When the Needles Spin
October 31, 2012
I was preparing for my instrument flight evaluation as part of my annual proficiency and readiness test. On this day, I would be flying from Fort Wainwright, Alaska, to Fort Greeley with the company standardization pilot/instrument examiner. The weather forecast was great for both the departure and arrival airfields. However, the SP/IE and I could expect to be flying in instrument meteorological conditions for almost the entire en route portion of the flight. Due to the limited instrument flight rule route structure in central Alaska, we had both flown this route numerous times. We expected an easy instrument flight evaluation. Little did we know what was in store for us.
With the oral evaluation and preflight complete, we departed Ladd Army Airfield IFR, headed toward Fort Greely. Departing to the south was uneventful and actually pleasant. The atmosphere in the cockpit was relaxed, a feeling I have learned to temper with added vigilance. The UH-60A we were flying was one of the oldest in the fleet at that time. Having recently been moved from Korea to Alaska, there was no doubt this airframe had some time on it.
Halfway to Fort Greely, established on the Victor airway at 4,000 feet and in the clouds, I noticed something strange with my attitude indicator. It began rocking left and right and then started to spin very quickly. I announced this to the crew, then looked cross cockpit and saw the same thing happening on the co-pilot's side.
Next, I noticed a problem with my horizontal situation indicator. All the needles were spinning. Every second the indicator needle swung 180 degrees, stopped and then returned to the present heading. As I announced this, the same situation was also occurring on the other side of the cockpit. The seasoned warrant officer SP/IE, who had more than 4,000 hours, told me he had the controls. He said I was doing fine and we would have to put into practice our flying partial panel training. He then told me to contact air traffic control, advise them of our situation and request radar vectors to the precision approach radar at Fort Greely, where we would land. We followed the vectors to the PAR, executed the approach and landed safely. Later, a maintenance test pilot conducting the post-flight inspection found a loose cannon plug on the command instrument processor. That is what caused the gyros to spin out of control.
We practice partial panel flying in the flight simulator, but it can be unsettling when you unexpectedly encounter it during flight. Flying without an attitude indicator can be challenging. Flying without a horizontal situation indicator can also be challenging. Flying without both is my idea of a bad day. Using the standby magnetic compass requires skills we, arguably, all need to review. What is the magnetic variation on your path of flight? Do you add it to your magnetic course or subtract it for your direction of travel? Did your flight planning include the true course and magnetic course on your navigation log?
Fortunately, I was a young warrant officer on my second instrument flight evaluation thus far in my career, so I completed my navigation log with great attention to detail. But it shouldn't take an evaluation to force us into our most thorough work through of a problem. I attribute the safe outcome to the SP/IE that day. I learned a valuable lesson about complacency. Even if you've memorized Chapters 5 (operating limits and restrictions) and 9 (emergency procedures) of the -10, there are still malfunctions that can endanger an unprepared crew.
Finally, always be prepared with the right publications. As professional aviators, we should always have current aircraft pubs with us, no matter the training situation. Knowing what to do and how to do it can make all the difference when the needles spin.