AA383 Chicago 767 fire highlights evacuation safety issues

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The passenger and crew casualties of the uncontained engine failure of the Boeing 767-300ER operating American Airlines flight 383 from Chicago O’Hare number only in the tens of relatively minor injuries. That is a testament to the skills of 1980s Boeing engineers, today’s American Airlines flight deck and cabin crew, and decades of safety improvements driven partly by investigations into incidents like this one.

At the same time, the reduction in the rate of incidents also means that the number of real-world data points for further safety improvements is decreasing, increasing the safety value of learning as much as possible from each incident. That’s particularly true in light of ongoing and increasing reliance on computer simulation by airframers and regulators when conducting safety certification.

Rear slide inversion continues worrying trend

The inversion of the rear slide is typical of an ongoing issue with safety evacuation, most recently raised in the UAE crash investigation report of Emirates flight EK521 in Dubai, where zero of the slides functioned optimally during the evacuation of a Boeing 777. The runway at O’Hare does not seem to have been abnormally or unusually windy, nor indeed at the limits of slide operation (25-knot or 28-mph winds).

This video shows the incident from just prior to the first doors being opened, and demonstrates the ferocity with which the fire was already burning at a very early stage in the incident.

Of particular note, the rear left-hand slide appears to bounce upwards and towards the tail of the aircraft. A later video appears to show two evacuating passengers or crew righting the slide before evacuation could begin.

The impact of this slide being out of commission could have been significant, given its location at the denser economy class cabin, that the right hand side of the aircraft was engulfed in a fire strong enough to melt a substantial portion of the starboard wing, and that each side of the aircraft has just two full-sized doors and two overwing exits to begin with.

The fire in this incident seemed unusually strong and fast

The strength and speed of the fire has been a topic of particular concern in industry circles overnight Friday, and investigators will need to determine whether the fire’s characteristics mean further consideration must be given to the planning and certification assumptions around aircraft incidents involving fire.

“Within that time, I think it was seven seconds, there was smoke in the plane and the fire is right up against the windows, and it’s melting the windows,” a passenger reported.

Apparent reduction in passengers grabbing bags is a positive, but problems still exist 

A passenger video shows a low number of overhead bins opened, given examples from recent flights where half of the aircraft seems to be evacuating with rollaboards, duty free and other personal items.

However, a number of issues immediately jump out. While larger, swing-down overhead bins are an overall passenger experience positive, they do create solid obstacles at head level in a constrained space. Many passengers already bump their heads on a lowered overhead bin during relatively calm boardings and disembarkations.

It may well be time to consider the long-proposed solution — locking of the overhead bins during taxi, takeoff and landing — which would likely have other net positives. These might include reducing the number of items that inadvertently fall out of closed-but-not-fully-latched bins, and indeed reduce the benefit of passengers standing up after landing but before the aircraft has come to its final stop at the gate.

RGN’s Seth Miller highlighted this issue just hours prior to the AA383 incident. There’s a motivational difference between “please sit down” and “the bins are locked” for passengers who might think of disregarding the rules.

An issue where this evacuation does not provide any additional initial data points is on the evacuation safety of increasingly densified economy class cabins. American’s relatively spacious 2-3-2 economy class cabin with 31” seat pitch means that the overall density of this aircraft is uncharacteristically high in the modern context.

Amount, frequency and location of crew directions may need attention

A further issue highlighted by the interior passenger video is that of audible instructions to passengers. The passenger recording hears only “Stay seated, jump and slide” when four people back from the slide, and one further “jump and slide” a few seconds later.

The information was delivered by the flight attendant, but in the age of small speakers and audio directions, it may be sensible to evaluate whether some of this information can be automated — and indeed internationalised.

As an industry, do we need to add pre-programmed audio, potentially with multiple tracks for various sections of the aircraft, once the pilots hit the evacuation switch? “Leave Everything! Do not take bags!” in the centre of the cabin, and instructions for safe jumping at the door?

Can this be in multiple languages, selectable by route and passenger profiles? What information might it make sense to convey by the increasingly large inflight entertainment screens?

Few of these options are likely to be individually game changing, and there is of course a strong argument about information overload. But with increasing survivability of 16G-certified seats and cabin monuments, some action may well be sensible.

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