Abstract:
An electromechanical flight deck door locking system capable of functioning to keep a cockpit door locked in the event of an interruption in electrical power to the system. The flight deck door locking system includes a locking assembly including a locking component and a manually graspable handle for displacing the locking component. Further, the locking system includes an electronic control panel configured to receive data from an individual seeking access to the cockpit and for electrically locking and unlocking the locking assembly. The locking system also includes a mechanical locking assembly, such as a key lock, whereby a user can use a key to lock and unlock the door if electrical power to the system is unavailable.

Description:
FIELD OF THE INVENTION  
       [0001]     This application is a divisional of U.S. patent application Ser. No. 10/255,916 filed on Sep. 26, 2002. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to door locking systems, and more particularly to an aircraft cockpit door locking system that allows the cockpit door to remain locked and functional in the event of a power shortage affecting the electronic components associated with the door locking system.  
       BACKGROUND OF THE INVENTION  
       [0003]     Effectively controlling access to the cockpit of a passenger aircraft helps to control numerous risks associated with unauthorized cockpit entry. Typically, aircraft personnel have controlled access to cockpits through electronic locking mechanisms disposed on or in the cockpit door. Electronic locking systems typically involve solenoid systems comprising an electric solenoid and a keypad, wherein the solenoid automatically locks upon closing the door and unlocks upon a cabin crew member entering an access code with the keypad.  
         [0004]     While the electronic system effectively controls access, some situations could arise where the effectiveness of the system may be compromised. For example, an individual might be able to traverse the security of the electronic system by cutting the power supply conductors to the system, thus de-energizing the solenoid and unlocking the door. This scenario would apply to those systems where power is being supplied to the solenoid to hold it in an engaged, i.e., locked position. Furthermore, an individual might be able to traverse an electronic security system by witnessing a cabin crew member enter an access code, and subsequently re-entering the same access code.  
         [0005]     Thus, it would be desirable to provide an even safer, more secure cockpit door locking system. More specifically, it would be desirable to provide a locking system that eliminates the aforesaid risks of a purely electronic system in the event of a power shortage or unauthorized use of the access code. Furthermore, it would be desirable to have a door locking system that remains locked, yet otherwise operational, in the event of an interruption of power to the components of the door security system.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention is directed to a cockpit door locking system having an electromechanical locking assembly capable of maintaining a door locking mechanism in its locked position in the event of a power shortage. One preferred embodiment of the present invention includes an electronic control panel for controlling the cockpit door locking assembly when supplied with electrical power. The locking assembly is situated in or on the cockpit door and includes a locking component, such as a latch or a dead bolt, that remains locked whether or not the system remains energized. The electronic control panel further controls a user input device adapted to receive an access code from a cabin crew member. The electronic control panel thereafter informs the cockpit crew that a cabin crew member has requested access, and the cockpit crew can choose to grant or deny access. The cockpit door locking system also includes a mechanical key lock assembly that requires engagement by a physical key which can: (1) lock or unlock the locking assembly in the event of a power shortage; and (2) act as a substitute for the security code when power is available for system operation.  
         [0007]     The cockpit door locking mechanism of the present invention therefore provides the benefit of restricting access to the cockpit of an aircraft through the use of a robust electromechanical system. Importantly, the system is capable of maintaining the cockpit door in a locked condition in the event of a power shortage.  
