🗂️ Operational Procedures
The rules and procedures behind every airline flight — from the certificate that lets an operator fly to the state of the runway at the far end. Each chapter opens with the one idea to hold on to, then the numbers, the comparisons that cause most mistakes, and worked examples you can open.
🧰 Quick tools & cheat sheet play with the numbers
Seven small helpers for the sums operational procedures asks for again and again, and a one-screen list of the numbers worth knowing by heart.
👁️ Visibility to RVR
🌊 Distance from land
🧑✈️ Cabin equipment by seats
📅 Day of the year (track message)
💧 Aquaplaning speed
🛬 Approach category
😴 Minimum rest
📋 Cheat sheet — numbers worth knowing
| Idea | Number / rule |
|---|---|
| 🗓️ Accident or serious incident report | within 72 h |
| 📼 Recordings kept after an incident | 60 days |
| 🍷 Alcohol before duty | none within 8 h · max 0.2 promille |
| 🌊 Ditching rule (> 30 seats) | 120 min or 400 NM, lesser |
| 🛬 Destination with no alternate | ≤ 6 h · 2 runways · ceiling 2000 ft or circling + 500 · vis 5 km |
| 📉 Approach ban | outer marker (precision) · 1000 ft (non-precision) |
| 🌫️ Low visibility take-off | RVR < 400 m · lowest normal 150 m (Cat D 200 m) |
| 🔻 CAT I / II / IIIA / IIIB RVR | 550 · 300 · 175 · 50 m (operator tables 200 · 75 m) |
| 🔄 Circling minima A/B/C/D | 400/1500 · 500/1600 · 600/2400 · 700/3600 |
| 😷 Crew oxygen | > 13 000 ft always · 10–13 000 ft after 30 min |
| 👥 Passenger oxygen | 100% >15 000 · 30% 14–15 000 · 10% 10–14 000 after 30 min |
| 🧑✈️ Cabin crew | 1 per 50 seats (or part) when > 19 seats |
| ⏱️ Duty limits | 60 h/7 d · 190 h/28 d · block 100 h/28 d · 900 h/year |
| 🌍 NAT high level airspace | FL285–FL420 · RVSM FL290–410 |
| 🌪️ Wake: light behind heavy | 6 NM · 2 min departure |
| ⛽ Fuel jettison level | ≥ 6000 ft |
| ☣️ Dangerous goods report | first report within 72 h |
| ❄️ Take-off depth limits | water/slush 15 mm · dry snow 60 mm |
1 International Operating Standards Chapter 1
One international standard sets the baseline for running an airline across borders: who holds operational control, which alternates exist, what flight time means and how safety is managed.
The operator holds operational control — the authority to start, continue, divert or end a flight. It can delegate that only to the pilot-in-command (or, with an approved supervision method, a flight dispatcher).
Part 1
Aeroplanes in international commercial air transport.
Part 2
Aeroplanes in general aviation.
Part 3
Helicopters in international commercial air transport.
Alternates
| Alternate | Used when |
|---|---|
| Take-off alternate | The departure aerodrome cannot be used shortly after take-off |
| En route alternate | An abnormal or emergency condition arises en route |
| ETOPS en route alternate | An engine is shut down on an extended twin operation |
| Destination alternate | Landing at the destination becomes impossible or inadvisable |
Safety management and lights
- 🛡️ The State sets a safety programme; each operator runs its own safety management system.
- 📊 Aeroplanes over 27 000 kg need a flight data analysis programme.
- ⏱️ Flight time runs from first movement for take-off until the aeroplane finally comes to rest — block to block.
- 💡 Navigation lights: red left, green right (each 110°), white tail (140°). Seeing red on your right and green on your left means the other aircraft is heading towards you.
2 General Requirements Chapter 2
The everyday rules of commercial operation: the commander's authority, fitness for duty, documents on board, what stays on the ground, and how leasing changes who the operator is.
