Birds Can Be Deadly
by H. Dean Chamberlain
Some might say flying is for the birds. Others might even say that birds invented flying. But regardless of what you think about birds and flying, we think birds have been flying relatively safely for thousands of years. We don't know for sure, since the FAA has no Neolithic bird accident statistics on file. Apparently, the government's data systems weren't on-line then. A quick review of history lists only one reported flight accident involving some type of bird-like experimental aircraft made of feathers and wax.
Apparently the reported midair breakup was caused by the sun's heat. According to early, unconfirmed reports, important flight feathers fell off the pilot because the heat melted the wax attaching the feathers to the man when he busted his assigned altitude and flew too close to the sun. But it must have been a myth because we all know a little bit of sun could never melt FAA-approved, TSO'd, human-feather-attachment wax. Plus, we all know that no FAA inspector would ever sign off on an experimental "aircraft" made of feathers. Mylar maybe, but not feathers.
Today, we have a different problem involving feathers and birds. Humans have mostly gone beyond trying to imitate birds flying, but we still have a problem with our fine feathered friends. Ever since humans started to fly, birds and bird(persons/men/women, your choice) have managed to collide with each other with increasing frequency and with increasing damage. It seems that birds and flying humans just can't stay out of each other's way.
Although birds and some pilots (such as glider pilots who often share the same thermal with soaring birds) can operate near each other with relative safety, birds can and do occasionally strike great fear in the hearts of the most intrepid aviators because a bird strike through the cockpit can ruin any pilot's day, especially if the bird is a big, fat goose.
The problem is easy to understand. It is harder to fix. In today's world of ever expanding urban areas, increased air operations, and decreasing amount of unused airspace, it is inevitable that birds and aircraft are going to conflict with each other both in the air and on the ground. Bird strikes and jet engine bird ingestion have caused aircraft to crash. Birds have also caused millions of dollars of aircraft damage. The birds lose too; few birds escape a midair collision or engine ingestion unharmed.
Jet aircraft are even more vulnerable to birds than prop aircraft. Although the larger jet engines are designed to be able to ingest an occasional small bird with minor damage to the engine, a large bird or large numbers of smaller birds sucked into a jet aircraft's engines have caused more than one aircraft to crash. In other cases, cockpit strikes have disabled pilots. In some of those strikes, the pilot or a copilot was able to safely land the aircraft. In a few cases, the aircraft crashed.
Military aircraft are especially vulnerable to cockpit bird strikes when the aircraft is flying low and fast on nap of the earth training missions at 500 feet and 500 knots. The U.S. Air Force has spent a lot of money and effort in trying to develop safer canopies for its low flying aircraft. One large bomber reportedly crashed because of birds. According to one Air Force study titled "Determination of Body Density For Twelve Bird Species," dated April 1993--a project designed to develop test data for bird strike research--Air Force aircraft average 3,000 to 3,500 bird collisions each year at an annual cost of more than $65 million. The report also noted a 1992 report which said seven Air Force personnel had died from bird strikes since 1987 through the time of the 1992 report.
Regardless of the type of aircraft involved, military or civilian, bird strikes are a classic case of "lose/lose" for both the bird and the aircraft.
We printed a tongue in cheek article called "The Kamikaze Kanaries of Operation Revenge" in our March-April 1992 issue. The article discussed the dangers of bird strikes from the bird's perspective and told of actions birds can take to eliminate the metal pollution of aircraft from the bird's natural flight environment. It was a humorous way to point out some important flight safety issues for pilots when dealing with birds. In this article, we want to discuss the issue seriously from a pilot's perspective.
Two items brought the importance of bird strikes to mind. One was seeing a flock of about 50 large Canada geese flying in their classic "V" formation about two miles south of Washington National Airport. Fortunately, the geese where flying relatively low, and they were westbound on the west side of Alexandria, VA. They were not on the east side of the town which is along the Potomac River just south of the airport and down river from Washington, DC. The scary thought is they could have already flown low across the river.
Birds flying over or across the Potomac River near National Airport are always a threat because jet aircraft arriving and departing the airport have to fly over the river both inbound and outbound to avoid the prohibited airspace over Washington and for noise abatement. In addition to migratory birds such as the geese (which today seem to migrate less and less in the Washington area), National Airport has a year-round problem with seagulls on and near the airport. Other airports have similar problems with local bird populations such as JFK International Airport in New York which is located near a protected bird breeding area. In other cases, landfills or dumps near airports attract large numbers of birds which then threaten the safety of flight operations.
