U.S. patent application number 11/111957 was filed with the patent office on 2005-09-15 for aircraft boundary transition warnings and auto alerting.
Invention is credited to Smith, Alexander E..
Application Number | 20050200501 11/111957 |
Document ID | / |
Family ID | 33568802 |
Filed Date | 2005-09-15 |
United States Patent
Application |
20050200501 |
Kind Code |
A1 |
Smith, Alexander E. |
September 15, 2005 |
Aircraft boundary transition warnings and auto alerting
Abstract
In combination with a Geographic Information System (GIS),
3-dimensional shapes may be used to designate or identify blocks of
airspace. These shapes may be defined in many ways including
lat/long, local coordinates, or FAA transmitted directions for TFRs
and ADIZs. These restricted areas and zones may be modeled using
suitably modified AirScene.TM. software from Rannoch Corporation.
AirScene.TM. software can locate various aircraft in the vicinity
of restricted airspace, determine whether the aircraft is about to
enter restricted airspace, and issue a warning to the pilot of such
aircraft that restricted airspace is about to be violated. Such a
warning can be audible (e.g., radio communication message) or
visual (e.g., graphic display or even a flashing light or text
message) and is much less distracting than having a laser shining
in the cockpit. Since the AirScene.TM. system is ground-based,
ground personnel can also be advised if restricted airspace is
being violated, or even about to be violated.
Inventors: |
Smith, Alexander E.;
(McLean, VA) |
Correspondence
Address: |
Robert Platt Bell
Registered Patent Attorney
8033 Washington Road
Alexandria
VA
22308
US
|
Family ID: |
33568802 |
Appl. No.: |
11/111957 |
Filed: |
April 22, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11111957 |
Apr 22, 2005 |
|
|
|
10457439 |
Jun 10, 2003 |
|
|
|
6885340 |
|
|
|
|
11111957 |
Apr 22, 2005 |
|
|
|
09971672 |
Oct 9, 2001 |
|
|
|
6567043 |
|
|
|
|
09971672 |
Oct 9, 2001 |
|
|
|
09516215 |
Feb 29, 2000 |
|
|
|
6633259 |
|
|
|
|
10457439 |
|
|
|
|
10319725 |
Dec 16, 2002 |
|
|
|
6812890 |
|
|
|
|
11111957 |
Apr 22, 2005 |
|
|
|
10743042 |
Dec 23, 2003 |
|
|
|
10743042 |
Dec 23, 2003 |
|
|
|
10638524 |
Aug 12, 2003 |
|
|
|
6806829 |
|
|
|
|
10638524 |
Aug 12, 2003 |
|
|
|
09516215 |
Feb 29, 2000 |
|
|
|
6633259 |
|
|
|
|
10743042 |
|
|
|
|
10319725 |
Dec 16, 2002 |
|
|
|
6812890 |
|
|
|
|
11111957 |
Apr 22, 2005 |
|
|
|
11031457 |
Jan 7, 2005 |
|
|
|
11031457 |
Jan 7, 2005 |
|
|
|
10638524 |
Aug 12, 2003 |
|
|
|
6806829 |
|
|
|
|
10638524 |
Aug 12, 2003 |
|
|
|
09516215 |
Feb 29, 2000 |
|
|
|
6633259 |
|
|
|
|
11031457 |
|
|
|
|
10319725 |
Dec 16, 2002 |
|
|
|
6812890 |
|
|
|
|
11111957 |
Apr 22, 2005 |
|
|
|
10756799 |
Jan 14, 2004 |
|
|
|
10756799 |
Jan 14, 2004 |
|
|
|
10638524 |
Aug 12, 2003 |
|
|
|
6806829 |
|
|
|
|
10638524 |
Aug 12, 2003 |
|
|
|
09516215 |
Feb 29, 2000 |
|
|
|
6633259 |
|
|
|
|
10756799 |
|
|
|
|
10319725 |
Dec 16, 2002 |
|
|
|
6812890 |
|
|
|
|
10756799 |
|
|
|
|
10751118 |
Jan 5, 2004 |
|
|
|
10756799 |
|
|
|
|
10743012 |
Dec 22, 2003 |
|
|
|
PP15865 |
|
|
|
|
10756799 |
|
|
|
|
10457439 |
Jun 10, 2003 |
|
|
|
6885340 |
|
|
|
|
11111957 |
Apr 22, 2005 |
|
|
|
10830444 |
Apr 23, 2004 |
|
|
|
10830444 |
Apr 23, 2004 |
|
|
|
10457439 |
Jun 10, 2003 |
|
|
|
6885340 |
|
|
|
|
10830444 |
Apr 23, 2004 |
|
|
|
09516215 |
Feb 29, 2000 |
|
|
|
6633259 |
|
|
|
|
10830444 |
Apr 23, 2004 |
|
|
|
10319725 |
Dec 16, 2002 |
|
|
|
6812890 |
|
|
|
|
60440618 |
Jan 17, 2003 |
|
|
|
60123170 |
Mar 5, 1999 |
|
|
|
60440618 |
Jan 17, 2003 |
|
|
|
60123170 |
Mar 5, 1999 |
|
|
|
60123170 |
Mar 5, 1999 |
|
|
|
60343237 |
Dec 31, 2001 |
|
|
|
60440618 |
Jan 17, 2003 |
|
|
|
60534706 |
Jan 8, 2004 |
|
|
|
Current U.S.
Class: |
340/963 ;
340/981; 340/988; 701/300 |
Current CPC
Class: |
G01S 5/0284 20130101;
G01S 13/781 20130101; G08G 5/0082 20130101; G08G 5/006 20130101;
G01S 13/86 20130101; G08G 5/0013 20130101; G01S 5/06 20130101 |
Class at
Publication: |
340/963 ;
340/981; 340/988; 701/300 |
International
Class: |
G08B 023/00 |
Claims
I claim:
1. A method of providing information indicating the relative
proximity of an aircraft to restricted airspace, comprising the
steps of: determining position of the aircraft, determining
boundaries of restricted airspace local to the aircraft position,
generating at least one aircraft alert zone representing a region
surrounding the aircraft, determining whether the aircraft alert
zone intersects boundaries of the restricted airspace, and
indicating whether an aircraft alert zone has intersected
boundaries of the restricted airspace.
2. The method of claim 1, wherein the step of determining position
of the aircraft comprises the steps of: receiving radio signals
from the aircraft at a plurality of receiver sites, time-stamping
the radio signals when received at the receiver sites, and
determining aircraft position through multilateration of the
time-stamped radio signals from the receiver sites.
3. The method of claim 1, wherein the step of determining position
of the aircraft comprises the steps of: receiving altimeter data
from the aircraft radio signals, and correlating the altimeter data
from the aircraft radio signals with aircraft position determined
through multilateration.
