Podcast: What Does Aircraft Decompression Feel Like? A Pilot's Experience

Listen in as pilot and aviation expert Pat Veillette explains to Aviation Week Network's Lee Ann Shay what happens when aircraft decompression occurs—speaking from his own experience of decompression when co-piloting a Hawker. Pat shares his tips for crew in this type of emergency and explains how pilot training compares to real-life decompression.

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Rush Transcript

Lee Ann Shay: Hello, and thank you for joining us for this BCA Podcast, Aviation Week's business aviation podcast. I'm Lee Ann Shay, Aviation Week's executive editor of MRO and business aviation. Today, we're going to be talking about a very newsy topic, aircraft decompression, which happened January 5th on an Alaska Airlines Boeing 737-9 part of the fuselage, where an optional emergency exit blew out. We wanted to address this from a pilot standpoint. Dr. Pat Veillette, a 20 year BCA contributor is joining us. Welcome, Pat. Pat has accumulated more than 20,000 hours of flight experience in 240 types of aircraft, including business aircraft, rotorcraft, seaplanes, gliders, warbirds, supersonic jets, and large commercial transports, and he's also an adjunct professor at Utah Valley University. Pat, you flew a Hawker that depressurized. What happened, and can you describe it? What was it like being in the cockpit?

Pat Veillette: There were a lot of positives from this event that show the strengths of the aviation safety system. And that's the overwhelming message that I'll end with. We were cruising at flight level 390, over the Gary, Indiana area. And I was in the right seat, co-pilot for the flight, flying with a very capable captain. And as we're given an instruction to descend, when the captain pulled back the throttle, all of a sudden this noise. And our sinuses and our ears just went pop. And it was physiologically attention-getting. And all of a sudden you knew something was wrong. So out of mere reflex, both of us quickly glanced at the cabin altitude. And the needle was just buried at 2,000 feet-per-minute descent. And one of us might have uttered, "We're losing the cabin." Simultaneously, both of us reached up for our oxygen mask.

This is one of the positive aspects that go to the training that we reinforce every six months in the simulator, because we did this without thinking. Immediately, I reached up, and just by reflex you pop the band that flips, which expand the harness. And you begin to slip it on. And you do this without thinking. This is the funny part. It's the sort of funny part. I self-induced some errors here that you don't experience in the sim. The sim training is fabulous in this scenario.

The problem is that I wear sunglasses. And we were wearing those light, business jet headsets. As I went and started sweeping the mask over my face, and by reflex releasing the pressure in the mask, well, my eyeglasses were now skewed like this, and my headset was skewed like this as I released the pressure and it clamped it onto my head. So I've got sunglasses and headset and it was not my most graceful moment. Okay, this is not the way we do it in the sim. So it involved a few seconds of reinflating the harness, knocking off the sunglasses and the headset, and getting it mounted on.

Afterwards, when I reviewed this in some ASRS reports, I saw this actually is pretty common. It happens to a lot of crews. So if there's a modification I would mention to simulator training, when we develop our motor reflexes to put that pressure mask on, yeah, a lot of us wear sunglasses and/or the headsets, practice, just sweep it off your head because you don't want that getting stuck under your harness.

So anyhow, after that ungraceful first few seconds of this, we've got the oxygen masks on. And the other part of the training that kicked in right away is that Neil, the captain flying, automatically, I glanced over, his hands are sweeping back the throttles. He's getting the dive brakes out, that nose is getting buried. And he's going right through the proper procedure to get us into the emergency descent.

That motor reflex training that's embedded in us every six months, wow, we didn't really have to consciously think about these steps. So it's a great aspect of how the recurrent training works well. The rest of the scenario... And by the way, it all ended without incident, which was the best part of this. But the simulator does not replicate, and it can't, the sensations that you feel in this rapid decompression. And by the way, these recent incidents, they had an explosive decompression, which is magnitudes worse than what we had. So your sinuses and your ears are all of a sudden exposed to this low pressure condition in the cabin, and they just want to explode because of that rapid pressure change. And you feel like you're at the bottom of a swimming pool trying to listen. Your ears are so plugged up that it's hard to hear.

