In 1967, when I was in Undergraduate Pilot Training (UPT) at Laughlin Air Force Base, I devoured everything I could read about flying, like every other student pilot. The UPT leadership helped us by providing a variety of flying periodicals in the magazine racks on the inside of every lavatory stall - Flying, Plane and Pilot, Private Pilot, the works. Early in our careers we learned about multi-tasking!

In one of the magazines, I can't remember which, I read an article titled "The Box Canyon Maneuver". A box canyon is a formation in which there is no room to perform a normal 180-degree turn, which has sides too high for the airplane to outclimb. The maneuver is basically a hammerhead turn, in which the pilot pulls the airplane up to vertical, remaining unloaded to avoid a stall, and then steps on a rudder to bring the airplane to a nose-down attitude facing the other direction. I was fascinated, and I practiced the maneuver whenever I had the chance during solo flight. I became reasonably proficient at it.

A little over a year later, I was flying the O-2A in Vietnam. In addition to combat flying, I flew Functional Check Flights (FCFs), where I would test all the systems of the airplane following maintenance. The FCF had to be conducted in visual flight conditions.

On this particular day I was scheduled for FCF duty, but the weather at DaNang Air Base was lousy. Drizzle and low clouds, and it looked like it would stay that way all day. Certainly not conducive for an FCF. I convinced our Operations Officer that I could climb out through the overcast on a heading of East, over the ocean, until I got into the clear to conduct the FCF. 

I took off to the North on Runway 35 Right and immediately turned East. At about 300 feet I was in clouds, flying entirely on instruments, holding steady on a heading of 090 degrees. As a new pilot, I had never flown in solid clouds, and I was pretty proud of myself, feeling like a real pilot. 

I was in the clouds, flying over the ocean as I climbed out. Nothing to look at out the windscreen, but for some reason I had the urge to look straight ahead. Suddenly, through the windscreen, I saw the jungle rushing up at me at 100 knots! I instinctively pulled up to vertical, unloaded, and stepped on the left rudder. When the airplane was headed downhill I pulled up to level flight and looked at my heading indicator. Now it showed I was heading West. Then I looked at the Standby Compass, sometimes called the Whiskey Compass. It showed I was heading South!

Finally, I realized what had happened. My heading indicator had precessed 90 degrees to the left, so that shortly after entering the clouds I had slowly turned to North, directly toward Monkey Mountain.

I discontinued the FCF and obtained a gyro-out Ground Controlled Approach (GCA). 

I've had a lot of close calls in combat, but this was the closest I ever came to unquestionably losing my life. Every day since then has been on borrowed time.

https://youtu.be/fqH4tujxuTA