飞航工程师（又称飞行工程师、随机工程师，英文：Flight Engineer，缩写：F/E），在旧一代的大型飞机，主要在起飞前与降落后检查飞机，并在飞行期间检查操作飞机的系统，包括液压操控、燃油消耗、机舱增压、电力等系统。在部分军用飞机，飞航工程师更会进行飞行前的完全检查。基本上，飞航工程师是飞机系统专家，专责解决飞机系统的问题、提供飞行紧急情况的处理方案，并计算起飞与降落的数据。

在旧式民航机与及部分军机上，飞航工程师坐在正副飞行员的后面，并面向侧面的一排仪表。有些军机，例如P-3猎户座海上巡逻机与C-130H飞机，飞航工程师则坐在正副飞行员的中间。图-134更特别，飞航工程师是坐在机头尖端。

A flight engineer (FE), also sometimes called an air engineer, is the member of an aircraft's flight crew who monitors and operates its complex aircraft systems. In the early era of aviation, the position was sometimes referred to as the "air mechanic". Flight engineers can still be found on some larger fixed-wing airplanes, and rotary wing helicopters. A similar crew position exists on some spacecraft. For U.S. civilian aircraft that require a flight engineer as part of the crew, the FE must possess an FAA Flight Engineer certificate with reciprocating, turboprop, or turbojet ratings appropriate to the aircraft. Whereas the four-engine Douglas DC-4 did not require an FE, the FAA Type Certificates of subsequent four engine reciprocating engine airplanes (DC-6, DC-7, Constellation, Boeing 307 and 377) and early three- and four-engine jets (Boeing 707, 727, early 747, DC-10) required FEs. Later three- and four-engine jets (MD-11, B-747-400 and later) were designed with sufficient automation to eliminate the FE position.