Volume 4 AIRCRAFT EQUIPMENT AND OPERATIONAL AUTHORIZATIONS
Chapter 3 AIRPLANE PERFORMANCE AND AIRPORT DATA
Section 4 Safety Assurance System: Airport Data Acquisition Systems
4-571 GENERAL. This section contains specific information, direction, and guidance
to inspectors for the review and approval of airport data acquisition systems.
An airport data acquisition system is a subsystem of the performance data system described in
Volume 4, Chapter 3, Section 3. Most
of the data required for flight operations
can be obtained by a subscription to a standard government or commercial aeronautical
navigation charting service, such as the National Oceanic and Atmospheric Administration
(NOAA), the Department of Defense (DOD), or the Jeppesen/Sanderson Company.
Operators of large, transport category airplanes and commuter category airplanes
require obstacle information for takeoff performance analysis which is more
detailed than information provided by standard navigational charting services.
This section is related to Safety Assurance System (SAS) Element 3.2.1 (OP),
Aircraft Performance Operating Limitations.
A. Regulations. Title 14 of the Code of Federal Regulations (14 CFR) part
121.117(b) require that a part
system of obtaining, maintaining, and distributing airport information be approved. A 14 CFR part
system must be acceptable. The criteria for approval and acceptance for both parts
121 are identical.
B. Approval or Acceptance. Approval or acceptance of the operator's
system of obtaining aeronautical data by the Federal Aviation Administration
(FAA) is expressed in Operations Specification (OpSpec) A009. All operators should list one or more standard charting
services in OpSpec A009. For operators requiring obstacle data and maintaining
a department to collect and process that data, a statement that the operator
shall maintain the airport data acquisition system in accordance with a specified
document should be entered in OpSpec A009. For operators who contract from another
party for obstacle data, both the contracting party and the contract containing
the specific responsibilities of both the operator and contractor shall be identified
in OpSpec A009, or the document itself should be identified in OpSpec A009.
4-572 OBSTACLE DATA SOURCES. There are several data sources that an operator or
contractor may use to acquire obstacle data. Principal operations inspectors (POI) should be aware that no
one source of data is sufficient and a combination of the following sources is required.
A. Airport Obstruction Charts (AOC). AOCs are produced by the National Ocean
Service (NOS) under contract to the FAA. An airport analysis must be based on
an AOC if one has been published for the airport being analyzed. AOCs must be
augmented with other information sources, however, for the following reasons:
1) AOCs are primarily produced for airports with precision instrument approaches.
Only approximately 750 of 10,000 public-use airports in the United States have
now been charted. There are 700–800 airports which have only nonprecision approaches
for which there have not been any AOCs prepared.
2) Terrain surrounding the airport, which can have a significant
impact on allowable takeoff weight, may not be shown on an AOC. The coverage
of AOCs is limited to 10,000 feet from a nonprecision runway and 52,000 feet from a precision runway.
3) Chart revision is usually conducted every 3 years. For many
airports, however, the most recent chart revisions are considerably older.
B. Obstruction Data Sheets (ODS). ODSs are digital derivatives
of the AOC which contain runway and obstruction data in a tabular format. ODSs
are issued to supplement the AOC before its publication. When AOCs are ordered
for a particular airport from NOS, the ODSs should also be obtained. The NOS
publishes quarterly notices that provide the dates of the latest editions of the AOC and the ODS.
C. Terrain Charts. Terrain or quad charts are produced by the
U.S. Geological Survey for aviation usage as well as various other uses. The
quad chart accurately depicts all terrain surrounding an airport; however, man-made
obstruction data is not depicted. Terrain charts are primarily used for mountainous
airports where the obstacles consist of terrain rather than man-made objects.
D. Local Layout Plans. Local layout plans may be used when AOCs
are not available. Since local layout plans must be prepared as a condition
of federal funding to airports, the layout plans are available for many of the
airports that do not have an AOC. Local layout plans contain depictions of obstructions
and terrain that penetrate the 14 CFR part
77 planes. The
layout plans may be as much as 3 to 5 years old so local surveys must
be made. Local layout plans may be obtained from airport owners.
E. FAA Form 5010-1. FAA Form 5010-1, Airport Master Record, is
prepared for all public use airports. This master record contains comprehensive
data on airports, including obstacles. The master record is updated annually
for those airports where scheduled part
121 or part
are conducted. For other airports this data may not be updated
for 3 to 5 years. Master records for the entire United States are maintained
by the National Flight Data Center (NFDC), an agency of the FAA (AJV-21). FAA
personnel can access copies of the form which are kept in regional airport division
offices for each airport in the region.