The commander is responsible for everyone on board from boarding until leaving, and for the aeroplane from first ready to taxi until it finally stops with the engines shut down.
Fitness for duty
- 🍷 No alcohol within 8 hours of duty or standby; blood alcohol no more than 0.2 promille.
- 🤿 Not on duty until a reasonable time after deep diving or blood donation.
- 🔇 The "sterile" period: take-off, initial climb, final approach and landing — essential duties only.
- 📼 Flight recorders are never switched off in flight; after an incident the CVR may be stopped to protect the recording.
Documents
Originals
Certificate of registration, certificate of airworthiness, noise certificate, radio licence.
Copies are enough
The AOC and the third-party insurance certificate.
Leasing
Dry lease
Aeroplane only. Flown under the lessee's AOC.
Wet lease
Aeroplane and crew. Flown under the lessor's AOC.
Worked example — ditching distance
An aeroplane with more than 30 passenger seats cruises at 180 kt. The limit is 120 minutes at cruising speed or 400 NM, whichever is less.
120 min at 180 kt = 360 NM, which is less than 400 NM, so it may go 360 NM from land suitable for an emergency landing unless it meets the ditching requirements.
After an incident, flight data and voice recordings are kept for 60 days unless the authority asks for longer.
3 Operator Certification and Supervision Chapter 3
Before carrying a paying passenger, an operator needs an air operator certificate, a set of named managers, a main base, and an operations manual in four parts.
The AOC comes from the State of the operator's principal place of business, and lists the types of operation, aircraft, areas and every special approval (CAT II/III with minima, ETOPS, RVSM, RNAV, dangerous goods).
- 👔 The accountable manager makes sure operations and maintenance can be financed and done to standard.
- 🧑💼 Four nominated posts: flight operations, maintenance system, crew training, ground operations.
- 🔁 Authority audits include the operator's internal audits and its financial records.
The operations manual
| Part | Contents |
|---|---|
| A | General: organisation, crew, flight time limits, procedures, dangerous goods, security |
| B | Aeroplane: limitations, procedures, performance, mass and balance, MEL |
| C | Routes and aerodromes, including operating minima |
| D | Training |
Terms worth knowing
- 🛬 Isolated destination (turbine): going on to the nearest alternate would need more than 2 hours of fuel.
- 📍 Equivalent position: a fix 3 to 5 NM from the threshold, standing in for an outer marker.
- ⛽ 3% ERA: an en route alternate that lets contingency fuel drop to 3% of trip fuel.
4 Operational Procedures Chapter 4
How a flight is planned and flown: alternates and their minima, when an approach may be continued, how visibility becomes RVR, fuel, passengers and reporting.
Planning minima are deliberately higher than operating minima. A plan built on the higher figure leaves room for the weather to get worse before the flight arrives.
Take-off alternate distance
Twin
Within 1 hour at one-engine-inoperative cruise speed (or approved ETOPS time, max 2 h).
Three or four engines
Within 2 hours at one-engine-inoperative cruise speed.
Planning minima for alternates
| Approach available | Plan with |
|---|---|
| CAT II or III | CAT I RVR |
| CAT I | Non-precision RVR, ceiling at or above MDH |
| Non-precision | Non-precision RVR + 1000 m, ceiling MDH + 200 ft |
| Circling | Circling minima |
ETOPS en route alternates add 200 ft and 800 m for a precision approach, 400 ft and 1500 m for a non-precision or circling one.
When no destination alternate is needed
- ⏱️ Flight no longer than 6 hours.
- 🛬 Two separate usable runways.
- ☁️ From 1 h before to 1 h after ETA: ceiling at least 2000 ft or circling height + 500 ft (higher), visibility at least 5 km.
The approach ban
The touchdown zone RVR always controls. Midpoint minimum 125 m (75 m with roll-out guidance); stop end 75 m.