BIRD STRIKE PREVENTION TECHNIQUES
The other important item which resulted in this story was seeing an article in the Orlando, FL, FSDO-15 Aviation Safety Program Newsletter on how to avoid bird strikes. Written by the Florida Association of Flight Instructors, the article said about eight aircraft are lost each year because of bird strikes. In paraphrasing the article, it said if you hit a two-pound seagull while you are flying at 120 mph, the resulting impact would have a force equal to 4,800 pounds. If you are flying in a jet at 600 mph the same impact would have a force of 72,000 pounds. The newsletter noted, "Some anti-aircraft rounds exert less force than that."
The article listed several suggestions to help pilots avoid bird strikes:
Don't fly beneath a flock of birds because birds tend to dive to avoid danger. Pilots should pitch up to try to avoid a bird collision because the bird will probably dive. Turn on your landing lights when flying near areas with birds. The lights might help the birds see you in time to get out of your way. [Editor's Note: Don't expect the birds to turn on their landing lights for you. They were not type certificated with electrical systems or landing lights. They also don't have transponders for the same reason.]
The final suggestion is to avoid flying near areas where birds concentrate such as marshlands, dumps, and landfills.
PRIME MIGRATION PERIODS
The FAA Aeronautical Information Manual (AIM) has a complete section on bird hazards--Section 4, Chapter 7, on page 7-4-1. According to the AIM, 90 percent of the reported bird strikes occur at or below 3,000 feet. Strikes at higher altitudes are common during migration. Ducks and geese are frequently observed up to 7,000 feet. March through April and August through November are listed as the prime migration periods.
The AIM notes there are four major migration routes across the U.S. with numerous other smaller flyways. The major routes are the Atlantic Flyway which parallels the Atlantic Coast, the Mississippi Flyway which includes the Great Lakes and Mississippi River areas, the Central Flyway located east of the Rocky Mountains, and the Pacific Flyway which parallels the West Coast. These routes are flown by birds traveling from Canada and the northern U.S. to the southern U.S., Mexico, and Central and South America.
When flying in and near one of the flyways, pilots should avoid flying low. If operationally possible, another suggestion you might want to consider is to fly as slowly as possible consistent with safety when flying near birds to minimize the force of a bird strike. The impact forces are both a function of the closing velocities and the weight of the bird and aircraft.
Pilots should also avoid charted wildlife refuge areas. If overflight is necessary, please comply with the minimum overflight altitude listed on the chart. If possible, you should fly at a higher altitude both to minimize disturbing the protected wildlife and to minimize the chance of a bird strike. The higher altitude also provides extra time in case of an engine failure, bird strike, etc.
DEALING WITH THE INEVITABLE
No one wants to hurt or kill a bird, but sometimes bird strikes are unavoidable. Although airport operators, aircraft operators, the military, and the FAA have spent millions of dollars and years of effort trying to solve the bird strike problem, the problem will continue as long as birds and pilots share the same airspace. But as we start a new year and as the birds wintering in the south start their annual trek north to their spring nesting areas, pilots need to be especially watchful and avoid birds and their flyways whenever possible. In the case of operating in and out of airports with known bird problems, pilots need to be very careful. In such cases, pilots should develop an emergency plan of action in case of a bird strike or engine ingestion.
In the case of an engine or engines sucking in birds during takeoff, like any takeoff emergency, the question becomes one of do you have enough power to go-around, or do you have to abort on the runway? This is the classic go-no-go decision.
A bird strike or engine ingestion while you are en route becomes a question of can you continue to an airport for a landing or must you make an off-field landing? In some reported bird strike accidents, there was control damage, but the pilots were able to continue flying. In others, especially those involving helicopters, the pilots had to make precautionary landings.
If in-flight, what are your plans if a bird strikes your windshield and penetrates your cockpit? Assuming you are uninjured, are you prepared for the noise, confusion, increased drag, and bird parts and blood in the cockpit? If the bird is not killed by the impact, what are you going to do with an injured, terrified, wild bird in the cockpit? What are you going to do if that bird is the size of a duck or goose and it lands in your lap? Or, for that matter, what are you going to do with an injured, terrified, wild passenger in the cockpit? These are only some of the questions a pilot must be prepared to answer when operating near birds.
NTSB BIRD STRIKE ACCIDENT REPORT REVIEW
A review of 67 accidents covering the period from January 1983 through April 1995 revealed some interesting data. For one thing, bird strikes or birds being ingested into jet engines can happen to any type aircraft from small, single-engine aircraft to helicopters to ag aircraft to Boeing 747's. There were 12 fatalities listed from all causes and 11 serious injuries listed in the 67 reports. The good news is the number of bird strikes that resulted in substantial aircraft damage resulted in minor or no injuries to those on the aircraft.
The key point here is how few bird-related accidents are fatal to the aircraft occupants or pilots. Of the 12 fatalities listed in the reports, one fatality was only indirectly related to the bird strike. Apparently because of a misunderstanding between the pilot and his passenger, the passenger jumped to his death after he misjudged his height above the water as the helicopter was making an emergency water landing after a bird strike.
