U.S.
Department of Transportation Federal Aviation Administration Advisory Circular Subject: Use of Noncertified Weather Observations in Noncontiguous States Date: 1/13/26 AC No: 135-45A Initiated by: AFS-200 Change:
1 PURPOSE OF THIS ADVISORY CIRCULAR (AC). This AC provides information and recommendations to air carriers operating under the authority of Title 14 of the Code of Federal Regulations (14 CFR) part 135 and in the noncontiguous States (i.e., Alaska or Hawaii) on the use of noncertified weather information in support of instrument approaches conducted under instrument flight rules (IFR) at airports without destination weather reporting approved by the National Weather Service (NWS) or the Federal Aviation Administration (FAA).
1.1 This AC provides information and examples that may assist operators in developing sources of noncertified supplemental weather information and associated training procedures that can be submitted for approval for use in their operations. Additional procedures not contained in this AC will be considered on a case-by-case basis to determine suitability for approval.
Note: This is a guidance document. Its content is not legally binding in its own right and will not be relied upon by the Department as a separate basis for affirmative enforcement action or other administrative penalty.
Conformity with the guidance document is voluntary only. Nonconformity will not affect rights and obligations under existing statutes and regulations.
2 AUDIENCE. This AC is for existing and prospective 14 CFR part 135 air carriers operating in the noncontiguous States of Alaska and Hawaii and their employees.
3 WHERE YOU CAN FIND THIS AC. You can find this AC on the FAA’s website at https://www.faa.gov/regulations_policies/advisory_circulars and in the Dynamic Regulatory System (DRS) at https://drs.faa.gov.
4 WHAT THIS AC CANCELS. AC 135-45, Use of Noncertified Weather Observations in Noncontiguous States, dated October 6, 2020, is canceled.
5 RELATED CFR PARTS. Title 14 CFR parts 1, 91, and 135.
6 PRINCIPAL CHANGES. This revision incorporates the addition of an application template for use by operators (see Appendix A, Application Template for 14 CFR Part 135 Noncertified Weather Observations in Noncontiguous States). The application template assists operators in identifying the procedures and training that will be the basis of their program for using weather information from noncertified systems (refer to
2 Section 339 of the FAA Reauthorization Act of 2024, Public Law (PL) 118-63 (May 16, 2024) (Title 49 of the United States Code (49 U.S.C.) §§ 44701 and 44720)).
7 DEFINITIONS.
7.1 Altimeter Setting Source. An instrument approved by the FAA that displays the current altimeter setting. If it is not available or cannot communicate the current altimeter setting to the pilot conducting an instrument approach at a destination airport, the pilot must apply altitude corrections as shown on the instrument approach procedure (IAP) for that airport.
7.2 General Operations Manual (GOM). A manual setting forth the certificate holder’s (CH) procedures and policies acceptable to the Administrator, which, as required by 14 CFR § 135.21, each CH, other than one who uses only one pilot in the CH’s operations, must prepare and keep current. The GOM provides relevant information to the CH’s flight, ground, and maintenance personnel to use in conducting its operations.
Under 14 CFR § 135.23, the manual must include, at a minimum, sections addressing IFR flight planning procedures and an FAA-approved en route and destination weather evaluation procedure (refer to Section 322 of the FAA Reauthorization Act of 2018, PL 115-254 (October 5, 2018) (49 U.S.C. § 44720 note)). The operator’s GOM must be acceptable to the FAA (refer to 14 CFR § 135.21(a)), and though it may contain procedures and programs approved by the FAA, these required approvals of individual sections do not supersede the overall acceptance requirements of the manual.
7.3 Instrument Flight Rules (IFR). Rules governing the procedures for conducting instrument flight whether under instrument meteorological conditions (IMC) or visual meteorological conditions (VMC).
7.4 Instrument Meteorological Conditions (IMC). Meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling less than the minimums specified for VMC.
