‘Tree Strikes’ From Above Threaten Aircraft Battling Yosemite Wildfires


Most pilots are well aware of the hazards of hitting trees, but last weekend several firefighting aircrews reported that they narrowly missed being struck by large branches at altitude. Britt Coulson of British Columbia, Canada-based Coulson Aviation told the San Francisco Chronicle that aircraft battling the Washburn Fire in Yosemite National Park reported branches and other debris swept high enough by convective currents that it dropped in clear view of the company’s aircraft, even striking the fuselage of one waterbomber, according to the paper.

The pilot of a lead King Air posted this radio transmission on Twitter: “Hey, just want to let you know 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.”

In a wildfire, convection is caused when cool air replaces rising hot air. The inflow at ground level creates an updraft that can be strong enough to generate a “reverse tornado,” carrying debris high into the sky. Coulson said, “There is a lot of stuff the convective air around a fire can bring up.”

Mark Phelps
Mark Phelps is a senior editor at AVweb. He is an instrument rated private pilot and former owner of a Grumman American AA1B and a V-tail Bonanza.

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  1. Stay safe up there boys. That kind of flying is close to being that of military combat in terms of risk factors.

    • Shouldn’t be at treetop level, IIRC medium and small try for 200 feet clearance, bigger ones somewhat higher.

      And attack paths are crucial, that’s what the ‘bird dog’ guide aircraft are for.

      Two tankers lost in BC several years ago because they did not follow guide aircraft’s instructions – judging varying terrain with trees on it is very difficult, fatal fools did not turn into valley as told to.
      Martin Mars lost in BC early in history of that operation, perhaps flying uphill after drop which is not wise path, possibility that drop doors did not open to release load.
      10Tanker drug gear and flaps through trees one day, a very close call.
      Coulson lost a C130 in Australia a few years ago, investigation ongoing, was flying in gently rising terrain and circling after partial drop, hit a big tree.

  2. Seems to me the branches aren’t striking the aircraft but the aircraft are striking/narrowly missing the branches. I know, picky, picky,picky.

    • Sorry but incorrect. Branches can often fly high into the air due to the convection near a fire. I have had flaming branches pass my aircraft between 1,000-1,500 feet AGL near a fire.

      Typical drop height is 150’ over lighter fuels (grass and sage) to 220’ over heavier fuels (trees).

      The day previous to this incident, a BAe-146 was struck on the top of the fuselage while maneuvering for a drop as he was still a couple hundred feet over the ground.

  3. Ask any veteran firefighter what a super hot blazing fire is capable of. Plus, the first sentence states they were at altitude. This indicates they were not at treetop level.
    A hot enough raging fire flames would even leap across a street that hungry for oxygen.

    In this case it was especially convention created, and forexample, you all know how strong and high an updraft in a thunderstorm can be.

  4. Flying higher is not effective for the drop. The flame retardant will dissipate and not give you the required coverage.

    I’ve done this mission in C-130s when I was in the Air National Guard. It can be very dangerous. The effective drop altitude is between 150 to 300 feet AGL. Sometimes you’re dropping in a narrow valley with trees above you and not far off your wing tip.

    So, sometimes you are below the trees on the ridgelines. The fire can create a fire tornado that obviously can lift all kinds of debris into the air. The burning tree sap can also explode sending shrapnel of bark and other tree materials into the air.

  5. As much as Britt and Wayne Coulson LOVE seeing their names in the news (free publicity), my understanding is none of their aircraft were involved. The aircraft in the near miss were a U.S. Forest Service “Lead Plane” and an Erickson Aero Air MD-87. The aircraft that was struck the previous day was a Neptune BAe-146.

    But, as Mayor Daly used to say, never let a good crises go to waste.