Operating on the Edge
CHIEF WARRANT OFFICER 2 JUSTIN C. POWERS
Headquarters, Headquarters Company
1st Battalion, 108th Aviation Regiment
Kansas Army National Guard
I experienced a situation one summer where power management and performance planning were of the utmost importance. I was on a firefighting mission in central California, flying a UH-60A. The average mission condition was a 15,000-pound aircraft with a 4,000-pound water bucket working between 4,000 feet mean sea level/30 Celsius and 6,000 feet MSL/25 C.
Going into this mission, we knew performance planning was essential, as our normal operations were at 15,000 pounds and 1,500 feet. Our initial calculations showed we did not have out-of-ground effect (OGE) capability at 6,000 feet and only marginal performance at 4,000 feet, which meant we couldn’t perform water bucket operations.
One control measure we put into play was eliminating any nonessential equipment and passengers. Next, we used our performance planning cards and a U.S. Forestry Service helicopter load card to calculate the amount of fuel we could take on because we couldn’t reduce our bucket weight any further. We found our max gross weight OGE for the conditions and subtracted the aircraft and full bucket weight. The remaining weight was the maximum fuel we could have on board.
We chose the best approach paths, using the wind to our advantage for performing max gross weight approaches because of our low power margins. We kept track of the winds by observing smoke drift and ripples on the water since the automated weather observation system and automated surface observing systems were not available or accurate in the mountains.
During approaches, we slowed down early and got the power back in to avoid mushing and transient rotor droop. We weren’t always able to choose our landing direction (helicopter controllers sometimes dictated landing direction for traffic deconfliction because there were many aircraft working the fires), but we tried to use the longest approach paths with the shortest trees as much into the wind as possible.
Fuel on board was normally 1,900-2,000 pounds, which translated to about 2½ hours of endurance. Since we reduced our fuel, we then had to be more vigilant with fuel management, especially with constantly changing conditions of gross weight and density altitude. By efficiently managing our fuel, we were able to deliver more water on fires, knowing exactly how long we could stay on station and how much fuel we needed to get back to base with our appropriate reserve.
I found the -10 was accurate with the fuel storage. The first water load with the Bambi Bucket of each mission was right on the edge of our power margin at 6,000 feet MSL. As the mission progressed, we gained more and more power as we burned off fuel. In power-critical situations, crew coordination and familiarity are key, as you know what to expect from each other and what calls the other pilot needs to hear to be effective. Because of this fact, we used battle rostering as a control measure, and it worked well.
This mission reinforced the importance of performance planning, crew coordination, fuel management, power management and landing zone selection. Power management is critical when operating at the edge of the performance envelope. After these missions, I realized training at the High Altitude Army Aviation Training Site in Gypsum, Colorado, would be invaluable. This course is essential for both wartime and peacetime missions because it teaches crews to properly use their performance planning, crew coordination and mission planning for all scenarios. These types of missions are becoming more common with our resources stretched.
As professional aviators, we must stay vigilant, know our aircraft, use proper crew coordination, understand the mission and always use proper pre-mission planning. Today’s modern aircraft are extremely powerful and capable. However, there is always that time when we’ll be working on the edge of power available and we must be ready for it.