Boeing 747-200B simulator checkride
Copyright ©1997 Tim Vasquez
(Click any image to enlarge it)
The flight deck of the 747-200.
The evening of Saturday, July 26, 1997 was a clear and calm one at Dallas-Fort Worth International Airport. Our United Airlines Boeing 747 sat at the gate. Sitting left seat in the cockpit I glanced out the flight deck window. The sun had already set, and the sky was painted in dark blue and reddish colors.
However, this wasn't a real flight we were taking. This was one of United Airlines' sophisticated training simulators. Manufactured by Rediffusion Simulation, this simulator was a 6-axis model (three axes of tilt, plus three axes of motion, using huge hydraulic jacks). The simulator cab resembled a metal box, 15 feet square, 10 feet high, and completely enclosed, standing nearly 30 feet high. Inside the cab was an actual aircraft flight deck, featuring state-of-the-art graphics just outside the windows projected at optical infinity using collimation displays. In fact, I was beginning to forget that it was all just an illusion. That's the entire point of these multi-million dollar simulators, which are in operation 20 hours a day at an operating cost of up to $700 per hour for maintenance and electricity alone.
For this trip, the flight engineer was our instructor, Don Sinel, a captain who had just retired with United. He looked like the captain of a merchant ship, with a friendly, authoritative voice, an ivory-white beard, and a spirited gaze that spoke of many years of experience in the flight deck. Don sat in the middle, just aft of the center panel, and was busy flipping switches to prepare for engine start. Sitting in the right pilot seat was Bob Clarke. Sitting in the left seat was myself.
The massive 747 simulators at United's Denver training complex.
Thanks to the excellent wraparound video displays, the suspension of reality was easy. Outside the confines of our cockpit, though, past an array of video screens, we were safely inside a large building in Denver, housing a cluster of giant full-motion aircraft simulators.
"Okay, let's go ahead and push back from the gate for engine start," said Don.
Using both of my toes, I pressed hard with simultaneous force on the rudder pedals. The parking brake lock released, causing a small lever to snap gently backward near my right hand.
The simulator took this as a cue for tug pushback, and I watched as the terminal building slowly receded. The simulator motion was now perceptible as the aircraft bounced gently. Once we were a few hundred feet from the gate, the aircraft came to a rest. The tug disconnected and drove away. Don swiftly began turning knobs and switches on the overhead panels. One by one, our four engines started up and came to life. I spent those minutes looking carefully at the instrument cluster.
"Okay," said Don after about a minute. "All engines are up. DFW isn't really a United hub, so I really don't know the layout here. You'll need to navigate."
What the simulator view looks like at San Francisco International Airport. The graphics look great, but the video scan rate was low enough to cause an awful flicker on daytime graphics. For this reason, we did most of our flying at dusk where it was less noticable.
We sat there on the tarmac, facing east towards Dallas. A yellow stripe was underneath us, leading the way towards the main taxiway. The cockpit was quiet, except for the rush of the air conditioning, the whine of the engines, and the buzz of transformers and the gyroscopes. The suspension of reality was quite effective.
Carefully, I took the thrust levers and advanced them forward a couple of inches. The friction lock was snug so it took some pressure to move them forward.
The engines spooled up and the rush of the air conditioners instantly became louder. The electromechanical engine gauges responded to the new thrust lever setting with a chorus of clicking noises as the digits on the engine gauges changed, settling into their new positions. Soon the aircraft was slowly moving, and I pushed the right rudder pedal hard with my feet to turn the nosewheel and keep us on the stripe. It felt rather sluggish and uncoordinated, and the height of the flight deck gave me the vague impression that I was sticking my legs outside and pressing on the tarmac to stop the plane, rather than pressing on pedals. Well, at least I wouldn't be driving the plane out to the freeway.
Layout of the primary instruments. Click to see the text better.
As we rolled gently along, Don pointed out the INS speed gage below the artificial horizon. It showed "011", our groundspeed in knots (see photo). I pulled the thrust levers back to idle, vaguely aware of the mechanical chattering from the instrument panel and the sudden quieting of the air conditioner ducts.
"Flaps 20," said Don. Bob reached over near the thrust levers and pulled the flap levers to the 20-degree position to lower the flaps. I watched as the flap position gauge slowly moved towards the 20 mark.
As we approached the 90-degree turn to get on the main taxiway, I pressed the tips of the rudder pedals with my feet to brake the aircraft. Gingerly I had to let the nose of the 747 go almost into the grass, since the main body gear was almost 100 feet behind the cockpit. The 747 slowed to a creep as I eased the nosewheel close to the turf.
