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Bush Pilot Tale - Bird strike

2 Apr 2019

It was the 2nd of April 2013, I had overnighted at Sasakwa, in the Serengeti National Park. I was operating a Cessna Grand Caravan C208B, parked on the concrete stand down at the bottom of the hill, next to where the airstrip made a slight tangent with rounded rise in the hill of Sasakwa... Sasakwa Overlooked miles and miles of Serengeti Savana grass, and was in close proximity to Fort Ikoma a place I'd often seen Wildebeest by the hundreds from the air milling around the grass runway. I always enjoyed my overnights there, with the comfortable room and pleasant staff.

It was a standard run to set up for an arrival at Seronera the hub airstrip of Tanzanian Serengeti... Usually with a 1035 am departure out of there, either via overhead the 9777 foot Masai Mountain of God 'Oldonya Lengaai' or via the Ngorongoro Crater back to Arusha, to connect passengers with transfers to Zanzibar or outbound international flights from Kilimanjaro or Dar es Salaam.

On this particular morning I remember feeling like everything was perfect, weather, aircraft's state of serviceability, my currency, my health, my planning.... All seemed 100% and it would just be another A to B to C to D set of sectors. Oh, but how wrong I would be about that.

I was tasked to fly Sasakwa to Seronera pick up ten Pax then direct to Ndutu in the south eastern side of the park at the foot of the Crater where I'd collect another three Pax. Then airborne with (one crew and thirteen + bags) and about 800 lbs of fuel, over the crater to intercept the eastern bearing of Arusha's zero nine runway. Drop off, refuel and continue to Zanzibar or head back to the Park on afternoon transfers depending on operational needs.

The legal limit for a Nav over the park is 1500 feet above ground level until you are within 5 nautical miles of the airstrip of intended landing. There are a number of reasons for these limits, and I'll identify the main reasons in a moment.

 

The flight between Sasakwa was a short one, I was empty there were no problems on a beautiful clear morning. It was particularly evident that the temperature after nine in the morning had risen steadily, and that guaranteed it would be a warm day. I arrived at Seronera and parked nicely abeam a number of other caravan aircraft awaiting passengers to fly out. I shut down and met the group of ten who I was due to fly out for their connections from Arusha to the Island of Zanzibar. It was a standard briefing for the leg detailing our track and altitude over the park, covering a major portion of open flat expansive Serengeti Savanah

 

plain, where at that time of year we were bound to spot lines of wildebeest migrating north toward the Mara river for the deadly crossing. The briefing developed into safety items, including the use of the safety belts, the location of emergency exits, location of fire extinguisher, and sick bags in case it was bumpy.

The guests were from Bulgaria, Sweden and America, and were very excited about the prospect of photographing the migration from the air. The track between Seronera and Ndutu is 36 nautical miles at 164 magnetic, the general elevation of the ground in the area is about 5000 feet above sea level, so your lowest altitude should be 6500 feet, however at the time, the semi-circular rule was being adhered to below 3000' above ground. So really 7500' should have been the lowest usable VFR level for this sector on an easterly track.

 

I got airborne just after about twenty to eleven and climbed to 7500 feet and as the scenery opened up the guests enjoyed the expanse of the Serengeti plains and lines upon lines of wildebeest heading north. There must have easily been a few thousand of these walking beasts in the same direction, it was absolutely stunningly beautiful. I was giving commentary on the diversity below, including the migration and herds of zebras and other indigenous antelope in the plain. The track was relatively straight with one of two banks left and right to manoeuvre closer for guests to snap photographs.

 

The moment which changed my day and a portion of my flying career, was about 13 nautical miles from the destination, the guest on my right pointed out a massive herd of around 5000 wildebeest, west of the tree line approaching Ndutu. The guest really wanted to take a picture directly overhead. I had flown for five years in the bush up to this point in the Okavango, Kafue, Lower Zambezi, South and North Luangwa, Hawange and the Kruger Park, and had over 4000 flying hours without ever having a problem before in terms of doing the extras for guest enjoyment.

 

This time I would make a cardinal error in Aviation Decision Making and threat and error management. I deviated off my track to the west and descended to below 6000 feet for the perfect photograph. I planned to do two medium turns left and right, tightening up to steep for the overhead picture. Briefing the guests over the PA system, I asked if they'd mind banking more than thirty degrees for the photo opportunity, everyone was excited and gave thumbs up.

 

Now any experienced bush pilots will tell you what I failed this day to observe. Between 10 am and 3 pm the earth is at its hottest, there is vast latent heat rising off the crust, raptors and scavengers of many varieties will circle the herds and wait for opportunities to eat. Bearing in mind that while the migration occurs nature is taking its course, lions are hunting, some of the wildebeest die naturally on their way... There is a lot of road kill and dead meat in and around the migration. Vultures circling by the tens.

I had just completed the turns left and right through 360 degrees still headed south west, when in my scan on the horizon I picked up at about four raptors circling at about 1/4 of a mile, I maneuverer left and away from them but failed to identify a fifth elliptical flight path in a target in the green of the horizon olive drab.... It happened so quickly an olive to grey flash past my head, then BLATT!