         [0008]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the following detailed description and specific examples discussed herein are only provided to illustrate the invention and should not to be construed as limiting its scope. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0010]      FIG. 1  is an elevation view of a cockpit door including a preferred embodiment of a door locking system in accordance with the present invention as viewed from the cabin of an aircraft;  
         [0011]      FIG. 2  is an elevation view of the cockpit door of  FIG. 1 , including the door locking system of a preferred embodiment of the present invention, as viewed from the cockpit of an aircraft;  
         [0012]      FIG. 3  is a detailed elevation view of the door locking system shown in  FIG. 1 ;  
         [0013]      FIG. 4  is a detailed elevation view of the door locking system shown in  FIG. 2 ;  
         [0014]      FIG. 5  is a sectioned elevation view taken at Section  5  of  FIG. 3  showing the latch and dead bolts and the interconnection between the solenoid and the latch;  
         [0015]      FIG. 6  is a sectioned elevation view taken at Section  6  of  FIG. 3  showing the monitor and the camera lens in the microphone on both sides of the cockpit door;  
         [0016]      FIG. 7A  is a side elevation view taken at Section  7  of  FIG. 4  identifying an L-shaped striker plate having apertures for both a latch and a dead bolt and power contact points for electrical connection between a door jam and the door locking system of the present invention;  
         [0017]      FIG. 7B  is a side elevation view of  FIG. 7A  identifying the power wires connected to each of the power contact points;  
         [0018]      FIG. 7C  is a top plan view of the L-shaped striker plate of  FIG. 7A ;  
         [0019]      FIG. 8A  is an elevation view of a flat striker plate embodiment of the present invention;  
         [0020]      FIG. 8B  is a side elevation view of the flat striker plate of  FIG. 8A  further showing rectangular power contact points and the power wires connected to the contact points;  
         [0021]      FIG. 8C  is a top plan view of the flat striker plate of  FIG. 8A ;  
         [0022]      FIG. 9  is an elevation view of a door access panel of a preferred embodiment of the present invention mounted on an aircraft cockpit panel;  
         [0023]      FIG. 10  is a schematic of the major components for a preferred embodiment of a door locking system of the invention; and  
         [0024]      FIG. 11  is a block diagram identifying the operational steps to operate a door locking system of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]     Referring to  FIGS. 1 and 2 , a cockpit door  10  includes a door locking system (DLS)  12  of the present invention.  FIG. 1  provides a view of the cockpit door  10  looking forward from the cabin area of an aircraft. A main cabin panel  14  replaces the door knob/lock known in the art. A secondary cabin panel  16  is also provided above the main cabin panel  14 .  FIG. 2  provides a view of the cockpit door  10  looking aft from the cockpit spaces showing a main cockpit panel  18  which interconnects through the cockpit door  10  with the main cabin panel  14 . A secondary cockpit panel  20  interconnects through the cockpit door  10  with the secondary cabin panel  16 . A latch  22  (shown in an extended and locked position) extends from the DLS  12  to engage within a suitable recess within a door frame  24 . When extended, the latch  22  provides a positive means to close and/or lock the cockpit door  10 . In a retracted/unlatched position for the latch  22  (shown in phantom in  FIG. 3 ), the cockpit door  10  is free to rotate about a hinge  26 . For the embodiment shown in  FIGS. 1 and 2 , a portion of the main cabin panel  14  overlaps the door frame  24  therefore permitting the cockpit door  10  to open in an aft only direction. By slightly overlapping the main cabin panel  14 , unauthorized access to attempt to displace the latch  22  is prevented.  
         [0026]      FIG. 1  also shows an access panel  31  which is known in the art. The access panel  31  can be used as an overpressure plug which permits equalization of pressure on both sides of the cockpit door  10  in the event of a rapid depressurization. The cockpit door  10  shown is depicted as a left handed door (i.e., hinged on the right in  FIG. 1 ). The DLS  12  can also be used on a right handed door (i.e., hinged on the left).  
         [0027]     Referring now to  FIG. 3 , the portion of the DLS  12  shown in  FIG. 1  is further detailed. The main cabin panel  14  includes an overlap portion  28  which extends beyond the door edge  29  by a panel overlap dimension A. Panel overlap dimension A can be varied depending upon the thickness of the cockpit door  10  and the available access to the latch  22  at the overlap portion  28 .  
         [0028]     A latch handle  30  is shown in its biased latched position. A spring means (not shown) biases the latch handle  30  in the biased latching direction B as shown. A latch handle open position C, shown in phantom, is achieved by manually sliding the latch handle  30  against the tension of the spring means. The latch handle  30  is connected to a latch lever  32  which in turn connects to the latch  22  to displace the latch  22  between its extended position (shown) in its retracted position (shown in phantom). In a preferred embodiment, the latch handle  30  includes a recess between the latch handle  30  and the main cabin panel  14  such that an operator reaches within the recess and therefore within the enclosure of the main cabin panel  14  in order to access the latch handle  30  for manual operation. By providing a recess for the latch handle  30 , the extension of the latch handle  30  above the surface of the main cabin panel  14  is minimized and therefore the ability to damage or dislodge the latch handle  30  is reduced.  
