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Never Again Online: Fuel gauge on empty

I had flown two forensic scientists to view the site of an accident in the vicinity of Redding, California. They did their thing at the accident site, and by 2 p.m.

I had flown two forensic scientists to view the site of an accident in the vicinity of Redding, California. They did their thing at the accident site, and by 2 p.m. it was time to head back to Monterey. Redding can get unbelievably hot, and this was one of those days when it was well over 100 degrees F. With three large persons and the extreme heat, I was concerned about the weight of the Cessna 172. So, I decided to limit refueling to 20 gallons, which — combined with the remaining fuel on board — would provide close to five hours of total fuel for the trip back.

Our return flight was uneventful. I dropped off one passenger at Sebastopol and the other in Palo Alto. As I prepared for takeoff from Palo Alto, I noticed that the gas gauge indicated close to empty for both tanks. The rental aircraft was more than 30 years old, and I figured that the many years of sloshing fuel had begun to take its toll on the fuel tanks' rheostats; over time these sending devices most likely had lost sensitivity in the mid range so the fuel gauges would probably tend to read close to either full or empty. A precise computation of fuel burn would be necessary to accurately determine fuel remaining in the tanks. But my rental aircraft did not have a fuel dip stick to check the amount remaining in the tanks.

The aircraft climbed away from the runway at Palo Alto, and I pointed the nose toward the Santa Cruz Mountains. I was aware, but unconcerned, of the near-empty reading of the gas gauges. After all, my fuel computations had confirmed nearly three hours of fuel remaining for the trip from Palo Alto to Monterey.

When I was just north of Watsonville, I noticed that the fuel gauge needles seemed glued to the empty position in a persistently motionless state. Should I land at Watsonville? I pulled out the aircraft's pilot operating handbook and again computed the fuel burn for my flight's cruising altitude and power settings. I confirmed that I had at least two more hours of fuel to cover the 20 minutes to my destination. So, I motored on.

As I arrived in Monterey's air space, the air traffic controller delayed my landing for about three minutes to make room for a larger aircraft. Now it was my turn. I lined up on the final approach, slowed the airspeed, and put down full flaps. At this point, the engine quit.

At altitude, engine failure is not that big a deal for an experienced pilot. It might be distracting, but well within the realm of one's ability to cope. At 5,000 feet an aircraft often can glide long enough to allow you to pick out a suitable place to land. However, on short final, at 500 feet, with full flaps deployed, one's options become a bit thin — even thinner as you lose altitude while contemplating what to do next, and I was definitely contemplating.

I pushed the transmit button and said matter of factly, "Monterey Tower, Cessna 372 has a Mayday, my engine has quit and I am going to land to the north." I was trying hard to be "Joe Cool" and not sound uptight. It must have worked well, because Monterey Tower did not recognize that there was a very real emergency going on just off the end of its runway. The controller replied, "Roger, 372 is cleared to land." I thought, "Wow, I just don't have time to discuss this further with them." I had entered survival mode.

Things were now getting worse in a hurry. Whereas I had been on a glide path to arrive at the runway approach end, I now was without power and on a glide path that would have me arrive at the face of the cliff located at the east end of the runway. I wondered if I should retract the flaps to decrease my glide angle. But to do so would initially cause me to lose some of my precious altitude. If I tried to make the runway and wound up short, I'd be dead for sure. Turning away from the airport, I decided to keep the flaps extended and try for a narrow road that I could see off to the right of the runway. The road was perhaps 200 or 300 feet lower than the runway, which gave me another half-mile of glide distance. I then heard the pilot of an airplane behind me on the radio. He had seen me turn and heading lower, so he called the tower and confirmed that I had a problem and was headed for an emergency landing.

At this point I shut out everything else and focused on my chosen landing area, looking for potential problems. There was no time to mess with further transmissions or restart procedures. My mind was racing: Was the road too narrow? Where was the wind from? Were there telephone poles defining unseen wires? I was now committed to the landing area, and I had begun to talk to myself about the approach, glide path, the trees overhanging the road, and how narrow the road was. I then noticed a dirt road to my left with no trees and decided to turn to it.

Whoosh, the airplane sank into the soft dirt just beyond a small hill, rolled 200 feet, and then came to rest. No crash, no dents, no damage. All those years of practicing forced landings had paid off after all.

There were sirens in the distance. The first group to arrive was a news reporter and photographer. The next ones to pull up were the police. Then the fire engines arrived. I stepped out of the airplane and could not believe it was over. What a day this had been.

So what had happened? The gas tanks were indeed empty. When I was on final and had put the flaps down, the nose had dropped, and the change in angle of attack must have un-ported the last drops of gas. I do not know why the fuel consumption was higher than my calculations. But, I could have avoided this situation by taking accurate fuel measurements before takeoff and computing fuel burn with a broader safety margin, considering the aircraft was old.

R. Ren Hart, AOPA 526477, is an aircraft accident consultant. He holds a commercial pilot certificate with multiengine, instrument, and helicopter ratings. In 50 years of flying he has accumulated more than 3,700 hours of flight time. Hart, a retired U.S. Army colonel, participated in 240 combat missions in Vietnam and received seven air medals.

You can find additional information about fuel starvation at the following links:

Look for the latest installment of "Never Again" in the July issue of AOPA Pilot. While practicing engine-out procedures the CFI and student were in for a surprise.

Return to the "Never Again Online" main page.

Posted Thursday, June 07, 2007 4:45:58 PM

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