Patent Abstract:
The invention discloses differing embodiments of methods, aircraft, and apparatus for determining the landing conditions of a runway. In one embodiment, braking data may be collected from an aircraft which has landed on the runway; a braking performance measurement of the aircraft may be calculated based on the braking data; and a normalized braking performance measurement may be determined based on the braking performance measurement. The invention may be utilized to predict the expected braking performance of various types of aircraft on the runway. The invention may provide landing performance information to a broad host of users, and/or may be used as a basis for the development of a new aviation standard for the reporting of runway braking action.

Full Description:
BACKGROUND OF THE INVENTION 
       [0001]    There are existing methods and devices for determining aircraft runway landing conditions. Some of these methods and devices rely on pilot perception of current landing conditions. However, pilot perception may be inaccurate and inconsistent. Some of the other methods and devices rely on ground friction measuring vehicles which attempt to predict the runway landing conditions for aircraft. However, these vehicles may provide inconsistent readings when water, slush, or snow is on the runway; they may not measure real-time changing conditions; and their low relative speed to aircraft may not accurately depict the braking performance of landing aircraft at much higher speeds. 
         [0002]    One or more of the existing methods and devices may experience problems taking accurate, consistent, quantitative, definitive, reliable, and/or real-time prediction of runway conditions. This may lead to increased cost, decreased safety, lower runway efficiency, lower braking determination consistency and accuracy, and/or other types of problems. 
         [0003]    A method, apparatus, and aircraft, is needed which may solve one or more problems in one or more of the existing methods and/or devices for determining aircraft runway landing conditions. 
       SUMMARY OF THE INVENTION 
       [0004]    In one aspect of the invention, a method is disclosed for determining the braking conditions of a runway. In one step braking data is collected from an aircraft which has landed on the runway. In another step, a braking performance measurement of the aircraft is calculated based on the braking data. In yet another step, a normalized braking performance measurement is determined based on the braking performance measurement of the aircraft. 
         [0005]    In another aspect, the invention discloses a landed aircraft on a runway. During landing of the aircraft, braking data was collected, a braking performance measurement of the aircraft was calculated based on the braking data, and a normalized braking performance measurement was determined based on the braking performance measurement of the aircraft. 
         [0006]    In a further aspect of the invention, an apparatus for aircraft is provided. The apparatus collects aircraft braking data, calculates aircraft braking performance measurements, and determines normalized braking performance measurements based on calculated aircraft braking performance measurements. 
         [0007]    These and other features, aspects and advantages of the invention will become better understood with reference to the following drawings, description and claims. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  depicts one embodiment of a method under the invention for determining the braking conditions for a runway; and 
           [0009]      FIG. 2  depicts a perspective view of a landing aircraft in multiple locations as the aircraft touches down and proceeds down a runway. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]    The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
         [0011]    In one embodiment of the invention, as shown in  FIG. 1 , a method  10  for determining the braking conditions for a runway is provided. In one step  12 , braking data may be collected from an aircraft which has landed on the runway. The braking data may include any data regarding braking of the aircraft on the runway. The aircraft may comprise any type of airplane, or other type of device capable of flying in the air. 
         [0012]    As shown in  FIG. 2 , which depicts a landing aircraft  15  in multiple locations as it lands on a runway  17 , the collected braking data may comprise an initial touch-down location  14  of the aircraft  15  on the runway  17 . The initial touch-down location  14  may comprise the approximate coordinates on the runway  17  where the aircraft  15  first touches down upon landing. The collected braking data may further comprise an initial aircraft velocity of the aircraft  15  at the initial touch-down runway location  14 . This initial aircraft velocity may comprise the velocity of the aircraft  15  on the runway  17  when the aircraft first touches down at the initial touch-down location  14 . 
