Understanding the Under Seat Cabin Bag
An under seat cabin bag is a specific type of luggage designed to fit neatly into the confined space beneath the seat in front of you on an aircraft. Unlike standard carry-on bags that are stowed in overhead compartments, these smaller bags offer immediate access to essentials during your flight. They are a popular choice for travellers seeking to maximise their carry-on allowance, often serving as a personal item in addition to a main carry-on suitcase.
The primary appeal of an under seat cabin bag lies in its convenience and its role as an additional storage solution. It's the perfect repository for items you might need during the flight: your entertainment, snacks, travel documents, or a change of socks. Many airlines permit passengers to bring one main carry-on item and one personal item, and an under seat cabin bag frequently fulfils the latter role, providing valuable extra capacity without incurring extra charges. Understanding the nuances of airline policies and the typical dimensions associated with these bags is paramount for any traveller.
The dimensions for these bags can vary significantly between airlines, and adhering to these restrictions is vital to avoid last-minute repacking or additional fees at the gate. While some airlines provide a generous allowance, others are notably stricter. This variability means that a bag compliant with one carrier's rules might not be with another's. Researching the specific airline's policy before purchasing or packing your under seat cabin bag is therefore not merely advisable, but a necessity for a stress-free travel experience.
The Functionality of Personal Item Luggage
Airlines categorise under seat cabin bags primarily as 'personal items'. This designation is key, as it typically means this piece of luggage is allowed in addition to your standard carry-on bag, which usually resides in the overhead locker. The purpose is to allow passengers to keep vital or frequently accessed items within arm's reach throughout their journey. This includes items such as laptops, books, medications, and snacks. The crucial distinction is that personal items must, as the name suggests, fit under the seat in front. This constraint dictates their size and shape, differentiating them from larger cabin bags.
Why Choose an Under Seat Cabin Bag?
The core benefit of opting for an under seat cabin bag is the immediate access it provides. During a flight, especially a long-haul journey, being able to retrieve your tablet, a book, or a warm layer without disturbing fellow passengers or rummaging through overhead bins is invaluable. Furthermore, it serves as an excellent overflow for items that don't quite fit into your main carry-on or for things you might need to access quickly upon arrival, such as a change of clothes or toiletries for freshening up. For budget airlines, where strict carry-on allowances are common, a well-chosen personal item bag can significantly enhance the amount of gear you can bring onboard without incurring extra costs.
For many travellers, especially those on shorter trips or city breaks, an under seat cabin bag might be the only luggage required. Its compact nature encourages minimalist packing, saving time at check-in and baggage reclaim. The discipline of fitting everything into such a confined space can also lead to more efficient packing strategies for future trips. The tactical advantage of having essentials readily available, combined with the potential for added storage, makes this type of bag a favoured accessory in the modern travel landscape.
The primary advantage is immediate access to flight essentials.
- Designed to fit under the seat in front of you on aircraft.
- Often serves as a 'personal item' in addition to carry-on luggage.
- Provides convenient access to essentials during your flight.
- Can help maximise carry-on allowance without extra fees.
Navigating Airline Cabin Bag Size Restrictions
When selecting an under seat cabin bag, the absolute critical factor is understanding the diverse size restrictions imposed by different airlines. These dimensions are not universal; they can vary considerably, and a failure to comply can lead to your bag being gate-checked, incurring additional fees, and causing significant inconvenience. Therefore, knowing your airline's specific requirements is paramount. Typically, airlines will specify maximum dimensions in centimetres for both height, width, and depth. Common dimensions often cited for under-seat bags hover around 40cm x 30cm x 20cm, but this is a generalisation and should never be relied upon without verification.
Budget carriers, in particular, are known for their stringent enforcement of carry-on rules. For instance, a typical allowance might be around 40x30x15cm. Full-service carriers might offer slightly more generous allowances, sometimes up to 55x40x20cm for overhead cabin bags, but their personal item dimensions are often still quite specific. It is not uncommon for airlines to provide a physical sizing frame at check-in or the departure gate. If your bag does not fit into this frame, it is deemed oversized.
Typical Dimensions to Consider
While you must always check with your specific airline, many under seat cabin bags are designed with typical dimensions in mind. A frequently seen maximum size for a personal item is 45cm x 36cm x 20cm, or a slightly smaller 40cm x 30cm x 20cm. These measurements are designed to ensure the bag can slide under the seat in front of you without obstructing passengers in the rows behind. It is important to remember that these are external dimensions, including any wheels, handles, or pockets.
