It's not always practical or even possible to book all connecting flights under a single reservation, with many travellers fronting up at the airport with two or more separate bookings and hoping their bag will reappear at their final destination.
But it's not necessarily that simple: many airlines may only check you and your luggage as far as your first ticket takes you, even if your connecting flight is on a common alliance partner, such as of Oneworld, Star Alliance or SkyTeam.
Australian Business Traveller rounds up the connecting flight policies of the three major airline alliances – and in short, you're best to fly under a single booking wherever you can.
Connecting baggage policies: Oneworld
Under the alliance’s ‘minimum standards’ policy, Oneworld airlines must check passengers and their baggage through to their final destination, wherever possible, when their connecting flights are both booked under the one reservation.
There’s no issue if each flight is booked under a separate ‘ticket number’ within that reservation – they just need to be booked under the same reservation code, PNR or booking reference, depending on which term you prefer.
However, when a journey spans multiple reservations, such as Qantas to Singapore on one booking and British Airways to London on a separate booking, the first airline is no longer obligated to check you right through.
Qantas is making an exception until September 1 2016, but after which this benefit will no longer apply.
That means clearing passport control in the middle of your journey, collecting your baggage, clearing customs, lining up to re-check that bag and obtain your onward boarding pass, another sweep through passport control and security and then heading to the lounge or your boarding gate.
Airlines are still free to go above and beyond what’s required, with American Airlines and Malaysia Airlines among those that will continue through-checking connecting passengers with multiple bookings.
Connecting baggage policies: Star Alliance
Star Alliance operates a similar policy to Oneworld in that connecting passengers will be checked through to their final destination on any Star Alliance airline, provided all flights were booked under the same reservation.
Front up at the airport with multiple bookings, however, and your luck may be lost in transit.
Some airlines may elect to go above and beyond with Australian Business Traveller readers sharing positive experiences with Singapore Airlines and Thai Airways in recent weeks – but of course, this isn't to be expected.
There's no harm in asking politely to be checked through on an onward flight, but we'd strongly recommend allowing ample time in between flights to collect and re-check your baggage if necessary, should the airline or check-in agent be unable or unwilling to extend you a favour.
Connecting baggage policies: SkyTeam
As you'd expect, SkyTeam alliance airlines will also check you through to your final destination when your entire journey is covered under one booking, and any of those connecting flights are also on SkyTeam member airlines.
That means you could fly Korean Air from Sydney or Brisbane to Seoul and connect onward to Amsterdam with KLM, with your bags and KLM boarding passes taken care of in Sydney.
Through-check is also available via SkyTeam's automated check-in kiosks, again when flights form one booking.
As to connections across separate tickets, that's again left at the discretion of each SkyTeam alliance airline, with any policies and processes here "governed by individual commercial and/or bilateral agreements between the members," a SkyTeam spokesperson has confirmed.
In other words, don't hesitate to ask at the check-in desk, but book flights separately only under the assumption that you'll be picking up your bags along the way.
Follow Australian Business Traveller on Twitter: we're @AusBT