Field of the Invention This invention relates to a security system and especially, but not exclusively, to such a system for use in the aerospace industry.

Background to the Invention In airplanes, it has become crucial, for safety reasons, that the flight deck is secured to prevent entry of unauthorised personnel and also to protect the flight crew from danger from, for example, bullet or knife attack.

Previously a flight deck door has been the only barrier between the flight deck and the cabin.

Traditionally flight deck doors are constructed from lightweight materials such as plastics and are generally hollow in construction to allow for bulging caused by depressurization. Consequently, the flight deck doors do not form a secure barrier against attack from weapons such as knives or bullets, or from other forces, such as a blow from a foot.

Flight deck doors generally have simple locking mechanisms which may be accessible from outside the flight deck and consequently could be

broken or picked with relative ease by an unauthorised person trying to gain access to the flight deck.

The object of the invention is to provide a security system which is inoperable from outside the flight deck and therefore substantially reduces the ability of an unauthorised person to enter the flight deck or attack the flight crew through the flight deck door, whilst also securing the flight deck against attack with bladed weapons, such as, knives, axes and the like, as well as against low to medium velocity bullets and other projectiles.

Accordingly, the invention provides a security system comprising a ballistic screen (as herein defined) which is movable reciprocably between respective open and closed positions across an opening (as herein defined) to permit or prevent access therethrough and securing means which is associated with the ballistic screen, which is engagable with complementary securing means associated with one side of the opening and which, when so engaged, secures the screen in its closed position across the opening and is inaccessible from the other side of the opening.

As used herein the term"ballistic screen" refers particularly but not exclusively to any rigid, semi-rigid or flexible curtain, panel, door or any suitable covering for an opening, which is constructed from a material which has anti-ballistic

properties, for example, KEVLARO. The anti-ballistic properties of the screen, renders a protective barrier which is relatively impervious to bladed weapons such as knives or axes, as well as against any low to medium velocity bullets and other projectiles.

As used herein, the term"opening"refers particularly but not exclusively to any aperture of a vehicle, airplane, building or the like, which is openable to provide access therethrough, examples of such openings being a, window, door, vent, gate and sunroof.

Preferably, the ballistic screen comprises a ballistic shielding material, such as that sold under the Registered Trade Mark"KEVLAR", with, optionally, a durable cover comprising a suitable material, such as a plastics material.

The ballistic screen may be mounted to the area, such as a wall, surrounding the opening.

Alternatively, the screen may be mounted to an openable closure, such as a door, for the opening.

Also, the ballistic screen may be rigid, semi-rigid or flexible and may be slidingly or pivotally, for example hingedly, movable between its open and closed positions across the openings.

Also and in a preferred embodiment to be described hereinbelow, the ballistic screen comprises a KEVLAR@ curtain which may be contained

along three of its edges, namely the leading or free, top and bottom edges thereof, within a hard plastics, aluminium, composite or other suitable material border. In this embodiment, the border is mounted to the corresponding edge regions of a closure, namely a door, for the opening, such that the screen is movable with the door.

In one embodiment, a zone on the top and bottom edges of the curtain nearest the hinged edge of the closure for the opening is not contained within the border, thereby allowing the curtain to partially flex and to gather if drawn back into, say, its open position.

Also, the curtain or other ballistic screen, when mounted to the closure for the opening along its top and bottom edges, may be so-mounted by means of channels which are mounted on the top and bottom of the closure and along which any associated borders can slide, with the back edge of the screen being fixed directly to the closure or the area surrounding the opening by a strip or other suitable fixing.

In one embodiment, the channels which are mounted on the top and bottom edges of the door, are T-shaped in cross-section, such that an associated T-shaped curtain border can be slid through the channel, thus ensuring the curtain is secure against any attempted forced detachment.

The securing means associated with the ballistic screen, when engaged with the complementary securing means on one side of the opening, ensures that the screen can be locked securely in place in its closed position, rendering it immovable and thus inoperable from the other side of the opening. The leading edge of the screen may be arranged to slide past the corresponding edge of the closure for the opening, into its closed position.

Preferably, where the securing means is associated with the leading edge of the screen, a lock and a channel, into which the leading edge of the screen can be slid, on or in an outer frame of the opening, is positioned beyond the edge of the closure, such that it is inaccessible from the other side of the opening.

Also, when the closure for the opening is to be opened, the complementary securing means can be disengaged on the one side of the opening and the leading edge of the screen slid back towards the hinged edge of the closure.

The invention is particularly, but not exclusively, relevant to the doors of flight decks, as will be evident from the following description of the preferred embodiments.

Also, this invention could be coupled with a security camera to allow the area outside, say, a

fight deck to be viewed, thereby further monitoring who is allowed access to the flight deck, thereby increasing security In order that the invention may be more fully understood, preferred embodiments of a flight deck security system in accordance therewith, will now be described by way of example only and with reference to the accompanying drawings.