         [0029]     The main cabin panel  14  also includes a key lock assembly  34  having a key slot  36  for insertion of a mechanical key (shown in  FIG. 5 ). The mechanical key when placed in the key slot  36  provides the capability of initiating an unlock procedure of the DLS  12  when power is supplied to the DLS  12  or manually unlocking the DLS  12  when power is unavailable to the system. The key is normally stowed in a secured area in the passenger cabin of an aircraft. An electronic keypad  38  is also shown. The electronic keypad  38  includes a plurality of depressible keys  40  for entering a security code to unlock the DLS  12 . As soon as one of the depressible keys  40  is depressed, an in-process light  42  illuminates, indicating that the system is energized and is ready to accept the access code from the user. If a valid access code is entered using the depressible keys  40 , cockpit personnel have an option to admit or deny admission, which is discussed further herein. An OK-to-access light  44  illuminates if authority to enter is provided. If an improper access code is entered, or by selection of one of the cockpit crew to deny access to the operator, an access denied light  46  illuminates. After entering the predetermined number of digits for the access code, the operator presses an enter/clear button  48  to enter the data into the DLS  12 . An emergency button  50  is also provided for an operator to identify an emergency situation to members of the cockpit crew. The secondary cabin panel  16  provides a microphone  52 , a speaker  54 , and a camera lens  56 . The operator can speak to cockpit crew in the cockpit area by speaking into the microphone  52  and can hear a reply through the speaker  54 . The camera lens  56  provides an image of the operator standing at the cockpit door  10  to personnel in the cockpit area via a monitor shown and described in reference to  FIG. 4 .  
         [0030]     Electrical power is provided to the DLS  12  by a plurality of power contact points  58 . In a preferred embodiment, a power source (discussed in reference to  FIG. 10 ) provides direct current power through two power contact points  58 . The power contact points  58  provide a mechanical/electrical connection between the DLS system  12  and the power source through similar mechanical/electrical connectors provided on the door frame  24  (discussed in reference to  FIGS. 7A through 8B ). The power contact points  58  are preferably deflectable using a spring biasing system such that closure of the cockpit door depresses each of the power contact points  58  and a spring bias ensures electrical contact is maintained when the cockpit door is in a closed position.  
         [0031]     In another preferred embodiment of the present invention, power contact points  60  are used to provide electrical power to the portion of the DLS  12  mounted on the cockpit door  10 . The power contact points  60  are connected to a hinge edge  62  of the cockpit door  10  and the power contact points  60  electrically connect to contact areas on a frame panel  64  of the door frame  24 . Similar to the power contact points  58 , the power contact points  60  are preferably deflectable using a spring biasing mechanism (not shown) to ensure electrical contact.  
         [0032]     Referring to  FIG. 4 , the DLS  12  as viewed from the cockpit side of the cockpit door  10  is further detailed. In another preferred embodiment of the present invention, the main cockpit panel  18  provides a sliding dead bolt  66  actuated by a dead bolt knob  68 . The dead bolt knob  68  slides in the dead bolt slide direction D from a normally open position E to the locked position shown in  FIG. 4  by manual displacement of the dead bolt knob  68 . The dead bolt knob  68  and the dead bolt  66  provide an additional security level for the cockpit door  10  in the event of an emergency situation. The dead bolt knob  68  translates within a slot  70  provided in the main cockpit panel  18  for this purpose. The latch  22  is also shown in its extended and locked position. An access use panel  72  provides visual and audible indication to personnel in the cockpit area of an aircraft of an operator on the cabin side of the cockpit door  10  attempting to enter an access code to open the cockpit door  10 , or using a key to manually open the cockpit door  10 . If an attempt to use a key in the key lock assembly  34  shown in  FIG. 3  is made, a manual key-use light  74  is illuminated. A speaker  76  sounds a chime or similar distinguishable audible signal to cockpit crew of either entry of an access code or manual insertion of a key. A special indicator light  78  illuminates if personnel in the cabin spaces of an aircraft identify a special condition exists in the cabin area. An emergency indicator light  80  illuminates if an operator in the cabin of the aircraft depresses the emergency button  50  on the main cabin panel  14 . Similarly, an electronic key pad indicator  82  is provided on the access use panel  72 . The electronic key pad indicator  82  illuminates when a user enters one or more numbers on the electronic key pad  38  shown in  FIG. 3 .  
