Never Again Online: Off radar in the Mojave Triangle

October 1, 2003

When my sister suggested that I meet her in Las Vegas for her fiftieth birthday last May, I decided to fly there; it had been a year since I had flown solo to a new destination.

I chose Henderson Executive Airport, 11 miles south of The Strip and under the Las Vegas Class B airspace, as my destination airport. I reserved a Cessna Skyhawk from my flying club.

Friday morning dawned cloudy and humid in San Diego. The weather briefer advised me that Gillespie Field had 15 miles visibility and scattered cumulus. Las Vegas was overcast at 15,000 feet with 10 miles visibility. The sky would be overcast at 10,000 feet for most of my route with a 20 percent chance of thunderstorms. The winds were 220 at 26 knots over the local mountains, dropping to 12 kt in the desert. I would have a tailwind for the entire trip.

I took off at 11:05 a.m., obtained flight following, and climbed to 9,500 feet. I crossed the local mountains in surprisingly smooth air, and surveyed the desert before me. Looking north, I could see Palm Springs in the haze and on my left the southern shores of the Salton Sea faded into mist. The ceiling, 500 feet above me, was uniform and thick. Though I had crossed this desert before, it had always been with at least 20 miles visibility.

Crossing the ridge east of Thermal, I glanced over my shoulder; the Salton Sea had vanished. I entered the Mojave Desert. There was a long period of silence on the radio. Past Twentynine Palms I turned up the air corridor between Bristol and Turtle military operations areas (MOAs) and changed the number-one nav to the Goffs VOR and the 005 radial. I was now heading north to Las Vegas.

"Cherokee One-Two-Three, Cessna Skyhawk is at two o'clock, three miles, northbound at 9,200 feet." The controller's voice interrupted my thoughts.

Cessna Skyhawk northbound? That's me. But I should be at 9,500 feet. I scanned the altitude indicator; I was at 9,200 feet. I pulled the nose up and climbed back to my assigned altitude.

I scanned the VOR. The needle was way off to the right. The heading indicator and compass both showed me on a course of 21 degrees. Hadn't I intercepted the 005 radial some time ago? Shouldn't the needle be centered or off to the left? I turned the plane back to a heading of 5 degrees and watched the VOR needle for a while; it didn't budge.

I looked out the window. M-shaped mountains marched in a parade through the desert sand like the pink elephants in Dumbo's drunken dream. The VOR needle was still off to the right. I peered at the chart and tried to identify the terrain below but nothing made sense. I had this strong gut feeling I was flying south to Mexico. I scanned the instruments. According to them I was northbound. Were they lying? I was dropping altitude again. My head throbbed. Brown spots jumped before my eyes; I was exhausted.

What's wrong with me? Why do I feel so poorly? Maybe I should descend. "L.A. Center, Cessna Four-Bravo-Tango. Request descent to 7,500 feet."

"Four-Bravo-Tango, approved as requested. Descend at own discretion."

I shoved the yoke down and descended at 1,500 fpm, rpm in the red. The heading indicator now read 25 degrees. I was zigzagging across the desert!

Thunk! My head hit the roof as the right wing dipped. I tightened my seat belt. Thunk! The left wing plunged.

"Four-Bravo-Tango, I can't see you at 7,500 feet. Radar services terminated. Squawk VFR. Have a good day." Thunk!

"Roger," I gasped, leveling the wings again. What? Have a good day? This is not a good day! I don't know where the hell I am, I'm bouncing around in thermals and you have just terminated my flight following! I wished I were home in the familiar San Diego skies. I could find my way back to Gillespie, couldn't I? It was only two hours away.

It was so difficult to remember procedures. I contemplated drifting along until a fuel emergency forced me to act. How I wished there was a flight instructor in the right seat!

I turned to the right seat, hopeful. There was no professional flight instructor there, just my black leather purse. I was pilot in command of this aircraft.

I had to fly the plane. Wiping sweat from my brow, I scanned the instruments, verified course and altitude, and checked the vertical speed indicator. My compass and heading indicator agreed. My engine gauges were in the green. I was flying straight and level at 7,500 feet.

Navigate. I groped for the flight plan under my purse. It was not there. I looked around and behind me. The charts and flight plan had fallen onto the floor in the turbulence. Straining backward against my shoulder belt and reaching one arm through the narrow opening between the seats, I grabbed a handful of papers. I bounced to the left and the papers spilled back onto the floor. I scavenged for them again and grabbed the Phoenix chart, folded to show Las Vegas. A fat blue line filled the right margin from Yuma to Boulder City.

The Colorado River! I can follow the river into Las Vegas! I looked outside the airplane where directions still swirled. Where was the river? East. Where was east? Ninety degrees on the compass.

I turned to 90 degrees. The frequency for the Boulder City VOR was visible on the chart so I punched it in. I flew perched on the edge of my seat with my shoulders hunched forward and straining against the shoulder harness.

