Except it wasn't working. His terrain-mapping scope was almost blank, but for a completely different reason. A five-mile-long ridge loomed ahead, its tree-lined crest still seven hundred feet above the Old Dog's altitude. The ridge cast a dark shadow behind it, as if the radar beam was a headlight being blocked by an oncoming brick wall.
McLanahan knew that if the shadow behind the ridge got larger instead of smaller they'd eventually plow into the ridge.
At over seven hundred feet per second, the two-hundred-ton bomber would smear itself right up and over the ridge and scatter pieces of itself for tens of miles beyond. The radar altimeter readout on the video display was flashing, warning that the aircraft was below the desired terrain clearance altitude.
McLanahan glanced at the flight instruments. The vertical velocity indicator was showing a climb, but it didn't seem like a very steep one. The ridge was now only three miles away, and the shadow beyond blotted out all else right to the edge of the scope.
"High terrain, three miles," McLanahan reported over the interphone.
"I've lost TTG signals, navigator," Campos radioed to McLanahan.
He quickly glanced at the annotations he had placed on the chart the night before. "Elevation eight thousand feet," McLanahan asked. "Blank scope. Not painting over it. Also a blinking radar altimeter."
The terrain-avoidance computer was not designed tofollow the contours of the surrounding hills and valleys as it would in the B-1 Excalibur or the FB-111 — The B-52 didn't have enough power. The terrain-avoidance system anticipated the terrain ahead of the aircrafts flight path and chose a safe altitude to clear it, as close to the pilot-selected clearance plane setting as possible. Approaching a ridge, the altitude should not be less won than the selected altitude-it should be more. Much more. And the Old Dog should be climbing a lot faster…
"Pilot, climb!" McLanahan ordered. The plane suddenly jumped, nearly tripling its former climb rate, and the throttles were jammed to full military thrust. The airspeed, however, bled off rapidly as the Old Dog traded altitude for airspeed, crawling skyward.
The radar scope was blank. The ridge was less than one mile off the nose… eight seconds before impact…
The radar altimeter indicated less than a hundred feet as the Old Dog ballooned over the ridge, at near minimum low-level safe airspeed. The automatic flight control system immediately commanded nose-down as the ridge line dropped behind them, but McLanahan didn't start to breathe again until they had regained the two hundred knots lost in the emergency climb and were safely clear of terrain.
"Clear of terrain for fifteen miles," McLanahan reported.
"Ground position freeze," Colonel Anderson said over the interphone.
The digital readouts and radar images froze on the screen. McLanahan sat back in the Old Dog's ejection seat, wiping sweat from his forehead and palms, and took a gulp of Tab.
"What the hell was all that, McLanahan?" Anderson shouted over the interphone. McLanahan backed the volume of the interphone panel down a notch in the anticipation of yet another yelling match. Harold Briggs, sitting in the newly installed navigator's seat beside McLanahan, slid off his headset.
"What was what, sir?"
"All those calls, goddammit!Terrain this, terrain that.
That's not your job."
"What do you mean, it's not my job. My first responsibility is to keep the plane out of the dirt.
Harold Briggs made an obscene gesture directed at Anderson. He felt fairly safe doing so, because Anderson and Ormack were in a B-52 simulator some two hundred miles away and were tied electronically into the computer simulation aboard the Old Dog. At the same time, Wendy Tork was at a research computer terminal twenty miles from Anderson, participating in the same exercise, and Campos and Pereira were sitting at a fire control test bench elsewhere at Dream land, also linked to the computer controlling the test. Briggs and McLanahan were inside the Old Dog itself, still in its hangar at Groom Lake, watching and responding to the computer-generated battle scenario.
"There's a multimillion dollar computer that can do that faster, easier, and better than you ever can, McLanahan," Anderson asked. "Why do you need to call out terrain elevation when if I wanted that useless piece of information I can just call it up on the screen?And I can see the damned radar altimeter blinking. I don't want you garbaging up the radios with all that stuff."
"I was calling to your attention, sir, " McLanahan said over the voice/data link, "the fact that we were fifty feet lower than the goddamned set clearance when we still had seven hundred feet to climb.
If the system was working right, we should have started the climb three miles earlier to cross that ridge line at two hundred feet. As it was, we barely had enough airspeed to cross the ridge at a hundred feet, and then we ballooned over it another thousand feet and almost hit initial buffet to a stall. The radar altimeter should never be blinking, and sure as hell not so close to a mountain. "Anderson had no reply to that, but someone else chimed in: "Excuse me, Captain," Campos interjected, his voice sounding hollow and metallic over the secure voice-data transmission line, "but please understand the situation here.
Right now you have two attackers off the nose, just within radar range.
You must spend less time in mapping mode and much, much more time in TTG mode. The Scorpions can be launched off threat detection signals from the receiver unit, but without range, elevation and tracking data the chances of a hit at long range are slim. We're relying on using the main radar to guide the Scorpions.
"Besides," Lieutenant Colonel Ormack added from Ed wards, "this is only a practice run. The elevation data in this simulation isn't plotted as accurately as the operational cartridge. There's bound to be some belly-scrapers. We're trying to nail down procedures, McLanahan-and until we get to the target area, your procedure is to help guide the defensive missiles. Let the computers keep us out of the dirt."
McLanahan rubbed his eyes and took a long, deep breath.
"This is such bullshit," he said to Briggs.
"Hang in there, buddy. You're really running this show, and they all know it.
"Like hell," McLanahan asked. "I'm a passenger. Extraneous material.
"You mean 'dead weight,"' Briggs said.
"Thanks for the clarification."
"Okay," Anderson radioed over to the widely separated crew. "We'll back up five minutes and do the leg over again.
This time, McLanahan, find the damn fighters before they find us.
McLanahan called up the prerecorded flight plan and waypoint readouts and watched as the present position coordinates slowly scrolled back to the beginning of the low-level navigation leg.
"You want to see what a collision with the ground looks like, Hal?"
McLanahan asked. "Just keep watching the scope."
"I saw," a voice behind them said. McLanahan whirled around to see General Elliott sitting in the back of the navigator's compartment, taking notes and listening to the interphone conversations from the instructor nav's station.
"Hello, General Nightmare," McLanahan asked. "How are we doing?I think we suck big-time."
"Patrick," the general said, "I don't want to undermine Anderson's authority-he's a great pilot and a genuine asset to the project-but follow your own instincts, your own training.
Everyone but you is trusting all this gadgetry with their lives because they don't know any better. Both Anderson and Ormack could see the terrain warning signals in the cockpit and they both ignored them.
Keep an eye out for the terrain and for fighters as you see fit."
The general paused, looking around the tiny compartment measuring his words, then said, "I've watched your work, Patrick. You seem to know when the fighters are near before the warning receivers do. You switch in TTG mode before Wendy tells you there are fighters, and you switch into mapping mode and call terrain just in time to avoid a mountain.