Birds and, to an even greater extent, bird-strikes come in all sorts of shapes and forms. Steve Ayres suggests that thinking through some of the potential consequences might help cushion the shock should you ever have the misfortune to meet a feathered friend…
Steve Ayres
16 March 2021
We have probably all practiced ‘ad nauseam’ bird-strike drills from different flight situations, but this round up of accidents goes to show how many different situations actually do occur. And you don’t even have to hit a bird to find yourself in a whole load of hurt. A spate of accidents occurred recently where pilots were distracted by birds either during take-off or during landing. No animals were harmed in those particular accidents but a number of aeroplanes were. Like anything that startles, thinking through some of the scenarios from time-to-time can only help at the moment critique.
The pilot of a Glasair Sportsman GS-2, was conducting a private flight from Southport, Queensland, to Moruya, New South Wales (NSW), with a refuel stop at Mudgee, also in NSW. The pilot was the only person on board. While cruising at 5,500ft above mean sea level near Bathurst, NSW, the aircraft collided with a large bird, believed to be a wedge-tailed eagle.
“Damage to the pilot’s headset meant he was unable to hear any incoming transmissions”
The bird broke through the windscreen on the left side of the aircraft and struck the pilot. The collision left the pilot with serious facial injuries and they were temporarily unable to see. The pilot was wearing a headset and spectacles, which were both dislodged and damaged during the collision. Following the bird-strike, the aircraft entered a rapid descent, but the pilot recovered sufficiently to regain control. Despite the broken windscreen and their injuries, the pilot was able to divert to Bathurst Airport and land successfully.
During their ordeal, the pilot had been able to locate the microphone of the headset and transmit a Mayday call, but damage to the headset meant that they were unable to hear any incoming transmissions.
Although air traffic control (ATC) received the Mayday call, they did not know the callsign or specific location of the aircraft involved, or the intentions of the pilot. About 30 minutes after the Mayday call, the Safety Officer at Bathurst airport contacted ATC to advise them that an aircraft with a broken windscreen (the result of a bird-strike) had landed at Bathurst.
The aircraft was on a circuit training flight with a student pilot in the left seat and flying instructor in the right.
The instructor was aware of the elevated risk of bird-strike in the summer at Liverpool, and had turned the window heat on, to improve the windscreen’s resistance to impact.
On a flapless final approach to Runway 27, at around 80-90 KIAS and about 650ft aal, the instructor suddenly saw a small flock of grey pigeons against the grey sky to the right of the nose, close by and flying into the aircraft’s path. Before he could react, the aircraft struck four or five birds. One bird struck the windscreen, which did not break, but another broke the right side window, causing bruising to the instructor’s shoulder. The approach continued to a flapless landing, and the aircraft vacated the runway. Post-flight inspection found bird-strike evidence in the engine bay, on the cowlings and wing.
The private pilot sustained serious injuries from which he later succumbed and the pilot-rated-passenger sustained minor injuries.
“In nearly every bird strike case, there is a massive element of surprise”
Visual meteorological conditions prevailed, and no flight plan was filed for the flight that originated from Naples Municipal Airport (APF), Naples, Florida, around 1315.
According to the pilot-rated-passenger, after fuelling the aeroplane to 20 gallons, he and the pilot departed the airport. They proceeded to climb to 2,500ft above ground level, and about 25 miles east of APF, the aircraft struck a large bird. The engine continued to operate for about two minutes, until the ‘low fuel’ warning indicator illuminated, and then the engine stopped producing power. The pilot declared an emergency and elected to perform a forced landing on a road. During the landing roll, the aeroplane struck a road sign and several large trees, which resulted in substantial damage to the aeroplane.
An examination of the aeroplane by a Federal Aviation Administration inspector revealed that the fuselage and wings were impact damaged during the accident sequence. The nosewheel fairing and the underside of the engine cowling revealed evidence of a bird-strike.
Examination of the carburettor revealed that the butterfly valve operated without anomaly, however, fuel was leaking from the assembly. Examination of the engine could not differentiate the damage that resulted from the bird-strike versus the collision during the landing.
The flight instructor reported that, while en route on an instrument flight plan, about 4,000ft, the aeroplane entered a cloud where a flock of large black birds were circling. A bird impacted the stabilator, and he then disengaged the autopilot and checked the flight controls for any adverse effects, he did not see any. The instructor then chose to return to the departure airport and landed without further incident. The aeroplane sustained substantial damage to the stabilator.
The flight was planned from Oban to Shoreham with three people and a dog on board. For departure the aircraft was close to its Maximum Takeoff Weight (MTOW) and the pilot backtracked to use the full length of Runway 19. At the threshold, he applied the brakes and advanced the throttle to an intermediate position. With all indications normal he released the brakes and applied full throttle, planning to accelerate to 85kt for take-off.
The Pilot’s Operating Handbook (POH) for the aircraft gives a lift-off speed of 73kt at the MTOW of 1,999kg. The pilot stated that, in his view, aircraft performance was very poor at the lift-off speed indicated in the POH and that he always used higher speeds. At approx 80kt the pilot became aware of a flock of birds at low level over the end of the runway. He was concerned that the aircraft would not have sufficient performance to climb above the birds and so decided to stop. The pilot was aware of the fact that locking the wheels would radically reduce braking performance and tried to avoid this while still applying significant braking effort. However, the aircraft failed to stop by the end of the paved surface, overran the runway and struck the airfield boundary fence before coming to a stop in an area of bushes just prior to the shoreline.
Using figures from performance tables in the POH, it was determined that an approx take-off run for an aircraft lifting off at 73kt would be 480 metres. An approximate landing roll at the same mass would be 280m. In this case, the braking effort commenced from approximately 80kt, so the distances to accelerate and stop would have been greater, but the manufacturer was unable to provide an accurate total distance.
Runway 19 at Oban is 1,246m long. The pilot reported that in the last 25m of the runway the brakes became ineffective and he believed that they had become overheated.
The aircraft struck the bushes and the perimeter fence at approximately 5kt. All those on board exited the aircraft without assistance and were clear of the aircraft when the airport fire service arrived on scene.
The pilot reported that as he was about to land on grass Runway 24, the aircraft struck a medium-sized bird at a height of approximately 20ft agl. This surprised the pilot who momentarily pitched the aircraft up and to the left, before adjusting the aircraft’s flightpath back towards the runway centreline to land with about 300m of runway remaining. When the aircraft touched down it bounced and became airborne. The pilot decided to land rather than go-around, due to the possibility that the aircraft may have sustained damage from the bird-strike. The aircraft subsequently touched down heavily on the nose gear which collapsed. The aircraft came to a stop and the pilot vacated the aircraft unaided.
It is easy to fall into the trap that encountering a bird in flight needs a rather simple, formulaic, response. However, the variety of these events shows how that is rarely the case and that getting the response right can be critical to the success of the outcome.
In nearly every case, though, there is a massive element of surprise. To come across something ‘out of the blue’ is probably more shocking now than ever. Not visible on radar, no transponder or other electronic conspicuity alert. How can that be? But that initial response is clearly crucial. During the take-off, not mishandling the aircraft is probably key. Speeds are usually relatively low and actual destructive damage usually slight. But at higher, cruising speeds, the shock and subsequent damage can be significant. Maintaining control is still at the top of the list but working out what to do next can be tricky. Sure, if it’s a lone bird you may know where it hit but a small flock? Not a chance!
From experience I have nearly always got it wrong. What I thought was a glancing blow turned out to be a crushed leading edge and loud thumps on the airframe have left almost no trace at all. Many of these incidents confirm my own experience. The only approach is to play things really cautiously. Once over the shock, plan for a divert to the nearest suitable airfield and keep an eye out for somewhere relatively safe to put down should things go pear-shaped quickly.
As in Accident 3, a strike on the engine cowl resulted in the entire fuel contents being dumped over the side and left the pilot with only a short time to respond. If they had known it was a massive fuel leak then they may have treated it as such and used the remaining fuel as best they could, but working that out when you are flying alone is difficult and most bird-strikes are best treated by leaving things pretty much where they are, at least initially. Get yourself into a safe area from which you can make a landing of sorts and then consider your options, all the time keeping an eye on the fuel contents. Don’t go faster than you have to, and certainly no faster than you were flying at the time of the strike. If you must use flaps, try them out at a safe height and be ready to reset them quickly if at any stage you have trouble maintaining control.
Finally, having got everything ‘dangling’ check out the handling down to threshold speed, adding a few knots for ‘granny’ if controllability seems a problem. Leaving everything as it is, all should now be set for a nice, safe approach. And for those who don’t think we have any big birds around the UK, rumour has it some of them now sport lifting rotors in each corner!