         [0013]    Additionally, the collected braking data may comprise a final runway location  18  of the aircraft  15 . The final runway location  18  may comprise the approximate coordinates on the runway  17  where the aircraft  15  has proceeded down the runway upon landing and reached a velocity where the aircraft  15  is ready to taxi off the runway  17 . In another embodiment, the final runway location  18  may comprise the approximate coordinates on the runway  17  where the aircraft  15  has come to a stop and has zero velocity. In yet another embodiment, the final runway location  18  may comprise the approximate coordinates on the runway  17  of a pre-determined location. The pre-determined location may be based in part on the total length of the runway  17 , or other criteria. 
         [0014]    In addition, the collected braking data may comprise a final velocity of the aircraft  15  at the final runway location  18 . The final velocity may comprise the velocity of the aircraft  15  at the final runway location  18 . The final velocity may comprise a velocity on the runway  17  when the aircraft  15  has reached a velocity where it is ready to taxi off the runway  17 . In another embodiment, the final velocity may comprise a zero velocity when the aircraft  15  has come to a stop. In still another embodiment, the final velocity may comprise the velocity of the aircraft  15  on the runway  17  at the above-referenced pre-determined location. 
         [0015]    Referring to  FIGS. 1 and 2 , in another step  22  of the method  10 , a braking performance measurement may be calculated for the landed aircraft  15  based on the collected braking data  12 . The braking performance measurement may comprise a measurement of the braking performance of the aircraft on the runway. The step  22  may comprise calculating one or more runway deceleration measurements of the landed aircraft  15 . The runway deceleration measurement may comprise the deceleration of the landed aircraft  15  between the initial touch-down location  14  on the runway  17  and the final runway location  18 . The deceleration measurement may be calculated by using a mathematical formula similar to the formula Deceleration=|((Velocity  2 ) 2 −(Velocity  1 ) 2 )/(2*Distance)|, wherein Velocities  1  and  2  represents the respective velocities of the aircraft  15  at two separate locations along the runway  17 , and the Distance represents the distance along the runway  17  between the respective locations where Velocities  1  and  2  are measured. The deceleration measurement may be taken in feet per second squared. In one embodiment, the deceleration may be calculated between the initial touch-down location  14  and the final runway location  18  by using, in the above Deceleration formula, the initial aircraft velocity as Velocity  1 , the final aircraft velocity as Velocity  2 , and the runway distance between the initial touch-down location  14  and the final runway location  18  as the Distance. 
         [0016]    In other embodiments, the deceleration measurement may comprise calculating the deceleration of the aircraft  15  at several different locations along the runway  17 . This iteration and calculation may be in the order of twenty times per second. In other embodiments, any number of deceleration measurements may be taken. A graph and/or dynamic display may be prepared to show the variation in deceleration of the aircraft  15  after it touches down  14  until it comes to its final runway location  18 . In other embodiments, only one deceleration measurement may be taken. In still other embodiments, the deceleration measurement may be taken along different portions of the runway  17 . 
         [0017]    Again referring to  FIGS. 1 and 2 , in yet another step  24  of the method  10 , a normalized braking performance measurement may be determined based on the calculated braking performance measurement  22  of the landed aircraft  15 . The normalized braking performance measurement may comprise a normalized value of the braking performance measurement. The normalized braking performance measurement may comprise the expected braking performance on the runway  17  of a standard aircraft on a standard day. The term “standard aircraft” may represent a generic, non-descript aircraft of no particular type, while the term “standard day” may represent a day having normal landing conditions. In one embodiment, a standard day may comprise a day where the temperature is 59 degrees Fahrenheit, having a 29.92 Altimeter setting, with no wind, and at sea level. The normalized braking performance measurement may represent a normalization of one or more deceleration rates of the aircraft  15  on the runway  17 . The normalized braking performance measurement may comprise an index, coefficient, or value used to represent the expected braking ability of a generalized aircraft on the runway  17 . 
         [0018]    In determining the normalized braking performance measurement  24 , a variety of factors may be taken into account in order to normalize the calculated braking performance measurement  22  to that of a standard aircraft. Some of these factors may include consideration of wind speed, wind direction, weight of the aircraft, type of the aircraft, air temperature, configuration of the aircraft, Minimum Equipment List (MEL) conditions, thrust reverse conditions, non-normal conditions, initial aircraft velocity at the initial touch-down runway location, final aircraft velocity at the final runway location, and/or other factors. 
