Podcast: Fighting Fires From The Air—A Pilot’s Experience

Pilots flying fixed- and rotor-wing aircraft face numerous challenges in fighting fires. Hear pilot and former aerial firefighter Pat Veillette describe what it is like flying into these hazards and explain concerns, including engine maintenance.

Welcome to the BCA Podcast. I'm Lee Ann Shay, executive Editor of MRO and Business Aviation at Aviation Week Network. Today's topic is aerial firefighting. Given the palisades eaten and other devastating fires that are burning around Los Angeles, we wanted to hear about the challenges that the firefighting pilots are facing day in and day out. Dr. Pat Veillete, a regular contributor to BCA for more than 20 years is joining us. He has accumulated more than 20,000 hours applied experience in 240 types of aircraft, including business aircraft, rotor craft, seaplanes, gliders, war birds, supersonic jets and large commercial transports. And Pat is also an adjunct professor at Utah Valley University. Pat, thank you so much for joining us.

Dr. Pat Veillette:

Thank you, Leanne. And of course, our hearts go out to all of those who are gravely affected by this natural disaster and kudos to all of those other persons, who are trying to contribute to the recovery. It's been humbling to watch the response by heartfelt people out there hoping to help. This is a tragedy that honestly, the wildfire community for many years has been hoping this would never happen, and it's a convergence of a number of factors and it's a true tragedy.

Lee Ann Shay:

Absolutely. And it's just a devastating, our hearts go out to everybody there. Everybody's trying to fight it, who's donating. It's horrible. And it's not good that the winds keep changing too, so that's not helpful. But, so Pat, help us understand what it's like to fly an aircraft into a fire. They're in there day in and day out and the conditions are not good. What's it like and how is it different doing that kind of operation?

Dr. Pat Veillette:

Yeah, this is a very challenging and unique field of aviation. As I've watched the newscasts and watched the aerial firefighters making their drops, having been there myself a couple decades ago, I'm cheering them on, I'm watching with admiration. They're nailing their drops. This is a high hazard form of aviation. There are a number of challenges, unique challenges. So there is prolonged maneuvering at low altitude and relatively slow speeds, and that is inherently, your safety margins just get thinner and thinner the slower and the closer you get to the ground. And that's necessary to drop these vital supplies, the retardant, the para-cargo, to the firefighters that are down there with their backs to the fire, they're digging fire line, and they are directly feeling the heat. That prolonged maneuvering, and most of us, especially out in the western United States in this undulating mountainous canyon terrain, the path to fly into a drop zone is often through curving canyons with steep walls.

It can be hard to see your drop zone as you're ingressing in. That's why we have lead planes who do some of this, and there are special procedures that we utilize to try to make certain we're never making a high risk decision prior to making a drop. So the terrain is an inherent threat with the low altitude maneuvering. And you see that in the California fires, and most of these drops, the helicopters or the air tankers, they're below the ridge line. They're having to proceed in from a higher altitude, generally flying downhill. The hard rule is that we would never make a drop going with uphill terrain in front of us. There always has to be a way out. In case the load of retardant doesn't drop, unwanted winds and engine malfunction, we always had to have a safe route going towards lower terrain. That in itself was a, normally most of the firefighting companies want you to have a certain number of flight hours in a comparable field of low altitude flying.

For that reason, before the tankers go into these tight spots, a lead plane, that was the forest service term, Cal Fire use OV-10s for some of this mission. The Forest Service used to use Barons. Now they're Canaries. Because they're a lighter aircraft, a little more maneuverable, they will go in first to look at the ingress route, to determine if there unwanted downdrafts, if the Canyon requires exceptional bank angles that just aren't acceptable, if there's too much turbulence. And their judgment is critical, before we send a heavy, relatively an air taker that just doesn't maneuver tightly, into these confined spaces. Furthermore, dropping the retardant or the para cargo, we don't have precision sites in the cockpit to say, here's the spot, drop now. This is all old-fashioned eyeball trying to estimate your aircraft wind drift, and do you have the right altitude, which is hard to estimate when all the terrain is sloping up and down. There are a multitude of factors that make this unique and a field in which pilots have to be expert decision makers and experts at proactively assessing the risks.

Lee Ann Shay:

In addition to, you mentioned so many challenges and topography, the mountainous areas, I mean, that's a big one, but then you've got weather, changing winds, and it's not like you've got really clear air you're probably dealing with either. But let's talk about the weather, and unfortunately it sounds like the winds might be coming up again in the Los Angeles area, which is-

Dr. Pat Veillette:

Yeah, in general, during the afternoon when the wildfires tend to be the worst just because of the higher temperatures, the winds can be erratic. In the Southern California situation recently, it's magnified by the Santa Ana winds, and the wind flow pattern comes in over the high desert. It flows over the mountains. That in itself induces horrific turbulence. And in some localized areas is that wind flow funnels down through canyons. It can cause extreme turbulence. That makes aircraft control difficult, if not hazardous. It creates a real beating on the wings of the fixed wing aircraft. To the helicopters, these erratic winds can cause possible control issues. If the wind comes from an adverse azimuth unexpectedly, it can cause what we call loss of tail rotor effectiveness in a helicopter. That's where the wind is coming generally from, say, a rearward quadrant. Or it can set up a helicopter flying at a slower speed.