4. The method of claim 1, wherein the step of determining position
of the aircraft comprises the steps of: receiving radar data from
an air traffic control system indicating aircraft position, and
correlating the aircraft position data from the air traffic control
system with aircraft position determined through
multilateration.
5. The method of claim 1, wherein the step of determining
boundaries of restricted airspace local to the aircraft position
further comprises the steps of: receiving restricted airspace data
from a restricted airspace database, and converting the restricted
airspace data into a three-dimensional model of restricted airspace
for a given region of interest.
6. The method of claim 5, therein the restricted airspace data
comprises at least one of Temporary Flight Restrictions (TFR) and
Air Defense Identification Zones (ADIZ) data.
7. The method of claim 5, wherein the step of generating at least
one aircraft alert zone representing a region surrounding the
aircraft further comprises the step of: generating at least one
alert zone surrounding the aircraft so as to provide one or more
warning levels of impending intersection with a restricted
airspace.
8. The method of claim 7, wherein the at least one aircraft alert
zone corresponds to the aircraft position so as to indicate when
the aircraft has entered restricted airspace.
9. The method of claim 7, wherein the step of determining whether
the at least one aircraft alert zones intersects boundaries of the
restricted airspace further comprises the steps of: generating a
three-dimensional model of the at least one aircraft alert zones,
and comparing the three-dimensional model of the at least one
aircraft alert zones with the three-dimensional model of restricted
airspace to determine whether any of the at least one aircraft
alert zones intersect any portion of the restricted airspace.
10. The method of claim 9, wherein the step of indicating whether
any of the at least one aircraft alert zones has intersected
boundaries of the restricted airspace further comprises the step
of: generating an alarm indicating that an aircraft alert zone has
intersected the restricted airspace.
11. The method of claim 9, wherein the step of indicating whether
an aircraft alert zone has intersected boundaries of the restricted
airspace further comprises the step of: generating a visual display
showing an aircraft alert zone and boundaries of the restricted
airspace.
12. The method of claim 9, wherein the step of indicating whether
an aircraft alert zone has intersected boundaries of the restricted
airspace further comprises the step of: displaying on an in-cockpit
display, position of the aircraft relative to boundaries of
restricted airspace.
13. A system of providing information means for indicating the
relative proximity of an aircraft to restricted airspace,
comprising: means for determining position of the aircraft, means
for determining boundaries of restricted airspace local to the
aircraft position, means for generating at least one aircraft alert
zone representing a region surrounding the aircraft, means for
determining whether the aircraft alert zone intersects boundaries
of the restricted airspace, and means for indicating whether an
aircraft alert zone has intersected boundaries of the restricted
airspace.
14. The system of claim 13, wherein means for determining position
of the aircraft comprises: a plurality of receiver sites for
receiving radio signals from the aircraft, means for time-stamping
the radio signals when received at the receiver sites, and a
processor for determining aircraft position through multilateration
of the time-stamped radio signals from the receiver sites.
15. The system of claim 13, wherein means for determining position
of the aircraft comprises: a receiver for receiving altimeter data
from the aircraft radio signals, and a processor for correlating
the altimeter data from the aircraft radio signals with aircraft
position determined through multilateration.
16. The system of claim 13, wherein means for determining position
of the aircraft comprises: an air traffic control system for
indicating aircraft position, and a processor for correlating the
aircraft position data from the air traffic control system with
aircraft position determined through multilateration.
17. The system of claim 13, wherein means for determining
boundaries of restricted airspace local to the aircraft position
further comprises: a restricted airspace database for providing
restricted airspace data, and a processor for converting the
restricted airspace data into a three-dimensional model of
restricted airspace for a given region of interest.
18. The system of claim 17, therein the restricted airspace data
comprises at least one of Temporary Flight Restrictions (TFR) and
Air Defense Identification Zones (ADIZ) data.
19. The system of claim 17, wherein means for generating at least
one aircraft alert zone representing a region surrounding the
aircraft further comprises: a processor for generating at least one
alert zone surrounding the aircraft so as to provide one or more
warning levels of impending intersection with a restricted
airspace.
20. The system of claim 19, wherein the at least one aircraft alert
zone corresponds to the aircraft position so as to indicate when
the aircraft has entered restricted airspace.
21. The system of claim 19, wherein means for determining whether
the at least one aircraft alert zones intersects boundaries of the
restricted airspace further comprises: a processor for generating a
three-dimensional model of the at least one aircraft alert zones,
and a processor for comparing the three-dimensional model of the at
least one aircraft alert zones with the three-dimensional model of
restricted airspace to determine whether any of the at least one
aircraft alert zones intersect any portion of the restricted
airspace.
22. The system of claim 21, wherein means for indicating whether
any of the at least one aircraft alert zones has intersected
boundaries of the restricted airspace further comprises: an alarm
for indicating that an aircraft alert zone has intersected the
restricted airspace.
23. The system of claim 21, wherein means for indicating whether an
aircraft alert zone has intersected boundaries of the restricted
airspace further comprises: a visual display showing an aircraft
alert zone and boundaries of the restricted airspace.
24. The system of claim 21, wherein means for indicating whether an
aircraft alert zone has intersected boundaries of the restricted
airspace further comprises: an in-cockpit display for displaying
position of the aircraft relative to boundaries of restricted
airspace.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a Continuation-In-Part
application of U.S. patent application Ser. No. 10/457,439, filed
on Jun. 10, 2003, (RANN-0013) now U.S. Pat. No. 6,885,340 and
incorporated herein by reference in its entirety; U.S. patent
application Ser. No. 10/457,439 in turn is a Continuation-In-Part
application of U.S. patent application Ser. No. 09/971,672, filed
on Oct. 9, 2001, (RANN-0009) entitled "METHOD AND APPARATUS FOR
IMPROVING THE UTILITY OF AUTOMATIC DEPENDENT SURVEILLANCE", now
U.S. Pat. No. 6,567,043 which in turn is a Divisional Application
of Ser. No. 09/516,215, filed Mar. 5, 1999, (RANN-0005) entitled
"METHOD AND APPARATUS FOR IMPROVING THE UTILITY OF AUTOMATIC
DEPENDENT SURVEILLANCE", now U.S. Pat. No. 6,633,259, all of which
are incorporated herein by reference in their entirety; U.S. patent
application Ser. No. 10/457,439 is also a Continuation-In-Part of
U.S. patent application Ser. No. 10/319,725, filed Dec. 16, 2002,
(RANN-0011) entitled "VOICE RECOGNITION LANDING FEE BILLING
SYSTEM", now U.S. Pat. No. 6,812,890, and incorporated herein by
reference in its entirety; U.S. patent application Ser. No.
