Abstract:
A method comprises continuously discharging a persistent vapor of bird repellant from a non-propulsion apparatus on a flying aircraft into an elevated airspace to substantially cover a runway flight path corridor at a commercial airport to prevent birds from striking subsequent aircraft in the corridor. The discharging automatically begins from a runway at the airport and automatically ends when the corridor is substantially covered.

Description:
BACKGROUND 
     Bird strikes can cause damage to commercial aircraft. The resulting aircraft damage is costly to repair. Also, aircraft downtime during repair is costly as it results in lost revenues for aircraft operators. So, it is desirable to minimize bird strikes. 
     Some have suggested putting lights (flashing lights, for example) and/or noise makers on the aircraft themselves. Such expedients have proven ineffective. 
     Accordingly, a more effective way of keeping flying birds out of the flight path of aircraft at airports is needed. 
     SUMMARY 
     According to an embodiment herein, an aircraft comprises an aircraft body, and apparatus, carried by the body, for discharging a persistent vapor of bird repellant into an elevated airspace. 
     According to another embodiment herein, a method comprises discharging a persistent vapor of bird repellant from a flying aircraft into an elevated airspace to prevent birds from striking other aircraft in the elevated airspace. 
     According to another embodiment herein, an apparatus is configured to be carried upon an aircraft. The apparatus comprises a tank, a vaporizing nozzle, and control for causing bird repellant to be discharged from the tank via the nozzle. The control is configured to cause the bird repellant to be discharged into a selected elevated airspace above an airport runway. 
     These features and functions may be achieved independently in various embodiments or may be combined in other embodiments. Further details of the embodiments can be seen with reference to the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         FIG. 1  provides a diagrammatic representation of an airport with a runway, and of a landing approach flight path and a take off departure flight path to and from the runway, respectively. 
         FIG. 2  is an enlarged fragmentary view of a portion of  FIG. 1 , illustrating a method of protecting the airspace of the landing and take off flight paths by repelling birds from this airspace. 
         FIG. 3  provides a perspective view of an apparatus carried upon an aircraft for discharging into the airspace identified in  FIGS. 1 and 2  a persistent vapor of a bird repellant which will repel flying birds. 
         FIG. 4  is an illustration of an aircraft including apparatus for discharging a persistent vapor of a bird repellant into a selected airspace. 
         FIG. 5  is an illustration of an example of an apparatus for discharging a persistent vapor of a bird repellant into an elevated airspace. 
         FIG. 6  is an illustration of a method of discharging a persistent vapor of a bird repellant into an elevated airspace. 
     
    
    
     DETAILED DESCRIPTION 
     Recent bird strike studies have shown that over 90% of bird strikes occur at altitudes of less than 3000 feet, and within 9 miles of an airport runway for aircraft approaching landing, or within 2.5 miles of the airport runway following takeoff for an aircraft departing an airport. By far, the majority of bird strikes occur during approach to a landing, almost always during daylight hours, and during the summer and fall months (i.e., July through October). Both for aircraft approaching landing, and for those departing an airport, the elevated airspace (or flight path) to be occupied by the aircraft and to be kept free of flying birds is generally aligned with an airport runway, and extends to an elevation of about 3000 feet (sloping downwardly toward landing and sloping more steeply upwardly following takeoff), and extends generally less than a mile laterally of the runway alignment. This relatively thin flight path corridor at an airport runway (hereinafter the “runway flight path corridor”) is the airspace from which birds should be excluded if bird strikes are to be reduced or eliminated. 
     In view of the above, methyl anthranilate (“MA”) or another bird repellant may be used to protect flying aircraft from flying bird strikes within the runway flight path corridor. By discharging MA or another bird repellant into the runway flight path corridor in a vapor form that does not sink and remains persistently in the air, birds will be repelled and bird strikes against aircraft approaching and departing a runway will be significantly reduced or eliminated. 
     Reference is made to  FIG. 4 , which illustrates an aircraft  410  for discharging bird repellent into a runway flight path corridor. The aircraft  410  may be manned (for example, a general aviation aircraft, a helicopter, or a commercial passenger or freight aircraft) or unmanned (for example, a remotely piloted vehicle, or “RPV” or an unmanned autonomous vehicle or “UAV”). The aircraft  410  includes a body  420  and an apparatus  430 , carried by the body  420 , for discharging a persistent vapor of bird repellant into a runway flight path corridor. For a commercial aircraft, major components of the body  420  may include a fuselage, wing assemblies and empennage. The apparatus  430  may be carried by any of these major components. For an unmanned aircraft, the apparatus  430  may be stored, for example, in a payload bay. 
     The aircraft  410  discharging the bird repellant does not protect itself against bird strikes in the runway flight path corridor. Rather, it discharges the bird repellant into the runway flight path corridor so subsequent aircraft entering the runway flight path corridor are protected. Moreover, the aircraft  410  does not necessarily discharge the bird repellant directly into the runway flight path corridor. The aircraft  410  may discharge the bird repellant into a selected elevated airspace such that the bird repellant enters into the runway flight path corridor. For instance, the bird repellant may be discharged upwind of the runway flight path corridor and blown from the selected elevated airspace into the runway flight path corridor. 
