• Military Aviation

Above & Beyond: Milk Run

How a milk run from an aircraft carrier nearly killed me.

• By Chris McKenna
• Air & Space Magazine, May 01, 2007

For any Navy pilot flying aircraft carrier operations, the voice of the air boss, the officer in charge of all air operations on deck, is the sound of absolute authority. For this Navy helicopter pilot, the air boss represented trouble. He was a tyrant with a hair trigger.

In 1988 I was flying the Boeing CH-46 Sea Knight, a tandem-rotor helicopter deployed on the USS Niagara Falls, a support ship in the USS Dwight D. Eisenhower Carrier Battle Group. My crew and I delivered “beans and bullets” to the fleet. We hit the Ike every other day, restocking whatever was needed to keep a city at sea afloat. Ammunition, food, machinery, mail—referred to as “pony”—the ships in the battle group relied on us for everything except fuel. It was exciting, challenging flying, and I loved it. But always, just below the surface, was the fear of raising the ire of the air boss.

One morning, flying as Knightrider zero six, we launched before dawn on a replenishing mission. We moved tons of cargo attached as sling loads beneath the helicopter.

By noon we had only a load of internal cargo left to deliver. I radioed the carrier. “Boss, Knightrider zero six, 10 miles out for landing.”
“Recoveries in progress. Take Starboard Delta,” he replied, directing us into an established holding pattern.

We watched as jets made approaches and “trapped” (caught one of the arresting cables) or “boltered” (missed the wires and went around for another try). We should be next, I thought, once all the jets were aboard. But the voice of authority had other plans. “I’ve got another cycle 15 minutes out, Knightrider. I’ll recover them first, then bring you aboard.”
“Haven’t got fuel for that, Boss,” I said.

“Then go get some,” he snapped.

He knew we could get in and out in five minutes, but he was the air boss, so I bit my tongue and turned for the Falls. Then I remembered those orange bags marked U.S. Mail. In a mariner’s heart, mail call ranks just below liberty call. Not even an air boss can resist mail call. I keyed the microphone. “We have pony aboard, Boss.”
Everyone in the control tower would be staring at him. If he didn’t land us, all 6,000 sailors aboard would soon know he had denied them a mail call.

“Knightrider, you’re clear to land, spot three,” he relented, specifying the forward spot on the angled flight deck.

I flew a shallow approach, careful not to let my rotor wash disrupt his flight deck. As soon as I touched down, my aircrew lowered the ramp and began pushing pallets down the rollers to the forklifts. Minutes after receiving the air boss’ grudging clearance, we were empty and ready to go.

“Knightrider zero six, ready to lift, spot three,” I transmitted.

“Stand by, Knightrider,” he said. “Supply wants you to move a load of milk back to home plate for dispersal. How many gallons can we load, max?”
With our fuel load, we could lift about 7,000 pounds, but I hadn’t a clue as to how many gallons of milk that would be. I looked over at Dave, my copilot. “Any idea what milk weighs?”
Dave shrugged and turned his palms upward in what is known in Navy parlance as an ensign’s salute.

“I need a number, Knightrider,” the air boss growled.

Forklifts began driving off the elevators with pallets of milk. I pulled the calculator out of my helmet bag and typed 7000. Now I just needed to know what to divide it by.

“Knightrider! I need a number—now.”
“Milk must weigh about the same as fuel, right Dave?”
Dave gave me another ensign’s salute.

I knew that jet fuel weighed about 6.5 pounds per gallon. Even though the voice in my head told me to slow down and think this through, I decided that a liquid was a liquid. I plugged 6.5 into my calculator. Just as the Boss started to growl again, I transmitted, “One zero five zero gallons, Boss,” with far more confidence than I actually had. It was meager comfort that I had figured in a 27-gallon cushion, just in case milk was a little heavier than fuel. How much heavier could it be?
“Okay, Knightrider. Here it comes. Be ready to lift as soon as we stuff you.”
In minutes the cabin was crammed with hundreds of plastic jugs that I prayed weighed no more than my hasty calculation.

“Knightrider, cleared for takeoff.”
I pulled the aircraft into a hover and stabilized it for a ground-effect power check.

