Transcript Title of Presentation Name of Author(s)/Presenter

Purpose of the Evaluations
To determine whether Loran-C can provide the:
Accuracy
Availability
Integrity
Continuity, and
Coverage
to support Lateral Navigation through all phases of flight
– including Non-Precision Approach (NPA)
To determine what other ancillary benefits can be
derived from the continued provision of Loran-C
services, e.g.,
An alternate/robust/backup means of transmitting WAAS
corrections to aircraft and other transportation modes
A Stratum I timing source (i.e., accuracy of 110-11 or better)
to serve as an alternate/robust/backup in case GPS/WAAS
timing becomes unavailable
1
Overview of US Loran-C Evaluations
Federal Aviation Administration
Mitchell J. Narins
Systems Engineer
Navigation Integrated Product Team
AND-702
International Loran Association
Washington, DC
28 October 2002
Loran-C Navigation
Current Capabilities/Future Needs*
Accuracy
Availability
Integrity
Continuity
Current Definition
of Capability *
(FRP)
0.25 nm
(463 m)
0.997
10 second
alarm/
25m error
0.997
FAA NPA (RNP.3)
Requirements
0.16 nm
(307 m)
0.999 – 0.9999
0.9999999
0.999 - 0.9999
0.004 - 0.01 nm
(8 – 20 m)
0.997 - 0.999
10 second
alarm/
25m error
0.9985 – 0.9997
over 3 hours
USCG Harbor
Requirements
(to date)
* Loran also provides Stratum 1 level of timing capability.
3
FAA Program Participants
Government
FAA






Navigation Systems Engineering, AND-702
NAS Architecture, ASD-140
CNS Test and Evaluation, ACT-360
Flight Standards, AFS-400
Certification, AIR-130
Special Programs, AVN-5
US Coast Guard



Aids to Navigation
Navigation Center
Loran Support Unit
4
FAA Program Participants
Industry
Locus, Inc.
Rockwell Collins
Peterson Integrated Geopositioning
Illgen Simulation Technologies, Inc.
JJMA
WR Systems
Booz Allen and Hamilton
Academia
Ohio University
Stanford University
US Coast Guard Academy
University of Rhode Island
University of Alaska
5
Program Logo Collection
6
Loran-C Evaluation Program
FY 1994
Federal Radionavigation Plan (FRP) announced that Loran-C
service would terminate 31 December 2000
Congressional lobbying (primarily by aviation groups) resulted
in budgetary language to continue system development
FY 1997 ($4.6 M)
Congressional Mandate

The FY 1997 Congressional budget provided funds to the FAA
for “upgrades to the Loran-C navigation system and... to
implement an automatic blink system (ABS).”
FY 1998 ($3 M)
Congressional Mandate

The FY 1998 Congressional budget directed the FAA “to
continue Loran-C upgrades initiated in fiscal 97.”
FY 1999 ($7 M)
Congressional Mandate

The Congressional budget provided funds to the FAA for “further
development of the Loran-C navigation system.”
7
Loran-C Evaluation Program
FY 2000 ($10 M)
Congressional Mandate

The Congressional budget provided funds to the FAA for
“further development of the Loran-C navigation system.”
FY 2001 ($20 M requested, $25 M provided)
First year included in President’s budget
FY 2002 ($13 M requested, $19 M provided)
FY 2003 ($13 M requested, $21-25 M expected)
Senate (Appropriations Report) raised the level of funding to
$21 Million.
House (Appropriations Report) raised the level of funding to
$25 Million and expressed disappointment with the FAA for
trying to use Loran funding for “lower priority activities.”
8
A Most Substantial Investment
US Loran Evaluation Program
Cumulative Expenditures
100
90
Dollars (millions)
80
70
60
50
40
30
20
10
0
97
98
99
00
01
02
03
Fiscal Year
9
Contributions to the ILA
The U.S. Loran-C Evaluation Program has much
to be proud of…and equally much to report out
at this ILA Meeting.
What you will see and hear over the next few
days includes:
28 October:

The New Loran-C Time Scale and Possibilities for the Future
• Timing Solutions Corporation

The New Heartbeat of Loran
• U.S. Coast Guard Loran Support Unit

Loran-C Maintenance Support
• U.S. Coast Guard Maintenance and Logistics Command
10
…a very full program
29 October:
 The Loran Integrity Panel
• Stanford University, Peterson Integrated Geopositioning, USCG LSU, BAH, FAA

Improving the Availability, Accuracy, Continuity, and Integrity
over the Loran-C Coverage Area
• U.S. Coast Guard Loran Support Unit

Command and Control of the Loran Signal
• U.S. Coast Guard Loran Support Unit
30 October
 Status of GPS/Loran Prototype for FAA Trials
• Locus, Inc., Rockwell Collins, FAA

Flight Trials of All-in-View Loran Receiver and H-field Antenna
• Ohio University, Locus, Inc, FAA

Loran-C User Position Software Navigation Performance with
the August 2001 Cross-country Flight test Data
• Illgen Simulation Systems, Inc.

