# How many serious airline accidents have been caused by design faults alone?

That is, in the chain of events that led to death or injuries in an airline accident, how often has a design fault been solely responsible?

By a design fault I mean a problem such that even if the equipment:

• were maintained and operated to the highest possible standards
• flown in ideal conditions
• by pilots who committed no errors
• unaffected by manufacturing defects

eventually it would still inevitably eventually kill or injure its passengers.

I can think of only two examples: the early Comet's square windows, and the Boeing 737 rudder power control problem.

All the others I can think of include errors of piloting, manufacture, maintenance or just plain bad luck in the chain of causes.

Are there others?

• I don't know if the dH Comet's windows meets your "flown in ideal conditions" criteria. It's just that "ideal conditions" in that case weren't the same thing as the actual operating conditions, even if the aircraft was operated within its intended operating envelope. You might want to reconsider that criteria. – a CVn Mar 11 '19 at 8:07
• I'd agree the Comet is a good example. Most others would have been early aircraft that were built and crashed on their very first attempt to get airborne, at times when aerodynamics and other relevant sciences were so poorly understood that people designed aircraft through trial and error basically. – jwenting Mar 11 '19 at 9:02
• The Comet was flown as intended, in the conditions expected, that it should have been able to deal with by design. Even if the Comet had only flown in perfect conditions, eventually it would have succumbed unexpectedly. – Daniele Procida Mar 11 '19 at 9:23
• I think it is difficult to trace one single cause. Comet's windows: it was know the fatigue problem on windows. Just the procedures were to check after X hours, and not after Y cycles (that aircraft did a lot more short flights then expected). So more testing/procedural problem. OTOH "design" is very open. A optimal designed aircraft should reduce/remove most of other problems. – Giacomo Catenazzi Mar 11 '19 at 10:29
• The problem wasn't that the Comet's windows were square(ish). They had rounded corners, just not as rounded as modern windows. The root issue was the use of insufficient material and rivets to achieve the strength and fatigue resistance with that particular shape. They thought it was sufficient, but there were errors in calculations. If they'd made the corners beefier in the first place it never would've been a problem. Making them round later on was just a lighter solution than a beefier square. – John K Mar 11 '19 at 12:31

The Douglas DC-10 - The door latching mechanism was not robust and the design of the safety indication was flawed. In the Paris incident Douglas tried to blame the handler who closed the bulk compartment door for using excessive force when latching the door but ultimately the design was at fault.

• Nitpicking, but that incident was caused by a combination of a design flaw and incorrect aircraft handling, not solely the design flaw. Had the door been closed properly it's unlikely a crash would have resulted. – jwenting Mar 11 '19 at 9:00
• I don't think the DC-10 fits. There were design flaws that were later remedied, but I think that in each case the design flaw was a contributor, not a sole cause. – Daniele Procida Mar 11 '19 at 9:20
• The fact that the design was modified as a result of the crash shows that the initial design was flawed. Modifications to the system as required by a service bulletin were not carried out properly. – Anilv Mar 12 '19 at 2:47
• Another issues was the insufficiency vents between the lower and .main decks. In the WIndsor Locks incident the collapse of the aft cabin floor took out the control cables to the tail due to differential pressure between the lower and main deck. Additional vents were required so that pressure could be equalised without compromising the cabin floor. – Anilv Mar 12 '19 at 2:51
• Yes, the design had a flaw. But the design flaw was not solely responsible; you even mention incorrectly-performed modifications. – Daniele Procida Mar 13 '19 at 7:35

I'd say British Airways flight 38 qualifies. Flawed design of the fuel/oil heat exchanger allowed ice to block fuel flow. The aircraft was operated within intended limits and the crew did everything correctly. It was not a maintenance issue nor a manufacturing error.

One of the early ones is the crash of a BFW M.20 on the Berlin-Goerlitz route on April 14, 1931. In a gust the rear fuselage was twisted by 60°, the tail surfaces almost broke off and the aircraft crashed. The crash investigation concluded that the design was good enough to satisfy the certification requirements, but that flight loads exceeded those. As a consequence, the certification loads were doubled.