7.5 Noncertified Weather Observer. An individual who assesses weather conditions at a designated location and relays that information to the operator or pilot to determine that the weather is at or above required minimums.
7.6 Reasonably Accurate Estimate. A noncertified weather observer’s best estimate of ceiling or visibility that is determined by an approved method and is expressed as being above or below the required landing minimums without quantification of ceiling in feet or visibility in fractions of a mile.
8 RELATED READING MATERIAL.
8.1 ACs. Current editions of ACs can be found on the FAA website at https://www.faa.gov/r egulations_policies/advisory_circulars.
• AC 120-51, Crew Resource Management Training.
8.2 Other Documents (current editions).
• Aeronautical Information Manual (AIM).
• National Weather Service Training Guide in Surface Weather Observations: https://w ww.weather.gov/media/surface/SFCTraining.pdf.
• Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25).
8.3 Websites. The American Meteorological Society (AMS) Glossary of Meteorology (entry for “rain”): https://glossary.ametsoc.org/wiki/rain.
9 BACKGROUND. Section 322 of the FAA Reauthorization Act of 2018 requires the FAA to permit an air carrier operating pursuant to 14 CFR part 135 “to operate to a destination with a published approach, in a noncontiguous State under instrument flight rules and conduct an instrument approach without a destination Aviation Routine Weather Report (METAR) if a current Area Forecast, supplemented by noncertified local weather observations (such as weather cameras and human observations) is available, and an alternate airport that has [an FAA-approved] weather report is specified.” Section 339 of the FAA Reauthorization Act of 2024, which amends Section 322 of the FAA Reauthorization Act of 2018, directs the Administrator to develop an application template to assist FAA inspectors in objectively evaluating a 14 CFR part 135 air carrier’s application identifying the procedures and training that will be the basis of their program for using weather information from noncertified systems.
10 DISCUSSION. Title 14 CFR § 135.213(a) states that whenever a person operating an aircraft under 14 CFR part 135 is required to use a weather report or forecast, that person shall use that of the NWS, a source approved by the NWS, or a source approved by the Administrator. Additionally, 14 CFR § 135.213(b) provides that the Administrator may approve a deviation through the issuance of operations specifications (OpSpecs) allowing the use of weather observations taken at a location not at the airport where the IFR operations are conducted. The responsible Flight Standards office will issue the OpSpec after an investigation and determination is made by the FAA and the NWS that issuing a deviation from 14 CFR § 135.213(b) would be consistent with the standards for safety for that operation. Operators should use this option first when it is available. If the FAA does not approve a deviation from 14 CFR § 135.213(b), Section 322 of the FAA Reauthorization Act of 2018 may apply to provide relief. If the FAA approves an alternative weather source in accordance with 14 CFR § 135.213(b), relief under Section 322 is unavailable because it is not necessary. Section 322 also includes the requirement for operators to have approved departure procedures. Using the same authority to approve noncertified weather observations to operate to a destination, the FAA will approve departure procedures to operate from that destination.
11 PROCEDURES FOR GAINING FAA APPROVAL. FAA approval of procedures for the evaluation of en route and destination weather will be contingent upon the quality of documented procedures, training, and validation that demonstrates the procedures result in properly evaluated weather reports that both certified sources and noncertified observers provide.
11.1 Appropriate Documents. Each CH should provide its Principal Operations Inspector (POI) with a copy of the CH’s procedures for use by noncertified weather observers and interpreters of weather camera images, which the CH will typically incorporate into its appropriate manual. Each CH should also provide a training program syllabus based on these documented methods for personnel who will observe the weather or interpret the weather camera images.
11.2 OpSpec A010, Aviation Weather Information (for 14 CFR parts 121/135 and 135).
CHs requesting the use of noncertified weather observers should request amendment of OpSpec A010 to add the pertinent information in subparagraph e of the OpSpec.
