Appendix D, STOP for Operations in a Noncontiguous State D-1
Appendix D Special Terminal Operation
Procedures (STOP) for Operations in a
Noncontiguous State
D.1 Introduction
Air carriers often need to release flights to locations with missing weather reports (e.g., surface observations
such as METAR), missing elements of weather reports, or locations that do not have an ASOS or AWOS
facility or human weather observers.
The STOP program is designed for 14 CFR part 121 domestic and supplemental operations at airports in a
noncontiguous state (e.g., Alaska) without a complete surface observation and/or forecast.
This guidance provides acceptable methods and guidelines for the certificate holder (CH) to use to develop
the STOP program. The Aviation Safety Inspector—Aircraft Dispatch (ASI-AD) and the POI may refer to
this guidance as they review 14 CFR part 121 domestic or supplemental operat ions conducted in a
noncontiguous state to airports with no METARs, missing METAR elements, or n o weather reporting
facilities.
D.2 Weather Information
D.2.1 General
In accordance with 14 CFR § 121.599(a), no aircraft dispatcher may release a flight unless thoroughly
familiar with reported and forecast weather conditions on the route to be flown. Title 14 CFR § 121.601
requires the aircraft dispatcher to provide the PIC with all available current reports or information on airport
conditions and irregularities of navigation facilities that may affect the safety of the flight. Title 14 CFR
§ 121.601 applies to every phase of flight. In accordance with 14 CFR § 121.599(b), no PIC may begin a
flight unless thoroughly familiar with reported and forecast weather conditions on the route to be flown.
Title 14 CFR § 121.597 refers to the individuals authorized by the CH to exercise operational control over
the flight and to execute a flight release setting forth the conditions under which the flights will be
conducted.
IFR operations under 14 CFR part 121 require current weather reports and forecasts. Those approved
sources are official surface observation (e.g., METAR) and a TAF. If no NWS TAF is available, an
approved EWINS TAF may be used. Refer to FAA Order 8900.1 Volume 3, Chapter 26, Section 4 ,
Enhanced Weather Information Systems, for additional information about EWINS.
Landing limitations and aircraft performance require a CH to consider forecast (anticipated/probable) winds
at the destination airport. Therefore, weather forecasts that include wind information for the destination
airport are always required.
D.2.2 Supplements to NWS or EWINS TAFs
The AAG forecast product provides TAF-like information for locations where an NWS or EWINS TAF is
not available at the intended destination in Alaska. The AAG is intended for use under visual meteorological
conditions (VMC). Operators conducting operations under 14 CFR part 121 cannot use the AAG at alternate
airports. The AAG is also limited for flight times of two hours or less in duration. The AAG, in conjunction
Appendix D, STOP for Operations in a Noncontiguous State D-2
with METARs, PIREPs, the FA, SIGMETs, and AIRMETs, helps inform operators of the weather
conditions at the ETA and whether those conditions will be at or above the minimums, which determines
whether operations can be conducted within the performance limitations of the aircraft per
14 CFR § 121.101. In addition, the AAG does not indicate blowing snow or convective activity. If
precipitation is forecasted, other products, including SIGMETs and NEXRAD weather radar, where
available, can determine if hazardous convective weather will be present when the aircraft arrives. InFO
20002 provides more information on the AAG.
Table D-1 lists weather products that supplement NWS or EWINS TAFs.
