The magical rubber stamp.
First, you will be seated, strapped, or hung into myriad devices designed to drown you. Second, you will be herded into a large metal cylinder with a latex glove hanging from the overhead. The air then will be sucked out of the cylinder until you turn blue in the face, forget the answers to third-grade math problems, and turn giddy with laughter because the fool seated next to you keeps screwing up "patty-cake."
Our reward for begrudgingly undergoing such abuse is a magical rubber stamp in our NATOPS jacket that deems us qualified to fly for another four years. According to my records, I was good to go for another two years, but I guess my chamber qual expired early.
My C-130 crew was midway through our detachment. After two weeks in theater, we had settled into the repetitive grind of flying the daily double-shuttle to Fujairah and back. The aircraft had been holding up well, with only a couple outstanding gripes. One of these involved the pressurization system, which had difficulty regulating in the automatic mode. The flight engineer (FE) needed to manually control the pressurization to keep the cabin altitude within limits. This known discrepancy had existed for several weeks on the aircraft, despite maintenance's best efforts to troubleshoot the system. The replacement of multiple regulators, controllers and valves, as dictated in the maintenance manuals, did little to correct the problem. Fortunately, both crews on our detachment were comfortable flying the aircraft in the manual-pressurization mode.
On this morning, we enjoyed a typical, uneventful flight to Fujairah. We delivered our cargo and then uploaded four pallets for the return leg to Bahrain. As we climbed out and completed the after-takeoff checklist, the FE adjusted the pressurization controller to a comfortable 1,500-fpm rate. This setting would keep us adequately pressurized on our way up to our planned cruising level of FL220, or so we thought. Passing 10,000 feet, we verified the cabin altitude in accordance with SOP. The cabin altimeter read 3,000 feet, and the pressure controller still reflected a constant 1,500-fpm rate that matched up well with our loaded Herc's anemic rate of climb.
Several minutes later, the cockpit silence was broken by the FE calling over ICS, "Everyone, go on oxygen!"
The copilot and I reached back and grabbed our quick-don oxygen masks. We managed to shoot a quizzical glance back at the FE, and we instinctively looked for signs of smoke or fumes.
The FE pointed to the cabin altimeter and simply said, "Cabin altitude."
The altimeter read about 16,000 feet, as we climbed through FL190. The crew checked in over the ICS on oxygen, and the FE worked to regain control of the cabin pressurization. Within a matter of minutes, the cabin altitude returned to normal. We removed our masks and continued on to Bahrain without further incident.
On the way back, we felt obligated to look a little more closely at the chain of events. How did we get into this situation? On the positive side, once the malfunction was realized, effective crew-resource management prevented further deterioration. The FE communicated an instantaneous and assertive statement, which got us all on oxygen. This action bought the crew critical time and restored our cognitive ability to troubleshoot the malfunction and complete the NATOPS procedures.
Everything was normal at 10,000 feet, our standard pressurization checkpoint. So, why did the FE again look at the cabin altimeter? As it turns out, the engineer felt tingling in his fingers. Individuals may experience different symptoms when exposed to a hypoxic environment. In retrospect, I remember thinking on climb-out how tired and somewhat dehydrated I felt. I dismissed it, though, considering the early morning brief, coupled with the exhausting summer heat in the Gulf. Both are symptoms I experienced on a high-altitude chamber ride. I made an incorrect assumption and dismissed potential cues that quickly could have alerted us to the runaway-pressure controller.
We had succumbed to a degree of complacency as we flew the same repetitive and mundane mission day in and day out. The aircraft also had a known outstanding pressurization gripe we had gotten used to. We had stopped considering the potential hazards involved with that system. Why not pay more attention to the cabin altimeter throughout our climb profile with a known bad pressure controller? We checked it after takeoff and again passing 10,000 feet, but because everything appeared normal on those checks, we didn't give it another look, despite the remaining 12,000 feet of climb to reach our cruising altitude. It all seems foolish, as I look back on it now.
We discussed the events with the other crew and learned they had experienced an instance several days before of the pressure controller suddenly initiating a 1,000-fpm rate-of-climb while level at cruising altitude. Because the controller already was written up, a new MAF was not initiated. Perhaps they should have generated an amended MAF or info-only MAF. At the very least, it certainly was information that our crews should have had.
At first glance, this was a mundane emergency our crew handled promptly. I hesitate to even use the term "emergency." I also hesitated to submit an article relating our experience. I think we all can see how these minor instances can help illuminate underlying issues that might lead to bigger problems. Perhaps the lessons we gleaned from this simple logistics flight helped us avert a bigger disaster.
LCdr. Leslie flies with VR-62.
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|Title Annotation:||complacency and aircraft emergency|
|Article Type:||Personal account|
|Date:||May 1, 2008|
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