How to Check Your Airline's Policy
The most reliable method is to visit the official website of the airline you are flying with. Look for sections titled 'Baggage Information', 'Carry-on Allowance', or 'Travel Information'. These pages will detail the allowances for both cabin luggage (for overhead storage) and personal items. Pay close attention to the exact measurements provided, often listed in centimetres (cm). Some airlines may also specify weight limits for carry-on items, although this is less common for personal items than for standard cabin bags.
Verify your specific airline's dimensions before purchasing.
Consider the specific cabin bag size of 55x40x20cm – this is a very common allowance for overhead cabin bags on many European airlines, but it is far too large for an under-seat bag. Conversely, if you see dimensions like 45x36x20cm, these are much more likely to be suitable for under-seat placement, though still require checking against your airline's exact rules. Some airlines even have a more restrictive 40x30x15cm limit. Always look for the 'personal item' allowance, not just the general 'cabin bag' size.
What About Specific Airlines?
Different airlines have different approaches. For example, British Airways typically allows a main cabin bag and a personal item, with the personal item needing to fit under the seat in front. Ryanair and easyJet are known for their stricter policies, where often only one small bag (which must fit under the seat) is included in the base fare, with larger carry-on bags costing extra. Wizz Air also follows a similar model. For long-haul carriers like Emirates or Qatar Airways, personal item allowances might be slightly more accommodating, but the rule of fitting under the seat remains constant. It's always worth noting that specific routes or fare types can sometimes influence these rules, so consulting the airline's FAQ or customer service can resolve any lingering doubts.
Key Features of a Practical Under Seat Cabin Bag
Beyond dimensions, the functionality and design of an under seat cabin bag are critical for its utility. A well-designed bag will not only conform to size restrictions but also offer smart organisation, durability, and ease of use. These bags are often subjected to significant wear and tear, being frequently accessed, loaded, and stowed, so robust materials and construction are a definite plus. The layout of compartments and pockets can make a substantial difference in how effectively you can pack and retrieve your items during travel.
Consider the weight of the bag itself; an empty bag that is too heavy eats into your overall carry-on allowance. Materials like ripstop nylon, polyester, or durable canvas are common, offering a good balance of strength and lightness. Zippers are another component that warrants attention; smooth-gliding, robust zips are less likely to fail. The presence of external pockets, particularly for items like water bottles or travel documents, can add significant practical value.
Organisation and Compartments
Effective internal organisation is where an under seat cabin bag truly shines. Look for bags that offer multiple compartments, zipped mesh pockets, and padded sleeves for electronics. These features help separate items, prevent them from becoming jumbled, and protect sensitive devices like laptops or tablets. A dedicated compartment for documents or passports ensures they remain accessible and secure. Some bags feature a clamshell opening, allowing them to lie flat when opened, providing a clearer view of all contents and making packing less of a challenge.
Mobility and Handling
While many under seat bags are designed to be carried by hand or over the shoulder using a padded strap, some incorporate wheels. If you choose a wheeled option, ensure the wheels are low-profile and do not add excessively to the bag's overall dimensions or weight. A telescopic handle, if present, should be sturdy and retract fully without compromising the bag's internal space. For those preferring a non-wheeled bag, a comfortable, adjustable shoulder strap and sturdy grab handles are essential. Some bags also include a sleeve or strap on the rear that allows them to be securely attached to the handle of a larger piece of rolling luggage, which can be incredibly convenient when navigating airports.
Look for robust zips and smooth-gliding sliders.
Material Durability and Weight
The materials used in the construction of your under seat cabin bag directly influence its longevity and how much you can pack into it. Lightweight yet strong fabrics such as high-density polyester or ripstop nylon are excellent choices. These materials are often water-resistant, offering some protection against spills or light rain. Check for reinforced stitching at stress points, such as handle attachments and strap anchors. While durability is crucial, keeping the bag's empty weight as low as possible is also important, as airlines often have weight restrictions for carry-on items, even personal ones.
