Cold Weather Operations - Boeing
AAVA – FLIGHT OPERATIONS MANUAL
COLD WEATHER OPERATIONS – BOEING 737 SERIES (73x)
FOR FLIGHT SIMULATION USE ONLY
1.0 GENERAL & AAVA APPLICABILITY
This sectionmanual definesapplies coldto weatherevery AAVA flight operated in this aircraft family, regardless of airline branding, callsign, codeshare, heritage, event, charter, passenger or cargo designation. All AAVA flights use the same Hub Operations winter operating framework based on American Airlines-style operational standardsstandardization; forno actual American Airlines proprietary SOP or regulatory operations-specification approval is implied.
Cold-weather awareness is condition-driven and applies all year, not only November–April. Evaluate icing conditions, frost, snow, freezing precipitation, airport and runway conditions, freezing fuel/clear ice, and delays. Temperature alone does not establish every anti-ice switch requirement.
Hierarchy: applicable aircraft-specific AFM/FCOM/QRH and addon limitations → applicable FAA fluid guidance/aircraft performance data → AAVA Boeingflight-operations 737procedures. seriesIf guidance conflicts, use the higher-authority aircraft (including 737-700/800/900 variants). Procedures reflect Boeing FCOM/FCTM guidancelimitation and simulation-appropriatenotify bestHub practices.Operations.
Cold weather operations apply when any of the following exist:– OAT/TAT at or below 10°C– Visible moisture (rain, snow, ice crystals, fog)– Frost or ice present on aircraft surfaces– Operations from contaminated taxiways or runways
The Clean Aircraft Concept applies at all times.
2.0 CLEAN AIRCRAFT CONCEPT & PRE-FLIGHT
An aircraft mustDo not departbegin unlesstakeoff allwith frost, ice, snow or slush on critical surfaces areunless freea specifically applicable aircraft-approved exception is established. The captain is accountable for the final departure decision. Ground treatment is not a substitute for verification.
Inspect wings (upper and leading-edge surfaces), tail, control surfaces, slats/flaps/fairings, engine inlets, probes, ports, sensors and other aircraft-designated critical areas. Include contamination from contamination.overnight exposure, freezing fog, ground spray and cold-soaked fuel.
TheTransparent Captainice iscan responsiblebe fordifficult confirmingto identify visually. Do not assume an overwing-window or flight-deck view reliably establishes the aircraftcondition isof cleanevery aftersurface. deicing/anti-icingUse an authorized ground or tactile inspection when necessary, and priordo tonot takeoff.invent a manufacturer frost exception.
2.1 CRITICAL SURFACES
The following must be free of frost, ice, snow, or slush:
– Wing leading edges, upper wing surfaces– Horizontal stabilizer, elevators– Vertical stabilizer, rudder– Slats, flaps, flap tracks– Engine inlets, spinner, fan blades– AoA vanes, pitot probes, static ports– Flight controls and fairings
2.2 CLEAN AIRCRAFT VERIFICATION
A Clean Aircraft Check is required when:– Frozen precipitation continues after deicing– Holdover time is near expiration– A delay occurs after deicing– Fluid effectiveness is uncertain
Verification may be completed from:– Flight deck (within HOT)– Cabin overwing windows (HOT expired or heavy precipitation)
Left wing root is used as the reference point (first area sprayed, oldest fluid).
3.0 GROUND DEICING / ANTI-ICING
3.1 OVERVIEW
Deicing removes contamination.Anti-existing contaminants; anti-icing protectsuses againstan furtherappropriate accumulation.fluid to protect previously clean surfaces from renewed contamination for a limited time. When frozen precipitation is falling or expected before takeoff, assess whether anti-icing protection is required in addition to removal.
ClearSAE coordination between Flight Crew and Ground Deicing Personnel is required.
3.2 APPROVED FLUID TYPES
Type I Fluid
typically –provides Hotshorter glycolprotection. mixture–Types UsedII, primarilyIII for deicing– Short holdover time– Smooth glossy appearance indicates active protection
Typeand IV Fluid
have –distinct Thickened,aerodynamic long-lastingacceptance, anti-iceaircraft-speed fluid–eligibility Appliedand afterfluid-specific Typelimits. I–Do Providesnot extendedpresume protection before takeoff– Designed to shear off during takeoff roll
3.3 HOLDOVER TIME (HOT)
Holdover Time begins when the final anti-icing application starts.HOT expires when thea fluid canis nosuitable longersimply preventbecause frozenit contamination.is available; apply aircraft and FAA fluid restrictions.
PrecipitationDeicing anticipatedonly: at application time affects HOT selection.
3.4 ENGINE & AIRFRAME CONFIGURATION
Engines Running Deicing
– May be conducted onlyuse when the spray zone is safe– Crew and Ground Team must coordinate carefully– If APU is inoperative, crew may shut down the engine on the side being sprayed– Perform crossbleed start after completion
Flaps During Deicing
The Boeing 737 uses flap angles (1°, 5°, 10°, 15°, 25°, 30°, 40°).