12 CHARACTERISTICS OF NONCERTIFIED WEATHER OBSERVATIONS FROM NONCERTIFIED WEATHER OBSERVERS. Weather characteristics that noncertified weather observers estimate or that are derived by interpretation from weather camera images by image interpreters include visibility and cloud ceiling height. The operator may also include other weather characteristics, such as windspeed and direction;
type and intensity of precipitation; temperature and dewpoint; and presence of thunderstorms in the vicinity.
12.1 Determining Cloud Ceiling Height. Cloud ceiling height is an important weather element when planning the execution of an IAP. Cloud ceiling is the base of the bottommost of the broken (greater than 50 percent sky coverage) or overcast cloud layer.
A noncertified weather observer estimates the cloud ceiling height. Techniques for estimating ceiling heights include, but are not limited to:
12.1.1 Terrain Features or Cultural (Man-Made) Landmarks. Where possible, observations should be based on the ability of the observer to see natural terrain or man-made features with a known height above the destination airport as viewed from a specified location, preferably at the destination airport. Nearby hills of sufficient height, with distinct terrain features (i.e., natural or man-made landmarks), can provide a consistent and repeatable means of estimating ceiling. For example, a notch in a ridgeline or a distinctly shaped outcropping, or a man-made object that is a known height above the airport corresponding to the minimum descent altitude (MDA), could be used to verify quickly and effectively that the ceiling is at or above minimums if an observer can see the object at a specified location on the ground. Conversely, if the object is not visible and horizontal visibility is not limiting, the ceiling must be below minimums.
12.1.2 Temperature/Dewpoint Spread. As moist, unstable air rises, clouds often form at the altitude where temperature and dewpoint reach the same value. When lifted, unsaturated air cools at a rate of 5.4 °F per 1,000 feet and the dewpoint temperature decreases at a rate of 1 °F per 1,000 feet. This results in a convergence of temperature and dewpoint at a rate of approximately 4.4 °F per 1,000 feet increase in altitude. Apply the convergence rate to the difference (or spread) between the reported surface temperature and dewpoint to determine the height of the cloud base.
5 Example: With an outside air temperature (OAT) of 85 °F at the surface and dewpoint at the surface of 71 °F, the spread is 14 °F. Divide the temperature/dewpoint spread by the convergence rate of 4.4 °F, and multiply by 1,000 to determine the approximate height of the cloud base.
85 °F – 71 °F = 14 °F 14 °F ÷ 4.4 °F = 3.18
3.18 × 1,000 = 3,180 feet above ground level (AGL) The height of the cloud base is estimated to be 3,180 feet AGL.
12.1.3 Other Methods of Determining Ceiling Height. Other methods for determining ceiling height include:
1. The CH may choose to invest in a ceilometer or a laser range finder capable of detecting the surface of clouds. Such equipment would only need to have the range necessary to reach and estimate the height of the ceiling if it were at or below minimums, probably less than 1,000 feet over flat terrain for any IAP application.
2. Reports from pilots within 20 minutes of commencing an instrument procedure can also be useful in determining the cloud ceiling height for use in decision-making.
12.1.4 Cloud Types. The observer may, at the discretion of the operator, report the type of clouds (e.g., cumulus, stratus, etc.) constituting a ceiling as well as the presence of towering cumulus clouds in the area. The observer should provide the cardinal heading(s) from the airport toward the towering cumulus clouds and any observed direction of movement of those clouds. This may require the use of a compass.
12.2 Determining Visibility. The observer should also estimate visibility at the airport in the direction from which an arriving aircraft will approach, if known. In other words, if an aircraft will be landing on Runway 36, the observer should assess visibility to the south of the airport and on the airport.
12.2.1 Surface Visibility. Observers can estimate surface visibility in a variety of ways. The most common estimating technique is based on measured distances between the observation location and known objects, such as the peak of a ridgeline, towers, tree lines, buildings, etc. Operators may choose to erect markers, such as painted plywood panels, that are easily visible at known distances corresponding to IAP visibility minimums. Bear in mind, however, that the objective of observing visibility is to communicate the estimated visibility to a pilot to help the pilot determine whether the minimums for the relevant instrument approach are met.