 

It was sudden and shocking... I looked left through the perspex and saw the left wing root crumpled all the way to the wing spar, and further back, blood and feathers splat down the cabin windows. Furthermore, white faces on passengers behind me in absolute shock.

And then began the new flight characteristics of this damaged wing. A slow roll to the left, decaying airspeed and sink rate. I applied right rudder to pick up the port wing, and noticed I was still descending at 300 ft per minute. So applied full power with the propellers set to full fine 1900 RPM as if for take-off,  with 1800 foot pounds of torque... But the decent rate only slowed to 150 ft per minute. There was copious profile drag from the deformed wing root, and with ten passengers, luggage and 830 pounds of Jet A1... And a density altitude well over 8000 feet, even with full power we were still sinking, nose high, ailerons and rudder to the right to keep the port wing level.

 

I remember feeling like I would have to commit a forced landing in the grass, and ensure flying speed all the way down, and put the aircraft on the main wheels first for the landing. As sinking continued, I remembered the lift formula, asking God what could be done to arrest the sink rate and maintain altitude? my right leg was shaking from the nerves pending an unplanned impact with the ground, and then the answer came... I had maximum power, I had rolled enough and yawed enough to keep the aircraft level about the longitudinal axis, I could not make the air cooler to increase its density obviously, but I could increase the surface area of the wing, by adding flap.

 

This was a risk too because It would also increase the induced drag, so I crept with the flap lever down slowly to about 5 degrees... The marginal flap made a big difference to the wing performance for a minimal drag penalty. The sink rate stopped, I was now at 400 feet from the ground, maintaining altitude, slightly nose high banking to the right slightly less with the extra help from the flaps.

 

I declared an emergency on the uncontrolled frequency, informing other aircraft inbound to Arusha of my position, altitude and the nature of the emergency, namely a 'Bird Strike' and furthermore my intention to land runway zero five at Ndutu Lodge.

 

The other pilots were very professional and concise on the radio, in helping me run a number of observations to ensure I could make the last ten miles to Ndutu, for instance checking that I had in fact applied full power, checking that both fuel tanks were adequately balanced, as the last thing I needed was one wing majorly heavier than the other (in the C208B fuel feeds to the reservoir, from tanks in each wing simultaneously, with both cocks open, by gravity, and pilots control the shut off valves to regulate the weight of fuel in each wing) in terms of this severe aerodynamic dilemma.

 

One of the other company caravans began relaying to Arusha, while I continued to track south then slowly east to locate the final approach course for Ndutu runway zero five. I informed the passengers over the PA system that we'd hit a large vulture and would be landing in the next five minutes, and to please ensure all belts were fastened.

 

The last five miles were the first moments I knew we'd be ok... I saw the strip and flew a nice wide pattern to ensure minimum banking, and gradual turning... Kept the power on all the way down in the approach only applying full flap once I'd crossed the tree line before the threshold, keeping the nose down and the ball in the middle... Landing about 150m down from the markers, the touchdown was smooth and on the mains, deceleration even and we were in control and on the ground. Then started an applause behind me, which I really appreciated. One of the guests gave me a business card on their way down the stair case after shutting down, congratulating me, saying he would testify on my performance during the incident, but I knew deep down that there would be many questions on how I'd managed the flight in the first place.

I was in a state of shock and asked the guide on the ground to transport all the guests to camp and let them have a drink on my account while I arranged a rescue aircraft from Arusha to fetch them. Once they had driven off into camp, I had a little cry on the sand, and was very upset for the damage and the shock of the incident. About an hour and a half later I heard the PT6 drone in the distance and then saw an overhead joining procedure by my good long-time friend Darryn Cowell. He'd been dispatched from Arusha to fetch my guests and take them onwards for connection. After landing and shut down, he gave me a big hug, and even chuckled, as he saw the wing.....'geeez Goshe! That's a proper hit!' I was upset beyond belief knowing it would cost money and there would be a full Investigation.

A really good pilot wouldn't haven't got into that situation in the first place. Breaking the law in descending below the legal limit beyond the prescribed distances in proximity to the field of landing; all just to give the guests a photo opportunity of a lifetime. It was borderline suicidal to go that low at that time of day over that population of wildebeest. A birdstrike was imminent.

 

My risk management in that decision was poor, and I lacked a true understanding of the dangers of flying over populous areas of wildlife in the heat of the day, lacking consideration of the sheer population density of raptors and scavengers above such herds, let alone the breach of environmental codes of conduct, whereby low flying even at 800 feet above ground startles the herds, and disturbs the natural course in the harmony of the wild.

 

I tell the story in hope that others may learn from my errors. From that day on, I stuck to turbine circuits, correct profile management, and the correct altitudes in the park, as well sticking to exactly what is planned for the sector, and not deviating the track for any guest requests that places the safety of the flight into question, or into breach of regulation.

 

Procedures are not just guidelines to be optionally be followed, they are written in other pilots' blood, and while flying single crew and unaudited in the bush, it is quite easy to allow your standards to drop below an acceptable level of safety. Highly important to keep checking yourself and adapting to the threats of every sector you fly.

 

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