Deep in IIMC
RETIRED CHIEF WARRANT OFFICER 4 BRIAN K. CALHOUN
Author’s note: The following article is a brief account of what happened to my co-pilot gunner and me the night we inadvertently entered instrument meteorological conditions.
The night’s task was an AH-64D Readiness Level 3 progression local area operation including as many night and night vision system (NVS) base tasks we could complete within our three-hour period of instruction. This was our fourth flight together as a crew. Our three previous missions, flown during the day with an hour of hood training, went smoothly.
My co-pilot gunner (CPG) had more than 300 hours in Army aircraft with upward of 100 hours with NVS. By comparison, I had 1,600-plus hours in Army aircraft with more than 700 hours of NVS time. On this mission, he would be the pilot and I would be the instructor pilot (IP). Here is the rest of the background for the flight:
- NOTAMs: Robert Gray Army Airfield, Fort Hood, Texas, precision approach radar was out of service.
- Crew rest: The crew had greater than 24 hours of rest the day before.
- Mission brief: Briefed and approved for low-level risk.
- Weather brief: Ceilings scattered at 5,000 feet with overcast at 7,000, visibility 5 statute miles with localized rain showers in the area. Winds were from the northeast at 10-15 mph and we were told to expect reduced visibility due to the rain showers.
We met three hours before takeoff for our mission brief and table talk. We covered all the standard crew brief topics, including local procedures for inadvertent instrument meteorological conditions (IIMC). A half hour past sunset, we departed Hood Army Airfield on a single-ship flight directly to the eastern side of Fort Hood for our terrain flight training. I used night vision goggles (NVG) and my CPG used the pilot night vision system (PNVS) for better terrain identification. Upon arrival at the terrain flight area, we determined the rain reduced visibility to an unsafe level for training. We exited the low-level area to transition to the western side of Fort Hood in anticipation of better weather conditions. When we arrived there we found light rain and good visibility; however, in the airspace corridors, I estimated the overcast ceilings at 1,500 feet above ground level.
We arrived at a local dirt flight strip in the training area. For better situational awareness, we conducted terrain flight tasks in the area around the flight strip. After about 40 minutes of terrain flight and covering only a 4-kilometer radius of the flight strip, the rain increased to a level that I could not see as well as I wanted to with the NVG. As a result, I changed to the target acquisition and designation sight while the CPG used the PNVS. After completing our training, we departed the flight strip for a local orientation flight of a nearby landmark, located just a few kilometers north, to help complete the local area orientation.
As we traveled north at terrain flight altitude, I told the CPG that visibility had been reduced to less than 1 statute mile and it was time to return to Hood Army Airfield and call it a night. Within 30 seconds of making the call to return to base, the radar altimeter failed. I called on the area advisory frequency and informed everyone in the area that we were returning to base.
Another AH-64D pilot responded he was parallel inbound low level to the same checkpoint. Another aircraft, a CH-47, called and said they were at checkpoint Henry, outbound to the terrain flight area, but were going to turn back to Hood Army Airfield because of poor visibility. We were at 1,800 feet mean sea level (850 feet AGL) on the inbound corridor 5 kilometers north of checkpoint Henry.
The CPG thought he saw the CH-47 converging on our aircraft at our altitude and called out, “Traffic 12 o’clock our altitude, turn left!” I responded, “I don’t see it!” I was puzzled because checkpoint Henry was 20 degrees to our left. If there was any traffic, I would need to turn right. Because of the heavy rain, I turned 10 degrees right to see if I could get a better view from a different angle. Again, the CPG called out, “Traffic 12 o’clock our altitude, turn left!” I responded, “Negative, I don’t see any traffic.” The CPG announced very loudly that we needed either to turn left or break left. I thought he must have seen something so I turned left, banking between 60 and 90 degrees to avoid hitting the other aircraft.
We suddenly entered IIMC inside a cloud as we descended at more than 1,500 feet per minute. Although I experienced spatial disorientation, I was able to level the aircraft’s lateral attitude and select Attitude Hold. However, by that time, the tail rotor had produced a vertical lift and raised the Apache’s tail. I selected my flight page on the multipurpose display and noted a 25-degree nose-low attitude, 56 percent torque applied and 130 knots true airspeed. I noted our altitude was 1,100 MSL and that the terrain elevation was 950 MSL.
I thought we were about to crash! I increased torque to 95 percent and pulled aft on the cyclic, producing a 20 degree nose-up attitude on pullout. We climbed to 2,000 feet MSL. The CPG announced, “Airspeed 08 KTAS, I’ll take the controls if you need me to.” I felt we were out of immediate danger and replied, “No, I have the controls.” After applying forward cyclic and increasing airspeed, I executed the local procedures for IIMC. I called Robert Gray Army Airfield approach control, declared an emergency and requested radar vectors for GPS approach to Runway 15. During our approach, we exited the clouds and had the runway in sight. We requested to break off the approach and returned to Hood Army Airfield, where we landed safely. Lessons learned
This is not just another story; it is my story. I was the IP who almost didn’t make it home that night. I was responsible for my flight and crew safety. The lesson I learned was to depend on myself, my skills and training.
Like my situation, there may come a time when no one is available to help you make the right decision. That’s when your memory, skills and training will get you home safely. If you’re a pilot, I urge you to invest time to thoroughly study your manuals. One day, your life might well depend on your knowing what to do.
Oh, and remember the aircraft the CPG thought was coming at us? It was a light from a vehicle on the ground reflecting on the canopy glass — not a real CH-47. But I almost crashed my aircraft trying to miss it! Fly safe!