A Learjet 31A jet belonging to the Balochistan government
The Learjet 31A was announced in 1990 as a replacement. The model 31A boasted numerous modifications, however the most notable changes would take place on the flight deck. Key modifications and updates to the model 31A cockpit and avionics include; a Bendix King (now Honeywell after the merger with Allied Signal) Electronic Flight Information System 50, with Universal 1M, 1B and 1C flight management system, a dual KFC 3100 two-axis autopilot and flight director with yaw damper, and dual Bendix King (Radios sold to Chelton Avionics when Allied Signal combined with Honeywell) VCS-40A com units, VN-411B Series III navigation receivers.

In the year 2000 the Learjet 31A was again revised. Takeoff and landing weights were increased.[4] The original design N2 digital electronic engine control (DEEC) was replaced with an N1 DEEC,[4][5] and the thrust reversers became standard equipment. Another notable improvement is Honeywell’s TFE731-2 to -2C engine upgrade.[6] The original R12 freon air conditioning system was replaced with an R134A system divided into two zones – cockpit and cabin.