Update April 2015
The Empirical Skeptic
Viewers of last night’s (March 2014) Air Crash Investigators program (Australia on Channel 7) have asked me many questions including:
- Why didn’t we evacuate the A380 immediately after stopping on the runway in Singapore?
- What are my views about the Malaysian incident?
My answers centre around how I gather, judge, store and use data.
I am an Empirical Skeptic.
I am motivated by facts, not by presumptions, assumptions, bias nor group think. I assess new information for its authenticity, provenance and trustworthiness before judging whether to accept or to reject it. In this regard I adopt Richard Dawkins’ view:
“That which can be asserted without evidence, can be dismissed without evidence.”
Tom Haueter, a former NTSB investigator says that we should keep an open mind when trying to draw conclusion in an absence of data. One data point changes the direction, one data point changes everything. What we think we know today can and probably will change with the arrival of the next rumour or fact, and in our new connected world we are being flooded with “facts“.
In today’s society where everyone with a mobile phone is a journalist, the Golden Hour has gone and there has never been a greater need for full and open disclosure of the facts and personal guarantees. We should also remember Ronald Reagan’s words:
“Trust but Verify”.
The incidents of MH370, MH17 and QZ8501 reinforce the vital roles that leaders and media must take during a crisis. The truth is unfortunately the first casualty after most air crashes. Everyone must restrict their focus to the facts. We need hard facts not assumptions, presumptions and false leads dressed up as facts because eventually only one data point is needed to unwind the time wasted following a false assumption.
So the next time you hear about something that scares you, look for data. Be suspicious of absolute numbers that are provided without references, or no numbers at all.
Critics have commented: “de Crespigny should have evacuated the QF32 passengers quickly down the slides rather than delay and disembark them down the steps. The fuel pooling under the aircraft should have caught fire”.
Roy Ford, my wonderful father-in-law often tells me: those who “assume” make an “ass” of yo”u” and “me”.
We had a different reality on the “front line”. The firemen and ground engineers were our eyes and ears to the aircraft for the two long hours that we sat on the ground before the last passenger disembarked the aircraft. The firemen gave us information about the fuel leaks and any presence of fire. They kept us informed. We kept the passengers and crew informed.
We waited to be told if there was fire. We were never told that there was fire.
We had assimilated much knowledge over our long careers that would perhaps become relevant:
We knew that the aircraft was certified to evacuate 873 passengers and crew through half the 16 exits in just 90 seconds. In reality Airbus did not just satisfy this requirement, they excelled by evacuating everyone 12 seconds faster than certification required! In our case we had all 16 exits available. We carried only 440 passengers and 29 crew. So theoretically, it could have taken between 21 to 25 seconds to evacuate 469 through all the doors.
Gasoline and jet fuel have very different qualities. Jet fuel is actually very hard to ignite and keep alight!
- Jet fuel has a “flash point” (fuel temperature at which vapour can be ignited) that is at least 80 degrees Celsius higher than the flash point of gasoline.
- Jet fuel “blows out” like a candle flame in a wind of just 40 kmph. Frank Whittle, the inventor of the gas turbine engine, discovered this as he was unable to stabilise flames inside his first engine until he enlisted Shell’s help. Keeping the engine alight is still one of the greatest challenges in today’s latest generation jet engines. Inside an A380’s $20m Rolls-Royce Trent 900 engine in the cruise, the outside air must be slowed from 925 km/hr (500 knots) to swirl around each of the 20 fuel nozzles in the combustion chamber at no more than about 35 km/hr! The F111’s classic dump and burn at Sydney’s Olympic Closing Ceremony, was only possible because the engines’ after-burners were engaged to constantly ignite the jettisoned fuel.
- A moving flame front over jet fuel spreads at only 10% of the speed that a flame front spreads over gasoline. The “flame spread” speed of military, normal jet fuel and gasoline is about 6/30/230 metres per minute respectively. The “Die Hard” fantasy film’s scene that showed a “fuse” of flame moving along a track of jet fuel training behind the hijacker’s aircraft is just that – fantasy!
- Jet fuel has a much higher electrical resistance than gasoline. In our case this means that passengers walking through the pools of fuel can generate sufficient friction to create static discharges within that fuel. The principle is the same as as the electrical discharge that you feel when you walk over carpet then press an elevator button. Even the friction of jet fuel flowing through fuel pipes is sufficient to create discharges inside those pipes – hence the reason for the many grounding leads inside fuel tanks as per the photos opposite. (Click here to see static discharges in volcanic plumes)
Eight fire trucks surrounded our aircraft. The fire trucks were loaded with foam and water to protect the aircraft fuselage, the passengers and their escape path.