Visibility to RVR
| Lighting | Day | Night |
|---|---|---|
| High intensity approach and runway lights | 1.5 | 2.0 |
| Any other lighting | 1.0 | 1.5 |
| No lighting | 1.0 | — |
Twins without ETOPS approval
- ✈️ Class A, 20 seats or more, or 45 360 kg or more: 60 minutes one-engine-out.
- ✈️ Smaller Class A: 120 minutes (180 with approval for turbojets).
- 🛩️ Class B or C: 120 minutes or 300 NM, whichever is less.
Fuel, oxygen and reports
- ⛽ Taxi + trip + reserve; reserve = contingency + alternate + final reserve + additional (+ extra at the commander's choice).
- 🚫 No refuelling with wide-cut fuel or Avgas while passengers are on board or boarding.
- 😷 Crew on oxygen continuously above 13 000 ft cabin altitude, and above 10 000 ft after 30 minutes.
- 📝 Accident or serious incident report to the authority within 72 hours; ACAS RA and bird strike reports too.
- 📏 RVSM: 1000 ft separation from FL290 to FL410.
Worked example — planning minima for a non-precision alternate
The alternate has a VOR approach with MDH 400 ft and RVR 1500 m. For planning, add 200 ft and 1000 m: ceiling 600 ft, visibility 2500 m.
5 All Weather Operations Chapter 5
Approach categories, take-off minima, the precision categories and circling: the tables that decide whether you can go.
The lower the minimum, the more of everything is needed — aircraft certification, crew training, ground equipment and low visibility procedures in force. Without all of them, the higher figure applies.
Approach categories (VAT)
| Cat | VAT (kt) | Circling MDH / vis |
|---|---|---|
| A | < 91 | 400 ft / 1500 m |
| B | 91–120 | 500 ft / 1600 m |
| C | 121–140 | 600 ft / 2400 m |
| D | 141–165 | 700 ft / 3600 m |
VAT = VS0 × 1.3 or VS1g × 1.23 at maximum landing mass; if both are known, the higher result is used.
Take-off minima
| Facilities | RVR |
|---|---|
| Nil (day only) | 500 m |
| Edge lighting and/or centre line marking | 250 m (Cat D 300 m) |
| Edge and centre line lighting | 200 m (Cat D 250 m) |
| + multiple RVR information | 150 m (Cat D 200 m) |
| With approval and extra conditions | 125 m (Cat D 150 m) |
A low visibility take-off is one with RVR below 400 m.
System minima (non-precision)
- 📡 Localiser 250 ft · VOR/DME 250 ft · VOR 300 ft · NDB/DME 300 ft · NDB 350 ft · VDF 350 ft · RNAV/LNAV 300 ft.
- 📉 A non-precision approach: MDH not below 250 ft, RVR not below 750 m. APV: 250 ft and 600 m.
Precision categories
CAT I
DH ≥ 200 ft, RVR ≥ 550 m (single pilot 800 m unless coupled).
CAT II
DH 100–199 ft, RVR ≥ 300 m.
CAT IIIA
DH < 100 ft, RVR ≥ 175 m (operator tables often 200 m).
CAT IIIB
DH < 50 ft or none, RVR 50–175 m (operator tables down to 75 m).
VFR minima
- ☁️ Above 3000 ft AMSL or 1000 ft above terrain: 1500 m horizontally and 1000 ft vertically from cloud; visibility 8 km at or above FL100, 5 km below.
- 🌁 Special VFR: do not start below 3 km visibility; do not continue below 1.5 km.
- 👁️ No visual approach with RVR below 800 m.
Worked example — which category?
VS0 is 100 kt. VAT = 100 × 1.3 = 130 kt, which lies between 121 and 140 kt: Category C. Circling minima are 600 ft and 2400 m.
6 Aeroplane Equipment and Instruments Chapter 6
What must be fitted and carried, and the mass and seat thresholds that trigger each item. Most rules switch on at 5700 kg, 9 seats or 19 seats.
Learn the thresholds, not every item. More than 5700 kg or more than 9 seats brings in heated pitot, TAWS, standby horizon and weather radar; more than 19 seats brings in the flight deck door, cabin crew, PA and ACAS II (with 5700 kg).
Cabin equipment by seats
| Item | Rule |
|---|---|
| First aid kits | 0–99: 1 · 100–199: 2 · 200–299: 3 · 300+: 4 |
| Megaphones | 61–99: 1 · 100+: 2 |
| Crash axe / crowbar | flight deck (> 5700 kg or > 9 seats) · extra one in rear galley above 200 seats |
| Emergency medical kit | more than 30 seats and more than 60 min from a qualified medical facility |
Flight recorders
- 🎙️ CVR: 2 hours (over 5700 kg, certificated from 1 April 1998); 30 minutes for older ones; 25 hours for aeroplanes over 27 000 kg certificated from 1 January 2021.
- 📊 FDR: last 25 hours (10 hours allowed at 5700 kg or less).
Over water
- 🚣 Rafts and survival ELTs beyond 120 min or 400 NM (can continue after engine failure) or 30 min or 100 NM (all others), whichever is less.
- 📡 ELTs transmit on 121.5 MHz (homing) and 406 MHz (satellite).
Supplemental oxygen (pressurised)
| Who | Cabin altitude and duration |
|---|---|
| Flight crew on duty | All time above 13 000 ft; 10–13 000 ft after 30 min; minimum 30 min (2 h if certificated above 25 000 ft) |
| 100% of passengers | All time above 15 000 ft, never less than 10 min |
| 30% of passengers | 14 000–15 000 ft |
| 10% of passengers | 10 000–14 000 ft after 30 min |
| First aid oxygen | 2% of passengers (at least one) above 25 000 ft |
Unpressurised: crew above 10 000 ft always; 100% of passengers above 13 000 ft; 10% between 10 000 and 13 000 ft after 30 minutes. Crew PBE gives at least 15 minutes of oxygen.
7 Crew, Logs and Records Chapter 7
Who may fly, how often they are checked, how many cabin crew are needed, how long records are kept, and how far duty may stretch.
Checks run to the end of a month, and the 3-month rule protects early renewal. Pass within the last 3 months of validity and the new period counts from the old expiry date, not from today.
Recency and checks
| Item | Rule |
|---|---|
| Take-offs and landings | 3 in the last 90 days (extendable to 120 under supervision) |
| Operator proficiency check | 6 months + rest of the month of issue |
| Line check | 12 months |
| Emergency and safety equipment | 12 months |
| Route and aerodrome competence | 12 months + rest of the month |
| CRM topics | all covered within 3 years |
Crew
- 🧑✈️ Two pilots for IFR or night in all turbojets and in turboprops with more than 9 seats.
- 💺 Cabin crew: one per 50 seats or part of 50, when there are more than 19 seats.
- 🔁 A cruise relief pilot may act only in the cruise, not below FL200.
How long records are kept
3 months
Operational flight plan, journey log, mass and balance, NOTAMs, dangerous goods documents.
36 months
Aeroplane technical log, after the last entry.
3 years
Pilot training and checking records.
5 years
Quality system records.
Duty and rest
- ⏱️ Duty: 60 h in 7 days, 190 h in 28 days. Block time: 100 h in 28 days, 900 h in a calendar year.
- 📉 Basic daily flight duty period 13 h, minus 30 min per sector from the third (6 sectors or more: 11 h).
- 🌙 WOCL: 02:00–05:59 home base time.
- 😴 Rest: at least the preceding duty, and never less than 12 h at home or 10 h away, including 8 h of sleep opportunity.
- 🧭 Commander's discretion: up to 2 h (3 h augmented), reported within 28 days.