Also, the rudder hard-over with the early Boeing 737s comes to mind. Those accidents caught the poor pilots in a trap. And maybe the first deep stall with the One-Eleven in 1963. Later accidents with the Hansa Jet and the Trident could had been avoided had the engineers and test pilots studied the One-Eleven accident better. Tupolev did and increased the tail size of their Tu-124A (which became the Tu-134) by 30% as a reaction.

The 1991 Lauda Air Boeing 767 uncommanded thrust reverser deployment might also fit. It happened before, in 1990, on the C-5A when the thrust reverser of the No. 1 engine deployed right after takeoff. Similar to Hawker-Siddeley before them, Boeing refused to learn that lesson and tried to cover up this design flaw.

Borderline case: The Kegworth air disaster, when a fan blade on the uprated CFM56 engine of a Boeing 737-400 broke and the different sourcing of flight deck air caused the pilots to shut down the good engine. It turned out that the engines had not been sufficiently tested and the pilots had insufficient familiarity with the engine instruments, so they came to their wrong conclusions (which would had been correct on the earlier 737s).

The Douglas DC-6 apparently had a design flaw in the cabin heater that caused one fatal accident and another emergency landing in 1947 before the design was corrected:

The Lockheed 188 Electra had a design flaw with regards to the engine mounting that caused catastrophic resonance and broke off the wings of two aircraft before it was corrected:

De Havilland Comet (structural problems, BOAC Flight 783 and 781 crashes in 1954 resulted grounding the entire fleet).

• The question is about airliners, not experimental aircraft. The only airliner in this answer is already mentioned in the question. – Daniele Procida Mar 13 '19 at 7:32
• The question has been edited. – h22 Mar 13 '19 at 10:13

### Embraer Bandeirante

Pitch trim switch causes trim runaway. Crew puts excess stress on control system. Tail breaks off.

NTSB report

• I replaced your link with the original PDF on the NTSB website, which hasn't been mangled by OCR (random fonts like a cut-out ransom note and, e.g., "Provincetown-Boston Airlines" becoming "Provincetown-Won Airlines", reference to "visual fight conditions", "Plight 1039", etc. just in the abstract). – David Richerby Mar 11 '19 at 20:24
• Thanks, should have looked at it closer. – Dswanson2609 Mar 11 '19 at 20:29

The infamous Boeing 787 battery problem caused at least one emergency landing and evacuation, with a small number of passenger injuries:

"There was a battery alert in the cockpit and there was an odd smell detected in the cockpit and cabin, and [the pilot] decided to make an emergency landing," said Osamu Shinobe, an ANA vice president, at a news conference.

ANA said that the 129 passengers and eight crew were evacuated, with a number of people sustaining minor injuries.

The Reuters news agency reported that five people were injured, while Bloomberg said that one person was sent to hospital. ANA officials were not immediately available to confirm the figures.

To answer the title question of how many, we need to check the proper Accident Classification Taxonomy as used by IATA.

What you're interested in is the:

• Latent conditions:
• Design
• Design shortcomings
• Manufacturing defects

## 10% of the jet accidents are design related$$^1$$

$$^1$$ IATA Safety Report 2017 54th edition (not confined by 2017 or 2013–2017).

• That's answering a different question in a way; we'd need to know how often that 10% contribution to the overall rate was the only contribution to a particular accident. – Daniele Procida Mar 13 '19 at 7:11
• @DanieleProcida: I don't disagree. I know I took a different approach to the rest hoping it would be helpful in some way. Having design the only factor is hard to isolate (I've tried). At least as far as design is a factor, I think my answer is comprehensive. – ymb1 Mar 13 '19 at 7:43

D-LZ129 Hindenburg, operated by the German Zeppelin Airline Company (Deutsche Zeppelin-Reederei).

• The cause of the accident has never been determined conclusively. – Sanchises Mar 12 '19 at 15:30
• Also, if design was the sole cause, why would the airship have flown successfully previously? Design might possibly have played a role in the Hindenburg disaster, but that doesn't mean the cause was a design fault alone. – a CVn Mar 12 '19 at 15:36
• Also while the cause has never been determined conclusively, it is mentioned that it was not maintained to highest standards and accumulated damage from previous flights is cited as possible contributing factor. So it does not qualify for that reason. – Jan Hudec Mar 18 '19 at 20:31