Abstract:
Disclosed is a runway alerting method and system for an aircraft during a take-off maneuver. The method includes determining stopping positions for the aircraft along the runway using aircraft energy state, deceleration and braking information and displaying the stopping positions on a display.

Description:
RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 61/773,660 filed Mar. 6, 2013. 
    
    
     TECHNICAL FIELD 
     The technical field generally relates to aircraft, and more particularly relates to methods and apparatus for advising a pilot of an aircraft of the predicted stopping point of the aircraft in the event the pilot needed to abort the takeoff. 
     BACKGROUND 
     When performing a takeoff maneuver in an aircraft, it is sometimes necessary to abort the takeoff and stop the aircraft on the remaining available runway. Engine failure, system failure, or contaminated runway effects are some causes for a pilot to abort a takeoff attempt. Typically, during takeoff, the aircraft rapidly accelerates down the runway to a speed known as “V 1 ”, which is a decision speed where the pilot assesses whether to abort the takeoff or attempt to reach the “V 2 ” speed where the aircraft is capable of taking off even if only one engine is operational. 
     Pilots are trained to monitor conditions during takeoff and abort if necessary. However, the takeoff/abort decision is left to the discretion of the pilot. Accordingly, pilots with varying levels of experience and training may respond differently to the same situation, and some pilot responses may not be the optimal choice. 
     Accordingly, it is desirable to assist a pilot during the takeoff phase of flight. It is further desirable that the assistance be as objective as possible and not dependent upon pilot skill or judgment. Other desirable features and characteristics will become apparent from the subsequent summary and detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. 
     SUMMARY 
     In one embodiment, a runway takeoff alerting method is provided in the event of an aborted takeoff. The method includes determining stopping positions for the aircraft along the runway using aircraft energy, deceleration and braking information and displaying the stopping positions on a display. 
     In another embodiments, a system is provided that includes, but is not limited to an aircraft system that includes a first apparatus that is configured to determine an aircraft speed relative to the ground and a second apparatus that is configured to determine a position along a runway when the aircraft begins deceleration. A flight system coupled to the first apparatus and the second apparatus and configured to determine a minimum stopping position for the aircraft along the runway using the aircraft speed and the predicted position along a runway when the aircraft begins deceleration. Also, a corporate stopping position is determined for the aircraft along the runway using the aircraft speed and the predicted position along a runway when the aircraft begins deceleration. These stopping positions are displayed to aid the pilot in making decisions. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention will hereinafter be described in conjunction with the following drawing figures, where like numerals denote like elements, and: 
         FIG. 1  is a block diagram of various aircraft flight systems in accordance with an embodiment; 
         FIGS. 2A and 2B  illustrates an aircraft preparing to takeoff in accordance an embodiment; 
         FIGS. 3A-C ,  4 A-B and  5  are illustrations of a graphical indication provided by an embodiment; and 
         FIG. 6  is a flowchart of a method in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” The following detailed description is merely exemplary in nature and is not intended to limit application and uses. Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. All of the embodiments described in this Detailed Description are exemplary embodiments provided to enable persons skilled in the art to make or use the embodiment and not to limit the scope that is defined by the claims. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, summary or the following detailed description. 
       FIG. 1  is block diagram of various flight systems  100  for an aircraft that implements a runway overrun monitor system and/or is capable of executing a runway overrun monitor method in accordance with exemplary embodiments. The various flight systems  100  includes a flight computer  102 , an Air Data System (ADS)  104 , a Flight Management System (FMS)  106 , an Enhanced Ground Proximity Warning System (EGPWS)  108 , an Inertial Reference System (IRS)  110 , a Positioning System  111  (e.g., GPS, GLONASS or Galileo) and a display unit  112 . Optionally, other proprietary or commercial sensor systems  114  provide additional input signals to the flight computer  102 , such as, for example, a weight-on-wheels (WOW) sensor. 
     The FMS  106  is configured to provide to the flight computer  102  data regarding the flight including a landing approach plan, while the EGPWS  108  provides the flight computer  102  with a geometric altitude, where the geometric altitude is based on a three-dimensional model of terrain. The ADS  104 , the FMS  106 , the EGPWS  108 , and the IRS  110  are disposable within the flight computer  102  or within other avionics shown in  FIG. 1  or at other locations in an aircraft. 
     The display unit  112  displays information regarding the status of the aircraft. The display unit  112  receives input from various systems to provide information to the pilot. For example, the EGPWS  108  generates information for a runway placement display  116  to the pilot regarding the geometric altitude position of the aircraft with respect to the runway. The display unit  112  typically also includes, but is not limited to an annunciator  120  to provide verbal warnings, alert or warning tones or other audible information. The display screens  122  of the display unit  112  include icons  124  that are illuminated to indicate the occurrence of certain conditions and a text message screen  126  to display text information. 