– For uniform protection, extend flaps to 15° prior to deicing when contamination on flap areas exists– If contamination is present on upper wing surfaces, extending to 15° does not risk damage– If flaps remain at 15° for flap-area contamination removal, do not retract until contamination is removed and the aircraft will stay clean to takeoff. One-step deicing/anti-icing: use only where fluid/application conditions produce an applicable valid HOT. Two-step: remove contamination and apply a compatible anti-icing fluid when continued protection is needed. Where degraded fluid exists, use the applicable removal/re-treatment procedure, not a simple top-off.
3.1 Ground crew coordination
1. Confirm aircraft identifier, location, contamination and weather conditions, type of treatment requested, and estimated taxi/departure delay.
CAUTION:Retracting2. flapsCoordinate belowrequired 15°aircraft withflap/slat contaminationposition, presentengine/APU canand causepneumatic flapconfiguration, trackwindows/doors, damage.truck clearances, anti-collision lights and safety zone using the exact aircraft-specific procedures.
3. Receive fluid type/brand, mixture/concentration, final application start time and confirmation that treatment and post-treatment checks are complete; record them for the departure decision.
4. Do not taxi until the ground team reports clear personnel/equipment and the crew completes the applicable after-treatment checklist.
4.0 IN-FLIGHTFAA ICINGWINTER OPERATIONS2026–2027 HOLDOVER / ALLOWANCE TIMES
The separately distributed FAA Holdover Time Guidelines for Winter 2026–2027 (original issue 11 August 2026) and the companion FAA Ground Deicing Program General Information are the controlling reference for table selection. Hub Operations must check for revised editions. Notice 8900.784 describes this winter’s FAA program.
HOT begins with the start of the FINAL deicing/anti-icing step for a two-step treatment (or the start of the applicable one-step treatment), as specified by the FAA guidance. It is an estimated protection interval, not a certification that the aircraft remains clean.
Select the proper table using SAE fluid type, tested fluid brand, concentration, aircraft-material category where applicable (particularly Type I aluminum versus composites), temperature and precipitation. Follow table notes, lowest operational use temperature and aircraft-speed restrictions. Degree-specific HOT may be available under the FAA program.
Check the current precipitation and temperature before departure. If precipitation intensity/type changes, temperature decreases, or an unexpected delay occurs, reassess the validity of the selected protection. No published HOT means no assumed HOT.
Allowance times for ice pellets/small hail are distinct from normal HOT; they depend on eligible validated fluids and precise FAA conditions. Do not use a visual cabin check to create an unlimited extension. Heavy snow and particular freezing precipitation may have no HOT: follow the current FAA limitation and authorized inspection/re-treatment path.
4.1 Pre-takeoff contamination decision
5. Confirm treatment completion, ground crew clearance and clean-aircraft inspection status.
6. Update airport weather and identify the precise precipitation type/intensity and temperature.
7. Confirm applicable fluid data and that the correct FAA table, notes and HOT/allowance logic remain valid.
8. Perform any required aircraft-specific pre-takeoff check or pre-takeoff contamination check, by authorized person/method and within the applicable time requirement.
9. If critical surfaces cannot be confirmed clean, no permitted protection path exists, or the condition changed beyond current guidance: do not depart; inspect and/or re-treat.
5.0 CONTAMINATED RUNWAY & FLIGHT PLANNING
Before takeoff and landing, review reported runway condition, runway condition codes (RWYCC) when available, precipitation depth/type, braking-action reports, runway length and slope, crosswind, and available aircraft-specific performance calculation. A dry-runway calculation must not be treated as a contaminated-runway result.
Evaluate delays and alternate/diversion planning. Landing distance margins and takeoff power/flap choices are model-specific; “maximum thrust for all contaminated runways” and a universal reverse-thrust reduction speed are not reliable substitute procedures.
A slippery rejected takeoff or landing requires the aircraft-specific braking, directional-control and reverse-thrust technique. Follow the specific FCOM/QRH rather than a blanket rudder/braking speed threshold.
6.0 BOEING 737 ENGINE ANTI-ICE
Use the engine anti-ice system whenever the applicable 737 variant FCOM requires it for ground or flight icing conditions. Assess temperature, visible moisture, snow/slush/standing water and indications of possible icing. A broad “10°C plus visible moisture” reminder is not a complete or universally sufficient switch procedure.
Identify engine type and flight phase (NG versus MAX) before applying takeoff thrust limitations, bleed or anti-ice configuration. Engine anti-ice operation can change thrust and performance. Review checklist indications and restrictions for the actual model.
Under prolonged taxi or low-thrust flight in icing, engine ice-shedding run-ups may be required. Their trigger, frequency, N1 and duration are not interchangeable between CFM56-equipped NG and LEAP-equipped MAX; perform ONLY the exact model-specific FCOM/QRH run-up and clearance procedure. Do not treat legacy “70–80% N1 every 15 minutes” or “50% N1 for five seconds” as fleetwide requirements.
7.0 BOEING 737 WING ANTI-ICE OPERATION/ FLIGHT IN ICING
BoeingIdentify WAIwing mayicing beconditions and operate wing anti-ice as directed by the actual NG/MAX FCOM. Some procedures respond to observed icing and some require preventive use; do not reduce system activation to “wait for visible ice” or apply a generic below −40°C SAT exception without flight-phase/aircraft context.