1) Much of the information on FAA Form 5010-1 comes from unverified
sources. Often, obstacle heights and positions are estimates which have not
been measured and verified by instruments. For these reasons, obstacle information
taken from the master record must be verified by other sources before use.
2) Obstacles that do not penetrate the obstruction planes defined in part
not necessarily included in the FAA Form 5010-1 data. When the takeoff
flightpath passes over an area not covered by a part
obstacles can be present which are not identified. Even when the part
overlaps the takeoff flightpath, obstacles lower than 200 feet can be seriously limiting
to airplane takeoff performance but not be included in the FAA Form 5010-1 data.
F. Digital Airport Database. The digital airport database consists
of the information from FAA
Form 5010-1 for all U.S. airports. The data is recorded
in digital form on magnetic tape and is updated every 56 days. This database
is available to the public from the NFDC.
G. Digital Obstruction Database. The NOS maintains an obstruction
database. This database is revised quarterly, with revisions being available
to the public in digital format recorded on magnetic tape from the NFDC. These
tapes are revised every 56 days. This database contains all known, manmade objects that penetrate a part
plane. The database does not, however, contain all obstacles which are significant in the takeoff case.
H. National Flight Data Digest (NFDD). The NFDD is published
daily by the NFDC. The Thursday edition of the NFDD contains changes to obstruction data.
I. Foreign Government Publications. Runway and obstacle data,
similar to U.S. publications, is available for most (but not all) foreign airports.
Access to this information must be obtained through the appropriate government.
J. International Civil Aviation Organization (ICAO) Aeronautical
Information Publications. ICAO publishes several forms of aeronautical data
in forms similar to U.S. publications in format, purpose, and coverage. This
information is available by subscription.
K. Station Managers. Most domestic and flag operators give station managers
the tasks of maintaining surveillance of airports, gathering obstruction data,
and reporting any actual or potential changes. Managers do this through personal
observation, liaison with the airport management, and participation in groups,
such as a snow removal committee. Before such information may be used, it must
be verified by an official source. For example, one operator performs this verification
by sending the airport manager a copy of the AOC and requesting that the airport
manager plot the new obstacle and then sign and date the chart.
L. Airlines for America (A4A). A4A maintains an airport data
exchange committee through which members exchange airport and obstacle data.
M. Notices to Airmen (NOTAM). Temporary and immediate changes
to airport information are published as NOTAMs.
N. Customer Interaction. Large commercial services selling airport
data are rapidly alerted to changes in obstacles by their customers. The commercial
service then verifies the data from an official source and publishes the change.
4-573 APPROVAL OF DATA ACQUISITION SYSTEMS. POIs may
approve data acquisition systems using the following information and guidance.
A. Characteristics of Approvable Systems. An approvable or acceptable
system for the acquisition of obstruction data must have the following characteristics:
1) The system must include all airports and runways on which
operations are conducted. The original data should be based on AOCs or the ICAO
equivalent. Data must be updated by active surveillance. When an operator serves
airports where AOCs are not available, other systems based on other data sources
may be approved. The operator must show that the data is complete and accurate.
To ensure accuracy, the data must be maintained. In individual cases, the POI
may approve the use of data from an operator-conducted survey.
2) The operator must demonstrate the capability of maintaining
continuous surveillance on the airports and runways served. Subscribing to a
government publication is not sufficient surveillance because of the stated
limitations of the data in these publications. Updated data must be validated
and documented. The operator must have an active and timely revision process
with sufficient personnel and physical resources to collect, process, and revise the data.
B. Contractors and Commercial Sources. POIs may approve or accept
data systems that are operated by a contractor for the operator and that meet
the criteria of subparagraph 4-573A.
1) The primary issue in approving a contractor-operated system
is the contractor's ability to maintain the required airport surveillance. The
contractor may do this by demonstrating that its client base adequately performs
this function. Further, most legitimate contractors have access to A4A data
through their clients. A contractor who cannot demonstrate adequate surveillance
capabilities cannot be approved.
2) POIs do not have to require that operators provide extensive
documentation of the contractor's capabilities if the contractor is well established,
has a wide client base, and provides a standardized service. When the POI has
concerns about the contractor's capabilities, however, or when the operator
proposes that the contractor provide a unique service, the POI shall require
that the operator conduct a full analysis of the contractor's competence and
then submit the analysis to the POI. When the POI is unsure of which course
of action to take, the POI should seek guidance from the regional Flight Standards division (RFSD).
RESERVED. Paragraphs 4-574 through 4-590.