     In accordance with one embodiment, the various flight systems  100  illustrated in  FIG. 1  is implemented with software and/or hardware modules in a variety of configurations. For example, flight computer  102  comprises one or more processors, software module or hardware modules. The processor(s) reside in single integrated circuits, such as a single or multi-core microprocessor, or any number of integrated circuit devices and/or circuit boards working in cooperation to accomplish the functions of the flight computer  102 . The flight computer  102  is operable coupled to a memory system  128 , which may contain the software instructions or data for the flight computer  102 , or may be used by the flight computer  102  to store information for transmission, further processing or later retrieval. In accordance with one embodiment, the memory system  128  is a single type of memory component, or composed of many different types of memory components. The memory system  128  can include non-volatile memory (e.g., Read Only Memory (ROM), flash memory, etc.), volatile memory (e.g., Dynamic Random Access Memory (DRAM)), or some combination of the two. In an embodiment, the runway overrun monitor system is implemented in the flight computer  102  via a software program stored in the memory system  128 . 
     Although not illustrated in  FIG. 1 , it will be appreciated that each of the various flight systems  100  typically includes one or more sensors. In general, a sensor is a device that measures a physical quantity and converts the measurement into a signal received by a system or the flight computer  102 . In general, sensors are used to sense any number of physical quantities, such as light, motion, temperature, magnetic fields, gravitational forces, humidity, vibration, pressure, electrical fields, current, voltage, sound, and other physical aspects of the aircraft or a surrounding environment. Non-limiting examples of sensors include, but is not limited to weight-on-wheel sensors, vibration sensors, air speed sensors, altimeter, gyroscope, inertial reference unit, magnetic compass, navigation instrument sensors, throttle position sensor, pitch, roll and yaw sensors, etc. 
     According to exemplary embodiments, a runway takeoff monitor is provided that computes or predicts stopping points on the runway to provide the pilot with guidance on where the aircraft could stop if a takeoff was aborted. A first stopping point is the minimum stopping distance computed using a maximum deceleration value that the aircraft is capable of achieving. A second stopping point (sometimes referred to as a “corporate stop”) is computed using a reduced deceleration capability that might be expected when only using alternative deceleration devices, such as thrust reversers or a reduced braking capability consistent with the design of the aircraft. Some embodiments include additional stopping points as selected by the pilot, based upon integration with an aircraft autobrake system. Thus, the deceleration capabilities of the aircraft are known, and may be determined during flight testing or validation of the aircraft. In some embodiments, the aircraft deceleration information, inertial three-dimensional (horizontal and vertical) velocities, inertial three-dimensional position, runway start and end points, runway heading, runway glideslope angle, runway slope, and weight-on-wheels sensors are used by the runway overrun monitor. 
       FIG. 2A  illustrates an aircraft  200  on a taxiway  202  preparing to takeoff. As the aircraft  200 ′ leaves the taxiway  202  heading for the runway  204 , the aircraft  200 ″ will pause at the beginning of the runway  204  awaiting clearance from local Air Traffic Control (ATC) to begin the takeoff maneuver. At some point on or prior to moving onto the taxiway  202  the takeoff runway monitor system will be activated. In some embodiments, the runway takeoff monitor system is manually activated by the pilot or co-pilot. Preferably, in manual activation embodiments, activation by the pilot or co-pilot is part of a takeoff Standard Operation Procedure (SOP) provided by the flight department to the flight crew. In some embodiments, activation of the runway takeoff monitor system is automatic, such as by the flight computer  102  as shown in  FIG. 1 , at some point on the taxiway  202  or the runway  204 . The aircraft position information may be known to the flight computer such as via a Global Positioning System (GPS) onboard the aircraft. 
     Once activated, the runway takeoff monitor system is monitoring one or more operational parameters of the aircraft to compute the minimum and corporate stopping positions on the runway. As the aircraft  200 ″ accelerates down the runway  204 , the takeoff runway monitor is computing (predicting) where the aircraft will come to a stop should the pilot abort the takeoff maneuver and provides this information to the pilot as will be discussed in more detail below. 
       FIG. 2B  illustrates a side view of the aircraft  200 ″ on the runway  204 . In the illustrated example, point  206  is where the aircraft would reach the “V 1 ” speed and the pilot would make a decision to continue with takeoff or to abort the takeoff. A pilot may make this decision due to an engine failure, a system failure, or contaminated runway effects. As the pilot evaluates conditions to make this determination, the pilot is provided with a graphical indication of where it is predicted that the aircraft could stop on the runway using a maximum stopping effort (to have the minimum stopping distance) and a reduced effort that may not involve using thrust reversers for full braking (sometimes called a corporate stop). Moreover, should a pilot initially determine to continue with the takeoff attempt, and a failure should occur between “V 1 ” and “V 2 ”, the pilot is provided with some guidance as to where the aircraft will stop as opposed to attempting to reach the “V 2 ” speed  208 . 
       FIGS. 3A-C  are illustrations of exemplary graphical indications that may be provided to the pilot such as on the display screen  122  of  FIG. 1 . As can be seen, a runway depiction  300  is provided. An overlay  302  indicates both the computed (or predicted) minimum stopping point  304  and the corporate stopping point  306 . Accordingly, to exemplary embodiments, the minimum stopping point and the corporate stopping point are computed (predicted) using equation (1); 
     
