This article is a travel topic
Traveling as an air courier is a way to get cheap air-fare by giving up most or all of your luggage allowance. You generally have to organize ahead of time, but sometimes, last-minute deals are available.
 How it works
Courier companies are well paid for delivering things quickly. Frequently, time is very important with business documents, spare parts for an urgent repair, etc. On some routes, the larger companies have their own planes, but for other routes and smaller firms there is a problem. If they send things by air freight, it may take days to get through unloading and customs. The only way to get it through faster is to send it as checked luggage. Airline regulations will not allow them to send luggage without a passenger, which is where you come in.
Courier companies routinely book one seat each way, every day on flights between two major business centers. For example, from New York to Hong Kong. These are always economy class, generally on major airlines, and usually a flight that departs in the evening. Of course, the airlines give them a very good price.
You can occupy that seat at a discount -- provided you accompany their stuff. A courier representative will meet you at the airport with your ticket, the shipment (which is checked in for you) and the shipping documents (which you carry). Another rep will meet you at the other end to take delivery. You just deliver the documents, and they do the rest. In no case, do you have to help with carrying their luggage load.
Sometimes, someone will also meet you in the middle; e.g. on a Sydney-London courier flight, you stop in Tokyo, where you drop off the Sydney-Tokyo stuff and pick up Tokyo-London.
Discounts are often substantial, 20% and up. Once the company knows you as a regular and reliable courier, deals may get even better. If someone cancels and they are stuck, they may offer a last-minute free flight. In other words, someone else paid dearly for your free trip!
A few years back, courier travel was possible within North America or Europe. That has been eliminated by air express companies such as FedEx and DHL which have their own planes or long-term contracts with the airlines. Nowadays, courier flights are almost all intercontinental.
Courier travel is not for everyone, and there are serious restrictions:
Booking through an agency is generally worth the small fee of joining the agency, as they are given most access to the flights. They may be able to offer flights that you could not find as a freelance courier.
 Stay safe
You need to be very careful about the legitimacy of the jobs you take. The last thing you want is to be caught transporting contraband (or worse) on a plane. A good way to avoid this is to use an agent (usually a representative of the service you are working for), who will take you through customs and clear the contents. Always check the reputation of the courier company before booking. None which are reliable and legitimate would ever try to ship anything illegal.
If you prepay any money for participation as a commercial airline envoy, you are being given the run around.
Not very long ago, taking a position as a commercial airline courier was an attractive way to travel on a small allowance. You essentially were contacted to transport a parcel from one city to another and your carry-on baggage allocation was “rented.” You were then rewarded with a low fare for the trip. This type of agreement isn’t as prevalent anymore, due to the fact that companies don’t rely on couriers as much as they used to, because air shipping is faster than it ever was before. Another reason is that security requirements have grown more rigorous in the wake of the 2001 terrorist attacks in New York and Washington DC.
These days, few companies can offer someone the chance to serve as a courier. Although in the 1970s, one would pay a token passage as a courier, nowadays, you barely save 15 to 50 % off the full ticket price (i.e., a flight from Washington to Madrid or Rome could possibly come to about £499 for a round trip, but one can regularly find these types of ticket prices being sold to the general public).
If you do decide to become a courier, you won’t receive many options in where you can travel. You go to whatever location they need you to visit, whether it is the Middle East, North America or another location. You obtain a last minute permit for the trip and are often times restricted as to the number of bags you are approved to have with you. Chances are, you will get better discounts by finding reasonably priced flights using other means.