Preliminary Results of Differential Loran Studies with All-inView Receiver
• Locus, Inc.

A Preliminary Study of Loran-C Additional Secondary Factor
(ASF) Variations
• U.S. Coast Guard Academy, University of Rhode Island, JJMA, FAA
11
Current US Loran-C Policy
“While the Administration continues to evaluate the long-term
need for continuation of the Loran-C radionavigation
system, the Government will operate the Loran-C system in
the short term. The U.S. Government will give users
reasonable notice if it concludes that Loran-C is not needed
or is not cost effective, so that users will have the
opportunity to transition to alternative navigation aids. With
this continued sustainment of the Loran-C service, users
will be able to realize additional benefits. Improvement of
GPS time synchronization of the Loran-C chains and the
use of digital receivers may support improved accuracy and
coverage of the service. Loran-C will continue to provide a
supplemental means of navigation. Current Loran-C
receivers do not support nonprecision instrument approach
operations.”
Para 3.2.5 B 1999 US Federal Radionavigation Plan
12
Volpe GPS Vulnerability Study
The vulnerability study released on 10 September 2001
recognized the potential for Loran-C to be a robust backup
system for GPS navigation and augmentation and timing.
“In an effort to provide the greatest benefit to the users,
encourage the development of affordable vehicle-based
backups such as GPS/inertial receivers, and, in the event
Loran-C becomes a viable terrestrial backups to GPS, aviation
certifiable Loran-C receivers, and GPS/Loran-C receivers.”
“Conduct a comprehensive analysis of GPS backup navigation and
precise timing options including VOR/DME, ILS, Loran-C, inertial
navigation systems, and operating systems.”
“Continue the Loran-C modernization program of the FAA and
USCG, until it is determined whether Loran-C has a role as a
GPS backup system. If it is determined that Loran-C has a role
in the future navigation mix, DOT should promptly announce
this to encourage the electronics manufacturing community to
develop new Loran-C technologies.”
13
…but Loran still has issues
This Year’s Challenges
FAA Loran Issue 1: Accuracy
Current Accuracy:
Target Accuracy (NPA):
Issues
Old timing sources
Old timing equipment
Tube technology
Simple propagation model
0.25 nm, 2drms., 95%
0.16 nm (307 m) - RNP 0.3
0.43 nm (802 m) - RNP 0.5
Potential Mitigations
New cesium clocks
New timing suite
Solid State Transmitter
(SSX) technology
New ASF* tables/algorithms
*additional secondary factors
15
FAA Loran Issue 2: Availability
Current Availability:
Target Availability (NPA):
Issues
Precipitation Static
Loss of Station Power
Lightning
Chain Availability
Tube overloads
0.997
0.999 - 0.9999
Potential Mitigations
H-Field Antenna
UPS
New Lightning Protection
All-in-view receivers
Solid State Transmitters
16
FAA Loran Issue 3: Integrity
Current Integrity:
10 sec. alert @ + 100ns or other
specified error conditions
Target Integrity (NPA): 0.9999999*
556m HPL, 10 sec. alert
Issues
Presumed Integrity
Potential Mitigations
Loran Integrity Panel (LORIPP)
*the probability of providing Hazardous or
Misleading Information (HMI) is 1 x 10-7
17
FAA Loran Issue 4: Continuity
Current Continuity: 0.997
Target Continuity (NPA): 0.999 - 0.9999
Issues
Same as Availability plus:
Receiver acquisition time
Potential Mitigations
New DSP technology
New SSX Switch Units
18
FAA Loran Issue 5: Coverage
Current Coverage: See FRP Chart
Target Coverage (NPA): NAS
Issues
Lack of navigation coverage
on Alaskan North slope and
Southern Florida
Potential Mitigations
Additional Loran stations
Policy/Process Changes
19
FY ‘03 FAA Loran-C Plans
To determine Loran Accuracy:
ASF studies and calibration
Receiver studies
To determine Loran Availability:
H-Field Antenna/P-static testing
CONUS All-in-view receiver analysis
Noise analysis
SSX and TFE modifications and evaluations
To determine Loran Integrity
Loran Integrity Performance Panel (LORIPP)
Time of Transmission studies
To determine Loran Continuity
Receiver studies (in concert with availability efforts)
Combined GPS/Loran receiver/antenna research
20
Status of H-Field Test Activities
FAATC flight testing of H-Field antennas and allin-view receivers
Delayed to ensure safety of aircraft static charging
system, installation of field mill and measurement
equipment, and aircraft structural considerations
Still working issues – hoping for Nov/Dec 2002 test
21
E-Field - H-Field Comparison
22
E-Field - H-Field Comparison
E-Field
5
SNR (dB)
- 1
H-Field
E-Field
- 5
Severe P-Static (Snow)
-9
Secondary Y NorthEast U.S. (9960)
Aircraft: Beechcraft V35A
Time 0 = 0734 EST on 20 March 2000
Loran Receivers: II Morrow Apollo 612A
(TSO’d)
Flight from N39 W82 to N36 W83
Avionics Engineering Center
Ohio University, Athens, OH 45701
0
20
40
E-field: II Morrow A-16 Whip (TSO’d)
H-field: King Radio ADF (TSO’d)
60
80
100
120
Time in minutes
23
Status of Integrity (HMI) Analysis
Objectives
Develop error models and mitigation techniques to ensure
LNAV integrity
Develop software to predict coverage and to determine
sensitivity of coverage to various parameters
Determine where effort needs to be placed to achieve
desired levels of availability and continuity
Approach
Ad hoc integrity performance panel akin to WAAS Integrity
Performance Panel (WIPP) or RTCA Working Group
Key Participants
Dr. Per Enge, Dr. Todd Walter, Dr. Sherman Lo, and
Mr. Lee Boyce, Stanford University
Dr. Ben Peterson, Peterson Integrated Geopositioning
Mr. Robert Wenzel, Booz Allen Hamilton
24
Status of Integrity (HMI) Analysis
Results to date:
Developed initial algorithms and initial fault-tree for
determining Loran integrity and horizontal protection
limit-- work continues;
Analyzed RNP 0.3 performance-- feasible throughout
CONUS, but may require changes in the system
infrastructure, policy, processes etc. and continued
operation of Canadian stations -- work continues;
Analyzed RNP 0.3 approaches-- may be feasible with the
improved infrastructure -- work continues; and
Developed Web site for project tracking, documentation,
and information-- work continues.
Final report expected in 12-18 months