12.2.2 Visibility Chart. Operators can develop a visibility chart for a noncertified weather observer to use as an aid for determining visibility around the airport. This chart should be posted near and centered at the point from which one observes visibility. This chart should list or otherwise indicate the location of all visibility markers, their distance from the station, and whether they are daytime or nighttime markers. It is also very important that the operator maintains and distributes this type of visibility chart.
12.2.2.1 Figure 1, Sample VFR Visibility Chart, shows an example of a visual flight rules (VFR) visibility chart. An IFR chart may have only a few markers at or slightly beyond the minimum visibility required for each IAP as viewed from the center observation point on the airport, or from the end of the runway in use beyond the approach end of the runway served by the approach.
12.2.2.2 When estimating IAP visibility minimums, do so from a common point on the airport or very close to the approach end of the runway in use. Bear in mind that the observer is estimating whether visibility meets or exceeds IAP minimum visibility, which is generally less than 2 miles; therefore, visibility targets should be sufficiently large so that an observer can see them at that distance in typical low lighting.
Figure 1. Sample VFR Visibility Chart
12.2.2.3 Another visual aid would be a set of photos that depict known landmarks or locations of panels corresponding to the minimum visibility, a point beyond, and a point closer to the observer.
12.3 Determining Windspeed and Direction. At airports without an automated windspeed and direction device such as an anemometer, estimates of wind direction and speed may be based upon the response of a calibrated windsock to wind or the appearance of wind effects on water, smoke, or vegetation (refer to the Beaufort Wind Scale). An observer may estimate wind direction based upon the required windsock, wind tee, or tetrahedron as available at the airport.
12.3.1 Windsocks. A limp windsock indicates calm air. A windsock that is fully extended alerts you of significantly windy conditions. A windsock should move freely about its vertical shaft and indicate the true wind direction within 5 degrees (plus or minus) when subjected to wind of 3 knots or more. A fully extended windsock should indicate surface wind of at least 15 knots. Therefore, a windsock that partially extends and fully extends, in an alternate manner, indicates gusting conditions with gusts up to or exceeding 15 knots. Windsocks that meet these specifications are available from a number of vendors.
12.3.2 Appearance of Wind Effects On Land.
Wind (mph) Appearance of Wind Effects On Land < 1 Calm, smoke rises vertically 1–3 Smoke drift indicates wind direction, wind vanes are still 4–5 Wind felt on face, leaves rustle, wind vanes begin to move 6–9 Leaves and small twigs constantly moving, light flags extended 10–14 Dust, leaves, and loose paper lifted, small tree branches move 15–18 Small trees in leaf begin to sway 19–23 Larger tree branches moving, whistling in wires 24–29 Whole trees moving, resistance felt walking against wind 30–35 Twigs breaking off trees, generally impedes progress 36–41 Slight structural damage occurs, slate blows off roofs Note: In the absence of being able to provide a magnetic direction from which the wind is coming, observers should advise the pilot of which runway the wind favors and an estimation of the windspeed.
12.4 Other Significant Weather Characteristics.
12.4.1 Precipitation. Precipitation in any form poses a potential threat to safety of flight. The observer should warn the pilot via their observation report of any precipitation, such as snow, snow pellets, ice pellets, hail, mist, drizzle, or rain, along with the intensity of the precipitation. The observer should also warn the pilot of any form of precipitation that indicates freezing of liquid water on exposed surfaces or aloft in the lower atmosphere
(i.e., freezing mist, drizzle, rain, or ice pellets) occurring on or near the airport. Methods of determining precipitation intensity may be found in the AMS Glossary of Meteorology under the term “rain.”
12.4.2 Altimeter Settings/Barometric Pressure. If no local altimeter setting source for the destination airport is available, the pilot may use the current altimeter setting that the facility designated on the approach chart for the destination airport provides.