     The aircraft  410  discharging bird repellant into the selected airspace may be flown along the approach flight path(s) to an airport, and along the departure flight path(s) from an airport, either within these paths, or upwind of these flight paths, most desirably during daylight hours and during the months of the year when bird strikes are most common. In commercial aircraft, for example, the apparatus  430  may be configured to be easily installed onto and removable from an aircraft  410 . 
       FIG. 1  provides a diagrammatic view of an airport with a runway  10  to which a commercial aircraft  12  approaches along a landing corridor  14 , and from which aircraft  16  departs along a take off corridor  18 . The corridors  14  and  18  have a thickness in the vertical direction of but a few hundred feet, and extend laterally of the alignment of the runway  10  by a mile or less within the relevant altitude and distance from the runway  10 . That is, as discussed above, the majority of bird strikes occur at elevations of 3000 feet or less. So, it is in the elevations from 3000 ft. above runway  10 , down to the runway  10 , and within the flight path corridors  14 ,  18  that birds are to be repelled in order to prevent flying bird strikes by aircraft.  FIG. 1  well illustrates the airspace (generally indicated with numeral  20 , and including landing corridor  14  and take off corridor  18 ) from which it is desired to repel flying birds in order to make this airspace safer for the transit of aircraft using these flight paths to and from the runway  10 . 
       FIG. 2  depicts a portion of the airspace  20  at an enlarged size so that it is seen that a commercial aircraft  22  flies along paths as are generally indicated by the arrows  24 ,  26 , and  28 . Arrow  24  depicts the aircraft  22  flying relative to (possibly within) the approach or landing corridor  14 . That is, it is to be noted that the aircraft  22  may actually fly within the corridor  14 , or may fly upwind of but generally parallel to and at elevations corresponding generally with the corridor  14 , depending on wind conditions at a particular time. It is to be noted that the length of the runway  10  has been foreshortened in both of  FIGS. 1 and 2 . Arrow  26  depicts the aircraft  22  transitioning along the length of the runway  10  (generally parallel to but not necessarily over runway  10 ) from landing corridor  14  to take off corridor  18 . Arrow  28  similarly depicts aircraft  22  flying relative to (possibly within) the take off corridor  18 . During flight the aircraft  22  discharges, from an apparatus generally indicated with dashed line box  30  on  FIG. 2 , a persistent bird repellant into a selected one or both of the landing corridor  14  and take off corridor  18 . 
     In  FIG. 2 , an apparatus  30  for discharging a persistent vapor bird repellant is depicted by a dashed-line box.  FIG. 2  shows the apparatus  30  aboard the empennage  22   d  of the aircraft  22 . In some embodiments, the apparatus  30  may be located in an auxiliary power unit (APU) bay in the empennage  22   d . However, the location of the apparatus  30  is not limited to the empennage  22   d . In other embodiments, the apparatus  30  may be located in or near a fuselage  22   a , landing gear bay  22   b , or in a wing-to-body fairing  22   c  of the aircraft  22 . 
       FIG. 3  illustrates one embodiment of an apparatus  30  for discharging a persistent vapor bird repellant from aircraft  22  and into the airspace  20 . The apparatus  30  may include a base or panel  32 , which is adapted for quick installation into and removal from the aircraft  22 . That is, the apparatus  30  when carried aboard a general aviation aircraft, aboard a helicopter, or even aboard a commercial passenger or freight aircraft, may be installed within the aircraft during the months of the year when bird strikes are most common, and is preferably removed for the remainder of the year. The apparatus  30  may receive power for its operation (electrical power, for example—indicated with the character “P” on  FIG. 3 ) as well as control signals (“on” and “off” signals, for example—indicated on  FIG. 3  with the character “C”) from the aircraft  22  upon which it is carried. 
     Mounted upon the panel  32  is a tank  34  having an inlet  36  for receiving MA or another liquid bird repellant. The inlet  36  is closed by a cap  38 . A pump  40  also mounted to the panel  32  receives bird repellant from tank  34  and during operation of the pump  40  delivers the liquid bird repellant pressurized to an atomizing or vaporizing nozzle  42 . The nozzle  42  preferably extends at least slightly outwardly of the aircraft carrying the apparatus  30  and into the surrounding air stream so, during flight, it can discharge atomized bird repellant in the form of a persistent vapor. For instance, the nozzle  42  may extend through a hole in an APU access door. 
     This vapor of atomized persistent bird repellant is delivered through an orifice (generally indicated at  42   a ) in the nozzle  42 . Particle size of the vapor may be set according to the size of the orifice  42   a  Particle size of the vapor may be about 30 microns or less. For example, the atomized vapor of bird repellent has a vapor particle size of from about 5 microns to about 25 microns. Such a small particle size provides a vapor that is essentially “dry” and leaves no wet residue, and which is very persistent within the runway flight path corridor. That is, this small particle size allows the persistent vapor of bird repellent to remain suspended in the runway flight path corridor, so that the bird repellent does not sink to the ground. Accordingly, as the persistent vapor of bird repellent disperses into the runway flight path corridor, flying birds are repelled from the runway flight path corridor, and subsequent aircraft can more safely transit this airspace to and from the airport and runway  10 . 