         [0019]    In another embodiment, the method  10  for determining the braking conditions for a runway  17  may further include the step of displaying on the aircraft  15  the braking performance measurement  22  and/or the normalized braking performance measurement  24 . This may be displayed on an apparatus on the aircraft  15  such as a computer monitor or other device. The method  10  may further include the step of communicating the braking performance measurement  22  and/or the normalized braking performance measurement  24  to air traffic control and/or other uses of this information—i.e., arriving aircraft, airline dispatch offices, airport operations, military operations, corporate flight departments, departing aircraft, and/or others using braking action reports as an element in making rejected takeoff decisions. This may be accomplished by the pilot radioing air traffic control, or through other means such as data link, Automatic Dependent Surveillance-Broadcast (ADS-B) or other automatic networking communication. 
         [0020]    In yet another embodiment, the method  10  may further comprise the step of determining an expected braking performance of a particular type of aircraft on the runway based on the normalized braking performance measurement  24 . This may be achieved by taking into account the configuration, weight, and performance capabilities of the particular aircraft. In such manner, the expected braking performance of a whole host of different aircraft may be determined. 
         [0021]    In still another embodiment, the method  10  may further comprise the step of preparing, for one or more aircraft, one or more graphs and/or dynamic displays showing at least one of the braking performance measurement  22  and/or the normalized braking performance measurement  24  at particular locations over the runway. These graphs and/or dynamic displays may allow air traffic control to determine the runway deceleration conditions on a continuing time spectrum along various portions of the runway  17  for varying numbers and types of aircraft. 
         [0022]    In still another embodiment, the method  10  may additionally comprise the step of assigning a minimum standard sustainable deceleration rate for continued operation of the runway  17  in hazardous weather conditions. The method  10  may further comprise the step of determining whether the runway  17  should be shut down due to hazardous conditions by comparing at least one of the braking performance measurement  22  and the normalized braking performance measurement  24  to the assigned minimum sustainable deceleration rate. If the braking performance measurement  22  and/or the normalized braking performance measurement  24  is below the assigned minimum sustainable deceleration rate for the runway  17 , the runway  17  may be shut down until conditions improve. 
         [0023]    Any of the above referenced steps for any of the disclosed embodiments of method  10  may utilize one or more apparatus located on the aircraft  15 . Such aircraft apparatus may comprise one or more computers, aircraft auto-braking apparatus, or other types of devices. 
         [0024]    In another embodiment, the invention may comprise a landed aircraft on a runway. During landing of the aircraft, braking data may have been collected, a braking performance measurement may have been calculated based on the braking data, and a normalized braking performance measurement may have been determined based on the braking performance measurement. Any of the embodiments disclosed herein may have been utilized during landing of the aircraft to collect the braking data, calculate the braking performance measurement, and determine the normalized braking performance measurement. 
         [0025]    In yet another embodiment, the invention may comprise an apparatus for aircraft which collects aircraft braking data, calculates aircraft braking performance measurements, and determines normalized braking performance measurements based on calculated aircraft braking performance measurements. Such aircraft apparatus may comprise one or more computers, an aircraft auto-braking apparatus, or other type of device. Any of the embodiments disclosed herein may be used as part of the apparatus to collect the aircraft braking data, calculate the aircraft braking performance measurement, and determine the normalized braking performance measurement. 
         [0026]    One or more embodiments of the disclosed invention may solve one or more problems in existing methods, aircraft, and apparatus for determining the landing conditions of a runway. One or more embodiments of the invention may provide a substantially real-time, quantitative, definitive, reliable measure of runway landing conditions in such manner, the invention may decrease cost, increase safety, increase runway efficiency, increase braking determination consistency and accuracy, and/or address other problems known in the art. For instance, the invention may aid in the determination of runway/airport plowing and closure decisions, may aid in rejected takeoff decisions, may aid in airline dispatch, may aid in flight crew divert decisions, and/or may aid in other problem areas. 
         [0027]    It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.

Technology Classification (CPC): 6