Worked example — the 3-month rule
An OPC expires on 31 December. Passed in October (within the last 3 months), the new one runs 6 months from 31 December: 30 June. Passed in August (too early), it runs 6 months plus the rest of August: 28 February.
8 Long Range Flight and Polar Navigation Chapter 8
Far from ground aids, the crew relies on its own systems. Knowing which one is wrong, and keeping it honest, is the whole game.
Three systems can vote; two can only disagree. With two, an independent fix — radar, a beacon, other aircraft's winds — is needed to decide which one has drifted.
- 📍 Plot the present position about 10 minutes after each waypoint.
- 🧲 Above about 65°N, steep dip and changing variation make magnetic references unreliable: grid navigation, inertial and satellite systems take over, and far-north VORs are aligned to true north.
- 📻 Polar flight also means HF communications, few alternates and large gyro corrections (earth rate, transport wander).
- 📝 If the aircraft cannot keep to its clearance, get a revised clearance first, using urgency or distress procedures if needed.
Shortest distance
The minor arc of the great circle.
Minimum time route
The quickest track within ATC limits, often longer because of the winds. Computer-generated.
9 North Atlantic High Level Airspace Chapter 9
The busiest oceanic airspace in the world, with few ground aids: tracks that change twice a day, strict navigation standards and contingency procedures everyone flies the same way.
The high level airspace runs from FL285 to FL420 (formerly MNPS airspace), containing the RVSM levels FL290–410. Aircraft and crews need approval to enter it.
The organised track system
Westbound tracks
Crossing 30°W 1130–1900 UTC.
Eastbound tracks
Crossing 30°W 0100–0800 UTC.
- 🗺️ Oceanic boundaries at 30°W (Shanwick/Gander), 40°W (Santa Maria/New York) and 45°N between them.
- 🗓️ The track message identifier is the day of the year: 15 March is 074 (075 in a leap year). Amendments add a letter: 074A.
- 📍 "59/10" means 59°N 010°W. Reports every 10° of longitude (20° above 70°N).
- ⚠️ About 80% of gross navigation errors follow a reroute — always cross-check the waypoints.
Communications
- 📻 HF voice and datalink; long-range VHF within about 250 NM of land.
- 🗣️ Monitor 121.5 MHz, and 123.45 MHz air-to-air.
- 🕰️ Oceanic clearance at least 40 minutes before entry; revise the entry estimate if it changes by 3 minutes or more.
- ☀️ HF: "the higher the sun, the higher the frequency".
Contingencies (current procedure)
- ⛈️ Weather deviation: under 5 NM, stay level; beyond 5 NM, change level by 300 ft.
- ↘️ Strategic lateral offset: centre line or up to 2 NM right only.
- 📏 Report a height deviation of more than 300 ft.
10 Special Procedures and Hazards Chapter 10
Ice on the airframe, birds, and the noise a departing aeroplane makes: each has its own procedure.
Ice needs liquid water and a surface below 0 °C. A thin deposit can cut lift by up to 30% and raise drag by up to 40%, so take-off starts only with clean surfaces.
Noise abatement departures
NADP 1 — close in
Reduce power at or above 800 ft, climb at V2 + 10–20 kt with take-off flap to 3000 ft, then accelerate.
NADP 2 — distant
From 800 ft, accelerate and retract flap, then climb at zero-flap speed + 10–20 kt to 3000 ft.
Never below 800 ft. Turns not below 500 ft, bank limited to 15°.
When noise must not choose the runway
- 💨 Crosswind over 15 kt or tailwind over 5 kt (including gusts).
- ☁️ Ceiling below 500 ft, or visibility below 1900 m.
- ❄️ Runway not clear and dry, or windshear reported.
On approach: landing configuration by the outer marker or 5 NM, and never above the glide path. A continuous descent final approach uses about 300 ft per NM.
11 Fire and Smoke Chapter 11
Engine fires, cabin fires, smoke and hot brakes: drills, extinguishers and the classes of cargo compartment.
