IBM 9020
The air traffic control software ran on a modified version of OS/360 MVT as an embedded operating system, OS/9020, also referred to as the “Monitor”.
The relocated 9020A remained at Jacksonville to become the hardware platform for the Central Flow Control Function within the FAA's Washington-based ATCSCC.
It was renamed the Central Flow Control Computer and had a digital data link to the Washington command center.
Under the terms of the treaty the FAA would provide technical assistance to improve the Iranian National Airspace System.
The 9020As and 9020Ds were in service in North America until 1989 when they were finally replaced by IBM 3083 BX1 mainframes as part of the FAA's HOST Computer System (HCS) upgrade.
[11] At least during the first phase of the upgrade, the 9672s were running the FAA's original assembly language code in System/360 emulation mode.
Because of the failure of the FAA's Advanced Automation System (AAS) project, the 9020E Display Channel Complexes lasted well into the 1990s.
The third CE and IOCE provided backup in case of a hardware error and they would be automatically switched into the configuration upon failure of the online system.
The Air Traffic Control Software, Known as NAS in the UK had five primary operational functions: (in the US, NAS refers to the Whole Air Traffic System - National Airspace System) 1) ROUTE PROCESSING - Convert a flight plan into a series of fixes.
Stereographic projection converts the data to a flat-earth model with the point of tangency (where the flat plane meets the round earth) near to Oxford.
This allowed the flight strip data presented to the air traffic controllers to be updated with actual times.
Later in its life NAS Terminator processing was added to detect if the same flight causes two startovers in a parameter time.
To save system resources at run time, the geographic database of the UK airspace and the addresses of all of the peripherals are pre-processed, sorted and linked into a pre-populated database by an offline build tool which is attached to the Applications and Monitor at system build time.
If the Standby processor fails to receive a heartbeat in a parameter time, it promotes itself to Main, switches all of the peripherals to itself and performs a startover to rebuild the flight plan database.