12.4.3 Thunderstorms. The observer should also provide reports of the presence of any thunderstorm within 5 miles of the airport to the pilot along with any observed direction of movement of the storm, if possible. One can determine the approximate distance to the storm by counting the number of seconds between the flash of lightning and the sound of thunder. Divide the number of seconds by five to arrive at the approximate distance of the storm in miles.
13 USE OF WEATHER CAMERAS. Weather cameras can provide information relative to ceilings and visibility based on reference points or other data.
13.1 Operator-Provided Weather Camera. An operator can use weather camera images to determine visibility and, when adequate references are available, the height above the airport of the bases of clouds. Operators should position weather cameras where there is a clear view of the approach end of the airport and ceiling and visibility landmarks.
Cameras can be hard-mounted, mounted on a rotator, or handheld, provided the individual holding the camera always aims the camera in a known and consistent manner.
Weather camera image interpretation methods should be based upon photographic comparison standards. The operator should provide the observer interpreting the weather camera images or images from the operator’s own camera with master images of key landmarks and features that must be visible to assess ceiling and visibility and should provide the interpreter with sufficient resolution and visual references to estimate whether the instrument approach weather minimums are met or exceeded. Operators should exercise caution when utilizing weather camera images, as wind direction and speed and approaching adverse weather may not be observable or accurately assessed.
13.2 FAA Weather Cameras. FAA weather camera imagery, aviation and weather data, flight planning and weather monitoring tools, and other resources for pilots, weather forecasters, and noncertified weather observers are available on the FAA WeatherCams website at https://weathercams.faa.gov. Pilots, forecasters, and noncertified weather observers may choose to utilize this tool to provide information related to cloud ceiling heights and visibility.
9 14 COMMUNICATIONS. The pilot should receive communications regarding weather observations either directly or through an operations controller or other company facility that will relay the appropriate information via radio, satellite phone, or other reliable means. The noncertified weather observer should estimate this information based on observations made or images captured within 30 minutes prior to departure and again within 30 minutes prior to the scheduled arrival of the flight at the destination, or when the weather is observed to change from at or above IAP minimums to below IAP minimums, or the opposite case.
15 TRAINING REQUIREMENTS.
15.1 Training and Testing. Before submitting a request for authorization to use noncertified local weather observations at airports without a destination METAR, operators should develop an appropriate training program and ensure that personnel who will be making the weather observations are appropriately trained on the topics outlined in paragraphs 12 and 13 above.
15.2 Training Topics. The FAA expects noncertified weather observation techniques may vary from destination to destination, depending upon the availability of natural terrain and landmarks.
15.2.1 Operators should base training on the accepted documented method for each location and should include repeatable and consistent methods of estimating:
• Whether cloud base height is at or above/below IAP minimums and cloud types;
• Whether visibility is at or above/below IAP minimums;
• Windspeed and direction;
• Types and intensities of precipitation; and
• Distance to thunderstorms.
15.2.2 The operator should provide training to weather observers about the following, consistent with the observer’s responsibilities:
• Use of radio communication equipment and uniform noncertified weather reporting phraseology;
• Care and routine preventative maintenance and calibration verification (as appropriate) of any instruments, equipment, or photos, maps, or charts used;
• Requesting replenishment of supplies or replacement equipment, charts, maps, or comparison standard photos; and
• Circumstances under which the observer may not be able to provide accurate noncertified weather observations based upon missing, broken, or uncalibrated tools, instruments, or other equipment and comparison standards.
15.3 Recurrent Training and Testing. Operators should conduct recurrent training annually and emphasize those areas where pilots observe significant differences between reported weather and weather conditions experienced on each approach. As part of the procedures for en route and destination weather evaluation and for the purpose of continued refinement of noncertified weather reports, the operator should record and analyze differences between noncertified weather estimates provided by the noncertified weather observer and weather observed by the pilot.