       
         
           
             
               Stopping 
               ⁢ 
               
                   
               
               ⁢ 
               point 
             
             = 
             
               
                 
                   Brk 
                   on 
                 
                 ⁢ 
                 Pt 
               
               + 
               
                 
                   V 
                   2 
                 
                 
                   2 
                   × 
                   
                      
                     A 
                      
                   
                 
               
             
           
         
       
     
     Where: 
     Brk on Pt is the position on the runway (distance from runway start) where the breaks would be applied if the takeoff were aborted (typically estimated at one second from abort); 
     V is the velocity of the aircraft as determined by aircraft speed sensors; and 
     A is the absolute value of the acceleration (deceleration being a negative value) using either the maximum deceleration or the corporate deceleration depending on which predicted stopping point is being computed. 
     If the aircraft aborts takeoff, the velocity term (V) will be rapidly decreasing, thus shortening the predicted stopping distance. To provide an indication of this information to the pilot, trend arrows  308  provide an indication as to whether these predicted stopping points are trending further down the runway or treading toward the aircraft being able to stop within the remaining runway distance. Thus, shortly after takeoff abort and application of the brakes, the trend arrows  308  may be pointed down the runway depiction  300  as shown in  FIG. 3A . However, in  FIG. 3B  and  FIG. 3C , the aircraft has slowed enough for the trend arrows  308  to reverse to indicate a safe stop should be achieved. 
     If the aircraft is equipped with an autobrake system, then a label indicating the brake setting is depicted in autobrake label  312 . An aircraft autobrake system allows the pilot to select braking deceleration characteristics ranging from low (L) to medium (M) to high (H). The minimum stopping point  304  corresponds to the high (H) autobrake setting.  FIG. 3C  shows a depiction of a medium (M) braking deceleration selected by the pilot. A similar embodiment would be presented for a low (L) or other autobrake setting. The pilot would anticipate that a runway excursion could occur if either the minimum stopping point  304  or the autobrake setting stopping point  312  were to exceed the end of the runway. 
     Also, a runway buffer  316  (horizontal dashed line) is depicted in  FIGS. 3A-C , and is nominally the one-thousand foot remaining marker. However, in some embodiments, this buffer line can be pilot selectable as a desired runway stopping point. This capability allows the pilot to pre-select a stopping point that may correspond to desired taxi way exit point from the runway, or provide a safety margin. The pilot can then monitor the display and adjust aircraft approach and landing performance to meet the desired runway stopping point. 
     However, in some circumstances, the aircraft may have too high an energy causing the potential for a runway overrun if the takeoff is aborted. Thus, in  FIGS. 4A-B , the overlay  402  indicates the predicted corporate stopping point  406  exceeds the available runway. However, the minimum stopping point  404  is still shown on the runway indicating that the pilot should apply the maximum braking/stopping systems available to avoid the potential of overrunning the runway. In this circumstance the color of the runway depiction  400  may change to amber or some other color indicative a warning. 
     In  FIG. 5 , a more serious scenario is illustrated where the runway takeoff monitor predicts that both the corporate stopping point  506  and the minimum stopping point  504  will exceed the available remaining runway. In this circumstance, the runway depiction  500  may change to a red color. This indicates to the pilot that it is predicted that the aircraft cannot stop on the remaining available runway. 
       FIG. 6  is a flowchart of a method  600  performed by the runway takeoff monitor system in accordance with an embodiment. In one embodiment, the various tasks performed in connection with the method  600  of  FIG. 6  are performed by software executed in a processing unit, hardware, firmware, or any combination thereof. For illustrative purposes, the following description of the method  600  of  FIG. 6  refers to elements mentioned above in connection with  FIG. 1  to  FIG. 5 . 
     In an embodiment, portions of the method of  FIG. 6  performed by different elements of the described system. However, in accordance with another embodiment, portions of the method of  FIG. 6  are performed by a single element of the described system. 
     It should also be appreciated that the method of  FIG. 6  may include no additional or alternative tasks or may include any number of additional or alternative tasks, and that the method of  FIG. 6  may be incorporated into a more comprehensive procedure or process having additional functionality not described in detail herein or implemented as a stand-alone procedure. Moreover, one or more of the tasks shown in  FIG. 6  are removable from an embodiment of the method  600  of  FIG. 6  as long as the intended overall functionality remains intact. 
     The routine begins in step  602  with an activation of the runway takeoff monitor system. In some embodiments, the runway takeoff monitor system is manually activated by the pilot or co-pilot or automatically activated by movement toward the runway. After activation of the runway takeoff monitor system, step  604  computes the minimum stopping point and the corporate stopping point of the aircraft as discussed above in connection with equation (1). Step  606  displays one of the graphic indications as discussed above in connection with  FIGS. 3-5 . Next, decision  608  determines whether the aircraft has a predicted minimum stopping point that will exceed the runway. If so, then a warning is give in step  610  and the routine continues to compute or predict the aircraft stopping points until the aircraft is stopped or the aircraft achieves takeoff. If not, then decision  612  determines whether the corporate stopping point will exceed the remaining available runway. If so, step  614  provides a warning message for landing distance, so that the pilot will understand to apply the maximum available stopping systems to avoid the potential for overrunning the runway should the takeoff be aborted. 
     If both the minimum stopping point and the corporate stopping point are predicted not to exceed the runway ( FIGS. 3A and 3B ), decision  616  determines whether the aircraft has come to a stop or achieved takeoff. If so, the runway takeoff monitor system deactivates in step  618  and the routine ends. 
     The disclosed methods and systems provide a runway takeoff monitor system for an aircraft that enhances safe air travel by augmenting pilot judgment with an objective determination of whether an aircraft is can safely stop on a runway. 
     It will be appreciated that the various illustrative logical blocks/tasks/steps, modules, circuits, and method steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. Some of the embodiments and implementations are described above in terms of functional and/or logical block components or modules and various processing steps. However, it should be appreciated that such block components or modules may be realized by any number of hardware, software, and/or firmware components configured to perform the specified functions. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope as set forth in the claims. 
     For example, an embodiment of a system or a component may employ various integrated circuit components, for example, memory elements, digital signal processing elements, logic elements, look-up tables, or the like, which may carry out a variety of functions under the control of one or more microprocessors or other control devices. In addition, those skilled in the art will appreciate that embodiments described herein are merely exemplary implementations 
     The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. The word exemplary is used exclusively herein to mean serving as an example, instance, or illustration. Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. 
     The steps of a method described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. 
     In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Numerical ordinals such as first, second, third,” etc. simply denote different singles of a plurality and do not imply any order or sequence unless specifically defined by the claim language. The sequence of the text in any of the claims does not imply that process steps must be performed in a temporal or logical order according to such sequence unless it is specifically defined by the language of the claim. The process steps may be interchanged in any order without departing from the scope of the invention as long as such an interchange does not contradict the claim language and is not logically nonsensical. 
     Furthermore, depending on the context, words such as connect or coupled to that are used in describing a relationship between different elements does not imply that a direct physical connection must be made between these elements. For example, two elements may be connected to each other physically, electronically, logically, or in any other manner, through one or more additional elements. 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments.