Adverse weather introduces severe safety and operational hazards for ground handlers, line maintenance engineers, and flight crews. Modern airports manage these threats through a phase-based Adverse Weather Event Plan (AWEP). Using Airport Collaborative Decision Making (A-CDM), apron control coordinates with airlines to scale back operations, secure assets, and prioritize personnel safety.
Ramp safety protocols are strictly dictated by the specific weather category. Below are the mandatory operational guidelines for handling adverse weather on the tarmac.
1. High Winds & Cyclonic Storms
High surface winds create high-velocity Foreign Object Debris (FOD) and equipment displacement hazards. Operations must be modified when sustained winds or gusts approach structural thresholds (typically 40 knots for standard equipment, lower for high-profile vehicles).
Aircraft Securing & Mooring
- General Aviation (GA): Light aircraft are highly susceptible to wind-flipping. Moor them immediately using heavy mooring stones or permanent ground tie-downs.
- Turboprop Safety: Never approach a turboprop aircraft in high winds until the propellers have completely stopped. Secure the propeller blades by lacing to prevent uncommanded wind-milling.
- Bridge-Mounted Equipment: Ground Power Units (GPU) and Pre-Conditioned Air (PCA) hoses must be rolled back and safely stowed immediately after disconnection to prevent them from swinging into the fuselage.
Ground Support Equipment (GSE) Securing
- High-Profile GSE Limits: Operations utilizing scissor-lift mechanisms (catering trucks, ambulifts, and main-deck cargo loaders) must be suspended and the vehicles lowered when wind gusts reach 25 to 30 knots. Lateral wind force can tip these vehicles into the airframe.
- Step Ladders: Discontinue passenger boarding or disembarking via step ladders during strong surface winds. Step ladders must be lowered, parked safely, and stabilized with jack plates.
- Cargo & ULDs: Fasten cargo pallets securely to dollies or stack them using lacing. Lock all Unit Load Devices (ULDs) onto racks or dollies.
- Equipment Braking: Park all ramp vehicles with handbrakes strictly ON. Engage jack plates and use heavy-duty chocks to stabilize non-motorized equipment on the apron.
- Ramp Debris (FOD): Ground personnel must retrieve and secure all unattended equipment. Anchor all garbage bins to designated hooks using chains. Avoid walking or driving on the apron unnecessarily during extreme gusts.
2. Thunderstorms & Tarmac Lightning Safety
Lightning is a direct, fatal threat to ground personnel. Airports utilize a phased alert system based on lightning proximity:
- Phase 1 (Yellow Alert – Lightning in the Vicinity): Triggered when lightning is detected within 5 to 8 miles. Non-essential open-ramp activities scale down.
- Phase 2 (Red Alert – Lightning on Station): Triggered when lightning is within 3 miles. All ramp operations must stop immediately.
- Aircraft fueling is strictly suspended. Fuel hoses must be disconnected.
- Ground personnel must disconnect wired communication headsets from the aircraft.
- All personnel must take shelter inside terminal buildings or fully enclosed, metal-topped vehicles.
3. Winter Weather: Snow, Ice, & Deep Freeze
Freezing conditions require operations focused on preventing contaminant accumulation on aerodynamic surfaces and protecting mechanical systems.
- Chocks vs. Brakes: Aircraft parked for extended periods in freezing rain or snow must rely entirely on chocks placed on both sides of the main gear wheels. Do not leave the aircraft parking brake ON, as brake assemblies can freeze directly to the rotors, rendering the aircraft immovable.
- Sensor Protection: Line maintenance engineers must install covers for pitot tubes, static ports, and engine inlets immediately upon block-in to prevent instrument blockages from ice accumulation.
- De-Icing Zones: Ground equipment must remain clear of designated de-icing pads to allow specialized fluid trucks safe maneuvering space.
4. Extreme Heat & Thermal Tarmac Hazards
Concrete and asphalt aprons absorb and radiate heat, frequently pushing tarmac temperatures significantly higher than ambient air limits.
- Thermal Tire Blowouts: High temperatures cause the nitrogen inside aircraft tires to expand. If parked for extended periods in extreme heat, thermal fuse plugs in the wheel assemblies are designed to melt and safely deflate the tires to prevent a catastrophic blowout.
- Avionics Cooling: Without immediate connection to Pre-Conditioned Air (PCA) units, internal aircraft temperatures climb rapidly, triggering thermal shutdowns in the sensitive avionics bay.
- Ground Crew Safety: Ramp operations must enforce hydration cycles and mandate frequent crew rotations into air-conditioned break rooms to prevent heatstroke.
5. Low Visibility Procedures (LVP)
When fog or heavy snow drops the Runway Visual Range (RVR) below minimums, airports initiate Low Visibility Procedures (LVP) to prevent ground collisions and protect automated landing systems.
- ILS Protection: Ground vehicles and taxiing aircraft are restricted from entering Instrument Landing System (ILS) critical areas. This prevents radio signal interference for incoming aircraft flying CAT II or CAT III autoland approaches.
- Follow-Me Guidance: In extreme low visibility, ground handling vehicles and taxiing aircraft may require the assistance of “Follow-Me” cars to safely navigate the apron layout.
6. Heavy Rain & Monsoon Operations
Standing water introduces hydroplaning risks for GSE and severe engine ingestion hazards for aircraft.
- Engine Ingestion: High engine thrust during taxi in standing water can cause engines to ingest massive amounts of water, risking a flameout. Apron control coordinates specific taxi routes to avoid known pooling areas.
- Reporting Breakdowns: Heavy rain frequently causes electrical shorts in ground equipment. In case of GSE breakdown in the movement area, ground crew must immediately inform the Operations Duty Manager or Apron Control to initiate swift towing and prevent gridlock.
7. Sandstorms, Dust, and Volcanic Ash
Particulate weather fronts mandate immediate defensive maintenance. Fine sand and volcanic ash act as destructive abrasives to engine turbine blades and avionics sensors.
- Total Aircraft Sealing: Upon block-in during a dust or ash event, maintenance engineers must immediately install all engine blanks, APU exhaust covers, and pitot-static covers.
- No Wiping Rule: Ground crew must never wipe dust or ash off cabin windows or the radome with dry cloths. The microscopic particles will severely scratch acrylic panes and composite structures.
- Dry Motoring: Post-storm, engineers may be required to perform a dry motoring of the engines (spinning the engines using the starter without introducing fuel) to blow out accumulated sand before standard ignition.
8. Frequently Asked Questions (FAQs)
When is aircraft fueling suspended due to weather?
Aircraft fueling is suspended when an airport declares a Red Alert for lightning (strikes detected within 3 to 5 miles of the airfield). Operations cannot resume until the storm cell passes and an “All Clear” is issued.
What are Airport Low Visibility Procedures (LVP)?
LVP are specific rules enacted when fog or snow severely reduces visibility. LVP restricts ground vehicle movement, increases spacing between taxiing aircraft, and strictly protects the radio signal areas of the Instrument Landing System (ILS).
How are light aircraft secured during high winds?
General Aviation (GA) aircraft are secured using specific mooring procedures. Maintenance personnel tie the aircraft’s designated anchor points directly to ground mooring rings or heavy mooring stones using specialized ropes or chains to prevent uncommanded movement.