10/457,439 also claims priority from Provisional U.S. Patent
Application No. 60/440,618, filed Jan. 17, 2003, (RANN-0012)
incorporated herein by reference in its entirety;
[0002] The present application is a also Continuation-In-Part
application of U.S. patent application Ser. No. 10/743,042, filed
on Dec. 23, 2003, (RANN-0015) and incorporated herein by reference;
U.S. patent application Ser. No. 10/742,042 in turn is a
Continuation-In-Part application of U.S. patent application Ser.
No. 10/638,524, filed Aug. 12, 2003, (RANN-0014), entitled "METHOD
AND APPARATUS FOR IMPROVING THE UTILITY OF AUTOMATIC DEPENDENT
SURVEILLANCE", now U.S. Pat. No. 6,806,829, which is incorporated
herein by reference in its entirety, which in turn is a
Continuation of U.S. patent application Ser. No. 09/516,215, filed
on Feb. 29, 2000, (RANN-0005) which in turn claims priority from
Provisional Application Ser. No. 60/123,170, filed Mar. 5, 1999,
(RANN-0005) both of which are incorporated herein by reference in
its entirety; U.S. application Ser. No. 10/743,042 is also a
Continuation-In-Part of U.S. patent application Ser. No.
10/319,725, filed Dec. 16, 2002, (RANN-0011), entitled "VOICE
RECOGNITION LANDING FEE BILLING SYSTEM", Now U.S. Pat. No.
6,812,890, incorporated herein by reference in its entirety; U.S.
application Ser. No. 10/743,042 is also Continuation-In-Part of
U.S. patent application Ser. No. 10/457,439, filed Jun. 10, 2003,
(RANN-0013) entitled "Correlation of Flight Track Data with Other
Data Sources", incorporated herein by reference in its entirety;
U.S. application Ser. No. 10/743,042 also claims priority from
Provisional U.S. Patent Application No. 60/440,618, filed Jan. 17,
2003, (RANN-0012) incorporated herein by reference in its
entirety;
[0003] The present application is also a Continuation-In-Part
application of U.S. patent application Ser. No. 11/031,457, filed
on Jan. 7, 2005, (RANN-0016) and incorporated herein by reference,
which in turn is a Continuation-In-Part application of U.S. patent
application Ser. No. 10/638,524, filed Aug. 12, 2003, (RANN-0014)
entitled "METHOD AND APPARATUS FOR IMPROVING THE UTILITY OF
AUTOMATIC DEPENDENT SURVEILLANCE", now U.S. Pat. No. 6,806,829,
which is incorporated herein by reference in its entirety, which in
turn is a Continuation of U.S. patent application Ser. No.
09/516,215, filed on Feb. 29, 2000 (RANN-0005) now U.S. Pat. No.
6,633,259, which in turn claims priority from Provisional
Application Ser. No. 60/123,170, filed Mar. 5, 1999, all of which
are incorporated herein by reference in its entirety; application
Ser. No. 11/031,457 is also a Continuation-In-Part of U.S. patent
application Ser. No. 10/319,725, filed Dec. 16, 2002, (RANN-0011)
entitled "VOICE RECOGNITION LANDING FEE BILLING SYSTEM", now U.S.
Pat. No. 6,812,890, incorporated herein by reference in its
entirety; application Ser. No. 11/031,457 is also a
Continuation-In-Part of U.S. patent application Ser. No.
10/457,439, filed Jun. 10, 2003 (RANN-0013) entitled "Correlation
of Flight Track Data with Other Data Source", incorporated herein
by reference in its entirety; application Ser. No. 11/031,457 also
claims priority from Provisional U.S. Patent Application Ser. No.
60/440,618, filed Jan. 17, 2003, (RANN-0012) incorporated herein by
reference in its entirety;
[0004] The present application is also a Continuation-In-Part
application of U.S. patent application Ser. No. 10/756,799 filed
Jan. 14, 2004, (RANN-0017) and incorporated herein by reference;
Application Ser. No. 10/756,799 is a Continuation-In-Part
application of U.S. patent application Ser. No. 10/638,524, filed
Aug. 12, 2003, (RANN-0014) entitled "METHOD AND APPARATUS FOR
IMPROVING THE UTILITY OF AUTOMATIC DEPENDENT SURVEILLANCE", which
is incorporated herein by reference in its entirety, which in turn
is a Continuation of U.S. patent application Ser. No. 09/516,215,
filed on Feb. 29, 2000, (RANN-0005) which in turn claims priority
from Provisional Application Ser. No. 60/123,170, filed Mar. 5,
1999, (RANN-0005) both of which are incorporated herein by
reference in their entirety; application Ser. No. 10/756,799 is
also a Continuation-In-Part of U.S. patent application Ser. No.
10/319,725, filed Dec. 16, 2002, (RANN-0011) entitled "VOICE
RECOGNITION LANDING FEE BILLING SYSTEM", incorporated herein by
reference in its entirety, which in turn claims priority from
Provisional U.S. Patent No. 60/343,237, filed Dec. 31, 2001,
(RANN-0010) also incorporated by reference in its entirety;
application Ser. No. 10/756,799 is also a Continuation-In-Part of
U.S. patent application Ser. No. 10/457,439, filed Jun. 10, 2003
(RANN-0013) entitled "Correlation of Flight Track Data with Other
Data Source", incorporated herein by reference in its entirety;
application Ser. No. 10/756,799 is also a Continuation-In-Part of
U.S. patent application Ser. No. 10/751,118, filed on Jan. 5, 2004,
(RANN-0012) entitled "Method and Apparatus to Correlate Aircraft
Flight Tracks and Events with Relevant Airport Operations
Information" which in turn claims priority from Provisional U.S.
Patent Application Ser. No. 60/440,618, filed Jan. 17, 2003,
(RANN-0012) incorporated herein by reference in its entirety;
application Ser. No. 10/756,799 also claims priority from
Provisional U.S. Patent Application Ser. No. 60/440,618, filed Jan.
17, 2003, (RANN-0012) incorporated herein by reference in its
entirety; application Ser. No. 10/756,799 is also a
Continuation-In-Part of U.S. patent application Ser. No.
10/743,012, filed Dec. 23, 2003 (RANN-0015) entitled "METHOD AND
APPARATUS FOR ACCURATE AIRCRAFT AND VEHICLE TRACKING" (Alexander E.
Smith et al.), incorporated herein by reference; application Ser.
No. 10/756,799 also claims priority from Provisional U.S. Patent
Application Ser. No. 60/534,706, filed Jan. 8, 2004, (RANN-0016)
incorporated herein by reference in its entirety;
[0005] The present application is a Continuation-In-Part
application of U.S. patent application Ser. No. 10/830,444, filed
on Apr. 23, 2004, (RANN-0018) and incorporated herein by reference;
U.S. patent application Ser. No. 10/830,444 is a DIVISIONAL
application of U.S. patent application Ser. No. 10/457,439, filed
on Jun. 10, 2003, and incorporated herein by reference; U.S. patent
application Ser. No. 10/457,439 in turn was a Continuation-In-Part
application of U.S. patent application Ser. No. 09/516,215, filed
Mar. 5, 1999, entitled "METHOD AND APPARATUS FOR IMPROVING THE
UTILITY OF AUTOMATIC DEPENDENT SURVEILLANCE", Now U.S. Pat. No.