"Great," said Don, "now use that tiller for extra turning power. Remember, make sure and use a bit of thrust."
With my left hand, I took an odd shaped crank handle beneath the window, the 747's tiller, which was used to bring the nosewheel through sharp turns. With my right hand, I advanced the thrust levers about an inch. The engines spooled up and the aircraft began moving towards the grass. I cranked the tiller a full turn to the right, and the cockpit began moving sideways as we re-aligned with the taxiway. Soon we were lined up. I moved the crank back to center position and let the plane move down the main taxiway. I opened up the throttles about a third of the way until we reached 30 knots, then brought them back to idle. The 747 lumbered along, gently rising and sinking with the pavement.
The left turn for the runway entrance quickly came up. I braked the aircraft, took us up to the grass again, and used the tiller for a full left turn. Another hundred yards and we were on DFW's Runway 35L, length 11,388 feet (2.1 miles). I went to the edge of the runway, turned the aircraft left again, and we were lined up with the runway, sitting still and facing north towards the big blue sky.
Aborted takeoff run #1
"Let's do a dummy run," said Don. "We'll go for takeoff. Right when we hit V1, we're going to chop power and brake the aircraft to a stop. No thrust reversers. Just brakes."
V1, pronounced vee-one, is a key concept. It represents the highest speed at which an aircraft can safely accelerate to and then stop without going off the end of the runway. It varies depending on aircraft weight, runway length, and so forth. If the aircraft reaches V1, come hell or high water, the captain will not attempt to abort the takeoff. Any attempt to do so will most likely result in a dangerous excursion off the runway.
The calculated V1 speed for us was 130 knots (150 mph). So in effect, the plan was, on a runway only two miles long, to bring the fully-loaded 747, weighing about 700,000 pounds (350 tons) to 150 miles per hour, then stop it cold in its tracks. And we would use braking power only. This would be quite interesting. The brake systems on a jumbo jet have to absorb a colossal amount of kinetic energy. After a large plane is stopped using full brakes, the brake temperature readings often redline for 5 or 10 minutes. It's not uncommon for airline crews have to call upon the fire department to check the landing gear. The brake pads on a 747 can require up to three hours to cool down. It's not quite like bringing your Honda Accord to a stop on the freeway!
Just before brake release, we wait for the EPR readings stabilize at 1.1.
I pressed on the rudder tips, holding the brakes, and brought the thrust levers about a third of the way forward. I glanced down at the engine gauges and waited until the EPR readings settled on 1.1. This is done to ensure the engines are stable and ready for takeoff power. If we had went immediately for full takeoff power, a lazy engine can cause an aircraft to lose directional control as it begins its takeoff roll..
Taking my eyes off the EPR gauges, I glanced down the runway and said to Don, "Set takeoff thrust." It's the job of the flight engineer to bring the engines up to a predesignated takeoff setting -- high enough to give us sufficient takeoff power, but low enough to prevent overstressing the engine. Jet engines do not have mechanical means of preventing overspeed from occurring, so takeoff power is always carefully computed and is rarely full-throttle. Our EPR for today would be 1.5, about 95% of full power. Don would need to bring us up to that EPR reading of 1.5, ideally within about 20 seconds (before we reached 80 knots). I kept my hands on the levers in case I needed to chop power for an aborted takeoff, while Don worked a duplicate set of levers, about five inches behind my hand and which moved my own levers.
I loosened my grip and Don advanced both throttles forward nearly all the way. Our levers moved forward together. The engines surged with power and the engine instrument panel was clicking furiously as exhaust temperature, N2 (compression ratio), and EPR digits soared. The air conditioning ducts were now roaring, and the 747 was alive with energy. I could literally feel the rudder/brake pedals vibrating as the brakes strained to keep the aircraft in place.
I took my feet off the pedals, and the aircraft lurched forward and begin accelerating down the runway.
"Okay, keep her going straight," said Don, making adjustments to the thrust levers as we accelerated. "Remember, you'll need to put your right heel on the center line of the runway. Initially, you'll need coarse use of the rudder to keep it going straight."
Don was right. As the airspeed increased, however, it took less and less rudder inputs to steer the aircraft along the centerline. Unseen to us, the Boeing 747's systems were automatically transferring pedal control from the nosewheel gear to the rudders themselves as we reached higher ground speeds. I later discovered that this function represented a significant amount of engineering work by Boeing and was quite a source of pride.
