Type B is a messaging standard used by the Air Transport industry (not just airlines). Initally it was used as mechanism to send short messages to ensure bookings and reservations were guaranteed. Typically reservations and seat booking messages are less than 300 characters in length and contained many abbreviations that originally only trained operators could understand.
In the early days, the messages arrived in the form of punched tape (using a 7 bit Baudot format) that had headers defining their priority in telex queues. These heading queues at the top of the message, defined how quickly they were dealt with by the operators (QC,QU/ QX, QK and QK). Each had a different pricing scheme depending on the priority. Although considered as store and forward, a large amount of the messages were in fact manually sorted and delivered via centres equipped with many send and recieve telex machines.
Today, Type B is considered a centralised automated store and forward system with little manual interaction. High volume switching machines take the place of manual operators. A large percentage of today’s Type B messages are sent to and from airline hosts with a big portion begin seat availability and reservation information (also known as AVS). As well as Airlines, the Global Distribution Systems (GDS’s) are large senders and recievers of Type B messages.
The majority of the airlines seat avilability resides in either the host system of the airline or large databases hosted in GDS’s. Type B allows hosts to send seat availablity information and guarantees on seat booking between these host systems.
Sometimes instead of sending larger volumes of Type B transmissions to a 3rd party provider for switching, airlines tend to put in bi-laterial agreements in place to share the cost of single circuits between their respective hosts. This is a common practice between code sharing partners or larger airlines sending traffic to GDSs.
Type B is also used for the transmission of flight plans, departure control messages and cargo manifests. However typcially airlines try to avoid the large use of long message formats owing to the cost of transmission.
Cost. Type B can be considered expensive, and a number of airlines have sought ways to reduce the cost of transmissions including, by passing Type B and using internet for person to person e-mail.
Some suppliers offer a flat rate pricing scheme, others offer regional based pricing with volume discounts. Charges and discounts are usually defined by volume (e.g. price per million characters). Usually the sender pays the cost of Type B.
Suppliers: Several suppliers offer global switched Type services, including