East African Airways Flight 720

East African Airways

Company type	Airline
Industry	Aviation
Founded	1946
Headquarters	Nairobi , Kenya
Area served	East Africa, United Kingdom, Italy, Ethiopia

East African Airways Flight 720 (EC720) was a scheduled international passenger service operated by East African Airways using a Vickers VC10. The route connected Kenya with the United Kingdom, including stopovers in Ethiopia and Italy. On 18 April 1972, during takeoff from Bole International Airport in Addis Ababa, the aircraft caught fire and crashed, resulting in 43 fatalities among the 107 people on board. This incident ranks as the third most fatal aviation disaster on Ethiopian territory.

An inquiry conducted by the Ethiopian Civil Aviation Administration determined that the accident was primarily caused by a partial failure of the braking system, attributed to an improper reassembly of its components. This malfunction prevented the plane from halting within the available runway length. Additionally, the aircraft encountered a foreign object during its takeoff roll, which induced severe vibrations. Although the flight crew correctly initiated an aborted takeoff procedure, the ineffective braking led to the aircraft overrunning the runway.

Aircraft

The airplane involved was a five-year-old Vickers Super VC10, registered as 5X-UVA with manufacturer serial number 881. Manufactured by British Aircraft Corporation in 1966, it entered service that same year. Up to the time of the accident, it had accumulated 18,586 flight hours and had been maintained according to prescribed schedules.

Passengers and crew

Onboard the aircraft were 96 passengers along with 11 crew members, making a total of 107 individuals. According to The New York Times, a significant portion of the passengers consisted of children from British nationals returning from their Easter holidays. Additionally, there were Italian nationals among those aboard. The majority of the crew hailed from East Africa.

The flight was commanded by Captain John Vale, aged 42, who had accumulated 8,769 flight hours in total, including 752 hours on the Vickers VC10. His co-pilot, First Officer Ronald Botto, aged 26, had logged 2,744 flight hours with 640 hours on this aircraft type. Accompanying them were Navigating Officer Frank MacNabb, 45 years old, and Flight Engineer Brian Twist, aged 34.

Pre-accident

Flight 720 was scheduled to travel from Nairobi, the capital of Kenya, to London with stopovers in Addis Ababa and Rome. On April 18, 1972, the aircraft departed from Embakasi Airport in Nairobi (currently known as Jomo Kenyatta International Airport) at 09:55 EAT (06:55 UTC), reaching Bole Airport at 11:23 EAT. At this point, 40 passengers left the plane while 15 new passengers boarded.

While parked on the ramp, Flight Engineer Twist observed a leak of hydraulic fluid from the No.1 rear main wheel. He assessed the leak as tolerable for continuing the journey to London and chose not to report it.

The crew received clearance to start the engines and taxied toward runway 07 for takeoff. Shortly thereafter, they noticed dead birds scattered on the runway and informed air traffic control that they had struck one during landing. Consequently, they requested that the birds be cleared from the runway. A fire truck was dispatched by the tower for this purpose. Soon after, the aircraft reached the takeoff position at the runway's end and aligned itself for departure.

Accident

At 12:38 EAT, Flight 720 received clearance for takeoff. The pilots applied thrust and announced "rolling." Just past the runway midpoint, a loud explosion occurred—the right nose wheel had burst after colliding with a steel jacking pad left by a previously departed Cessna 185. The aircraft experienced severe shaking; its nose briefly lifted before settling back down. The crew chose to abort takeoff immediately, deploying thrust reversers and applying brakes to halt the plane. Passengers described hearing "screaming" brakes and observed white smoke emanating from the wheels. The aircraft slightly veered toward the right.

Soon after, a second loud explosion occurred as the No.1 rear main tire also burst. The plane overran the runway, crossed a storm drain, and momentarily became airborne. The left outer wing struck a steel lattice tower, rupturing fuel lines and igniting a fire. Witnesses recalled seeing flames trailing behind the aircraft as it crashed heavily onto the ground. The fuselage broke apart before coming to rest while engulfed in flames.

Immediate aftermath

The aircraft disintegrated into three primary sections, resulting in the release of nearly all of the 50,000 kg of fuel it carried. The blaze obstructed the right-side emergency exits, while the impact's force caused the left emergency exits to become stuck. Nevertheless, this impact also created a substantial opening in the forward left fuselage, through which most passengers chose to evacuate.

Although the majority aboard survived the crash, some passengers lost their lives due to the fire. Several passengers and crew members perished while assisting others in escaping from the burning plane. Those who managed to exit found themselves hindered by the airport’s barbed-wire perimeter fence. They were forced to move down a slope beside streams of jet fuel leaking from the wreckage. This fuel later ignited, trapping multiple individuals, some of whom died afterward.

The first emergency response at the scene came from a fire truck initially dispatched to remove dead birds from the runway. Additional fire engines arrived subsequently, and from 13:25 onwards, firefighting units from Addis Ababa joined the rescue efforts.

Following the accident, 20 individuals were transported to Addis Ababa Seventh Day Adventist Hospital, with 16 in critical condition. Some injured passengers were airlifted to the United Kingdom by the Royal Air Force. Rescuers recovered 36 bodies at the site. The fatality count increased as several survivors later died from their injuries. Ultimately, 43 people—comprising 35 passengers and 8 crew members—lost their lives in this tragedy.

Nose wheel failure

The failure of the nose wheel was traced back to damage caused by a steel object on the runway. This object was identified as a steel jacking pad belonging to a Cessna 185 aircraft. The jacking pad had been resting approximately 2,147 meters from the runway’s threshold for about 4 hours and 40 minutes prior to the incident. Due to its relatively small size, it was unlikely that ground personnel would have noticed it unless by chance. Since it appeared after the daily runway inspection had been completed, no one had discovered it during routine checks. Furthermore, the fire truck that had been sent earlier to clear dead birds from another section of the runway did not address the area where this jacking pad was located.

Decision to abort take-off

The crew operating Flight 720 chose to abort the take-off exclusively because of the nose wheel failure. The intense vibration and loss of aircraft control appeared to overwhelm the pilots. Faced with this urgent and distressing circumstance, the crew immediately assumed the aircraft was unfit for flight, prompting their decision to halt the take-off. Although the crew did not fully evaluate the exact cause of the emergency, their prompt choice was justified since the aircraft's speed remained below the decision speed (V1) threshold of 140 knots, and the severity of the situation warranted such action.

Additionally, their swift response was sensible given that the available runway length and current aircraft speed allowed for a safe rejected take-off. The nose wheel failure took place roughly 2,158 meters from the runway threshold, after which the pilots promptly engaged the brakes. Investigators’ calculations confirmed that under normal conditions, the aircraft could have stopped safely before reaching the runway’s end.

Faulty brake reassembly

Despite sufficient runway distance for a safe stop, Flight 720 ultimately overran the runway. Investigation revealed that only about 70% of the aircraft’s braking capability was utilized during this event. This reduced braking efficiency resulted from several malfunctions within the braking system, including the failure of the No.1 rear wheel due to bursting, diminished functionality of the No.4 front brake, and an unexplained malfunction in the No.2 rear brake.

The compromised braking performance stemmed from multiple issues: defects detected in the No.2 rear anti-skid system, improper installation of the left rear transfer tube, and blockage caused by incorrect assembly of a restrictor pack inside the No.4 front brake.

Inspection of the No.4 front brake’s servo unit showed that an incorrectly assembled restrictor pack limited hydraulic fluid flow to the brakes. When the flight crew activated the anti-skid system, brake pressure recovery was too slow, preventing optimal brake operation.

The No.1 rear brake was cross-connected to the No.2 anti-skid unit, while the No.2 rear brake was linked to the No.1 anti-skid unit via a rear transfer tube on the axle. However, examination found this tube installed in reverse. Although both brakes were functional, a foreign rubber seal inside the hydraulic coupling at the transfer tube’s end obstructed proper operation of the No.2 anti-skid unit. Consequently, brake pressure on the No.1 rear brake could not be relieved by this unit, causing wheel lock-up and subsequent tire burst.

Conclusion

The Ethiopian Civil Aviation Administration determined the accident resulted from a partial failure in braking performance caused by improper reassembly of a component within the braking system. Consequently, the aircraft was unable to halt within the designated emergency stopping distance after a correctly performed aborted take-off procedure.