Ground effect—the cushion of air that provides extra lift for a helicopter operating within one rotor diameter of the surface—can be a blessing or a curse. With a long hovering run, a pilot can accelerate in the ground effect cushion until reaching flying speed, thereby lifting far more than would be possible from a standard climbing transition. The carrier, however, presented the opposite situation. From our position adjacent to the deck edge, I would take off into a ground-effect hover, then transition over the edge of the flight deck, 90 feet above the water, to an immediate loss of ground effect. The voice in my head warned me as I raised the collective to increase rotor pitch and add engine torque, but the big voice in my headset drowned it out: “I need my deck, Knightrider!”
Normally I would have taken my time to evaluate a takeoff this critical. But this was the air boss’ deck, and he wanted it back. “Get that damn helo off my deck, now!”
Without the stabilized torque reading that would tell whether the aircraft would fly at this weight, and against my better judgment, I eased the cyclic stick forward and the aircraft lumbered across the deck edge.

Immediately we were in trouble. The aircraft settled, and I instinctively countered by raising the collective. But instead of slowing its descent, the helicopter settled faster. The steady hum of the rotors changed to a distinct whump whump whump, and the familiar blur of the rotors slowed until I could see each individual blade. A quick glance at the instruments confirmed that both engines were operating normally. I was simply demanding more power than they could produce, and the strain was making the rotor speed decay.

I should have predicted what would happen next. With a jolt, both generators kicked off and we lost everything electrical. Powered by the rotor system, the generators had been designed to “shed,” or drop offline, at 88 percent of optimum rotor speed to preserve torque for lift. The jolt was the loss of the flight control stability system. The helicopter was still controllable, but controlling it took far more work without the stability system. Things were starting to go very badly.

As the rotor speed continued to decay, I realized the only chance we had was to get back into ground effect. If I continued wallowing, the helicopter would “run out of turns”—lose lifting rotor speed—and crash, or settle into the ocean and sink. I had to try what the old salts called “scooping it out.”
Faced with an undesirable sink rate, it is counterintuitive to decrease either power or pitch, but scooping it out required both. To dive back into ground effect, I lowered the nose, and the windscreen filled with the sight of blue water and white foam. To preserve rapidly deteriorating rotor speed, I lowered the collective. The bottom dropped out and the ocean rushed upward. I blurted “Brace for impact!” Dave immediately understood what I was attempting and began calling altitude and rotor speed.

“Fifteen feet, 84 percent.”
I needed airspeed. I had to trade more altitude to get it, so I eased the cyclic forward a little more.

“Five feet, 84 percent.”
I checked the descent and stabilized in the ground effect run.

“Three feet, 83 percent.”
We were flying, and the rotor speed had stabilized, but I couldn’t seem to coax any acceleration out of it. This low, even a rogue wave could bring us down. Milk, I thought. Evil stuff.

With only the speed I had bought with the dive and no sign of acceleration, I despaired. Then the old salts spoke to me again. If you ever need a little something extra, try a 15-degree right yaw. The drag is negligible, but your aft rotors get undisturbed air.

What did I have to lose? I tapped the right pedal and the helicopter yawed.

“Two feet, 84 percent.”
Running through ditching procedures in my mind, I suddenly noticed the waves gliding by faster than they had only seconds before. Slowly, almost imperceptibly, we were accelerating.

I glanced at the airspeed indicator and my heart leaped: It was passing 40 knots. Then I felt that beautiful shudder every helicopter pilot knows as translational lift, the point where the aircraft is flying like an airplane more than hovering like a helicopter.

“Five feet, 90 percent.”
Then another jolt—the generators were back, bringing the stability system with them. I accelerated through normal climb speed. At 90 knots and with rotor speed back, I finally had the confidence to leave the ground cushion that had saved us. Climbing through 100 feet, and over a mile from the carrier, the voice of authority once more rang in my headphones. “Great to see you flying, Knightrider. We were all holding our breath up here.”
So, the air boss had a heart after all.

Turning for home, I passed the controls to Dave, took a deep breath, and noticed that my hands were shaking. I’d made a rookie mistake, and very nearly paid for it with four lives and a helicopter.

I later learned that milk weighs 8.7 pounds per gallon, a far cry from the 6.5 I had estimated. I had taken off from the carrier more than 2,100 pounds overweight, not counting the weight of pallets and packaging.

That was 20 years ago. Now I’m the old salt. Thousands of flight hours later, I still remember what I learned that day. Never allow external pressures to force a decision on any matter of safety. And never ignore the voice in my head that says something isn’t right. Frequently it is the only one making sense.

And when the guy at the supermarket asks me how I want to carry my milk, I always tell him to double-bag it.