6,633,259, which is incorporated herein by reference in its
entirety; U.S. patent application Ser. No. 10/457,439 was also a
Continuation-In-Part of U.S. patent application Ser. No.
10/319,725, filed Dec. 16, 2002, entitled "VOICE RECOGNITION
LANDING FEE BILLING SYSTEM", incorporated herein by reference in
its entirety. U.S. patent application Ser. No. 10/457,439 also
claims priority from Provisional U.S. Patent Application No.
60/440,618, filed Jan. 17, 2003, incorporated herein by reference
in its entirety.
[0006] The subject matter of the present application is related to
the following issued U.S. patents, assigned to the same assignee as
the present invention, all of which are incorporated herein by
reference in their entirety:
[0007] U.S. Pat. No. 6,049,304, issued Apr. 11, 2000, entitled
"Method and Apparatus for Improving the Accuracy of Relative
Position Estimates In a Satellite-Based Navigation System";
[0008] U.S. Pat. No. 5,999,116, issued Dec. 7, 1999, entitled
"Method and Apparatus for Improving the Surveillance Coverage and
Target Identification in a Radar Based Surveillance System";
[0009] U.S. Pat. No. 6,094,169, issued Jul. 25, 2000, entitled
"Passive Multilateration Auto-Calibration and Position Error
Correction";
[0010] U.S. Pat. No. 6,384,783, issued on May 7, 2002, entitled
"Method and Apparatus for Correlating Flight Identification Data
With Secondary Surveillance Radar Data";
[0011] U.S. Pat. No. 6,211,811, issued Apr. 2, 2001, entitled
"Method and Apparatus for Improving the Surveillance Coverage and
Target Identification in a Radar Based Surveillance System";
[0012] U.S. Pat. No. 6,448,929, issued Sep. 10, 2002, entitled
"Method and Apparatus for Correlating Flight Identification Data
With Secondary Surveillance Radar Data";
[0013] U.S. Pat. No. 6,567,043, issued May 20, 2003, entitled
"METHOD AND APPARATUS FOR IMPROVING THE UTILITY OF AUTOMATIC
DEPENDENT SURVEILLANCE";
[0014] U.S. Pat. No. 6,633,259 issued Oct. 14, 2003 "METHOD AND
APPARATUS FOR IMPROVING THE UTILITY OF AUTOMATIC DEPENDENT
SURVEILLANCE";
[0015] U.S. Pat. No. 6,812,890, issued Nov. 2, 2004, entitled
"VOICE RECOGNITION LANDING FEE BILLING SYSTEM"; and
[0016] U.S. Pat. No. 6,806,829, issued Oct. 19, 2004, entitled
"METHOD AND APPARATUS FOR IMPROVING THE UTILITY OF AUTOMATIC
DEPENDENT SURVEILLANCE".
FIELD OF THE INVENTION
[0017] The present invention relates to an aircraft tracking and
warning system. In particular, the present invention is directed
toward a system for detecting aircraft position relative to
restricted airspace and providing graphical data to a pilot and/or
a warning to inform the pilot of the position of the aircraft
relative to restricted airspace.
BACKGROUND OF THE INVENTION
[0018] Since Sep. 11, 2001, it has become common practice for air
traffic control authorities, militaries, and other organizations to
restrict airspace use. In the United States airspace may be
restricted through the use of Temporary Flight Restrictions (TFR)
and Air Defense Identification Zones (ADIZ). Similar practices are
employed in other countries. For background and several references
to TFRs and ADIZs please refer to
http://www.aopa.org/whatsnew/notams.html. The use of TFRs and ADIZ
by Government authorities has become more and more prevalent. TFRs
and ADIZs are used continually to protect airspace in major events,
ranging from major public/stadium events (e.g., NFL Super Bowl) to
affairs of state (Presidential events, visiting dignitaries, and
the like). Thus, it may be difficult for pilots to keep up with the
latest locations of TFRs and ADIZs.
[0019] The following is an excerpt from the Airplane Owners and
Pilots Association (AOPA) Website cited above and incorporated
herein by reference. As can be appreciated by one of ordinary skill
in the art, understanding the nature and scope of this ADIZ can be
difficult, even for a skilled pilot:
[0020] THE WASHINGTON DC METROPOLITAN AREA AIR DEFENSE
IDENTIFICATION ZONE (DC ADIZ) FOR PURPOSES OF THIS NOTAM ONLY, IS
THAT AREA OF AIRSPACE OVER THE SURFACE OF THE EARTH WHERE THE READY
IDENTIFICATION, LOCATION, AND CONTROL OF AIRCRAFT IS REQUIRED IN
THE INTERESTS OF NATIONAL SECURITY. SPECIFICALLY, THE DC ADIZ IS
THAT AIRSPACE, FROM THE SURFACE TO BUT NOT INCLUDING FL180, WITHIN
THE OUTER BOUNDARY OF THE WASHINGTON DC TRI-AREA CLASS B AIRSPACE
AREA; AND THAT ADDITIONAL AIRSPACE CONTAINED WITHIN AN AREA BOUNDED
BY A LINE BEGINNING AT 383712N/0773600W; THENCE COUNTER CLOCKWISE
ALONG THE 30-MILE ARC OF THE DCA VOR/DME TO 384124 N/0762548W;
THENCE WEST ALONG THE SOUTHERN BOUNDARY OF THE WASHINGTON DC
TRI-AREA CLASS B AIRSPACE AREA TO THE POINT OF BEGINNING.
[0021] FIG. 4 is a graphical plot of the DCA zones illustrating a
sample Restricted Airspace in the Washington DC area. As can be
readily appreciated from FIG. 4, the zones and geometry are quite
complex and extensive. It may be quite difficult for a private
pilot to understand the nature and extent of such zones and
successfully navigate such areas without inadvertently entering
into such zones. As a result, in many recent incidents, small
aircraft pilots have strayed into such restricted airspace, causing
some panic and also risking the lives of the pilot and passengers,
as well as those on the ground. Such inadvertent wanderings can
create grave consequences for the pilot, including fines and
possible suspension of licenses. In a worst-case scenario, the
pilot could be shot down by surface-to-air missiles maintained by
the military.
[0022] When planning any General Aviation (GA) flight, therefore, a
pilot needs to check on all possible TFRs and ADIZs and other
restricted airspace requirements anywhere near the flight plan.