NLT March 2004
25
FY 03 Highlights and Goals
Building on the excellent progress in FY02 the
expected FY03 accomplishments include:
Integrated prototype avionics and antennas that will allow
evaluation of Loran for all phases of flight and in both stand-alone
and multi-sensor configurations;
Completion of H-Field/P-static testing;
LORIPP results and analysis… ASF, noise, fault trees etc.;
Flight test data showing whether Loran can provide the required
accuracy (possibly approaching GPS lateral accuracy) when used
in conjunction with appropriate ASF information;
Modernization of the Loran infrastructure to support potential
aviation use;
Revised US Signal Specification/Loran Policy;
Determination of need for a Loran data channel;
Activation of evaluation team web-site for internal project tracking
and external documentation and information interchange; and
Delivery of 2nd Loran Evaluation Status Report to DOT.
26
Oh yes…
…by the way
…we managed to do a bit of flying this year to help
characterize ASFs…
28
…we managed to build a few things…
29
…and we also got some rather nice results!
Loran 7
Loran 1 GPS 1
GPS 8
Loran 8
GPS 7
Loran 2
Loran 7
GPS 7
Loran 3
GPS 2
GPS 3
30
Summary
We made excellent progress – our FY’02 goals
have been achieved – and more!
LORIPP is well on its way to showing that aviation integrity
requirements can be met
Flight tests are showing that Loran can provide excellent
accuracy (approaching GPS accuracies) when used in
conjunction with appropriate ASF information
We look forward in FY’03 to:
Development of integrated prototype avionics and
antennas to evaluate Loran for all phases of flight in
both stand-alone and multi-sensor configurations
Development of better ASF models
Publication of our H-Field/P-static test results
Publication of interim LORIPP findings
Continuation of the Loran community’s support while
we continue our evaluation
31
Questions