American Automates Reservations and Ticketing, Part One: Reservisor System

C.R. Smith knew reservation systems had to keep up with jet speeds

In the early days of the airlines, the reservations and ticketing process was all done by hand at a central office with a ledger that was passed among agents who recorded reservations and erased ones that were canceled. As airlines grew in the early 1930s with the introduction of larger aircraft like the Boeing 247 and in particular, the Douglas DC-3, a single book was obviously impractical so multiple ledgers for each flight was kept in a large lazy-Susan with the reservations agents sitting all around. As they took incoming calls, they retrieved the ledger for that particular flight. The books had to be frequently reconciled so that more seats weren't sold than available and even for small airlines, this process of inventory reconciliation was time consuming on top of the fact that it had to be done multiple times through the day. Books soon gave way to large chalk boards and reservation offices had to get bigger in size to not only accommodate every larger boards to display the seat inventory for each flight, but to also accommodate the increasing numbers of personnel to keep the system running. As agents took calls, they filled out cards that were then taken clerks to the other agents who maintained the boards. Supervisors watched the boards and in the case for large airlines, they would have to use binoculars or opera glasses to view the data. A typical reservations office for a large airline might be sixty agents taking phone calls with forty additional clerks and agents who maintained the boards and conveyed data back and forth. It was a personnel intensive and time consuming process become progressively more cumbersome as airlines added more flights and larger aircraft. The first systems in place were called "Request and Reply"- agents took calls and then passed a message to "Inventory Control" who were the agents who maintained the boards. The message went back to confirm that the seat was available and reserved and a third message confirmed the reservation. So even the most rudimentary system in use needed three messages and even in those days, the airlines were the biggest users of telephone lines in the United States. In 1939, the Boston reservations office for American Airlines had determined that until a flight was 80% sold, it was possible to sell seats freely without having to get a reply from inventory control. This streamlined the process as message volumes were cut in half. When a flight was 80% full, agents in inventory control sent out a stop-sale and any further sales on those flights required confirmation from inventory control. This system was called "Sell and Report" but became "Request and Reply" for any flight over 80% booked. Despite this, the airline still had to reconcile seat inventory as well as get out ticketing information to the airports. Clerical mistakes were common and it wasn't unusual for business traveler to book two flights just in case.

Typical reservations center with status boards (this one is Pan Am's)

In 1943 a system analyst with a background in electronics and communications, Charles Amman, joined American Airlines and was tasked to find a better solution. Running the military's Air Transport Command during the war, C.R. Smith astutely saw not just a postwar boom in air travel but the arrival of faster and larger aircraft that would hopelessly encumber the manual system. Amman had determined there were three key steps in the reservations process: determine seat availability, adjust the seat inventory, and record the passenger's name. Amman met with several manufacturers of adding machines and electromechanical equipment of the day and every single one thought what American wanted was impossible- too many variables to adjust in real time was simply beyond what the technology of the day could accomplish. Amman even pared down the requirements to just the first two steps in the reservations process, determining seat availability and adjusting the seat inventory but even this was too daunting for companies he approached. Amman had C.R. Smith's support to try and come up with an in-house solution. A series of tall cylinders with each representing a flight on a given day were filled with marbles. Each marble represented an available seat. An agent would use a cash register like device to select a flight to make a reservation. This sent an electrical signal to the cylinder that represented that flight and a hatch dropped one marble out of the cylinder. If a reservation was canceled, a marble was electrically released back into the cylinder. adjusting the seat inventory automatically. Amman's machine was bulky and impractical for an airline the size of American, but it demonstrated the principles of a solution.

An early Reservisor terminal

Amman's mock up convinced the Teleregister Corporation to sign on the develop the reservations system for American. Originally a division of Western Union, Teleregister was set up in 1948 as separate company and produced the stock ticker units used by stock brokers. This gave them the experience in remote data transmission that could be applied to the American reservations project. American called the system "Reservisor" and the first pilot system was a massive room of switches, relays, and plugs called "The Brain" which was installed in the Boston reservations office in 1946. Electrical relays replaced the marbles and cylinders of Amman's mockup with the agents using a smaller device that looked like the early adding machines used by accountants. "The Brain" replied on the agent's terminal if space was available- a green light meant space was available for booking, an amber light meant the flight was sold out. A one year pilot of the Reservisor at the Boston office showed two hundred additional passengers could be booked each day with twenty less personnel. C.R. Smith, back in the executive suite after serving as head of the Air Transport Command during the war, was excited about the possibilities of expanding the Reservisor system across American's network. But the Reservisor as it was still encountered delays as it only solved the first two parts of the reservations process- determining seat availability and adjusting seat inventory. Passenger names for the tickets were still taken down by hand and there was still a stop-sale system in place as agents were responsible for manually inserting control plugs into the proper parts of "The Brain" when a flight reached 80% full. But the Reservisor as it was was a quantum leap over what American had done before and because the airline wanted accuracy and reliability, Teleregister incorporated redundancy into the Reservisor system. The challenge at that point wasn't just addressing the last step of the reservations process but to also speed up the system and increase its memory capacity as the airline not only grew but added faster aircraft like jets. Recognizing that there was a sales advantage to a faster system, Amman also wanted an upgrade to Reservisor that would allow an agent to recommend an alternate flight should a passenger's first choice of flight be booked. What he wanted was for Reservisor to be able to not just store increasing amounts of flight information, but to also be quick to allow agents to easily query the system to find out seat availability on alternate flights. He had been following developments in computer memory and settled on what was called drum memory for Reservisor. 

Magnetronic Reservisor. Note the smaller terminal and drum memory units.

The drum was a large metal cylinder coated with a ferromagnetic material and a row of fixed read-write heads along the long axis of the drum. Each read-write head had its own track on the drum. It was a precursor to the hard disk platters of today which have a moving read-write head that moves across a spinning disk. In drum memory, each track on the circumference of the drum had its own read-write head. Drum memory is what replaced the relays and switches of "The Brain" of the first version of Reservisor. The new upgraded Reservisor was called the Magnetronic Reservisor and first went into operation in 1952 at American's reservations office at New York La Guardia Airport. The system had a response time of one second and the drum unit could hold data for 1,000 flights up to 10 days in advance. Four years later, a larger unit was installed in the West Side of New York City that had a half-second response time and could store data for 2,000 flights up to 31 days in advance. Amman redesigned the West Side reservations center of American Airlines to take advantage of the new Magnetronic Reservisor with 362 agents to take phone calls, each with their own terminal. Forty additional agents were devoted just to handling reservation requests from travel agencies and large business accounts. Another 140 agents acted as liaisons between the reservations center and the other reservations offices, airport stations, and airline operations center. Forty supervisors oversaw the West Side center that averaged 4,500 phone calls a day. 

Close up of the drum memory units. The wires ran to the read-write heads.

Despite the advances of the 1956 version of the Magnetronic Reservisor, Amman worked with IBM on the last step in the reservations process, connecting passenger information with the reservation. In 1956, the Reserwriter went into operation after testing in Buffalo. The Reserwriter basically read keypunched cards that represented passenger information and then automatically sent messages via teletype to the main reservations offices. Messages could go back and forth between the two systems (albeit manually) and for the first time for the airline, agents didn't have to be in the main reservation offices to book flights. By 1958, Reserwriter terminals were in key locations across the country in American's network. Despite the success of the whole system, it still suffered with errors on account of the number of individuals still required to make the system work. Approximately 8% of reservation transactions at American were in error despite the advances in the system. Passengers who benefited the most from the Reservisor system were those flying into and out of the largest of American's destinations. The Reserwriter terminals at outlying locations helped, but because manual action was needed to move information between Reserwriter and Reservisor, it was prone to error not to mention still time consuming. For example, a round trip reservation between Buffalo and New York La Guardia required 12 people, 15 distinct steps and could take as long as three hours. Passenger growth at American meant that over an eight year period from 1950 to 1958, the number of passengers flying on American per reservations employee had dropped from 5,100 to 3,100. Simply adding employees wasn't a solution in C.R. Smith's eyes. The transaction error rate meant the airline had to undersell a flight to avoid overselling a flight during times of peak volume. American would be taking delivery of its first Boeing 707s in 1959. This meant that a transcontinental flight was faster and could move more passengers- the airline's flagship DC-7 services moved 80 passengers across the United States in 10 hours but the 707s promised to move 112 passengers across the nation in just 5 to 6 hours. Smith was worried that the new jets would overwhelm the existing system. What American needed to keep up with the jet age was reservations system that moved just as fast, preferably in real-time and with as little manual intervention as possible. Charles Amman's original reservations problem from 1953 was still an issue that lurked in the background- determine seat availability, adjust the seat inventory, and record the passenger's name. Only now, it had to be done in real time if it was to keep up with jet aircraft. 

That solution will be the subject of a future post on this blog, so stay tuned! 

Source: Hard Landing: The Epic Contest for Power and Profits That Plunged the Airlines into Chaos by Thomas Petzinger. Times Business/Random House, 1996, pp 57-60. Waves of Change: Business Evolution Through Information Technology by James L. McKenney, Duncan C. Copeland, et all. Harvard Business Press, 1995, pp 97-106. Images: Wikipedia, American Airlines C.R. Smith Museum