     The base panel  32  may include a heating element with temperature sensing to maintain the repellent in a liquid state for dispersal into the selected elevated airspace on approach for landing. Even during summer, the APU bay for example would be cold at altitude as the APU is not generally used in flight. Repellent carried in flight but reserved for dispersal on landing would be heated in order to prevent freezing. 
     Reference is now made to  FIG. 5 , which illustrates an example of an apparatus  430  for the aircraft  410 . The apparatus  430  includes a tank  520 , vaporizing nozzle  530 , and control  540  for causing bird repellant to be discharged from the tank  520  via the nozzle  530 . In some embodiments of the apparatus  430 , the nozzle  530  delivers particles of fixed size (for instance, by using a fixed orifice size). In other embodiments, the particle size may be varied. As a first example, a single nozzle  530  having a variable orifice may be used. As a second example, the apparatus  510  includes at least one additional nozzle (not shown), where the different nozzles have different orifice sizes. The nozzle discharging a desired particle size is selected. 
     The control  540  may include a pump  542 , which receives electrical power from the aircraft  410  and pumps repellant from the tank  520  to the nozzle  530 . Other embodiments, however, may eliminate the pump and use other means to discharge the bird repellant (e.g., an airflow assisted gravity feed system). 
     The control  540  may further include a controller  544  for controlling the pump  542 . The controller  544  may be analog or digital. Although located onboard the aircraft  410 , the controller  544  is preferably not integrated electronically with other onboard systems (to avoid full failure could affect the other onboard systems). 
     In some embodiments, the controller  544  may include a simple on-off switch operated manually by the crew of the aircraft or automatically by aircraft avionics. In other embodiments, the control  540  may include a “weight-on-wheels” sensor, such that the repellant is not discharged while the aircraft is on the ground with weight on its landing gear. Once the sensor senses that the aircraft is off the ground, the controller  544  causes the pump  542  to start pumping bird repellant to the vaporizing nozzle  530 . 
     In still other embodiments, the controller  544  may include a digital processor that is programmed to control the operation of the pump  542 . For example, the digital processor may be programmed to control the pump  542  to discharge the bird repellant at a rate that follows a predetermined profile or a profile determined by real time data collection. The digital processor may also be programmed to make a “go” or “no go” decision to discharge based on a state table in response to real time data collected by onboard sensing systems and advanced radar systems, and also in response to inputs from pilots, air traffic control, and ground service spotters (e.g., spotters with visual “eyes on birds” reports). 
     In some embodiments, the controller  544  may also control the size of the particle discharged through the nozzle. As a first example, the controller  544  may control orifice size of a nozzle having a variable orifice. As a second example, the controller  544  may select a nozzle among a plurality of nozzles having different orifice sizes. 
     In some embodiments, the digital processor may be programmed to communicate with multiple on board sensing and information systems allowing the apparatus  430  to combine information regarding weather conditions (e.g., high winds, heavy precipitation, temperature) and more detailed information such as bird sighting and bird strike reports, advanced onboard radar systems reports, general air traffic congestion, pilot inputs, etc. The digital processor may use this information to modify dispersal rates, alter altitude of dispersal, or abort a planned dispersal. 
     Reference is now made to  FIG. 6 , which illustrates a method of using the apparatus with digital controller to discharge bird repellant into a selected elevated airspace. At block  610 , an aircraft carries the apparatus to an airport runway. At block  620 , the aircraft takes off, and begins discharging the bird repellant under control of the digital controller. At block  630 , in response to live aircraft data, the digital controller performs at least one of modifying discharge rate, altering altitude of discharge, and aborting a planned discharge. At block  640 , the digital controller either stops the discharge or allows the tank to run out of bird repellant. 
     In some embodiments, the digital controller leaves an amount of bird repellant in the tank for use during approach and landing. At block  650 , during approach of the aircraft, the digital controller causes the bird repellant to be discharged into the elevated airspace. 
     The bird repellant clears the runway flight path corridor of birds. As a result, subsequent aircraft entering the runway flight path corridor are protected against bird strike. 
     An apparatus herein may be refilled with bird repellant and used during each flight. However, use of an apparatus herein is not so limited. An apparatus herein may be used only when needed. For example, bird repellant is discharged according to a schedule of every tenth departure, when only a few birds are known to be in the area. Later, bird repellent is discharged on every other departure, but only for afternoon flights. 
     An apparatus herein is not limited to discharging bird repellant into the selected elevated airspace. For instance, if birds are sighted on the ground, an apparatus herein may discharge bird repellant on taxi. A wetter vapor that sinks to the ground may be desired for such discharge. In the case of a single nozzle having a variable orifice, orifice size may be increased to obtain a wetter vapor. In the case of multiple nozzles with different orifice sizes, the nozzle with a suitable orifice may be selected to obtain a wetter vapor. 
     An apparatus herein is not limited to commercial airports. An apparatus herein may be used, for example, in regional airports and military bases.