Human life comes first. On the ground, summon the fire service and be ready to evacuate; in the air, cut the fuel, fire the bottles and get on the ground.
- 🔥 Turbojet drill: thrust lever closed, HP cock off, pull the fire switch (isolates fuel), fire one bottle, wait 30 seconds, then the second. Turboprop adds feathering.
- 🧯 Flight deck: at least one Halon 1211 (or equivalent). No dry powder — poor visibility and residue.
- 🔢 Cabin extinguishers: 7–30 seats 1 · 31–60 2 · 61–200 3 · 201–300 4 · 301–400 5 · and so on.
- 🅰️ Class A fires: solids (paper, fabric). 🅱️ Class B: flammable liquids.
Cargo compartments
| Class | Feature |
|---|---|
| A | Fire easily seen and reached by a crew member |
| B | Detection system, crew access in flight |
| C | Detection, built-in extinguishing, no access |
| D | No longer cleared for passenger aircraft |
| E | Cargo aeroplanes only |
Hot brakes
- 🛑 Rejected take-off at high mass is the classic cause; brakes peak up to 30 minutes later.
- 💥 Tyres may ignite or burst; approach the wheel from the front or rear, never the side.
- ⏳ Wait the brake cooling time before the next take-off.
12 Pressurisation Failure Chapter 12
When the cabin loses pressure, the time of useful consciousness is short. Masks first, then down.
Oxygen masks on, then descend to 10 000 ft or the lowest safe level, whichever is higher. The cabin altitude warning sounds at about 10 000 ft.
Slow decompression
Gradual, may be noticed only by the warning or by symptoms of hypoxia.
Rapid decompression
Bang, mist, flying debris, cold, ear pain. Seconds count.
Crew oxygen: 2 hours if certificated above 25 000 ft (a 10-minute descent to 10 000 ft, then 110 minutes); 30 minutes otherwise. The 10-minute minimum for all passengers is a descent from maximum altitude to 15 000 ft.
13 Windshear and Microburst Chapter 13
A sudden change in wind speed or direction near the ground can take away more performance than the aeroplane has.
A microburst first gives a headwind, then a downdraught, then a tailwind. The early gain in airspeed is a trap — the loss that follows is bigger.
- 🚀 Recovery: full power briskly, pitch up to about 15° (or as the manual says), keep the configuration, follow the stick shaker limit.
- ⬇️ Below 1000 ft a downdraught is the bigger danger.
- 🌧️ Warning signs: virga, heavy rain from convective cloud, dust rings, reported airspeed changes.
- 🛑 If windshear is reported or forecast, delay the take-off or approach.
14 Wake Turbulence Chapter 14
Every wing leaves two vortices behind it, strongest when the aeroplane is heavy, clean and slow.
Heavy, clean and slow makes the strongest wake. Vortices sink up to about 1000 ft, spread outwards at about 5 kt near the ground, and a light crosswind of about 5 kt can park one on the runway.
| Category | MTOM |
|---|---|
| Super | A380 |
| Heavy | ≥ 136 000 kg |
| Medium | 7000–136 000 kg |
| Light | ≤ 7000 kg |
Spacing
| Leader → follower | Approach |
|---|---|
| Heavy → heavy | 4 NM |
| Heavy → medium | 5 NM |
| Heavy → light | 6 NM |
| Medium → light | 5 NM |
Departures behind a heavy: 2 minutes from the same point, 3 minutes from an intermediate point. Parallel runways less than 760 m apart count as one.
15 Security Chapter 15
Preventing and handling acts of unlawful interference, from screening on the ground to the locked flight deck door.
Squawk 7500 (7700 if the situation warrants), tell ATC what you can, and, if you must leave the cleared route, fly at a level 500 ft off the normal IFR levels where 1000 ft separation applies.