Three long minutes later, a saw-toothed range emerged from the blurred horizon. Though it was stripped of its reddish color by the haze, I recognized that shape as peculiar to the mountains that hemmed the river. Scouring my visual boundaries, I spotted a thin line of water dissecting the ground. The Colorado River! North and south snapped back into place.

I turned north and spotted a two-lane highway off my right wing. I followed it with my eyes and, where the horizon faded, I discerned a cluster of ghostly buildings. As I approached, the buildings grew into a city bordered by a massive lake. I glanced down at my chart and verified what I was seeing — Lake Mead and Boulder City! I had located the Las Vegas valley.

Encouraged, I ran my finger up the chart from my now-known location to Henderson. There was a ridge that peaked at 5,097 feet about 10 miles north of me and 5 miles east of the runway. I should fly north to that ridge and then turn west until I intercepted final approach for Henderson's Runway 36. I could safely descend to 5,500 feet now. I must find the airport quickly or risk intruding in Las Vegas' airspace.

I switched frequencies and contacted Las Vegas Approach, stating that I was 10 miles south of Boulder City over Highway 99 at 5,500 feet.

The controller gave me a squawk code and asked me to ident. I changed my squawk code, grateful to be on flight following again, and pushed the ident button.

"Four-Bravo-Tango, you are not on radar and I'm not familiar with Highway 99. Can you give me your location on a VOR radial?" The controller spoke as if to a child.

I cringed. Had I called Highway 95 the 99? Highway 99 was near Fresno in California. I struggled to center the VOR needle. I was still exhausted and the brown spots danced before my eyes. After overshooting center to each direction, the needle settled on 185. But 185 on what VOR? I fumbled for the chart and squinted to locate the boxes that identified VOR frequencies near me. Bingo! I was centered on the 185 radial from Boulder City.

"Four-Bravo-Tango, did you copy my last transmission?" The controller seemed concerned.

"Uh, yeah. Affirmative. And I'm sorry, I'm directly over the ninety-five highway and on the 185 radial for Boulder City. I was trying to center the needle; that's what took so long," I babbled.

"Four-Bravo-Tango, I have radar contact. Turn to a heading of 240 and caution for Black Mountain at three o'clock."

"Two-forty," I replied, surrendering the chore of navigation to him. I turned west and was approaching a north-south barren ridge about five miles long. As I crossed over a low spot, the fantastical skyline of Las Vegas appeared before me.

Five miles south of the airport I spotted the runway and was handed off to Henderson Tower. Landing smoothly and rolling to a stop, I looked at my clock. It read 1:30 p.m. I was exactly on time! How could that be? Hadn't I wandered for an eternity across the Mojave Desert?

On Saturday, the return trip haunted me. The winds blew fiercely in the Las Vegas valley, whipping the palm trees into a frenzy. It was cool in the shade and brick-oven hot in the sun. Would I get lost again?

I woke Sunday to a rosy-fingered sky. Cumulus scattered the sky north and east. The weather briefer predicted the same weather as I had encountered outbound: 10,000-foot ceiling, 10-mile visibility, and 10- to 15-mph winds out of the south.

I took off at noon. I headed slightly east of south to remain at 7,500 feet. Several flights from Los Angeles dropped off radar in the Mojave Desert; one commercial shuttle was way off course, according to the irate controller, and a light airplane strayed into a hot MOA. Was this the Mojave Triangle? I wondered.

In spite of my fears, the trip home was uneventful. I knew where I was, and I maintained course and altitude even through some nasty bumps over Anza-Borrego. I intersected the VORs exactly as planned. Why had it been so hard on the way to Las Vegas?

The answer is hypoxia. At 9,500 feet, I took in too little oxygen. The effects were subtle at first, a kind of cruising hypnosis followed by physical symptoms of ill being and anxiety.

What an eye-opener! I had wrongly concluded in flight training that oxygen deprivation became critical at 12,500 feet, where supplemental oxygen is mandatory after 30 minutes. Though I had flown above 9,000 feet before, I had never been so affected, probably because I had flown with a copilot and conversed, improving my oxygen uptake.

What frightened me was my lack of awareness that something was wrong until I became disoriented. I had relied too much on visual cues and pilotage. I will use dead reckoning on future flights and sign up for some instrument training. (GPS would have helped too.) My new personal threshold is 7,500 feet for flights longer than an hour without supplemental oxygen. Whenever I fly at or above 7,500 feet for more than an hour, I practice the Whittaker Wheeze, developed by a famous mountaineer and shared by my yoga instructor after this experience. He taught me to inhale normally, then exhale pursing my cheeks as if blowing up a balloon. The wheeze compresses my lungs, leading to greater oxygen intake, and is equivalent to dropping 1,000 feet in altitude.


Shelley Marquez, AOPA 4258400, is a private pilot with more than 400 hours. She is a university administrator in Southern California.


Additional information about hypoxia may be found at the following links:


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Posted Thursday, October 09, 2003 9:13:52 AM