Lead plane and air tanker avoid falling tree branch

Ensalados Fire Vandenberg Air Force Base
File photo of Tanker 103, July 9, 2017. Photo by Vandenberg Fire Department.

This article was first published at Fire Aviation

Yesterday July 9 a lead plane and a large air tanker had a close call while on a retardant dropping sortie on the Washburn Fire in Yosemite National Park.

There was virtually no wind over the fire most of the day and the area was smoked in causing very poor visibility making it impossible for air tankers to drop on the fire. But by 6 p.m. conditions had improved and at about 6:10 p.m. a lead plane was leading Tanker 103, an MD-87, over a target when they saw a falling tree branch above the lead plane. It fell between the two aircraft, in front of the tanker.

Twitter user Robert, @Rob_on_sisukas, captured an audio recording of the radio conversation. We’re not sure who the lead plane pilot was talking to, but we’ll call it “dispatcher” for now:

LEAD PLANE: Hey I just want to let you know that a branch went right over the top of us, pretty good size, probably 50 feet above us coming down and fell right in between Tanker 103 and myself.

DISPATCHER: OK. Copy. So it’s repeat of yesterday’s (unintelligible) 

LEAD PLANE: That’s exactly what I’m getting at. So if we keep seeing that we might have to knock it off. I don’t want to take a chance on busting a window in an airplane or hurting an aircraft for this. 

DISPATCHER: Absolutely. Keep me updated on this.

When a fire is burning intensely in an unstable atmosphere the convection in the rising smoke column can be powered by a tremendous amount of energy. As air at ground level rushes in to take the place of the rising column, the developing horizontal wind and the fresh oxygen feed the fire, causing an even higher level of intensity. The horizontal and then vertical movement of air can sometimes transport unexpectedly large objects up into the sky. Large columns may rotate as they rise and in extreme cases can actually become a fire tornado. You don’t want to be nearby when that happens. Fire tornados are not to be confused with small dust devils or fire whirls.

What is surprising about the incident yesterday is that the fire was smoked in most of the day, and tankers could not fly until about 6 p.m. I looked at various AlertWildfire cameras a few times and did not see any smoke columns. Maybe the cameras I saw were not able to see all of the fire, but I remember that late in the afternoon fire activity increased at the Sierra Fire Watch camera below, and columns may have developed.

Washburn Fire at 5:24 p.m. July 9, 2022
Washburn Fire at 5:24 p.m. July 9, 2022. Sierra Fire Watch image.

Firefighting aircraft being damaged by debris being lofted into the air over a fire is not unheard of. Here’s part of an article I wrote for Wildfire Today in 2018:

During the large vegetation fires in southern California in 2003 some of the convection columns were so powerful that the windshields on six air tankers were cracked by chunks of debris that were being hurled into the air (page D-6 in 2003 California Governor’s Blue Ribbon Report; huge 20 Mb file). One pilot saw a four by eight sheet of plywood sail past at 1,500 feet.

As of late morning today, July 10, the Washburn Fire has burned about 1,800 acres in Yosemite National Park. About 300 of those acres are in the Mariposa Grove of giant sequoia trees, some of them 3,000 years old.

Thanks and a tip of the hat go out to Kelly.

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Author: Bill Gabbert

After working full time in wildland fire for 33 years, he continues to learn, and strives to be a Student of Fire.

7 thoughts on “Lead plane and air tanker avoid falling tree branch”

  1. Nobody else has said it, so…
    When the complexity of managing a fire increases it is sometimes necessary for the Operations Section to expand the span of control. Maybe in this case the position of “Branch Director” should have been established.

  2. wIt seems that a rotating column would be necessary to lift such material into the convection column although I can imagine that branches might be lifted by ridge convection or airflow. Reviews of the flight recorders and interviews of the pilots might be revealing. The pilots’ senses would ordinarily feel red and green air changes, but they might have been too distracted to remember even significant G-forces. I’ve experienced mountain wave wind shear jolts and being lifted and dropped by ascending and descending air at in the realm of 1500 fpm despite my efforts to the contrary. Is anyone aware of any research on this? Even some hangar tales might be useful. An understanding of the total context–all contributing forces seems possible.


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