- 🚪 More than 60 seats or MTOM over 45 500 kg: a flight deck door lockable from either pilot seat, with a way to see who is outside.
- 🔍 Aircraft search checklist on board; crew trained in security procedures.
- 📝 Report acts of unlawful interference to the local authority and the operator's authority.
16 Emergency and Precautionary Landings Chapter 16
Landing off a runway, on purpose. Planning, briefing and getting everybody out.
Most ditchings are survivable — about 88% end with few if any injuries. The deaths come afterwards, mostly from drowning, so life jackets, rafts and a good brief matter most.
Swell
Long waves from distant weather. Land along the swell, on its back.
Wind waves
Short waves from the local wind. Into wind when the swell is small.
- 👥 More than 44 seats: evacuation demonstrated in under 90 seconds.
- 🦺 Life jackets are inflated outside the aircraft, never inside.
- 📣 Brief passengers on the brace position, exits and life jackets as early as possible.
17 Fuel Jettison Chapter 17
Dumping fuel to get down to landing mass quickly and safely.
A jettison system is required when the aeroplane could not otherwise get down to landing mass after a short flight, and it must dump enough in 15 minutes to meet the climb requirements.
- ⬆️ Jettison at 6000 ft or above so the fuel evaporates before reaching the ground.
- 📻 Tell ATC; keep clear of other traffic and of populated areas where possible.
18 Transport of Dangerous Goods by Air Chapter 18
Goods that could harm people, the aeroplane or property may fly only when the operator is approved and the goods are classified, packed, labelled and declared.
The shipper classifies, packs and declares; the operator accepts, loads and informs. The commander gets written information on what is on board and where.
- 📄 Two copies of the transport document, in English (plus any other language required).
- 🔍 Inspect packages for leaks or damage before loading and on unloading; remove a leaking one and check the rest.
- ✈️ "Cargo Aircraft Only" goods never go on a passenger aircraft.
- 📣 In an emergency tell ATC that dangerous goods are on board; report incidents within 72 hours, including undeclared goods found in baggage.
Labels at a glance
| Class | Hazard | Label |
|---|---|---|
| 1 | Explosives | Orange, exploding bomb |
| 2 | Gases | Red flame (flammable) · green cylinder (non-flammable) · white skull (toxic) |
| 3 | Flammable liquid | Red, flame |
| 4 | Flammable solids | 7 red stripes · white over red · blue (dangerous when wet) |
| 5 | Oxidiser / organic peroxide | Yellow 5.1 · red over yellow 5.2 |
| 6 | Toxic / infectious | Skull and crossbones · three crescents |
| 7 | Radioactive | Trefoil |
| 8 | Corrosive | White over black, liquid on hand and metal |
Also: "Cargo Aircraft Only" is black on orange; magnetised material is blue on white.
19 Contaminated Runways Chapter 19
Water, slush, snow and ice change the braking, the drag and the distances. The words used to describe a runway carry exact meanings.
Contaminated means more than 25% of the surface covered by water or slush deeper than 3 mm, snow, or ice.
Dry
Neither wet nor contaminated (includes well-kept grooved surfaces).
Damp
Not dry, but not shiny.
Wet
Reflective, without significant standing water.
Contaminated
Over 25% covered by a contaminant.
- 🚫 No take-off with more than 15 mm of water, slush or wet snow, or 60 mm of dry snow.
- 💧 Aquaplaning: 9 √P knots for a rotating tyre, 7.7 √P for a non-rotating one (P in psi; 1 bar ≈ 14.5 psi).
- 📊 Runway condition is now reported for each third of the runway with a code from 6 (dry) to 0.
- 🗓️ A snow report (SNOWTAM) in the current format is valid for at most 8 hours.
Worked example — aquaplaning
Tyre pressure 196 psi. √196 = 14. Rotating tyre: 9 × 14 = 126 kt. Non-rotating tyre at touchdown: 7.7 × 14 ≈ 108 kt.