Air travel rules and screening
Three separate rule systems govern what you can fly with. Understanding which applies at each stage prevents confiscation, delays, and fines.
Three layers of rules
Airline rules
Each airline sets its own baggage policies: size, weight, prohibited items, dangerous goods acceptance. These vary between carriers and even between routes on the same airline.
Security screening
Aviation security authorities (TSA, CAA, EASA, CASA) set rules for what passes through the checkpoint. The 100 ml liquids rule, sharp object bans, and battery restrictions all originate here.
Destination customs
The destination country's customs authority decides what enters the country. This is separate from whether you can fly with it. An item legal to carry on a plane may still be seized at customs on arrival.
This section covers layers 1 and 2. For layer 3 (destination customs), see the Traveling section and individual country profiles.
Your journey through the airport
Pack
Check-in
Security
Board
Transit
Arrive
Air travel guides
Cabin baggage
Liquids, electronics, food, and sharp objects in carry-on luggage.
Checked baggage
Lithium battery bans, alcohol limits, aerosol restrictions in the hold.
Lithium batteries
Wh ratings, spare batteries, power banks, airline-by-airline rules.
Liquids rule (3-1-1)
The 100 ml rule, LAG definition, exceptions for medication and baby food.
Sharp objects
Knives, scissors, razors, multitools — carry-on vs checked by authority.
Food on board
Snacks, meals, fruit, dairy — airline rules vs destination customs rules.
Medication
Prescription drugs, needles, inhalers, liquid medication over 100 ml.
Pets in cabin
Carrier dimensions, weight limits, breed restrictions, IATA rules.
Duty-free sealed bags
STEB bags, when they survive transit, common pitfalls.
Transit & layovers
Airside transit, customs clearance, re-screening at hubs.
Declaration forms
Arrival cards and customs declaration forms by country.
Pre-arrival apps
Digital arrival: MPC, Visit Japan Web, SG Arrival Card, ArriveCAN.