around 25 minutes, from the time I hit the first button, but the younger set that grew up on video games can probably do it faster. I like to take it a bit slow and get it right on the third try, at least. There’s a whole lot to do. Not like the old C-46 that takes me about 10 seconds to prepare for start.I love whomever it was that first came up with the idea of an APU (Aux Power Unit)! What a boon! Early ones simply provided electrical power for starting, but moderns ones do much more. Modern APUs are small jet engines that provide DC and AC power, and copious quantities of pneumatic air, making it possible to run everything in the airplane on the ramp, including air conditioning that can be run hot enough to roast chestnuts, or cold enough to freeze your nose hair. Well, I exaggerate, but only a little! It takes less than five minutes to bring the cabin to a comfortable temperature, regardless of outside conditions. Lovely stuff, the only price is a small amount of fuel, and a lot of noise on the ramp. Earplugs are mandatory, I have a set on a string around my neck at all times.One pilot will usually get the APU and the airplane going, while the other does the outside and inside inspection. The person in the cockpit will see no lights, and six big black holes in the front panel when he kneels in the doorway to start the process.First order of business is to push the arming switch for the emergency lights, then check that they come on, inside and out. If he times it right, the person outside will holler, “Emergency lights OK,” and all he has to do is look back in the cabin to see those lights. The two batteries are turned on, one at a time, checking each for full voltage. Then the emergency lights can be turned off (takes power to turn ’em off).Next, the APU fire test button is pushed, which sounds a loud bell in the nose wheel well. That is to alert those on the ground that there’s a problem if no one is in the cockpit when a fire breaks out. Then a boost pump is turned on for APU fuel pressure, the APU master is turned on, and when the “Oil Pressure” light comes on, the “Start” switch is pushed. It’s all automatic after that, with all kinds of automatic protection for starting malfunctions.Once the APU is up to speed, it is placed online, and the whole cockpit comes to life. As soon as the APU is online, the cabin, galley, and radio masters are turned on, all DUs are turned on, all three IRSs (Inertial Reference Systems) are placed in “NAV,” and two or three FMS systems are turned on, each with their own switches. The airplane is now fully powered, but “dumb,” because it doesn’t know where it is, or where it’s going. The GPS systems get switched on automatically somewhere in the process, so it figures out its location pretty quickly. It politely asks if we want to use the last known position, the airport reference point, or the GPS, and most pilots select GPS, as it is by far the most accurate. In any event, the GPS promptly starts talking to the FMS computers, and even if the initial position is slightly in error, it takes care of that quickly. Neat stuff.

Download That Clearance

More and more airports are now served by communications links that permit downloading flight plans, weather, digital ATIS, and digital PDC (Pre-Departure Clearance). As soon as the FMS is powered, I’ll punch in a couple of quick commands. Say we’re in Teterboro, a common destination for corporate types who need to visit New York City. “PDC/KTEB,” “ATIS/KTEB,” and a series of keystrokes that requests a download of our previously filed flight plan. It usually takes a minute or two for those to come in via a mysterious VHF radio link, so I’ll organize the cockpit during that time, checking the position of everything, setting it for takeoff if I can, or engine start if I can’t.When the flight plan comes in, the FMS will show a short route summary, and if that looks at all reasonable, I push “ACTIVATE.” In one fell swoop, the FMS computers get our route of flight, with all airways, waypoints, departures, and arrivals. If I don’t know the route from memory, I’ll cross-check it with the faxed paper printout I got in the hotel or at the FBO. In either event, I like to call up the “PLAN” view on the inboard DU, and step through the flight to make sure there are no hidden kinks in the course.I learned my lesson on that the hard way. On a flight from Van Nuys, Calif., to Jacksonville, Fla., the automatic routing called for many waypoints and airways, and finally to the JAX VOR, then the KJAX airport. That looked entirely reasonable to me as a list, but as it turns out, the JAX VOR is roughly 30 miles on the other side of the airport. Now that’s no big deal, but one of the displays I really like toward the end of the flight is “PROG” (Progress) which shows the air miles left to fly, not the direct miles to the airport. So this loading showed I had 30 extra miles to the VOR, and another extra 30 miles back to the airport, for 60 extra miles, total. All the automation was counting on that, plotting descent points, etc.Of course, ATC started giving us vectors and descending us more or less directly to the airport for the ILS, skipping the legs out to the VOR, and back. I was puzzled at how early they were letting us down, when in reality, they were really “dumping” us! When the FMS showed us with 70 nm to fly, we were 10 nm from touchdown! We made it, but it wasn’t pretty. After that, I always look at the plan view of the whole flight.

Hey Tower, Which Runway?

OK, at this point, the computers are getting happier, now they know where we’re going. You can almost hear them purr with contentment. But several things are still lacking. They mustknow what runway we’re planning to use, and what configuration we’re going to be in, because they need to calculate the performance, and make sure we can make it. Once they know that, they can calculate V1, Vr, V2, Vfs (flaps up speed), and Vsse (safe single engine speed). You can’t just take off without all this, in advance. Well, you can, but you’ll have so many warnings, flashing lights, and voice warnings, you won’t be able to stand it. Better to give the computers the stuff they want, believe me!By this time, the digital ATIS is showing on the FMS screen (if you push the right buttons), and on some airplanes, it will print out on paper. Using that, I’ll punch in the runway in use, the wind, the number of passengers, and the weight of cargo. Now, the computers are happy, and they will reward the pilot with performance numbers, runway required for dry and wet runways, and all the V-speeds. Still, there are traps for the unwary. The FMS knows only the total runway length, and does not know about displaced thresholds, or construction, so you need to check that the old-fashioned way, by looking at the airport diagram, and paying attention to the NOTAMs and the ATIS information. The systems are smart, but not clairvoyant (yet).There’s another trap. Suppose we plan to takeoff on 25R at LAX, and we’re holding short, waiting for a break in traffic. Suddenly the tower says, “Cleared to taxi across 25R, cleared for immediate takeoff on 25L.” In my beloved old C-46, we’d just waddle across one runway, and go on the other, without a thought.In the G-IV? Oops. Now we’re taking off on a runway the FMS doesn’t know about. Is it long enough? Does it have a different departure? A good, sharp pilot can quickly punch a dozen or so buttons and change the runway and departure, and complete a dozen or so line-up items on the checklist, but he needs to know exactly which buttons, and punch them in precisely the correct order to get it done. The first few times I tried that, I mangled the computers hopelessly, leaving the cockpit in shambles, and the poor guy flying really confused. That’s when the pilot flying says, “Tower, we’re not ready now.” The tower will get all testy, and say, “Gulfstream, move it quickly, taxi down 25L to the first left turn, and clear the runway.” After that, we’ve got lots of time to reprogram the computers, because we’ll have to wait to cross both runways, and back to the end. And we still won’t know which runway to program! Ain’t automation great? Meanwhile, the boss in back is now up front, demanding to know what happened, and why aren’t we on the way, yet.This is even more fun when ATC asks on final approach, “Can you sidestep to the other runway?” With a little pre-planning, and little practice, all this becomes routine, but at first, it’s terrifying for the button pusher.More next month.Be careful, up there!