Accessibility Features
Quick-access pockets are invaluable for an under seat cabin bag. External zipped pockets are ideal for boarding passes, passports, or phones. Side pockets can hold a water bottle or umbrella, keeping them separate from your main belongings. Internal organisation, such as key clips or pen loops, can prevent minor annoyances from escalating into major frustrations during your journey. For travellers who frequently use electronic devices, a bag with a dedicated, padded laptop or tablet compartment, and perhaps even an external USB charging port (though you'll need your own power bank), can be a significant advantage.
Choosing Between Soft-Sided and Hard-Shell Under Seat Bags
The choice between a soft-sided and a hard-shell under seat cabin bag hinges on a trade-off between flexibility and protection. Each type offers distinct advantages that might appeal to different travellers based on their priorities and packing habits. Understanding these differences can help you make a more informed decision about which style best suits your needs for fitting under an airline seat.
Soft-sided bags, typically made from nylon, polyester, or canvas, often offer a degree of flexibility. This pliability can be advantageous if you find yourself needing to squeeze the bag into a tight space or if your packing is slightly variable. They are generally lighter than their hard-shell counterparts, which can be beneficial when adhering to strict weight limits. The exterior pockets common on soft-sided bags also provide convenient, immediate access to items.
Advantages of Soft-Sided Bags
The inherent flexibility of soft-sided under seat bags is their most significant advantage. If an airline's under-seat dimensions are particularly tight, a soft-sided bag can sometimes be compressed slightly to fit. This can be a lifesaver at the boarding gate if your bag is borderline. They also tend to be lighter when empty compared to rigid cases, giving you more capacity for your belongings within any weight restrictions. Furthermore, the common inclusion of multiple external pockets on soft bags means essentials like your passport, boarding pass, or a drink bottle are always within easy reach.
Considerations for Hard-Shell Options
Hard-shell under seat bags, usually constructed from polycarbonate or ABS plastic, offer superior protection for their contents. If you are travelling with fragile items, such as electronics, cameras, or delicate souvenirs, a hard-shell case provides a more robust defence against bumps and knocks. While less forgiving in terms of flexibility, many hard-shell models are designed with very precise dimensions to maximise internal space within standard under-seat limits. Their smooth exteriors can also be easier to clean.
Hard-shell bags offer superior protection for fragile items.
When considering a hard-shell under seat bag, look for models that have integrated TSA-approved locks for added security. The rigidity also means that the bag generally retains its shape, which can be beneficial for keeping packed items organised. However, it's crucial to ensure the exact dimensions will comply with your airline's personal item policy, as their inflexible nature means they cannot be 'squashed' to fit.
Which is Right for You?
If your priority is to maximise every inch of space, maintain immediate access to items, and potentially squeeze the bag into slightly tighter spots, a soft-sided option is likely preferable. They are often more budget-friendly and offer greater versatility. Conversely, if protecting your valuables and maintaining a sleek, organised appearance are paramount, and you are confident in adhering to precise dimensions, a hard-shell bag might be the better investment. For frequent travellers, a durable, well-made bag of either type, chosen to match their specific travel habits and airline preferences, will prove invaluable.
Packing Strategically for Your Under Seat Bag
Packing an under seat cabin bag effectively is an art form. It's about balancing accessibility, security, and the sheer volume of items you can reasonably fit into a confined space. The goal is to have everything you need for the flight and immediately upon arrival readily available, without creating a jumbled mess that makes finding anything a challenge. Strategic packing ensures that your journey is smoother and less stressful, especially when dealing with limited space.
Start by considering what you will genuinely need during the flight. This usually includes items for entertainment, comfort, and essential documents. Think about items that can't be easily replaced if lost or that you'll need within minutes of landing. Furthermore, remember that the bag must fit comfortably under the seat, so avoid overstuffing it to the point where it becomes rigid and bulky, making it difficult to stow or retrieve.
Prioritising Flight Essentials
The contents of your under seat bag should primarily consist of items you'll need during the flight. This typically includes: entertainment (e-reader, tablet, headphones, book), comfort items (travel pillow, eye mask, earplugs, a light jumper or scarf), medications, essential toiletries (hand sanitiser, lip balm, travel-sized toothbrush and toothpaste), and any valuable or important documents (passport, boarding pass, wallet, laptop). Keep these items organised within the bag so they are easily accessible.
Using Packing Cubes and Organisers
Packing cubes are incredibly useful for compartmentalising items within your under seat bag. You can dedicate one cube for electronics and chargers, another for toiletries, and perhaps a smaller one for snacks or medication. This not only keeps items organised but also compresses them slightly, saving space. Smaller accessory pouches or toiletry bags can also be used to group similar items, preventing them from scattering throughout the main compartment.
Use packing cubes to maximise organisation and space.
Securing Valuables and Documents
It is imperative to keep valuables and important documents secure and easily retrievable. Utilise internal zipped pockets or a dedicated front compartment for your passport, boarding pass, cash, and credit cards. If carrying a laptop or tablet, ensure it is in a padded sleeve or compartment to prevent damage. Many travellers prefer to keep their wallet and phone in a pocket that is easily accessible but still secure, such as a zipped side pocket or a front pocket that can be closed.
Rolling vs. Folding Clothes
If you are packing any clothing in your under seat bag, such as a change of clothes or a warm layer, rolling items can often save space compared to folding. Rolled clothes tend to wrinkle less and can be packed more tightly into the available space. However, for bulkier items like jumpers, folding might be more efficient. The key is to assess the items and arrange them to fill the bag's shape without creating unnecessary voids or bulges.
Common Mistakes to Avoid with Under Seat Luggage
While the concept of an under seat cabin bag is straightforward, travellers often fall foul of common pitfalls that can turn a convenient accessory into a source of stress. Avoiding these mistakes can ensure your journey is as smooth as possible, from packing at home to stowing your bag on the aircraft. A little foresight can prevent costly errors and unnecessary hassle at the airport.
One of the most frequent errors is failing to ascertain specific airline dimensions. Relying on general guidelines or assuming your bag will fit is a gamble that rarely pays off, especially with budget carriers. Another common mistake is overpacking. While these bags offer extra capacity, they are still limited, and an overstuffed bag can be difficult to stow, uncomfortable to carry, and may even be refused by airline staff.
Ignoring Specific Airline Dimensions
As repeatedly emphasised, this is the most critical mistake. Many travellers assume all under-seat bags are the same size or that their 'standard' personal item will pass. Airlines are becoming increasingly strict, and a bag that is even a few centimetres too large can lead to it being checked into the hold, often incurring a significant fee. Always consult the airline's website for the exact personal item dimensions for the flight you are taking.
Overstuffing the Bag
A bag that is too full can be problematic. Not only does it become difficult to fit under the seat, potentially obstructing other passengers, but it can also put undue stress on zippers and seams, leading to damage. Furthermore, if the bag becomes rigid due to being overstuffed, it may fail to fit into the airline's sizing cage, even if its uncompressed dimensions are technically compliant. Pack only what you truly need and consider using compression cubes if necessary.
Don't assume; always verify your airline's specific dimensions.
Packing Fragile Items Insecurely
While under seat bags offer immediate access, they can also be subjected to bumps and jostles as people move around the cabin. If you are placing fragile items, such as electronics or glass containers, within your under seat bag, ensure they are adequately protected. Using padded sleeves, wrapping them in soft clothing, or choosing a more rigid bag can help prevent damage. Avoid placing heavy, hard items at the bottom of the bag where they could crush lighter contents.
Forgetting Accessibility Needs
The primary purpose of an under seat bag is to keep essentials within easy reach. A common mistake is packing it so efficiently that you can't access anything without emptying half the bag. Ensure that items you'll need during the flight – like your boarding pass, phone, or a snack – are placed in easily accessible external pockets or the very top of the main compartment. Likewise, items you'll need immediately upon landing should be easy to retrieve without a lengthy search.
Materials and Durability: What to Look For
The longevity and performance of your under seat cabin bag are heavily influenced by the materials used in its construction and the overall quality of its build. Given that these bags are often used frequently and subjected to the rigours of travel, choosing durable materials is a wise investment. The fabric, zippers, handles, and stitching all play a role in how well the bag will withstand repeated use.
When evaluating materials, consider a balance between lightness and robustness. Extremely heavy fabrics might reduce the amount you can pack within weight limits, while flimsy materials will quickly show signs of wear and tear. For zippers, ensure they are smooth-running and well-attached. Look for reinforced stitching, particularly at stress points like strap attachments and seams, to ensure the bag can handle being loaded and carried reliably.
Fabric Choices: Nylon vs. Polyester vs. Canvas
Nylon, particularly high-denier ballistic nylon, is renowned for its exceptional durability, abrasion resistance, and light weight. It's often found in premium travel gear. Polyester is another popular choice, offering good durability and water resistance at a more accessible price point. It's generally less resistant to abrasion than nylon but is still a very capable material for travel bags. Canvas offers a classic, rugged look and can be very durable, but it tends to be heavier and less water-resistant than synthetic alternatives, often requiring a protective coating.
Zipper Quality
The zippers are often the first point of failure on luggage. Look for reputable brands known for their quality zips, such as YKK. The zippers should glide smoothly without snagging. Metal zippers are generally more durable than plastic ones, though high-quality plastic zippers can also be very reliable. Double zippers, which allow you to secure the bag with a small padlock, are a useful feature for added security.
Stitching and Reinforcement
Inspect the stitching carefully. Threads should be uniform and strong, with no loose ends. Reinforced stitching, often using a stronger thread or double stitching, at points of high stress – like where straps attach, at the base of zippers, and along main seams – indicates superior construction. Some bags also feature reinforced corners or base panels to protect against abrasion when the bag is dragged or placed on rough surfaces.
Wheels and Handles (If Applicable)
If your under seat bag includes wheels, they should be robust and integrated smoothly into the bag's design without adding significant bulk. Inline skate wheels are often favoured for their durability and smooth rolling. For handles, whether telescopic or grab handles, they should feel sturdy and secure. Telescopic handles should retract fully and lock firmly in place. Well-padded shoulder straps and comfortable grab handles are essential for manual carrying.
Understanding Underseat Bag Weights and Travel Cases
While many airlines are less stringent about the weight of personal items compared to main cabin bags, it's still a factor to consider, especially for budget carriers or if you're carrying heavy electronics. An overly heavy under seat cabin bag can become cumbersome to lift and stow, and in some instances, might be subject to a weight limit. Understanding typical allowances and how to manage your bag's weight is part of smart travel planning.
The term 'travel case' in relation to under seat luggage often refers to the bag itself, distinguishing it from simpler tote bags. These cases are purpose-built for travel, incorporating features like structured interiors, durable exteriors, and organised compartments. When looking at travel cases designed for under-seat use, weight is a key specification, alongside dimensions and features.
Typical Weight Considerations
Most airlines do not explicitly state a weight limit for personal items. However, the implicit understanding is that you must be able to lift and stow the bag yourself. If your under seat bag contains a heavy laptop, camera equipment, or numerous books, its total weight can quickly add up. Aim to keep the empty weight of the bag itself as low as possible. Many lightweight under seat bags weigh between 0.5kg and 1.5kg. If your airline does impose a weight limit for carry-on items, it's usually around 8-10kg for the main cabin bag, and personal items might fall under this or have a separate, often unstated, limit.
What Constitutes a 'Travel Case'?
A 'travel case' in this context implies a piece of luggage specifically designed for transport, rather than a general-purpose bag. For an under seat cabin bag, this means it will typically feature:
- Structured compartments for organisation.
- Durable materials to withstand travel.
- Reinforced stitching and zips.
- Comfortable handles or shoulder straps.
- Dimensions optimised for under-seat storage.
This differentiates it from a simple canvas tote bag or a rucksack, although some rucksacks are very effectively designed for under-seat use. The term 'travel case' suggests a degree of inherent structure and purpose-built functionality for transit.
Manage the weight; you need to lift it yourself.
Comparison with Checked Baggage and Cabin Luggage
It's crucial to distinguish your under seat cabin bag from both checked baggage and standard cabin luggage. Checked baggage is stowed in the aircraft's cargo hold and typically has much higher weight and size limits, but it is not accessible during the flight. Standard cabin luggage, often referred to as 'carry-on', is usually larger (e.g., 55x40x20cm) and is stored in the overhead lockers. The under seat cabin bag is the smallest category, restricted to the space beneath the seat in front, and is intended for immediate access to personal items.
Balancing Weight and Capacity
When choosing an under seat travel case, consider how much you typically carry. If you travel with a lot of electronics, a lighter bag with robust padding is essential. If you plan to pack books or heavier personal items, look for a bag that is still within the reasonable weight limits once packed. Sacrificing a few non-essential items can make a significant difference to the overall weight, ensuring your bag is manageable and compliant.
Regulations and Compliance: What You Need to Know
Navigating the regulatory landscape of air travel can be complex, especially concerning baggage. For under seat cabin bags, compliance primarily revolves around adherence to airline-specific size and, occasionally, weight restrictions. While there aren't universal government regulations dictating the precise dimensions of personal items, airlines establish their own rules to ensure cabin safety, efficient boarding, and optimal space utilisation. Understanding these rules is your responsibility as a traveller.
The key principle is that anything designated as a 'personal item' or 'under seat bag' must fit entirely within the confines of the space under the seat in front of you. This is not just about avoiding fees; it's also about ensuring the safety and comfort of all passengers. An improperly stowed bag can become a hazard during turbulence or evacuation. Therefore, airlines enforce these dimensions strictly.
Airline Policies Are King
The most important compliance point is that airline policies supersede any general advice or manufacturer specifications. While a bag might be marketed as an 'under seat cabin bag', its actual dimensions must be checked against the specific airline's current policy. Airlines can and do change their regulations, so always check the most up-to-date information directly from the carrier you are flying with, ideally before booking and again before travelling.
The Role of Sizing Frames
Many airlines use physical sizing frames at check-in desks and departure gates. These frames are usually metal or wooden boxes designed to the exact maximum dimensions allowed for cabin and personal item baggage. If your bag, including any extensions like wheels or handles, cannot fit into the frame, it will likely be deemed oversized. This is a non-negotiable check, and staff will enforce it rigorously, especially on busy flights.
Always check the airline's website for the latest baggage rules.
What About Liquids and Prohibited Items?
While the size of the under seat bag is the primary concern for fitting it onboard, the contents are subject to standard aviation security regulations. This means liquids, aerosols, and gels (LAGs) must be in containers of 100ml or less and placed in a single, transparent, resealable plastic bag of no more than one litre capacity, carried separately in your personal item for easy inspection. Prohibited items, such as sharp objects (knives, scissors with blades over 6cm) or certain flammable materials, must not be carried in hand or under-seat luggage.
Ensuring Easy Retrieval and Stowage
Compliance also extends to how you manage your bag during the flight. It must be stowed securely under the seat in front of you. During taxiing, take-off, and landing, all carry-on baggage must be stowed. Passengers are often asked to refrain from accessing their under seat bags during these critical phases of flight. Ensuring your bag can be easily stowed and retrieved without requiring excessive force contributes to cabin safety and passenger convenience.
Frequently Asked Questions
Can I take a backpack as my under seat cabin bag?
Yes, many airlines permit backpacks as personal items, provided they adhere to the specified dimensions for under-seat storage. Look for backpacks specifically designed for travel, often featuring a streamlined shape, external pockets for easy access, and padded compartments for electronics.
What are the typical dimensions for a Ryanair under seat bag?
Ryanair's standard personal item allowance for its 'Small Personal Bag' is quite restrictive, typically measuring 40cm x 20cm x 25cm. This bag must fit entirely under the seat in front. Larger cabin bags are available for an additional fee.
Does my under seat bag need to have wheels?
No, wheels are not a requirement for an under seat cabin bag. Many excellent non-wheeled options, such as duffels or structured tote bags, are available. If you opt for a wheeled bag, ensure the wheels and handle do not cause it to exceed the airline's maximum dimensions.
Can I bring a laptop in my under seat cabin bag?
Absolutely. Laptops are frequently carried in under seat bags, as they are considered essential items. Many bags feature dedicated, padded compartments to protect your device during transit. Remember that the laptop's weight contributes to the bag's overall load.
What happens if my under seat bag is too big?
If your under seat bag exceeds the airline's specified dimensions or weight limit, it will typically need to be checked into the aircraft's hold. You will usually be charged a fee for this, which can be significantly higher if paid at the gate compared to pre-booking online.
How much can I fit in an under seat cabin bag?
The capacity varies greatly by bag design and dimensions. Generally, you can fit essentials for a short trip, such as a change of clothes, toiletries, electronics, books, and travel documents. Efficient packing using cubes and rolling clothes helps maximise space.
Is an under seat bag the same as a personal item?
For most airlines, yes. An 'under seat cabin bag' is the descriptive term for luggage designed to fit under the seat, and it commonly serves the function of a 'personal item', which is the airline's classification for an additional, smaller bag allowed onboard besides the main cabin carry-on.