         [0033]     The secondary cockpit panel  20  provides a microphone  84 , a speaker  86 , a monitor  88 , and a cabin view button  90 , respectively. The microphone  84  permits cockpit personnel to converse with an operator standing at the cabin side of the cockpit door  10 . The speaker  86  allows cockpit personnel to hear the operator standing at the aft side of the cockpit door  10 . The monitor  88  operates either by manual selection or automatically. The monitor  88  provides a visual image of the operator or the space adjacent to the cabin side of the cockpit door  10  when manually selected by depressing the cabin view button  90 . Personnel in the cockpit spaces can also depress the cabin view button  90  to get a general view of the cabin spaces if no operator is present before unlocking the cockpit door  10  for any other reason. The monitor  88  also automatically operates when either an access code is entered or a key is turned in the key lock assembly  34  on the main cabin panel  14 . The image for the monitor  88  is provided by the camera lens  56  identified in  FIG. 3 . Electrical power for the secondary cockpit panel  20  components is provided from the DLS  12  via wiring disposed in an electrical conduit  92  positioned on the forward facing surface of the cockpit door  10  between the main cockpit panel  18  and the secondary cockpit panel  20 .  
         [0034]     Referring to  FIG. 5 , further details of the DLS  12  are provided in a section view. A protective frame  94  joins the main cabin panel  14  to the main cockpit panel  18  via a plurality of fasteners  96  provided on the cockpit side of the cockpit door  10 . Individual layers of polymer such as Kevlar® ballistic resistant material form protective layers  98 . Within the access use panel  72  is a chime  100 . The audible sounds from the chime  100  are heard in the cockpit spaces of the aircraft via the speaker  76  provided on the access use panel  72  shown in  FIG. 4 . Within the envelope of the cockpit door  10  a solenoid  101  is positioned. The solenoid  101  includes a solenoid shaft  102  which is shown in a fully extended position engaging with a shaft recess  103  of the latch  22 . When the solenoid shaft  102  engages the shaft recess  103 , the latch  22  is mechanically and electrically retained in the fully extended and locked position shown in  FIG. 1 . A key  104  is shown engaging the key lock assembly  34 . By manually rotating the key  104 , a request to enter signal is passed to the DLS  12 . This request to enter signal is similar to the signal generated when a proper access code is entered into the electronic key pad  38 . If no power is available to the DLS  12  when the key  104  is rotated, the key lock assembly  34  acts to disengage the solenoid shaft  102  from the shaft recess  103  thus permitting the latch  22  to be disengaged from its extended and locked position by the latch handle  30 . If power is available to the solenoid  101 , actuation of the key  104  does not dislodge the solenoid shaft  102 ; therefore, action by cockpit personnel is required to authorize entry by providing a permission signal to open the cockpit door  10 .  
         [0035]     The protective frame  94  joins many of the DLS  12  component parts including the main cabin panel  14  to the main cockpit panel  18 . The protective frame  94  also provides physical protection against damage for the electronic components of the DLS  12  by impacting adjacent equipment before the electronic components impact the adjacent equipment. The fasteners  96  are positioned only on the cockpit side of the cockpit door  10  such that removal of the fasteners is only accessible from the cockpit side.  
         [0036]     Referring to  FIG. 6 , a cross section of the cockpit door  10  adjacent to the monitor  88 , the microphone  52 , and the camera lens  56  is shown. The camera lens  56  is disposed in a through aperture such that it optically connects the cabin side of the cockpit door  10  and the forward or cockpit side of the cockpit door  10 . In a preferred embodiment, the monitor  88  includes a diagonal dimension between approximately 15 cm (6 in) to approximately 18 cm (7 inches) such that an image on the monitor  88  is visible to cockpit personnel in their seated positions.  