16 DOCUMENTATION OF PROCEDURES. Operators using these procedures for en route and destination weather evaluation should document the procedures and incorporate those documented procedures into the GOM or other similar manual or resource the operator maintains so that pilots and noncertified weather reporting personnel use consistent methods for both requesting and providing weather information.
Those not required to have a GOM should ensure that personnel who will provide noncertified weather information are trained in the appropriate subject areas and provide their observers and interpreters with appropriate references as needed to ensure consistency in estimates from time to time and from observer to observer.
17 APPLICATION FOR NONCERTIFIED WEATHER OBSERVATIONS. Under 14 CFR § 135.213, the Administrator may approve operations that utilize weather information from a noncertified source. Appendix A, in accordance with Section 322 of the FAA Reauthorization Act of 2018 and Section 339 of the FAA Reauthorization Act of 2024, to this AC provides an optional standardized template for a CH’s application to use weather information from noncertified systems. This template suggests CHs list applicable procedures, training, and other items of consideration for the Administrator’s consideration for approval to use weather information from a noncertified source.
18 AC FEEDBACK FORM. For your convenience, the AC Feedback Form is the last page of this AC. Note any deficiencies found, clarifications needed, or suggested improvements regarding the contents of this AC on the Feedback Form.
R obert Reckert for Hugh Thomas Acting Executive Director, Flight Standards Service
Appendix A A-1 APPENDIX A. APPLICATION TEMPLATE FOR 14 CFR PART 135 NONCERTIFIED
WEATHER OBSERVATIONS IN NONCONTIGUOUS STATES Application Template for 14 CFR Part 135 Noncertified Weather Observations in Noncontiguous States A Operator Information 1 Name of Operator:
2 Operator Code:
3 Certificate No.:
B Operator Contact 1 Address:
2 Point of Contact (Name):
3 Phone Number:
4 Email Address:
C Operator Aircraft 1 Aircraft Make, Model, Series 2 Registration Numbers:
3 Number of Aircraft:
D Safety Assurance Office 1 Office:
2 Address:
E Certificate Management Team (CMT) 1 Operations:
2 Maintenance:
3 Airworthiness:
Authorization of Noncertified Weather in Noncontiguous States Procedures, Training, and Documentation Description of Procedure (if applicable) and the Location in the General Operations Manual (GOM) and Training Program (Indicate Manual/Revision/Page Number) A Operational Procedures 1 Describe the location(s) of operations:
1.1 Location of noncertified weather observations (airport ID(s)).
Appendix A A-2
1.2 Estimated number of flights to destination airports specified in 1.1 above (indicate number of operations per location if more than one location is approved).
2 Describe the conditions in which operations would occur under instrument flight rules (IFR) to a destination in a noncontiguous state that has a published instrument approach but does not have an Aviation Routine Weather Report (METAR); and to conduct an instrument approach at such destination if:
• A current Area Forecast (FA) or Graphical Forecast for Aviation (GFA), supplemented by noncertified destination weather observations (such as weather cameras and other noncertified observations), is available, and, at the time of departure, the combination of the FA/GFA and noncertified observation indicates that weather is expected to be at or above approach minimums upon arrival;
• Prior to commencing an approach, the air carrier has a means to communicate to the pilot of the aircraft whether the destination weather observation is either at or above minimums for the approach to be flown; and
• A suitable alternate airport that has a METAR is specified in the IFR flight plan.
3 Departure.
4 Specifically describe the weather information technique(s) to be utilized and how any noncertified human observations will be conducted. Describe how such observations will be communicated to the operator prior to dispatch, and how the weather information will be communicated to pilots prior to commencing the instrument approach. Considerations for the determination of whether the approach and/or departure is at or above the approach minimums prescribed for the procedures include:
4.1 Visibility.
4.2 Cloud ceiling height (examples include terrain features or cultural (man-made) landmarks, temperature/dewpoint spread, other).
5 The operator may also choose to include information that is utilized to determine the following: