The Kegworth air disaster that killed 47 people 25 years ago on 8 January 1989 resulted in changes in engine testing, pilot training, and guidelines for aircraft seat construction.
The regular flight from London’s Heathrow Airport to Belfast, Ireland operated by British Midland Airways got into troubles 13 minutes after take-off when an outer portion of a fan blade on the left engine failed as the aircraft was climbing up to reach its cruising altitude.
As a result of the fan blade failure, the aircraft was struck with intense vibration. The engine’s compressors stopped working correctly and smoke and fumes penetrated the cabin.
However, the flight’s captain Kevin Hunt and his first officer David McClelland were confused. Having been used to fly older versions of a Boeing 737, they believed air for air-conditioning the aircraft’s interior was drawn in through the right engine – which would indicate the right engine as the cause of the smoke inside. Unfortunately, the affected plane was a Boeing 737-400, the first Boeing-manufactured aircraft where air was drawn inside through both engines.
The pilots weren’t able to check the engines visually from the cockpit and decided to switch off the suspected right engine.
Some of the surviving passengers seated in the back of the plane later recalled seeing sparks and flames coming out from the remaining engine but didn’t feel qualified enough to question the captain’s decision. Back then, the rule that the captain knows best was respected, discouraging other personnel as well as passengers from questioning the decisions.
The fact that the vibration ceased after the right engine was switched off seemed to confirm the pilots’ conclusions.
The pilots steered the aircraft towards the East Midlands Airport for an emergency landing. However, about 2.4 nautical miles away from the runway, a fire warning and abrupt thrust loss occurred on the remaining left engine. Attempts to restart the right engine were unsuccessful, and the airplane crashed approximately one-half mile short of the airport into the embankment of the M1 motorway.
79 people, including the two pilots survived the crash though most of them with serious injuries.
The investigation later revealed the engines used in the Boeing 737-400 were an upgrade of the previous engine and were only tested in laboratory conditions. The review of the Kegworth disaster led to a decision that all new or upgraded engines have to be tested in flight before being used commercially.
After the accident, all Boeings 737-400 were grounded and engines modified to mitigate excess vibration at high power settings – the cause of the broken fan blade.
The official report into the disaster made 31 safety recommendations to improve aircraft safety and emergency instructions for passengers. A joint team from the University of Nottingham and a consultancy company Hawtal Whiting Structures revised the brace position for emergency landing and new guidelines were issued four years later.
The investigation concluded the relatively high number of survivors was due to the fact the aircraft had been voluntarily equipped with sturdier seats, capable to withstand accelerations of 16g that would later become a norm.