As a commercially-rated airplane pilot who’s read over 2,000 accident reports, I followed the Southwest Flight 1380 fatal uncontained engine explosion closely.
The FAA failed in it’s oversight responsibility of airline engine maintenance in two cases:
- The rotating fan blade that killed the passenger had not been tested since 2012, almost 5 years, meaning this was a preventable accident. Fatigue cracks were found at the blade dovetail, an obvious locus. Update 2018-10-01: engine inspections now 1,600 cycles.
- The engine shroud did not contain the flying blade, leading to the death of a passenger.
The FAA is likely investigating the following concerns:
- how well did the pilots handle the emergency (it appears well, handling the depressurization event and descending to a breathable altitude.)
- engine turbine blade failure (engine design and maintenance)
- uncontained engine shrapnel (engine design)
- uncontained engine shrapnel into passenger cabin, resulting in the death of a passenger and 7 with minor injuries (plus psychological trauma, esp. to first responders) (fuselage design)
- improper use of oxygen masks by most passengers (passenger safety briefing, oxygen mask design.)
- the passenger killed was wearing a seatbelt, yet was partially blown out of the airplane. Was the seat belt worn snugly. If so, do we need 3-point or 5-point harnesses?
- it’s the first US airline accident in 9 years, and the first en route fatal accident for Southwest. The FAA wants zero accidents for political reasons, and Southwest wants zero accidents as an operating airline.
The oxygen masks descended, but passengers wore the mask over their mouth. Masks are intended to be worn over the nose, so likely the mask shape will be changed and training materials updated.
Regarding the above items, a simple explanation of what was expected and what happened is this.
There are FAA regulatory and political expectations that uncontained engine failures don’t happen. However the physics of large machines with rotating components says otherwise. Likely this will result in armoring the engine shroud and hull with kevlar or metal, and further engine design changes based on energy of rotating components.
There are FAA expectations that the aviation industry mitigates risk so that the uninformed flying public is not injured. However, a passenger died en route.
After the depressurization, oxygen masks were expected to descend and be used by passengers over their nose. Instead they were put over their mouth. Likely passenger briefings will become more detailed, and oxygen masks will be changed from a round to pear-shaped.
Fortunately the pilots descended relatively quickly, at 3,000 fpm, to 10,000′, as:
- time of useful consciousness at 35,000′ is only about 1 minute
- the masks were worn incorrectly
- only about 10 minutes of oxygen is available in cannisters when properly provisioned
However, was the emergency descent actually fast enough? With an improperly-worn mask, generally-speaking the body needs sufficient cabin oxygen pressure within 4 minutes to prevent brain-damage or death.
avweb.com: Southwest Accident Brings Passenger Safety Briefings To The Forefront
philg: Southwest 1380: think about the flight attendants
avweb.com: Southwest 1380: “Flew Like a Rock”
ainonline.com: Southwest Airlines 1380 Engine Failure 4/17/2018 ATC Audio
1 killed as Southwest jet makes emergency landing after apparently blowing an engine in flight
Qantas Oxygen Mishaps (2007 and 2008)
These Qantas incidents illustrate the importance of vigilance when maintaining passenger oxygen canisters:
1) Careless filling with nitrogen instead of oxygen:
2) Oxygen canister valve failure due to unknown cause:
nytimes.com: Officials Ask Qantas to Inspect Oxygen Canisters
telegraph.co.uk: Exploding oxygen bottle caused hole in Qantas jet
smh.com.au: Valve in oxygen cylinder the culprit in 747 explosion
Oxygen canister valve failure causes depressurization in Qantas 747 (2008)
Regulators Mandate More Inspections for 737NG Fan Blades