Table D-1. Weather Products to Supplement NWS or EWINS TAFs
Weather Product
Location in
Handbook
(Section)
Website
AIRMET 26.3 https://www.weather.gov/aawu/airmets
https://www.weather.gov/aawu
Alaska Aviation Guidance (AAG) 27.16.1 https://www.weather.gov/arh/aag
Alaska
Graphical
Forecasts
AAWU Flying Weather 27.7.1
https://www.weather.gov/aawu/#map
Alaska Surface Forecast 27.7.2
Alaska Icing Forecast 27.7.3
Alaska Turbulence
Forecast 27.7.4
Alaska Convective Outlook 27.7.5
Alaska Significant Weather Forecasts 27.9.4 https://www.weather.gov/aawu/4panelsigwx
Area Forecast (FA)1 27.6 https://www.weather.gov/aawu/areaforecasts
Center Weather Advisory (CWA) 26.4 https://aviationweather.gov/gfa/#cwa
FAA Aviation Weather Cameras 24.9 https://weathercams.faa.gov
Graphical Forecasts for Aviation (GFA) 28.2 https://aviationweather.gov/gfa
Localized Aviation Model-Output
Statistic (MOS) Product (LAMP) 27.16 https://vlab.noaa.gov/web/mdl/lamp
Pilot Weather Reports (PIREP) 24.5.1 https://aviationweather.gov/data/pirep
Real-Time Mesoscale Analysis (RTMA) 25.7 https://nomads.ncep.noaa.gov/pub/data/nccf/com/rtma/
prod/airport_temps
Runway Visual Range (RVR) 24.4.3.7 https://rvr.data.faa.gov/cgi-bin/rvr-status.pl is the status
monitor site
Appendix D, STOP for Operations in a Noncontiguous State D-3
Weather Product
Location in
Handbook
(Section)
Website
SIGMET 26.2 https://www.weather.gov/aawu/sigmets
https://aviationweather.gov/gfa/#sigmet
Surface
Observations2
METAR 24.4.1
https://www.weather.gov/aawu/obs
https://www.weather.gov/aawu
SPECI 24.4.2
ASOS 24.3.1
AWOS 24.3.2
Notes:
1. An FA alone, without a valid TAF, is not an acceptable standalone forecast to satisfy the relevant
14 CFR part 121 weather reporting requirements. The FA is not intended for use in operat ional
decision making or as a substitute for a TAF. However, the FA may provide vital weather
information for the entire en route portion of flight, from point of origin to destination and all
applicable alternates.
2. Aircraft performance is predicated on aircraft weight, ambient temperature, wind direction, wind
speed, and altimeter setting. In order to ensure aircraft takeoff and landing limitations are met and
obstacles are avoided, a surface observation contains at least the following elements:
• The station identifier (e.g., airport code),
• Date and time of observation (to establish relevance of the report),
• Ambient air temperature at the station (e.g., airport or seaport),
• Wind speed and direction,
• Altimeter setting at the station (unless the current published approach plate lists an
alternate source),
• Visibility (for obstacle avoidance and IAPs), and
• Ceiling.
D.2.3 Manual Surface Observations by Flightcrews Using a Portable Weather
Observation Device at STOP Airports
D.2.3.1 Portable Weather Observation Device
A portable weather observation device is issued to the flightcrews who conduct STOP flights as part of the
preflight preparation. An acceptable portable weather observation device provides the following:
1. Date and time
2. Wind direction (degrees magnetic north)
3. Wind speed (knots)
4. Temperature (°C)
5. Dewpoint temperature (°C)
6. Altimeter or pressure (inHg)
Appendix D, STOP for Operations in a Noncontiguous State D-4
Note: Apply the appropriate variation to get the wind direction in true north, which is needed for
documentation and reporting.
Calibration of the device is done in accordance with the manufacturer’s procedures. A log with the date of
last battery change, latest calibration date, the result (satisfactory or unsatisfactory) , and the name of the
individual who performed the calibration should be kept with the device.
D.2.3.2 Visibility Estimation by the Pilot
Estimates of visibility can be made using the runway length (e.g., a 5,300-ft runway is 1 SM, geographical
features or prominent obstructions at a known distance, markers placed for the purpose of measuring
distance visually or with FAA cameras).
D.2.3.3 Ceiling Estimation by the Pilot
Ceilings can be estimated using geographical features or prominent obstructions of a known elevation of
height. Ceilings can be estimated using:
• Known geographic points;
• The conditions on arrival, provided they have not radically changed; and
• Temperature/dewpoint spread, which is the difference between the temperature and dewpoint,
divided by 2.5, multiplied by 1,000.
o If the temperature is 18°C and the dewpoint 9°C, a difference of 9°C exists.
o This result indicates that the lowest cloud layer should be 3,600 ft AGL.
o Comparing this to a visual assessment, the forecast (TAF (NWS or EWINS)), and PIREPs
(your own on arrival or provided by other aircraft) should provide reasonable estimated
ceiling information.