         [0037]     Referring to  FIGS. 7A, 7B , and  7 C, an exemplary L-shaped striker plate  105  is detailed. The L-shaped striker plate  105  is mechanically attached to the door frame  24  using a plurality of fasteners (not shown) mounted through a plurality of fastener apertures  106 . Latch apertures  108  are provided as clearance openings for the latch  22  and dead bolt  66  (if used). Power contact points  109  are aligned to contact each of the power contact points  58  or power contact points  60  (shown in  FIG. 3 ) to provide electrical power to the DLS  12 . Power wires  110  connect to each of the power contact points  109  and lead to a power source which is described in greater detail in reference to  FIG. 10 .  
         [0038]     Referring to  FIGS. 8A, 8B  and  8 C, another preferred embodiment for a strike plate is shown. A rectangular, flat strike plate  112  is similarly provided with a plurality of fastener apertures  114  to matably accept fasteners to join the flat strike plate  112  to the door frame  24 . Rectangular shaped power contact points  116  are provided with power wires  118  to contact either the power contact points  58  or the power contact points  60  (shown in  FIG. 3 ).  
         [0039]     Referring to  FIG. 9 , a door access panel  120  which is mounted on a cockpit panel  122  is detailed. The cockpit panel  122  can be any one of a plurality of panels available in the cockpit area of an aircraft. The door access panel  120  is positioned for operation by cockpit personnel. The door access panel  120  includes a manual switch  124 . The manual switch  124  is positionable in 3 positions. The manual switch  124  is normally biased into an automatic switch position by a spring mechanism (not shown). In the automatic position shown for the manual switch  124 , when an operator in the cabin attempts to input an access code or turns a key  104  (shown in  FIG. 5 ), an auto switch light  126  illuminates to identify to cockpit personnel that a predetermined time period (approximately 30 seconds) is initiated during which the cockpit personnel can elect to permit opening the cockpit door  10  or deny opening the cockpit door  10 . If the cockpit personnel elect to allow opening the cockpit door  10 , the manual switch  124  is rotated to an unlock position which illuminates an unlock switch light  128  and de-energizes the solenoid  101  (shown in  FIG. 5 ). This permits entry from the cabin area by disengaging the solenoid shaft  102  such that the latch handle  30  is operable. Release of the manual switch  124  returns the manual switch  124  to the automatic position as shown. If cockpit personnel elect to deny access into the cockpit, the manual switch  124  is rotated to a deny position and a deny switch light  130  is illuminated. In the deny position, electrical power to the solenoid  101  is maintained and the cockpit door  10  remains in a locked position. An auto unlock light  132  is illuminated any time that an operator attempts to open the cockpit door  10 . A lock fail light  134  is illuminated when power to the solenoid  101  and the DLS  12  is unavailable.  
         [0040]     Turning now to the operation of the DLS  12 , immediately subsequent to the cockpit door  10  closing, the latch handle  30  is spring biased to a closed position (shown in  FIG. 1 ) and the DLS  12  automatically provides power to the solenoid  101  to engage the latch  22  by displacing the solenoid shaft  102  into the shaft recess  103 . This position for the solenoid shaft  102  causes the latch  22  to be retained in a locked position (as shown in  FIG. 1 ). In this position, the latch  22  is not affected by either a power loss or temporary interruption to the DLS  12 , and remains in the locked position during a power loss to the solenoid  101 . At any time a user, such as a cabin crew member, can enter an access code into the electronic key pad  38 . The electronic key pad  38  is actuated by depressing each of a plurality of depressible keys  40  in appropriate sequence indicating a proper access code followed by pressing the enter/clear button  48 . The number of digits in a valid access code can vary and is preferably in a range between 4 to 6 numbers. It should be appreciated that any type of electronic input device could be implemented in lieu of a keypad and the present invention is therefore not limited to only the use of the electronic key pad  38  as an input device. Any form of personnel identification means (e.g., magnetic card, fingerprint identification, etc.) or a remote transmission device (not shown) can also be used to input the access code.  