MAINTAIN CONTROL OF YOUR AIRCRAFT
In reading the 67 National Transportation Safety Board (NTSB) accident reports, some of the pilots apparently forgot to remember the first and most basic rule of flying: Always fly your aircraft.
Even when involved in the confusion and shock of a midair cockpit bird strike, pilots must continue to fly their aircraft. The NTSB data told of accidents in which a few of the pilots took evasive action to avoid birds and either lost control of their aircraft or flew the aircraft into the ground or low wires. In some cases, the pilots lost control while taxiing, taking off, landing, or while trying to go around. In others they lost control in flight. As previously stated, one defensive technique to avoid birds is to pitch up or climb because birds normally dive to avoid danger, but if you pitch up to avoid a bird strike, you can't pitch up so high you stall. A stall/spin accident can be just as damaging as a bird strike.
Another surprising discovery was the number of fatal and serious injury accidents reported that were the result of what could best be described unofficially as pilot error. After the bird strike or while maneuvering to avoid birds, the aircraft crashed. In a surprising number of cases, the pilot ran off the runway or taxiway or failed to execute a successful go-around or collided with an object after trying to avoid a bird or a flock of birds. In a few cases, the pilot simply lost control of the aircraft after a bird strike or while trying to avoid a flock of birds and crashed. These reported accidents show that a pilot must always fly the aircraft no matter what happens.
And fly their aircraft is exactly what the majority of the pilots did in the 67 NTSB accident briefs. Most of the pilots were able to regain or retain control and execute a successful landing at an airport or an off-airport site. In some cases, this was done while injured. In one case, the pilot suffered facial injuries and his glasses impacted his head when he was hit in the face by a bird, but the pilot was able to land in spite of his injuries wearing a spare pair of glasses. In some cases, a copilot was able to land the aircraft. In a few cases, the pilot heard a thump while flying but did not discover that the aircraft had been hit by a bird or birds until after landing when damage was discovered.
STRIKES CAN HAPPEN ANY TIME OF DAY
The NTSB reports also highlighted another important observation. Bird strikes can happen any time day or night and at various altitudes. In many cases, the strikes occurred during darkness. In other cases, the strikes occurred during daylight. In one case, an IFR pilot hit birds upon breaking out of a low overcast. In some cases, it was known that large numbers of birds were on the ground when the pilot attempted to takeoff or land.
In the case of a night bird strike while in cruise, there is little a pilot can do to avoid such a collision. But when the pilot is aware of the possibility of birds on an airport or birds have been reported on the airport, a pilot must be prepared for a collision if a takeoff is attempted or a landing made while the birds are near or on the runway. In such cases, it would appear to be wiser to delay the takeoff or landing until the birds clear the area. If the birds are just loafing (a termed used in one government report to describe bird actions) on the runway and are not moving off, the pilot has to use good judgement in determining what to do. Contacting the tower, airport manager, or the local FBO is one solution. The airport may have noise devices to scare the birds away or someone could drive a vehicle to the area to make the birds move, etc.
Regardless of what the airport does, it may be safer for someone on the ground to make the birds move than to try to move them in an aircraft and risk a bird strike. If possible, the pilot might divert to another airport. Regardless, the pilot in command is responsible for the safe operation of his or her aircraft.
BIRD/WILDLIFE INFORMATION AND INCIDENT REPORTING
The appropriate FAA Airport/Facility Directory (A/FD) can warn pilots of potentially dangerous bird populations. Pilots flying into non-familiar airports can check the A/FD for any listings about birds/wildlife hazards. For example, the entry for New York's JFK International states, "Flocks of birds on and invof (in the vicinity of) arpt." The Washington National Airport entry says, "Flocks of birds on and invof arpt. Frequent seagull and geese and duck populations airborne over adjacent river areas." The Philadelphia International Airport entry also lists birds on and invof arpt. (Its entry also lists another common problem for many airports: deer--but that's another story.)
In its ongoing effort to compile and track operational hazards, the FAA's Office of Airport Safety and Standards FAA Form 5200-7, Bird Strike Incident/Investigation Report, that aircraft operators and pilots can use to report such incidents. The form asks for such information as extent of damage, estimated repair costs, incident location, effect on flight, phase of flight, and information about the number and type of birds involved. It also asks if the pilot was warned of birds. The report can also be used to report other wildlife species incidents or damages. The form is included in the AIM, as Appendix 1, Bird Strike Incident/Ingestion Report. It is also available from local FAA offices and airports.
Hopefully, no one will have to fill out a Bird Strike Incident/Ingestion report as we approach the beginning of another migratory season. Let's all keep a sharp lookout for our feathered friends. After all, we are sharing their airspace.
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