D.2.4 Documentation and Reporting
Prior to departure, the PIC records all required elements on the weather record log, then communicates with
the responsible aircraft dispatcher or flight follower. A mutual agreement is achieved on these conditions
for a flight release. In this process, th e PIC advises, and the aircraft dispatcher records the following
information:
• Station identifier.
• Date and time.
• Wind direction (degrees true north).
• Wind speed (knots).
• Visibility (SM).
• Ceiling (BKN, OVC).
• Temperature (°C).
• Dewpoint temperature (°C).
• Altimeter (inHg).
This information is part of the dispatch and flight release documents and is retained in the company’s
three-month retention file.
Appendix D, STOP for Operations in a Noncontiguous State D-5
D.3 Airport Data
D.3.1 Data Maintenance
All airports and runways on which STOP operations are conducted are documented in the CH’s Safety
Assurance System (SAS), which is maintained and updated by active surveillance.
D.3.2 Airport Analysis Program
For airports that do not appear in the Alaska Chart Supplement, the CH uses an airport analysis program to
ensure the facility is adequate for the proposed STOP operation. This may require a full airport risk
assessment, strip check , or airport condition report to be completed. If the airport appears in the Alaska
Chart Supplement but runway conditions are not monitored, only the runway contaminants section of the
strip check or an airport condition report is completed. The CH determines how this will be accomplished
and requests the POI’s approval.
For airports not listed in the Alaska Chart Supplement, or non-14 CFR part 139 in the State of Alaska only,
the airport risk assessment, strip check, or airport condition report includes airport pictorials to familiarize
the flightcrew with the area. Suitable pictorials include pictures taken from the air or from the ground,
satellite pictures, and excerpts from aeronautical charts, etc.
Flight operations to airports with weather reporting deficiencies are thoroughly evaluated to ensure the
facility is adequate for the proposed operation. For all STOP flight operations to temporary runways (frozen
bodies of water or flat open terrain), the CH may need to accomplish a physical, onsite inspection of the
runway and facilities and complete the company’s documented report.
The dispatcher, flight follower , and flightcrew member use the completed airport analysis, airport risk
assessment, strip check, or airport condition report during the crew briefing. If during the crew briefing the
PIC, dispatcher, or flight follower determines the conditions at the destination airport are not adequate for
safe operations, the flight is not released.
D.3.3 Civil Twilight Considerations
Flight operations to airports with weather reporting deficiencies are initiated unless the ETA and estimated
time of departure falls within the hours of the start of morning civil twilight and the end of evening civil
twilight. Dispatchers or flight followers note these hours in the “Remarks” section of the dispatch or flight
release.
Civil twilight is determined by the following U.S. Military database:
https://aa.usno.navy.mil/data/RS_OneYear.
Night operations may be authorized if the airport is equipped with lighting at least equivalent to medium
intensity edge lights (easily identifiable as lighting during daylight conditions). No operations outside the
start of morning civil twilight and the end of evening civil twilight will be conducted where this lighting
standard is not met.
The flightcrew determines the wind direction from an illuminated wind direction indicator or ground
communications before landing.
If temporary lighting (e.g., flare pots) are used, they are evenly spaced on each side of the runway, to replace
at least 50 percent of the normal lights. If permanent lighting is not installed at the airport, the temporary
light spacing is 200 ft apart. Four lights are placed at each runway end to clearly mark the threshold and
runway end. Lights are turned on 30 minutes prior to arrival and for 30 minutes after departure.
Appendix D, STOP for Operations in a Noncontiguous State D-6
The Director of Operations (DO) , PIC, dispatcher , or flight follower should agree that the lighting is
adequate for the proposed operation, with the approval by the DO or designee annotated on the flight
release. Temporary lighting may be placed and illuminated by qualified company personnel who are
familiar with these procedures.
D.4 Flight Planning
D.4.1 General
Flight operations to airports with weather reporting deficiencies are operated under IFR with the exception
of operations in the terminal area. In the terminal area of the STOP airport, flightcrews maintain the basic
cloud clearance as specified in 14 CFR § 91.155 and maintain the minimum altitudes prescribed in 14 CFR
§ 91.126, § 91.129, § 91.130, or § 91.131, as applicable for the airspace class in which the flight is operated.