A glance outside as we roll down the runway. Bob was doing this takeoff, and crashed the airplane by inadvertantly applying excessive aileron inputs after liftoff, causing us to roll left 80 degrees and smash into a nearby tarmac. Who said a crash couldn't be refreshing?
"EPR set," said Don, taking his hands off his thrust levers and sitting back. He glanced at the airspeed indicators. "Eighty knots."
Our aircraft continued racing down the runway. I could see the end of the runway looming just over a mile away, coming quick.
"A hundred knots."
No words were spoken. As we reached higher speeds, we could feel the bumps coming faster and faster, making the flight deck shudder rapidly. The aircraft controls were feeling nimble and it seemed as if it would take very little effort for the plane to leave the ground.
"Vee-one. Abort the takeoff."
I quickly pulled the thrust levers to idle and pushed the rudder pedal tips hard with my feet. The end of the runway was coming -- less than half a mile away!
"Stand on them," said Don. "Use everything you've got!"
I pushed harder, using all of the energy in my legs to push the pedals in, straining against my seatbelt. The speed was dropping nicely, but as we slowed through 80 knots (92 mph) I could see that not even 150 pounds of muscle force on the pedals was going to keep us from rolling off the end of the runway into the field. And as we dropped to 30 knots (34 mph), the aircraft rolled past the end of the runway and into the grass.
Once the aircraft was stopped in the middle of a field, Don punched some buttons on the simulator control panels. The sky turned white, and once again we were lined up for takeoff.
The airspeed indicator. It shows 207 knots. Note the red primary bug, which is set at 185 knots. A knob on the top center panel changed both mine and Bob's bugs together, giving us vital minimum speed references as flap settings changed. The striped bug at 385 knots is the aircraft's "redline" -- the never-exceed speed. There are also 5 other bugs near the 140-150 kt marks which can be set by the pilot for anything else.
Aborted takeoff run #2
"We're going to do the same thing this time," said Don, "but this time, we'll use brakes and reverse thrust."
I brought the throttles up, stabilized the engine, and Don took over, pushing the levers forward to give us full takeoff power. We rolled down the runway, rapidly gaining speed, and before long we had 80 knots, then 100 knots, and soon 120 knots.
I brought the thrust levers to idle, and pressed hard with my toes on the brakes, nearly standing on them. With my right hand, I grabbed a third set of thrust levers about four inches forward of the main ones, and pulled them backward. A loud roar sounded as the reverse thrust doors closed over the engines, and we were nearly thrown forward as the 747 rapidly decelerated. The difference in deceleration was amazing! In fact, the deceleration was making it quite a bit easier for me to stand on the brakes.
"Okay, 80 knots," said Don. He was reminding me to take the reverse levers back to idle, since running reverse thrust at speeds below 80 knots has the tendency to flame out the engines.
I brought the reverse levers forward, and the roar subsided. We decelerated quickly through 60 and then 40 knots. Once we stopped, I looked ahead. A quarter mile of runway was still left in front of us. Clearly the thrust reversers helped us gain an extra 3,500 feet of stopping distance.
The sky turned white again. Don mentioned that the area scenery in Dallas was pretty sparse, and we'd be better off using San Francisco for takeoff and some VFR maneuvering. We agreed to the suggestion.
"Now remember to get the nose up to fifteen degrees on climbout."
A runway appeared in front of me, and the hills of northwest California materialized around me.
We went through the same routine, stabilizing the engines, bringing them up to takeoff thrust, and accelerating.
"EPR set!" said Don. "Eighty knots."
I kept the aircraft steady along the centerline, watching us gain speed.
I removed my hand from the thrust levers. After all, we passed V1 and were now committed to fly.
"Rotate," he said. Rotate is the speed at which it's appropriate to pitch the nose upward to allow the aircraft to lift off. Rotating at too low a speed causes drag, slowing the acceleration to liftoff speed and lengthening the takeoff run, and at too high a speed it forces the plane to use up runway when it could already be airborne.
I pulled back slowly but firmly on the yoke, and the nose began rising.
"Vee-two," said Don. V2 is the speed at which the aircraft should begin lifting off.
The horizon dropped below the nose of the aircraft and the runway began falling away beneath us. We climbed skyward. "Positive rate of climb, gear up!" Bob reached toward the center panel and moved the gear lever from the DOWN to the UP position.
As instructed, I kept my eyes on the artificial horizon, keeping the wings level while seeking out 15 degrees of pitch for our climb and watching our airspeed to ensure a nice gradual acceleration.
"Not bad!" said Don. "Keep it at fifteen degrees. Flaps 15." Bob reached forward and retracted the flaps by five degrees, cleaning up the airplane so we could begin reducing drag and accelerate.
I looked outside at San Francisco in a July twilight. I looked down at the roads and could see headlights of cars. I was astounded. They were moving along in both directions! I was mesmerized, and for quite awhile I forgot I was in a simulator. My grip on the yoke tightened a little.
The artificial horizon. The 747 is pitched up 5 degrees, and is in a 25-degree bank towards the right. The "natural" pitch of the aircraft is 2.5 degrees.
After some assorted maneuvers and a few practice approaches, we were going in for the landing on San Francisco's runway 28R. Descending through 3,000 feet, I banked the aircraft for final approach, eight miles out.
"Okay, looks good," said Don. "Gear down, flaps 20!"
Bob lowered the landing gear lever and set the flaps to 20 degrees. He then glanced over at the flap speed chart and adjusted the speed bug. The speed bug is controlled by a knob on the autopilot rack along the top of the instrument panel. This set our red airspeed bugs to 175 knots (201 mph). The red bug represented our V-ref speed -- the lowest speed at which safe control of the aircraft can be maintained. We were at 190 knots (219 mph), well above that, but I wanted to get the plane down to V-ref plus 10 knots.
"Remember," said Don, "keep the nose at two and a half."
I glanced down at the artificial horizon, and pulled back slightly on the yoke to get the aircraft's pitch at 2.5 degrees upward. This placed the aircraft in its natural descent profile, allowing it to handle the descent better. But the added pitch also helped drop the airspeed somewhat, and within a few moments we had dropped down to 178 knots (205 mph).
Bob moved the flap levers to 25 degrees. He then looked at the data card and dialed the airspeed bugs to 164 knots (189 mph). As he did this I added a little thrust to check the increased drag and descent rate.
We were now descending through 1400 feet.
"Winds are calm?" I asked.
"Yep. Right on the glideslope! Beautiful!"
A flash of lightning illuminated the landscape, courtesy of the outstanding simulator graphics. We quietly continued our descent, while I made a few thrust adjustments.
"I like the lightning," said Bob. "That's good!"
The descent continued through 1000 feet with a sink rate of about 800 fpm. We passed through the altitudes of 800, then 600 feet.
"Just a shade low," said Don. "Two and a half."
The automated voice system began sounding. "Glideslope! Glideslope!"
Even more thrust would be needed to check the sink rate. I pulled back slightly and applied a bit of thrust to get us back on the glideslope. I noticed part of the reason for the steep descent was that it took increasing amounts of back pressure on the yoke to keep us at the 2.5-degree pitch. Yep, I'd been slacking, and the alert system politely reminded me.
"More power," said Don. "More power. More power."
A few hundred feet above the ground, making a few hasty last-minute adjustments to the approach.
I added a bit more power, and the aircraft responded sluggishly. At this point it took a bit of strength to keep enough back pressure on the yoke. I made a few aileron corrections, taking us through a series of unnerving banks as the runway approached, but soon got us lined up about a half-mile from the threshold, two hundred feet up. I quickly found it very easy to make minor adjustments using carefully-timed rudder inputs. As we rose up to the glideslope, I retarded thrust just a tad.
"Two and a half degrees," said Don. "Let her fly on."
We were soon over the approach lights, about a hundred feet off the ground and right on target at 160 knots (184 mph).
In the back of my head, I began calling, "Bob? Radar altimeter?? Heights???" I did not want to take my eyes off the runway. As if by magic, Don had me covered with the flight deck presets. A computer voice began calling out the radar altimeter readings. "Fifty." A few seconds passed. "Thirty."
I chopped power, bringing the thrust levers all the way back to idle. Using the advice given me by a 747 captain I knew over E-mail, I resisted the urge to flare the 747, applying only a slight amount of back pressure on the yoke. Sure enough, the "ground effect" took over and the plane flared on its own, blanketed by the ground effect. It gently touched the pavement.
"Beautiful!" said Don.
I eased the nose gently down to the runway, pressed the brakes in, and applied reverse thrust. As the aircraft slowed down, I kept the plane lined up.
"Ninety knots. Eighty knots."
I moved the thrust reverser levers to idle.
"Sixty knots. Okay, bring her to a stop!"
Keeping pressure on the brakes, I guided the plane to a gradual stop on the runway.
Don smiled. "Hey, nothing to it, right?"