         [0041]     Referring to  FIG. 10 , power to the DLS  12  is provided by a 28 volt DC power source  140  associated with the aircraft. The power wires  110  connect the 28 volt DC power source  140  to the power contact points  58 . As evident from  FIG. 10 , if the cockpit door  10  is in an open position and the power contact points  58  do not contact with their associated power contact points  109  (shown in  FIG. 7B ) or do not contact with the power contact points  116  shown in  FIG. 8B , power from the 28 volt DC power source  140  is disconnected from the DLS  12 . From the power contact points  58 , 28 volt DC power is provided to an electronic access system module (EASM)  142 . The EASM contains a stored version of the access code in a memory unit  144  of the EASM  142 . When an access code is entered by a user, the EASM  142  compares the entered access code to the access code stored in the memory unit  144  and identifies if a match exists. If a match exists, power is transferred along a power line  146  to the EASM and is distributed along one of a plurality of power lines  148  to individual components of the DLS  12 . As shown in  FIG. 10 , the individual components of the DLS  12  include the manual switch  124 , the monitor  88 , the camera lens  56 , the microphone  52 , the microphone  84 , the solenoid  101 , the key lock assembly  34 , and the electronic key pad  38 . The EASM  142  provides power to the solenoid  101  to withdraw the solenoid shaft  102  from its extended position preventing opening of the cockpit door  10  as discussed in reference to  FIG. 5 . Each of the connected components of the DLS  12  are connected to a second side of the 28 volt DC power source  140  by power lines  150 .  
         [0042]     In the event of a power shortage, a cabin crew member may still gain access to the cockpit area via the key lock assembly  34 . The key lock assembly  34  provides the ability to manually actuate the solenoid shaft  102  to displace the solenoid shaft  102  from its contact position with the latch  22 .  
         [0043]     Referring to  FIG. 11 , the operational steps to use the DLS  12  are described. At a step  160 , an operator on the cabin side of the cockpit door enters an access code into the electronic keyboard. When the access code is entered and the enter/clear button is depressed, several events occur simultaneously. The in-process light on the electronic keyboard illuminates after the enter/clear button is depressed. The electronic keypad indicator on the cockpit side of the cockpit door illuminates to indicate that an entry has been made into the electronic key pad. A chime sounds in the cockpit area via the speaker  76  in the access use panel and a 30 second operational period begins to count down automatically. At a step  162 , when the access code is entered into the electronic key pad, the EASM energizes the monitor and the monitor depicts on its screen the image taken through the camera lens of the area immediately adjacent to the cockpit door. At a step  164  the EASM compares the entered code to the preset code in its memory unit to identify if a match exists. If a match exists, at a step  166  the auto unlock light is illuminated on the door access panel attached to the cockpit panel.  
         [0044]     As further described in  FIG. 11 , at a step  168 , the cockpit personnel have a predetermined amount of time (approximately 30 seconds) to elect to unlock the cockpit door or deny access to the cockpit. During this period of time the personnel in the cockpit can rotate the manual switch on the door access panel to the unlock position, or they can choose to rotate the manual switch to the deny position on the door access panel. At a step  170 , if the unlock position of the manual switch is selected, the OK-to-access light illuminates on the electronic key pad. At a parallel step  172 , if the manual switch is not rotated to either the unlock or the deny positions for the period of 30 seconds, the EASM after 30 seconds automatically repositions the solenoid to permit opening of the cockpit door and the OK-to-access light illuminates on the electronic key pad. At an opening step  174 , after the OK-to-access light is illuminated on the electronic keypad, an operator on the cabin side manually slides the latch handle to unlock and open the cockpit door.  
         [0045]     At a step  176 , which parallels the step  166 , the EASM determines that no match exists to the entered access code. At a step  178 , which parallels the step  168 , the deny position for the manual switch  124  is selected. At a step  180 , which follows either the step  176  or the step  178 , the access denied light  46  is illuminated on the main cabin panel  14 , the solenoid  101  position is unchanged and the cockpit door  10  cannot be opened.  
         [0046]     An alternate method to open the cockpit door  10  provides that the key  104  can be inserted into the key lock assembly  34  and turned. When the key  104  is turned it provides a similar electronic signal to that sent when an operator enters an access code into the electronic key pad  38 . Cockpit personnel have the option of unlocking the cockpit door  10  or to deny opening the cockpit door  10  using the manual switch  124  as described above. The chime  100  also sounds in the cockpit area when the key  104  is rotated in the key lock assembly  34 , therefore audibly identifying that an attempt is being made to open the cockpit door  10 . The manual key use light  74  illuminates on the access use panel  72  when the key  104  is rotated.  
         [0047]     If cockpit personnel elect to deny access into the cockpit area and rotate the manual switch  124  on the door access panel  120  to the deny position, the access denied light  46  on the electronic key pad  38  illuminates indicating to the user that the cockpit door  10  cannot be opened using the latch handle  30 . If cockpit personnel are incapacitated and the manual switch  124  is in the normal automatic position, a 30 second wait period applies after entry of a valid access code or operation of the key  104  before the operator receives the OK to access light  44  signal to open the cockpit door  10 .  
         [0048]     At any time during operation of the aircraft when cockpit personnel need to open the cockpit door  10 , a visual inspection of the cabin via the monitor  88  is obtainable by depressing the cabin view button  90  on the secondary cockpit panel  20 . Depressing the cabin view button  90  displays a view of the cabin area immediately adjacent to the cockpit door  10 . This enables cockpit personnel to identify if an unsafe condition exists prior to opening the cockpit door  10 . At any time when cockpit personnel identify that an emergency situation exists on the cabin side of the cockpit door, the dead bolt  66  can be manually positioned to lock the cockpit door  10 . The dead bolt  66  is not controlled by the solenoid  101  and therefore the cockpit door  10  cannot be opened with the dead bolt  66  in its extended, (i.e., locked) position. The dead bolt  66  is an optional feature since it overrides the electrical features of the door locking system  12  of the present invention. Cockpit personnel can open the cockpit door  10  by positioning the manual switch  124  to the unlock position and operating the latch handle  30  on the main cockpit panel  18 . If power is unavailable to the DLS  12 , personnel in the cockpit (i.e., flight crew or maintenance personnel) can operate the latch handle  30  which from the cockpit side overrides the solenoid  101 .  
         [0049]     In another preferred embodiment of the present invention, Specific time periods are used for DLS  12  operation. If a cabin crew member enters a valid access code and the cockpit personnel take no action to reposition the manual switch  124  for a first fixed period of time (in a preferred embodiment, approximately 30 seconds), the EASM  142  repositions the solenoid shaft  102  automatically after the first fixed period of time. Subsequent to the first fixed period of time, a user can manipulate the latch handle  30  to displace the latch  22  for a second fixed period of time (in a preferred embodiment, approximately 30 seconds). If the user fails to displace the latch handle  30  within the second fixed period of time, the EASM  142  automatically returns the solenoid shaft  102  to its engaged position with the latch  22 , preventing opening of the cockpit door  10 . The first and second fixed periods of time are described herein as approximately 30 seconds; however any period of time can be selected by the aircraft designer or the aircraft operators.  
         [0050]     The electromechanical architecture of the DLS  12  of the present invention provides numerous advantages over prior systems. First, the architecture provides graphical identification that a user seeks access to the cockpit area, thereafter enabling cockpit personnel to grant access, deny access, or allow the DLS  12  to continue in an automatic mode. The architecture also provides the advantage of maintaining the cockpit door in its locked position in the event of a power shortage. The DLS  12  further includes a mechanical key mechanism to lock and unlock the cockpit door in the event of a power shortage or if the access code is unavailable to an operator on the cabin side of the cockpit door. The DLS  12  of the present invention further advantageously provides that electrical power for the system is provided through contacts at the cockpit door such that system power is disconnected when the door is in an open position and is connected while the cockpit door is in its closed and/or locked position. The use of power contact points between the door structure and the door locking system  12  of the present invention eliminates the need for flexible wiring or a more complex system of providing electrical power to the door locking system  12  of the present invention.