D.4.2 IFR Flight Plan
Both domestic and supplemental flights under STOP are planned as an IFR flight plan when the intended
flight is 50 NM or more from origin to destination.
D.4.3 Composite IFR/VFR Flight Plan
When the flight is to be greater than 50 NM but will exit the IFR structure within 50 NM of the destination
under VFR, a composite flight plan is filed. The IFR portion will change to a VFR transition point, at which
the PIC will activate the VFR flight plan.
D.4.4 VFR Flight Plan
Only to be used when the intended STOP flight is less than 50 NM from origin to destination. Only Group I
airplanes (propeller-driven, including reciprocating and turbopropeller -powered) operate under a 14 CFR
part 121 VFR flight plan.
Note: For a VFR flight, this distance will consider the route most likely to be flown. For example, a 50 NM
direct route would not be appropriate to consider i f high terrain would make point -to-point direct
impracticable. In this case, the flight would be released on an IFR flight plan.
D.4.5 Fuel Requirements
Domestic and supplemental STOP flights, regardless of aircraft type, are not released without considering
fuel to meet the requirements of 14 CFR § 121.647. This includes a landing area visual inspection (flyover)
of 15 additional minutes of the intended landing strip. This fuel is noted on the release in a manner which
is readily identifiable to the flightcrew. The CH determines according to aircraft type if an additional
15 minutes of fuel is sufficient or adjust s accordingly to accommodate a possible fly over pass of the
intended airstrip or airport.
D.4.6 Weather Minimums at STOP Destination Airports
The Administrator considers the ETA at the destination and the arrival minimums that are listed below to
contribute to mitigating risks and hazards to STOP destinations and will allow the CH to operate at the
highest level of safety. The aforementioned weather minimums apply even if the whole weather report is
missing or missing a required element.
Appendix D, STOP for Operations in a Noncontiguous State D-7
D.4.6.1 Domestic Operations
Forecast weather conditions one hour before and one hour after ETA at the STOP destination airport to be
at least a cloud ceiling of 3,500 ft above the airport elevation and visibility of 5 SM, and appropriate wind
velocity and direction.
D.4.6.2 Supplemental Operations
Forecast weather conditions 1 hour before and 1 hour after ETA at the STOP destination airport to be at
least a cloud ceiling of 3,000 ft AGL and visibility of 3 SM, and appropriate wind velocity and direction.
If the STOP destination airport has an approved IAP the required release minimums are a ceiling of 1,500 ft
above the airport elevation and visibility of 3 SM one hour before and one hour after ETA.
D.4.7 Required Destination Primary Alternate
A destination’s primary alternate is always included for both domestic and supplemental operations when
the STOP process is applied. It always includes the appropriate fuel requirements for the alternate. The
destination primary alternate must have a TAF and all required reporting elements of a METAR and meet
the air carrier’s alternate minimum requirements.
D.4.8 Designation of Secondary Destination Alternate
When weather conditions at the destination airport and the first alternate airport are marginal, 14 CFR
§ 121.619(a) requires that at least one additional alternate airport be designated. The term “marginal,” as
applied to domestic alternate minimums, is not defined by regulation. To some extent this is because the
definition of what constitutes marginal depends on the nature of the weather phenomena, the operation
conducted, and the equipment used.
If marginal conditions at the primary alternate are forecast, the CH must, per 14 CFR §§ 121.619, 121.623,
and 121.625, list a second alternate in the dispatch or ensure that the flightcrew is briefed prior to release.
When marginal conditions are present at destination and primary alternates, the secondary alter nate may
not be less than 2,000 ft above the airport elevation and the visibility must be at least 3 SM. Both the primary
and the secondary alternates must have a complete METAR and TAF at ETA.
D.4.9 Minimum Equipment List (MEL) Restrictions
When required by an MEL, flight operations to airports with weather reporting deficiencies are not to be
initiated with, or continue with, the following items deferred or inoperative:
• Any long-range navigation systems (LRNS) (e.g., GPS) that may be installed on the aircraft. In a
dual installation, one must be operational.
• OAT reporting system installed on the aircraft.
• One or both flight management system(s) (FMS).
• One or both radio altimeter system(s).
• Ground proximity system.
• Satellite voice communication available over the entire route and at any destination airport.