Since these can change on a day-to-day (or even hour-to-hour)
basis, it may be almost impossible for a pilot to be aware of all
airspace restrictions. On Feb. 6, 2005, for example, there were
approximately 50 TFRs nationwide listed on
http://map.aeroplanner.com, incorporated herein by reference. It
can be difficult for the General Aviation pilot to keep up with all
these constantly changing TFRs. From that same website, FIG. 8
illustrates TFRs for Super Bowl XXXIX on Feb. 6, 2005. Similar
techniques may be applied to national defense, border security, and
military test ranges. Test ranges usually have some form of
aircraft tracking but do not provide automated transition warnings.
FIG. 9 illustrates and an example of a test range for the U.S. Navy
at Nanoose, near Vancouver, Canada. (See,
http://www.rannoch.com/pdf/nanoose.sub.--2520.sub.--10.sub.--01.sub.--04.-
pdf).
[0023] Methods of warning aircraft of impending threats, such as an
air-to-air collision include establishing a virtual bubble or
envelope around the aircraft. These envelopes are sometime tiered
to represent different severities of warnings. Two warning levels
are represented in FIG. 10. The envelopes may be established based
on distance or range/rate of closure. Examples of these techniques
are found in Traffic Alert and Collision Avoidance Systems (TCAS)
and Aircraft Alert and Collision Avoidance Systems (ACAS), as well
as terrain avoidance systems including the following references,
all of which are incorporated herein by reference:
[0024] U.S. Pat. No. 6,750,815 Method, apparatus, and computer
program products for alerting surface vessels to hazardous
conditions
[0025] U.S. Pat. No. 6,710,723 Terrain data retrieval system
[0026] U.S. Pat. No. 6,707,394 Apparatus, method, and computer
program product for generating terrain clearance floor envelopes
about a selected runway
[0027] U.S. Pat. No. 6,691,004 Method for determining a currently
obtainable climb gradient of an aircraft
[0028] U.S. Pat. No. 6,606,034 Terrain awareness system
[0029] U.S. Pat. No. 6,571,155 Assembly, computer program product
and method for displaying navigation performance based flight path
deviation information
[0030] U.S. Pat. No. 6,477,449 Methods, apparatus and computer
program products for determining a corrected distance between an
aircraft and a selected runway
[0031] U.S. Pat. No. 6,469,664 Method, apparatus, and computer
program products for alerting surface vessels to hazardous
conditions
[0032] U.S. Pat. No. 6,445,310 Apparatus, methods, computer program
products for generating a runway field clearance floor envelope
about a selected runway
[0033] U.S. Pat. No. 6,380,870 Apparatus, methods, and computer
program products for determining a look ahead distance value for
high speed flight
[0034] U.S. Pat. No. 6,347,263 Aircraft terrain information
system
[0035] U.S. Pat. No. 6,292,721 Premature descent into terrain
visual awareness enhancement to EGPWS
[0036] U.S. Pat. No. 6,219,592 Method and apparatus for terrain
awareness
[0037] U.S. Pat. No. 6,138,060 Terrain awareness system
[0038] U.S. Pat. No. 6,122,570 System and method for assisting the
prevention of controlled flight into terrain accidents
[0039] U.S. Pat. No. 6,092,009 Aircraft terrain information
system
[0040] U.S. Pat. No. 6,088,634 Method and apparatus for alerting a
pilot to a hazardous condition during approach to land
[0041] U.S. Pat. No. 5,839,080 Terrain awareness system
[0042] U.S. Pat. No. 6,292,721 Premature descent into terrain
visual awareness enhancement to EGPWS
[0043] U.S. Pat. No. 6,127,944 Integrated hazard avoidance
system
[0044] The use of multi-layer threat analysis for terrain and
aircraft collision detection, avoidance, and warning is therefore
known in the art. However, to date, this technique has not been
applied to the problem of warning pilots of aircraft intrusion into
restricted airspace. FIG. 10 illustrates the two levels of Logic
Showing Multiple Layers of Aircraft Protection and Alerting.
[0045] FIGS. 1 and 2 are diagrams illustrating the threat detection
concepts of the TCAS system from a vertical and horizontal
perspective, respectively. Referring to FIG. 1, a number of ranger
criterion may be provided for the TCAS equipped aircraft. Such
range criterion may include a surveillance range of approximately
20 nautical miles, a Traffic Advisory range of approximately 3.3
nautical miles, and a Resolution Advisory of approximately 2.1
nautical miles. An intruder aircraft entering into each relative
range criterion may cause a corresponding advisory, warning, or
indication to be generated to alert the pilot of the TCAS aircraft
of the proximity of the intruder aircraft and/or provide
instructions (e.g., "pull up!") to avoid a potential collision.
[0046] FIG. 2 shows similar Altitude criterion, which are also used
to indicate the relative threat level of an intruder aircraft. If
the intruder aircraft is within 1200 feet of the flight level of
the TCAS equipped aircraft, and is within the range criterion, a
Traffic Advisory may be generated. If the intruder aircraft is
within 850 feet of the TCAS equipped aircraft and within the range
criterion, a Resolution Advisory may be generated.
[0047] Rannoch Corporation has been involved in the TCAS
Independent Validation and Verification (IV&V) process since
its inception in 1992. Its first task consisted in
reverse-engineering version 6.04a of the TCAS logic,--correcting
the original code and representing it using state chart diagrams
(See, http://www.rannoch.com/Statechartf.html, incorporated herein
by reference) and truth tables (See,
http://www.rannoch.com/TruthTablef.html, incorporated herein by
reference) reflecting the different conditions under which
variables in the logic are assigned specific values.
[0048] The subsequent version of the logic, called "Change 7",
included the following additions. A refined "vertical tracker" used
for altimetry, with a 25 ft quantization was added. A "horizontal
miss distance filter" was included to suppress unnecessary alerts
whenever the projected horizontal distance between two airplanes at
closest point of approach is beyond a predefined threshold. A
"multi-aircraft" capability was created, enabling the TCAS unit to
choose the best escape maneuvers in a threat situation involving
more than two aircraft.
[0049] Rannoch's verification of the logic featured the development
of analysis tools for the TCAS SIMulation program (TSIM) and the
design of logic-challenging aircraft encounter scenarios. See,
e.g., Rannoch Demos at http://www.rannoch.com/demosf.html, and the
TSIM software at http://www.rannoch.com/ZipFiles/tcasdemo.zip, both
of which are incorporated herein by reference. TSIM's purpose is to
test the TCAS logic, ensuring that its different representations,
pseudocode and CRS (CAS Requirements Specifications), perfectly
match. It comprises more than 300 encounter scenarios fully testing
every part of the collision avoidance logic. Each scenario features
"own" aircraft moving in a straight line and one or more "intruder"
aircraft with a three-dimensional freedom of movement. As soon as
an intruder aircraft becomes a threat, the CAS logic is activated
causing own aircraft to climb or descend. Throughout the scenario,
which can be displayed as seen from a plan or side view, relevant
parameters of the encounter are recorded, facilitating further
analyses.