Monitor ice accretion, cockpit/airframe indications, engine vibration and aircraft performance. Evaluate severe icing and abnormal handling using appropriate non-normal guidance; continued operation in conditions outside aircraft limits is not permitted under the simulation standard.
Review icing impacts on minimum speeds, climb/approach margins and fuel/performance calculations when specified by aircraft documentation.
8.0 BOEING 737 DEICING CONFIGURATION, ARRIVAL & POST-LANDING
The historic 737 material identified flap-area ice as a hazard during flap retraction and used flap-15 positioning for certain treatments. Keep the requirement to identify and clear contamination, but use the exact NG/MAX FCOM and ground deicing instructions to select flap position and timing; flap 15 is not a blanket setting for all deicing.
Configure engines, APU, packs, bleeds, flight controls, flaps and anti-ice for spraying using the actual aircraft checklist and ground provider instructions. Do not introduce a crossbleed engine start or control-column cycling merely because it appeared in twoan ways:earlier generic checklist.
Primary
For Methoddescent, —approach Deicerand Mode
Activateapply WAIthe whenmodel-specific engine/wing anti-ice requirements and contaminated-runway performance. After landing in freezing conditions, inspect for ice in flap tracks/fairings and follow the actual manufacturer flap retraction limitation; no unqualified “keep flaps at 15°” rule is observedissued on:–in Windowthis frames–edition.
9.0 arms
–SIMULATION Side& windowOPERATING posts
–LIMITATIONS
For leadingsimulators edgesthat model deicing, icing or runway braking, pilots must use the installed aircraft procedures and simulation limitations. If the platform does not model ground-fluid protection, simulate the realistic decision and paperwork sequence; a logged HOT does not create actual simulator protection.
This method:–manual Producesprovides cleanAAVA leadingoperational edges–expectations, Minimizesnot runbackreal-world ice–dispatch Reducesauthority fuelor an alternative to manufacturer-approved guidance. Do not apply a procedure from one aircraft engine or generation to another without verification.
10.0 REFERENCE CONTROL
FAA Holdover Time Guidelines, Winter 2026–2027, original issue 11 August 2026 (supplied separately; check for updates): https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/deicing/
FAA Notice 8900.784, 3 August 2026: https://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.information/documentID/1045444
FAA AC 120-60B, Ground Deicing and Anti-icing Program: https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/23199
Aircraft-specific Boeing FCOM/QRH and applicable simulator developer procedures (model/engine dependent).
AAVA Cold Weather Operations baseline and Hub Operations Deice/Anti-Ice Procedure / Winter Operations Reference Card. Standards apply across all AAVA operating divisions.
11.0 CHANGE RECORD
2026–2027 edition: separated general FAA ground-icing and contaminated-runway requirements from aircraft-specific cockpit settings; removed unsupported fleetwide N1, flap and thrust penalties
Secondaryadded MethodFAA —2026–2027 Anti-Icer Mode
Use WAI before ice accumulation during prolonged exposure in moderate or severe icing.
General Notes
– WAI is unnecessary below –40°C SAT– Turn WAI OFF when clear of icing– Avoid prolonged icing operation with flaps extended
5.0 ENGINE ANTI-ICE (EAI)
EAI must be used when:– OAT/TAT ≤ 10°C and visible moisture exists– Ice is detected or suspected– Conditions conducive to icing exist
Indicators of engine icing:– Fan vibration– Increasing EGT at constant thrust– N1/N2 instability– Engine spool-up sluggishness
Use ENGINE ANTI-ICE switches ON as required.
6.0 DESCENT IN ICING CONDITIONS
When descending or holding in moderate or severe icing with low thrust:
Every ~15 minutes:– Increase thrust on each engine separately to a minimum of 70–80% N1– Maintain increase for several seconds
This sheds ice from:– Spinner– Fan blades– Inlet lips
7.0 APPROACH, LANDING & CONTAMINATED RUNWAY OPERATIONS
7.1 FLAP RETRACTION AFTER LANDING (BOEING 737)
If ice accumulation is present after landing:– Do not retract flaps below 15°– Maintain flaps at 15° until ice is removed from:– Flap surfaces– Tracks– Fairings
Once contamination is removed, flaps may be retracted to UP.
7.2 REVERSE THRUST USE
On slippery or contaminated runways:– Use reverse thrust as required for a safe stop– Reduce reverse thrust smoothly below 60 kt, depending on deceleration rate
7.3 TAKEOFF FROM CONTAMINATED RUNWAYS
– Use maximum takeoff thrust– Within 5 minutes of takeoff:– Perform an engine run-up to ~50% N1 for at least 5 seconds– Confirm stable engine operation– During a rejected takeoff, rudder provides primary directionaldocument control toand approximatelyexplicit 60inspection/re-treatment ktdecision process; preserved aircraft-specific operational topics.
7.4 SAFETY PRIORITY
During landing or a rejected takeoff in contamination:Stopping the aircraft is always the highest priority.