Brief Description of Drawings Fig. 1 is an elevational view of one embodiment of a ballistic screen for a flight deck security system; Fig. 2 is a section of the top edge of the ballistic screen shown in Fig. 1 associated with a door opening ; Fig. 3 is an elevational view of the ballistic screen shown in Figs. 1 and 2 in its open position; Fig. 4A and 4B are sections of a part of another embodiment of a ballistic screen; Fig. 5 is a plan view of the leading edge of the screen shown in Figs 1 to 4 in its closed position; and

Fig. 6 is an elevational view showing the ballistic screen of Figs. 1 to 5 locked in its closed position.

Detailed description of the preferred embodiments As shown in Figure 1, a ballistic screen for a flight deck security system comprises a flexible curtain 1 in which a sheet of ballistic shielding material, such as KEVLARO, is contained within a durable plastics cover (not shown).

The flexible KEVLARO curtain 1 is slidingly mountable to a flight deck door, forming a ballistic screen within a flight deck which is resistant to, or substantially resistant to, attack from bladed objects such as knives as well as any low to medium velocity bullets or other projectiles The curtain 1 is contained along three of its edges, namely the leading or free, top and bottom edges 5,3, 4 thereof, within a hard plastics, aluminium, composite or other suitable material border 2, 2', 2", which acts. to stiffen the edges 5,3, 4 of the flexible curtain 1.

In this embodiment, the.. border 2 is mountable to the corresponding edge regions of a flight deck door (not shown), such that the curtain 1 is movable with the flight deck door.

A zone 6 of the curtain 1 along each of the top and bottom edges 3,4, nearest the hinged edge 7 of a flight deck door, is not contained within the border 2. Each zone 6 allows the curtain 1 to partially flex enabling the curtain 1 to gather if drawn back into. its open position.

Figure 2 shows the curtain 1 mounted at its top edge 3 to a flight deck door 14. The top and bottom borders 2', 2" of the curtain 1 are mounted to the flight deck door 14 by containment within channels 9 (only top one shown) which are themselves mounted to the top and bottom edges of the flight deck door 14.

Figure 3 shows the back edge of the curtain 1 which is fixed directly to the hinged edge 7 of the flight deck door or the flight deck door frame (not shown) by means of a strip 8 and fixings 13 which are all formed from a composite material or aluminium, conversant with aviation regulations. The channels 9 in which the top and bottom borders 2', 2" of the curtain 1 are mounted, are approximately equal in length to the length of the borders 2'2"which contain the top and bottom edges 3,4 of the curtain 1. The zones 6 at the top and bottom of the flight deck door 14 nearest the hinged edge 7 thereof have no channel, thus ensuring that the curtain 1 can be gathered in folds when slid into its open position, as shown.

Figures 4A and 4B show another embodiment of security system wherein channels 19 which are

mounted to the top and bottom edges of the flight deck door 14, are T-shaped in cross-section, such that an associated T-shaped curtain border 22 is slidable along the channel 19, thus ensuring that the curtain 1 is secure against any attempted, forced, detachment therefrom.

Figure 5 shows the leading edge 5 of the curtain 1 which is provided with the handle 17 enabling it to be slid past the corresponding edge 16 of the fight deck door 14, into its closed position, when desired. Securing means, indicated diagrammatically at 18, is associated with the border 2 and the leading edge 5 of the curtain 1, such that the curtain 1, when slid into its closed position, will engage complementary securing means, indicated diagrammatically at 20, positioned within a vertical channel 11 on or in the door frame on one side thereof and inside a flight deck. The curtain 1, once in its closed position, is locked securely in place, rendering it immovable and thus inoperable from the other side of the flight deck door 14.

Figure 6 shows the extent 16 of an existing flight deck door 14 in relation to the open edge of an associated vertical channel 11 which is of sufficient depth to ensure that the leading edge 5 of the curtain 1, once slid into place, is positioned beyond the edge 16 of the flight deck door 14, such that it is inaccessible from outside the flight deck. The securing means 18 associated with the leading edge 5 of the curtain 1 is locked

into place with the complementary securing means 20 in the vertical channel 11.

In this embodiment, the invention can be coupled with a security camera which would allow the pilots to view who was behind a flight deck door prior to it being unlocked and opened.

To open the flight deck door 14, the complementary securing means 18,20 are released and the leading edge 5 is slid from the vertical channel 11 towards the hinged end 7 of the flight deck door 14. The zone 6 of curtain 1 with no border enables the curtain 1 to be drawn back and gathered 12, as shown on Figure 3, as the curtain 1 slides from the horizontal channel 11 and along the top and bottom channels 9. The curtain 1 is slid back at least in line with the leading edge 16 of the flight deck door 14 which is now openable.