[0050] Since Jan. 1, 1994, every aircraft carrying more than 30
passengers aboard is mandated by Congress to be equipped with a
TCAS unit. As a direct consequence, major international airlines
equipped their fleet with TCAS units, thus providing additional
safety in other parts of the world. On an international level, the
U.N. ICAO (International Civil Aviation Organization) is promoting
the worldwide ACAS II (Airborne Collision Avoidance System)
equipage of all aircraft with more than 30 passengers by Jan. 1,
2000, and its extension to all aircraft carrying more than 19
passengers by Jan. 1, 2005.
[0051] Future collision avoidance systems will benefit from the use
of ADS-B (Automatic Dependent Surveillance--Broadcast) via the
spontaneous transmission of data such as position, velocity,
intent. It is expected that the former two will be based upon the
Global Positioning System (GPS), providing users with as little as
a sub-meter accuracy. The actual requirements needed to operate
such a transition are under investigation by RTCA Special Committee
186, Working Group 4, which is supported by Rannoch
Corporation.
[0052] FIG. 3 illustrates an enhanced TCAS system display from
MITRE Corporation, with other traffic and weather information. TCAS
targets are shown as diamonds, and range, heading, relative
altitude, and ground speed are displayed.
[0053] As illustrated in the events of Sep. 11, 2001, Prior Art air
traffic control systems are largely helpless if an aircraft turns
off its transponder signal. The transponder outputs a signal
identifying the aircraft and indicating its altitude based upon a
barometric altimeter. Without altitude information, it can be
difficult to properly track an aircraft and determine whether it
has entered a restricted area, as these areas are often
three-dimensional in shape. Barometric altimeters can be
inaccurate, or spoofed, as the ground level pressure reading can be
adjusted by the pilot. Thus, in addition to the other problems
stated above, it remains a requirement in the art to provide an
accurate method of determining an aircraft's altitude without
relying upon the aircraft transponder.
[0054] Preventing pilots from breaking TFR and ADIZ boundaries is a
constant challenge all over the United States and in other
countries. The U.S. Government has been trying all types of
solutions to prevent TFR and ADIZ "busts." As described in the
online aviation weekly AvWeb, the U.S. Government has recently
experimented with lasers to deter pilots from entering restricted
airspace. (see http://www.avweb.com/eletter/archives/-
avflash/335-full.html#188958)
[0055] NORAD has developed a "Visual Warning System" (VWS). NORAD
is planning to shine lasers into a pilot's cockpit if the pilot
"busts" the ADIZ around Washington, D.C. Red and Green lasers will
be aimed into the cockpit of an aircraft entering the restricted
airspace to warn the offending pilot of a violation of restricted
airspace. A warning will also be broadcast on the ATIS if the event
happens in the airport vicinity. As might be imagined, such a
system has been met with some criticism, as the laser lights might
arguably blind the pilot temporarily, thus leading to further
confusion and violation of the airspace. An alternative to such
drastic measures is needed.
[0056] Co-pending U.S. patent application Ser. No. 10/756,799 Filed
Jan. 14, 2004 and incorporated herein by reference, discloses A
Minimum Altitude Warning System is described to prevent Controlled
Flight into Terrain (CFIT). In that patent application, a
ground-based CFIT warning system provides pilots with CFIT alerts.
The system is based upon a ground-based tracking system, which
provides surveillance of aircraft, such as the AirScene.TM.
multilateration system manufactured by Rannoch Corporation of
Alexandria, Va. The system monitors both horizontal and vertical
positions of aircraft. When an aircraft has been determined to be
operating below safe altitudes, or too close to obstructions, the
pilot is provided with a warning. The warning may be delivered via
the pilot's voice communications and/or a data link or the
like.
[0057] FIG. 5 illustrates the fundamentals of the AirScene.TM.
method of tracking using triangulation or multilateration of the
aircraft's transponder signals as is known in the art, although
many other methods may be used to track an aircraft (e.g., radar
and the like). In the embodiment of FIG. 5, radio signals emanating
from aircraft on the ground 560 and in the air 510 may be received
at a number of discrete receiver locations 520 spaced throughout
the area of interest. The time stamps from these signals may be fed
to a processor 540 where the Time Difference of Arrival (TDOA) can
be used to calculate the position of aircraft 510 and 560 and
display such information in graphical or numerical form on a
display 530. Thus, it is possible to precisely locate the position
of an aircraft using radio signals emanating from the aircraft or
by other means.
[0058] Other means of tracking include radar systems and ADS-B.
Many countries are implementing a network of ADS-B ground stations
as described in the following references:
[0059] http://www.raytheon.co.uk/highlights/ATMS.html
[0060]
http://www.raytheon.co.uk/news_room/news/press.sub.--02022005.pdf
[0061]
http://www.airsysatm.thomson-csf.com/products/NAV/ads_b.htm
[0062]
http://www.eurocontrol.be/care/asas/tn-workshop1/asas-tn-vanderkraa-
n2.ppt
[0063]
http://www.eurocontrol.be/care/asas/tn-workshop1/asas-tn-howlett.pp-
t
[0064] An alternative to shining lasers into the cockpits of
aircraft that stray into restricted airspace is needed. The only
other alternative--shooting down such aircraft--is also
unacceptable. Thus, a need exists in the art to provide a system
for warning pilots that they are about to enter restricted airspace
before they enter such airspace, without blinding them or otherwise
distracting them from flying.
[0065] As illustrated herein, techniques exist in the art for
precisely locating the position of aircraft relative to one another
and relative to the ground and positions within the airspace. As
also noted herein, communications, warning, and graphical display
devices already exist in the cockpit to display the relative
position of an aircraft and/or warn a pilot of the position of the
aircraft relative to another aircraft, the terrain, or an obstacle.
Such a system should also be capable of warning personnel on the
ground of an aircraft entering restricted airspace. It remains a
requirement in the art to combine these existing technologies with
some new technology to create a better warning system for pilots so
that they can have proper situational awareness of their position
relative to restricted airspace, and also be properly warned if
they are accidentally straying into restricted airspace. Such a
system must be accurate and redundant so that false alarms are not
generated, and moreover human error or intentional spoofing of the
system does not cause the system to fail.
SUMMARY OF THE INVENTION
[0066] In combination with a Geographic Information System (GIS),
3-dimensional shapes may be used to designate or identify blocks of
airspace. These shapes may be defined in many ways including
lat/long, local coordinates, or FAA transmitted directions for TFRs
and ADIZs. These restricted areas and zones may be modeled using
suitably modified AirScene.TM. software from Rannoch
Corporation.
[0067] AirScene.TM. software can locate various aircraft in the
vicinity of restricted airspace, determine whether the aircraft is
about to enter restricted airspace, and issue a warning to the
pilot of such aircraft that restricted airspace is about to be
violated. Such a warning can be audible (e.g., radio communication
message) or visual (e.g., graphic display or even a flashing light
or text message) and is much less distracting than having a laser
shining in the cockpit. Since the AirScene.TM. system is
ground-based, ground personnel can also be advised if restricted
airspace is being violated, or even about to be violated.
[0068] In one embodiment, a graphical representation of restricted
airspace may be fed to a cockpit information display in the
aircraft, such as a flat panel display, which may also display
radar, mapping, and other information. For smaller General Aviation
(GA) aircraft, this information may even be displayed on a handheld
organizer (e.g., PalmPilot.RTM. or the like). The restricted
airspace data may also be displayed or overlaid on other existing
cockpit displays, including but not limited to radar displays, TCAS
displays, Air Chart displays, or displays comprising any or all of
these types of displays. Visual or audible warnings can be provided
if breach of restricted airspace has occurred or is imminent. As in
the TCAS system, a number of threat levels may be used to suitably
warn the pilot of the presence of restricted airspace, the
proximity of restricted airspace, and the breach of restricted
airspace.
[0069] In addition to the above features, the system of the present
invention may also be used to verify that altitude transponder data
is indeed correct, based upon independent verification from the
ground-based AirScene.TM. system. This aspect of the present
invention may also be provided as a stand-alone feature, which may
be used to calibrate, augment, or replace traditional barometric
altimeters used for aircraft transponders.
BRIEF DESCRIPTION OF THE DRAWINGS
[0070] FIG. 1 is a diagram illustrating the threat detection
concepts of the TCAS system from a vertical perspective.
[0071] FIG. 2 is a diagram illustrating the threat detection
concepts of the TCAS system from a horizontal perspective.
[0072] FIG. 3 illustrates an enhanced TCAS system display from
MITRE Corporation, with other traffic and weather information.
[0073] FIG. 4 is a graphical plot of the DCA zones illustrating a
sample Restricted Airspace in the Washington DC area.
[0074] FIG. 5 shows various examples of restricted areas and zones
using the AirScene software.
[0075] FIG. 6 illustrates how the Gates and Profiles of the
AirScene.TM. software may be used to mimic restricted airspace TFRs
and ADIZs.
[0076] FIG. 7 illustrates one example of how warnings may be
transmitted directly to a pilot.
[0077] FIG. 8 illustrates TFRs for Super Bowl XXXIX on Feb. 6,
2005.
[0078] FIG. 9 illustrates and an example of a test range for the
U.S. Navy at Nanoose, near Vancouver, Canada.
[0079] FIG. 10 illustrates the two levels of Logic Showing Multiple
Layers of Aircraft Protection and Alerting.
[0080] FIG. 11 is a diagram illustrating techniques employed to
validate enunciated position and altitude.
[0081] FIG. 12 illustrates one embodiment of the auto warning
system of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0082] FIG. 6 illustrates how the Gates and Profiles of the
AirScene.TM. software may be used to mimic restricted airspace TFRs
and ADIZs. Using this existing software, the three-dimensional
profile of TFRs and ADIZs may be programmed into the system and
displayed on a computer display screen or the like. Moreover, the
parameters of these TFRs and ADIZs can be compared with the
position and course of aircraft in the area, and a determination
made whether the aircraft is heading for restricted airspace.
[0083] Using the technology of co-pending U.S. patent application
Ser. No. 10/756,799, filed Jan. 14, 2004, and incorporated herein
by reference, the TFR and ADIZ data can be plugged into the system
in a similar matter as terrain and obstacle data. Instead of
warning a pilot of an imminent collision hazard, however, the
system may be programmed to warn also of possible "collision" with
restricted airspace.
[0084] In addition to providing alerts to static obstacles and
other aircraft the system may be used to provide pilot alerts to
TFRs and ADIZs. In addition the system can be used to provide
impending TFR/ADIZ busts to third parties. Thus, for example, air
traffic controllers, the military and other security organizations
may be alerted to a potential TFR/ADIZ "bust" and take appropriate
action, including attempting to contact the pilot by radio or the
like.
[0085] For general aviation aircraft and other small planes, such
data may be displayed on a pilot's palm organizer, as illustrated
in FIG. 7. FIG. 7 illustrates one example of how warnings may be
transmitted directly to a pilot. This display, developed by Rannoch
Corporation and Strategic Aeronautics, was originally designed to
alert an aircraft to the presence of another aircraft. This system
was successfully tested in December 2004 (see
http://www.airscene.com/news2004/12.sub.--22.sub.--04.pdf).
[0086] For commercial aircraft and the like, such restricted
airspace warnings may be displayed on an existing cockpit display,
either as a selectable display, or overlaid with other data, or
both. Thus, for example, the TCAS display of FIG. 3 may be suitably
overlaid with restricted airspace data, such that a pilot has a
greater situational awareness of their relative position to
restricted airspace. Restricted airspace may also be displayed on a
"heads up" or other type of display so that the pilot can view
restricted airspace through the cockpit windshield, superimposed
over the actual view from the cockpit.
[0087] As with terrain warnings and TCAS, audible or visual alarms
may be provided if restricted airspace is about to be breached, or
is actually breached. These warnings may be graduated, as with the
TCAS system previously discussed, so that the pilot will initially
be given a visual reference to restricted airspace in proximity to
the aircraft, then given a warning if it appears the pilot is
heading toward restricted airspace, and finally given a warning
that restricted airspace has been breached. In these latter two
cases, such warnings may be accompanied by instructions (as in
TCAS) as to how to avoid or exit the restricted airspace (e.g.,
"turn left"). If it has been determined that a pilot has entered
restricted airspace, a message may be played instructing the pilot
to tune to a particular radio frequency or take other action to
contact ground controllers to advise of his status, and thus avoid
a possible mistaken shoot-down incident.
[0088] Note that in some instances where airspace is crowded,
suitable modifications may be made to the system to prevent false
alarms. For example, approaches to Reagan National Airport in
Washington D.C., necessitate that aircraft approaching the airport
also are approaching the restricted airspace surrounding the
Capitol. As the system is ground-based, and not aircraft-based, it
is a simple matter to reprogram warning parameters accordingly for
each airport or zone, such that the pilot of a plane landing at
National Airport is not distracted by numerous false alarms
indicating the proximity of restricted airspace. The system may be
programmed to indicate whether or not the pilot is on the correct
approach path (and indeed, this is already a feature of the
AirScene.TM. software) and provide restricted airspace warnings
only if a significant deviation occurs from the approach path and
the course heading indicated a possible breach of restricted
airspace.