So Neil and I were probably yelling in our oxygen masks trying to communicate, and in that system, when we went hot mic through the microphone in the oxygen mask, the noise comes up over the speakers. Well, so I could hear both Neil and I breathing heavily through the mask, but I'm making radio calls to Chicago Center in the blind. I immediately declared an emergency, told them we had a rapid decompression and we're descending down at 10,000 feet. I never heard Chicago Center throughout most of our descent, because the ears are so plugged up with this pressure differential. And the sinuses as well. Your head just feels like it's going to explode. So Neil did a great job nailing the barber pole. We're coming out of the sky at 6,000 feet-per-minute. I grab the emergency checklist to start doing the checklist items and I'm calling out of the blind to Chicago to tell them, "Yeah, we're passing 25,000 feet right now, headed to 10,000."

I can't hear Chicago reply. I know they're doing their job on their end. So we just continued. I did my checklist, Neil kept flying the aircraft, he did a great job. But it takes a surprising amount of time. It seems like a fair amount of time to descend down out of 390 down to 10,000. The other interesting aspect is that the oxygen masks, they're pressure breathing devices that are necessary in jets, which means at really high altitudes, they force air under high pressure into your lungs. It's necessary to make certain that oxygen goes into your lungs. There's just not enough partial pressure of oxygen above 25,000 feet. So as I'm trying to talk to center or just trying to exhale, that air is forcefully coming from the oxygen mask into the body. This is an exhausting breathing exercise, and I reflect back in the Air Force altitude chamber training I had in Columbus, Mississippi in the '80s, we went through that exercise where we were exposed to pressure breathing.

And that's where we and our class learned the exhaustion after just a minute of forcefully working your diaphragm to force that air out. It's tiring. Our adrenaline was really pumping at this point, but still trying to talk against that and trying to breathe against that just adds to the difficulty of the situation. All of our training kicked in perfectly. I knew exactly what the captain, what Neil was going to do. He knew what I was supposed to be doing, and visually we could see what we were doing. We couldn't communicate because even though we were trying to yell over the noise, our ears were so plugged up. So when I listened to the news and they played back the ATC tapes for the Alaska flight or that very experienced expert crew on the Southwest flight that had the explosive decompression, because of the uncontained engine failure, they were under really difficult circumstances.

My hat is really off to them and their professionalism for their added difficulties, because they had an explosive decompression, and they had a cabin full of passengers to worry about. I really admire them. Once we leveled off at 10,000 feet, we could remove the oxygen masks. We could finally talk to each other. It was still a little loud. And I could finally hear Chicago Center saying, "[inaudible 00:09:56] one, two, three. Say again your intention." And that was the first point at which I actually heard Chicago Center. Later on, we learned that we, because thunderstorms had closed down the Chicago area airports, they're stacked up and holding. And as Murphy's Law would have it, we experienced our rapid decompression near a holding pattern. And we were off airway, so you don't know whether you want to... If turning left or right will get you into less congested airspace. And you're coming down so fast the TCAS isn't going to give you enough warning, especially at that rate.

So my hat is really off to Chicago Center for clearing out that airspace. At this point, we're at 10,000 feet, we've got an aircraft, we don't know what's wrong with it, and we don't have the diagnostic tools. At that point, obviously you need to get the aircraft on the ground safely. In the sims we normally end this scenario when we're 10,000 feet and go, "Okay, all right, that exercise is done." We had it easy because we had plenty of available suitable airports near us and the weather was good. So we didn't have to worry about fuel, we didn't have to worry about calculating do we have enough fuel to get to an alternate? What was the weather going to be? Runway lengths, runway condition, et cetera. It was an easy scenario for us in that regard.