For this phenomenon we call it vortex ring state. And realize that you're only 200 feet above the ground on many of these missions. So there's very little room to maneuver, do an emergency maneuver or recovery if this unexpected wind pops up like that. The visibility is a secondary factor that makes this difficult. On a good day, the smoke from the wildfires can drift into what would be the preferable flight path. It can obscure the visibility towards the target area. The gray haze from the smoke, it's a true visual illusion. It makes it hard to estimate your accurate assessment of the range from hillsides or mountains. It makes it hard to estimate the size. It will camouflage intervening hills that we call them false horizons. You'll look at what you think is the ridge line, will actually will be an intervening ridge line that's maybe just slightly lower, that's closer to you.

And that could be dangerous. If you drop your cargo or your target and you're expecting, you're thinking that you have a nice egress path out of there, and there's actually a really good video on YouTube that illustrates this. It was a British airspace 146, I think, dropped across a canyon. The crew on the ground was recording this, and after the air tanker dropped its load, it started its slight climb and turn to exit the canyon. Well, due to this false horizon effect, they missed that ridge line by feet, mere feet. I gassed every friend from the industry that was like, "Pat, did you see this? Oh, my." I mean, you can actually see the vortices kick up the dust on the ridge line. They were so low. So that's an illustration of the visual illusions that are inherent in this sloping terrain. One of the other aspects is many times the drop zones are down in the canyons.

So in the early morning or late afternoon, the sun is at a low angle and that can put part of the terrain in a shadow, thereby obscuring the drop zone and or obscuring these, we call them snags, the trees that stick up taller than the adjoining trees. And unfortunately, aircraft have hit those, and it has almost always resulted in substantial aircraft damage. And sometimes it's resulted in fatal injuries. So the visibility, the winds that, it can be chaotic. The Santa Ana winds are probably the most famous of the winds that produce just extreme turbulence in locations. If the winds get out of limits, they actually ground the air attack because of that, for the safety of the air crews.

Lee Ann Shay:

This just sounds like there's just so many negative factors. I can only imagine how challenging it must be for these pilots. You've researched firefighting, you've not only flown it, but you've done a lot of research around this topic. What are the biggest risks for both fixed and rotor wing? I'm assuming engines don't like to ingest dust, let alone the smoke and everything that could be going into the engines. Is maintenance one of the bigger risks?

Dr. Pat Veillette:

Yeah, so this answer, there are good parts of the answer, and there are other parts that indicate, well, we need help. The National Academy of Sciences recently published a study looking at the composition of smoke plumes from an urban area. And as you might imagine, if a house burns up, there are toxic compounds in the house, and those get combusted in the smoke plume. And not only are they toxic to people and the firefighters on the line, jet engines, turbine engines were never designed to ingest anything but clear air. And we've modified jet engines over the years to be tolerant of some hail, even bird strikes to some degree, but we don't know what the effects are in an engine when you're ingesting these harmful compounds. In the helicopter study that I did, both for NIFC, the National Interagency Fire Center, and then also stayed for the Flight Safety Foundation, engine failures in the immediate facility of the fire line were prominent in the helicopter accidents.

And when an engine fails and you're only 200 feet above the ground, possibly within what we call the height velocity diagram, meaning you just don't have enough velocity or height in order to successfully execute an autorotation, it's going to result in a hard landing. The pilot has very little margin to recover from this engine failure. When I did that study 25 years ago, none of the investigations had looked at the role of the fire environment on the engine, causing these engine failures. Australia has since learned that the exceptionally hot plumes can spike the temperatures in a helicopter's engine far outside of limits. We know that winds gusting from an adverse angle can affect the airflow into the engine inlet. On the positive side, it's SOP for the helicopter companies to do compressor washes frequently, almost daily, and this is to wash off any of the contaminants from the compressor blades.

And that's a very prudent practice and kudos to the maintenance staff, who are so attentive to that. In regards to the fixed wing side, traditionally the highest threat has been, the pilots got into a position where they couldn't avoid hitting a hillside. It was either through, not accurately seeing the terrain, not accurately predicting their aircraft's ability to maneuver the terrain, either turning and or climbing. A retired aircraft is heavily weighted with that retardant, so their maneuverability is limited. That was the reason that many decades ago, the Forest Service utilized this concept of the lead plane to go in first. And by and large, that's an effective risk management tool. Again, the general practices do not descend down into the canyon unless we have an assured path in the event of an engine failure. Now, how is this wildfire, especially the wildfire smoke over LA, with all those toxic compounds, how's that going to affect the engines of the aircraft currently fighting fire? I hope someone's looking at that and some astute engineers, who specialize in turbine engine functioning to see if this is an issue we need to take a closer look at.

Lee Ann Shay:

Good point. I know there was a lot of research after the volcano several years ago.

Dr. Pat Veillete:

So Exactly. Yeah, another really good example.

Lee Ann Shay:

Yeah. Well, we've run out of time, but Pat, thank you so much for being on this podcast today. And again, our thoughts are with everybody in the Los Angeles area. So thank you. And hopefully these fires are going to be extinguished soon. And Pat, thank you for your time. And thank you to Jeremy Karayuki, who is producing this episode. Don't miss the next episode by subscribing to the BCA podcast, wherever you listen to them. And one last request. If you're listening in Apple Podcast, please consider leaving us a star rating or writing a review. Thank you so much.