[0089] FIG. 12 illustrates one embodiment of the auto warning
system of the present invention. In the embodiment shown in FIG.
12, the tracking and identification can make use of dependent
aircraft information (such as ADS-B reported position and
barometric reported altitude) 1210 as well as independently derived
position (such as three-dimensional calculated position and
dynamics) 1220.
[0090] Independent data 1220 may be used to validate self-reported
data 1210 in step 1250. Thus, position and altitude data from
aircraft signals (e.g., transponder altitude data) is correlated
with independent tracking data, such as derived using
multilateration (e.g., Rannoch AirScene.TM. system). Discrepancies
between self-reported data 1210 and independent tracking data 1220
can be reported by the validation step 1250. If a serious
discrepancy is noted, authorities may be alerted accordingly, as
the altimeter data from the aircraft may have been intentionally
altered.
[0091] The TFR/ADIZ or other restricted airspace boundaries can be
either static or dynamic and may be input automatically from
sources 1230 including lat/long positions and other methods. In
this manner, temporary or new airspace restrictions are
automatically programmed into the system. While the pilot should
still brief himself on TFRs and ADIZs, the system provides a
redundancy if the pilot does not receive the latest information in
his briefing, or does not fully understand such a briefing or
merely forgets. A geographic information system (GIS) 1240 may be
used to relate aircraft, boundaries, and other geographic points of
interest relative to one another.
[0092] Based on the aircraft tracking it is possible to calculate a
series of aircraft alert zones 1260. For example, a series of
increasing warnings that airspace boundaries may be violated in a
certain time based on the dynamics of the aircraft (velocity,
acceleration, climb rate etc) in a similar manner to the TCAS
system or terrain avoidance systems. Combining the alert zone data
1260 with the restricted airspace data from block 1230 and 1240,
the system can determine whether a warning, and what level of
warning, should be sent.
[0093] Based on the anticipated boundary exceedance 1270, different
levels of warnings may be sent directly to the aircraft, other
aircraft 1280, or to ground based operators 1290. These warnings
may be transmitted using different formats including Traffic
Information Broadcast (TIS), Automatic Dependent Surveillance
(ADS-B), and other methods. An automated radio signal may be sent
to the pilot giving verbal instructions as to the airspace
violation. Alternately, ground personnel may be alerted, and they
in turn may communicate via radio with the pilot. As noted above,
the data may be communicated directly to the pilot via graphical
display, and/or visual or audible warning.
[0094] Furthermore, for security purposes, in addition to
determining an aircraft's identity, position, and dynamics
independently it is possible to use techniques to determine the
aircraft's altitude independently from the aircraft's barometric
altimeter--which could potentially be spoofed, intentionally or
unintentionally falsified. FIG. 11 is a diagram illustrating
techniques employed to validate enunciated position and altitude.
This embodiment of the present invention may also be provided as a
stand-alone feature, which may be used to verify, calibrate, or
otherwise validate aircraft position data.
[0095] Referring to FIG. 11, aircraft 1110 may be equipped with a
Secondary Surveillance radar (SSR) transponder or the like which
generates a radio signal (SSR Reply) in response to an
interrogation by an Air Traffic Control (ATC) radar 1130.
Traditionally, these transponders output a signal identifying the
aircraft by flight number, registration number, or other
identifying indicia, along with altitude readout from the
aircraft's altimeter. Traditional ATC radars generally cannot
determine aircraft altitude, but only the aircraft's relative
position (in a two dimensions) and thus rely upon the SSR reply to
indicate altitude.
[0096] Barometric barometers are relatively primitive devices,
which indicate relative altitude based upon air pressure. Provided
the proper ground level barometric pressure is fed into the
altimeter, the devices can be surprisingly accurate. However,
barometric pressure changes over time, and can even change quite
suddenly (with the advent of a storm front). In addition, the
traditional system requires intervention in most cases of the pilot
or crew to set the local barometric pressure on the altimeter,
often in response to garbled verbal radio commands from ground
control personnel.
[0097] If the barometric setting on the altimeter is not properly
adjusted, the resultant readout can be inaccurate. As a result, air
traffic controllers may not have accurate altitude information,
which could result in improper routing instructions, or even a
possible collision. Moreover. Inaccurate altimeter information can
affect other systems, including TCAS and the like, generating false
alarms or even failing to detect a possible collision. In the
present invention, improper altitude indications can affect
warnings for restricted airspace and the like. Moreover, a pilot
intentionally trying to breach restricted airspace could reset the
altimeter and/or tamper with it to make it appear as though the
aircraft was not within restricted airspace (e.g., flying below or
above).
[0098] In the present invention, the actual position of the
aircraft in three-dimensions can be found using the multilateration
techniques described in the priority applications and patents
previously incorporated by reference (collectively, the
AirScene.TM. patents). Multilateration provides an accurate
three-dimensional position of the aircraft relative to the
receivers 1140. Computing engine 1150, receiving the SSR reply
and/or other radio signals from aircraft 1110 can determine the
position of aircraft 1110 by detecting the time difference of
arrival of the signals at each of receivers 1140, which may
time-stamp the received signals before passing them to computing
engine 1150.
[0099] Receivers 1140 may also each receive a signal from global
position system (GPS) satellites 1120 (only one is shown here for
the sake of illustration). From these received signals, the precise
position of each receiver 1140 may be determined in computing
engine 1150. Knowing the exact position (latitude and longitude, as
well as altitude) of each receiver 1140, computing engine 1150 can
generate an accurate aircraft position, including altitude.
[0100] This independently generated aircraft altitude position may
be compared with the output of the SSR (or other) signal indicating
the aircraft's altimeter reading. If the two readings are within a
certain dead-band (determined by the accuracy of the aircraft
altimeter with an added fudge factor) the aircraft altimeter is
considered to be relatively accurate. If the aircraft altimeter
reading is outside of this dead-band, a signal may be generated
indicating the aircraft altimeter reading is false.
[0101] In response to such a signal, the pilot of aircraft 1110 may
be notified that their altimeter is not reading properly and the
pilot may take corrective actions (e.g., adjust calibration) to
correct the error. Alternately, a signal may be sent electronically
to the cockpit system software to automatically correct the
altimeter calibration. Such a system may eliminate the need for
verbally requesting barometric data and manually adjusting
instruments. During the busy approach and landing phases, this is
one less distracting task for the pilot to perform.
[0102] Moreover, if the altimeter reading from aircraft 1110 is so
far off from the actual altitude as measured by the system,
authorities may be alerted that a pilot is intentionally trying to
spoof the ATC system.
[0103] While the preferred embodiment and various alternative
embodiments of the invention have been disclosed and described in
detail herein, it may be apparent to those skilled in the art that
various changes in form and detail may be made therein without
departing from the spirit and scope thereof.
* * * * *
References