In reality, if this had occurred over oceanic airspace or over the polar regions or with bad weather or the middle of the Rockies at night, that would've been a much more complicated situation for the flight crew to then get on the phone with dispatch, if they work with a dispatcher, and begin figuring out, "How do we recover the aircraft to a safe airport." Communications were still really... It's quite possible that in that rapid descent you really injure your ears because my eardrums were aching for days after that. And that made it hard.

We probably were shouting at each other because we just couldn't hear. Our eardrums were so plugged up or possibly injured a little. Luckily our situation was, it was an easy divert. We went into Grand Rapids. But if we'd had to go through this lengthy discussion of where to divert to, fuel, weather, NOTAMs, et cetera, that adds a lot of workload in an emergency situation. So in retrospect, I'm very thankful that ours was a relatively simple situation.

Lee Ann Shay: Well, it sounds like you and Neil worked very well together. You followed the checklist, you've performed very well under extreme pressure. And your training prepared you well. Hopefully none of our listeners have to experience this in real life, but having gone through this, do you have any tips for pilots or is there any additional training, like you mentioned, that was the Air Force, the breathing training. Is there something additional that you think should change?

Pat Veillette: No, that's a great question. So the frequency with which we repeat that maneuver every six months in a simulator is about right. Simulator training is very valuable and I'm shy about adding extra exercises to a simulator. We want to make certain we're getting the most bang for the buck out of simulator time. Repeating this every six months, that's probably a good frequency. And the benefit, the fact that our motor memory just was so loaded to automatically reach for that oxygen mask and sweep it on and then go right into the high-dive maneuver really shows the value of that training. The altitude chamber training, I know there are alternative methods for doing hypoxia training, which is important. I'm grateful for the altitude training that I went through many times in the Air Force. That pressure breathing exercise, that was not a pleasant experience, to be honest.

It's difficult. It's painful. And reflecting back, now I can understand how and why, during an explosive decompression, that's what the flight crews are going to experience. It's tough. And anyone who listens to the TV replays of the ATC tapes, if it sounds like the flight crew is... What's the best way to put it? I mean, they're handling a lot at the moment and they're handling that in a compromised cockpit environment. So if it sounds like their breathing is labored, it is. That is a physiologically challenging, threatening environment. The simulator doesn't replicate the physiological challenge. The altitude chamber gives you a taste of it. But by and large, all of that training was very valuable. And again, I mean, we got the aircraft on the ground. We didn't have any excessive stress from it. We just kind of looked at each other and went, "Oh, okay. Hey, thanks for the help. Good job."

And [inaudible 00:15:24] the aircraft up. By the way, the last 10,000 feet, when we're changing altitude, because now the aircraft is not pressurized, ouch, did that hurt the ears. I mean, when we went from 10 to descend down to 7 or whatever, to get into Grand Rapids, I mean, we were doing our best to try to clear our ears and it was not easy. It still was hard to hear through the radio, and trying to clear our ears the whole time. My thanks to Chicago Center, because we handed them an all of a sudden real emergency and we must have just... They already had a bad traffic situation stacked up with the traffic getting into Chicago. So there's a team of controllers there at Chicago Center I never got a chance to personally thank, but yeah, hey, thank you. Whoever worked that. And they did a great job. I'm very appreciative. The whole system worked. The aviation safety system worked well in that regard.

Lee Ann Shay: Yeah, in this most recent incident, again, it was a team effort. ATC, the crew, there's a lot of professionals in the system working together to make safety happen.

Pat Veillette: Absolutely. And even the investigators now, you know how devoted they are and how passionate. So I have a high level of confidence that they've got some top-notch people looking at this. It'll be very interesting to read the full [inaudible 00:16:58] investigation report and make the changes so that this doesn't happen again.

Lee Ann Shay: Absolutely. Well, Pat, thank you so much for your time and insights. Great to talk to you, and we really appreciate this.

Pat Veillette: Thank you.

Lee Ann Shay: Thank you to our producer, Cory Hit, and of course, thank you to all of our listeners. Please make sure you don't miss the next episode by subscribing to the BCA Podcast on Apple Podcasts or wherever you listen. Until next time, we're signing off. Thank you.