Evacuations are dangerous. My studies show that about 15% of the passengers are injured when evacuating normal jet aircraft. In our case, almost all our A380’s doors are higher than doors on normal aircraft. The Main and Upper Deck door sills are 5.3 and 8.0 metres above the ground respectively.
We had elderly and wheelchair passengers on board and a toxic scene outside.
(Four percent of the passengers were injured in the latest Avro RJ100 passenger evacuation at London this week. (RJ100 door sills are about one quarter as high as A380 door sills).
To evacuate or not to evacuate – that is the question
The previous points are relevant because we faced new threats when we stopped our A380 on the runway. We needed different knowledge, training and experience to identify, rate and process these new risks and to make the best decisions.
We faced two significant threats; the possibility of fire and the toxic environment outside if we evacuated down the slides. Timing was critical.
- If fire had been confirmed, then we were prepared to evacuate the passengers down the slides under the protection from the eight fire trucks and emergency services. It’s not a pretty thought of the elderly and wheel chair passengers jumping onto, then sliding down a 45 degree sloped slide from an 8 metre (3 story) high floor.
- We tried to mitigate the toxic environment outside the aircraft. We called for aircraft steps to avoid the injuries that would result from an evacuation using the slides. We also requested buses to ensure that we would keep the passengers away from the pooling fuel, the running engines and the fire trucks. We tried to shut down number one engine that was still running. Fire services was spreading foam over the spilled fuel and water over the hot brakes.
The threats reduced rapidly as the fire services covered the fuel and cooled the brakes. The passengers and crew were still safer on board our aircraft than outside the aircraft.
The rest is history. There were no injuries.
Building a plan in the absence of facts can result in incorrect decisions and actions and potentially dangerous outcomes.
Just before my book went to print, the ATSB informed me that after we had stopped, that the four brakes (brakes numbered 1, 2, 5 & 6) on the left wing slightly inboard from Engine 2 (and under the fuel leaks) were COLD. All four brakes were between 30-40 degrees (ambient) Celsius!
We did not know on the day of the event that these brakes were cold. We didn’t know that the brake’s sensors and wires had been damaged by the explosions. We did not know that these four brakes would also be 100% useless for stopping us on the runway that day – but that discussion is for another day.
I was not able to include this information about the COLD brakes in my book “QF32″. It would have been a Criminal Offence to release this privileged information before the ATSB published its Final Report on QF32. The left wing brake temperatures are now shown in the ATSB report at page 240 – although the reader would have to look carefully to notice it, and few have.
We reacted dynamically to mitigate the threats that challenged us on the ground that day; what we saw, what we knew, but never what was presumed. We did not presume that a fire was present or that it would erupt. We wanted proof. We knew the environment was toxic outside the aircraft, so we mitigated the threats.
How many passengers and crew would have been injured if we had evacuated on the presumption that there would be a fire?
… a wing had been perforated, there was fuel all around the aircraft. [They] made the decision, unique to my mind, to not evacuate the passengers. [They] waited until the fire crews had secured the site. To me, that flight was the finest example of mastery of the aircraft”. (Captain André Turcat)
Given that there was no indication of an immediate threat to the safety of those on board, and that the option of an immediate evacuation remained throughout, the crew’s decision to evacuate via the stairs likely provided the safest option. With the uncontrolled No. 1 engine, fuel leakage hazard and the large number of passengers, the airport emergency services action to control the passengers in proximity to the aircraft reduced risk to the passengers themselves, the crew and emergency services. (ATSB report of the QF32 incident, page 30)
If there is a bigger safety message to be drawn from these incidents than the technical analysis done by the ATSB, it is that a perforce costly and continuing and renewing investment in pilots trained to deal with the unexpected upset situations that stalk all airliners comes with incalculable safety benefits for airlines . Your people are your best and most vital asset. (Ben Sandilands)
It’s now three years after QF32 and only a few weeks after the shocking Malaysian tragedy.
I share the world’s grief.
I am continually asked: “what do you think?”
My answer has never changed: I’m an Empirical Skeptic. I react only to facts and I don’t have enough facts!
I don’t know!
I’ll then repeat these guiding words from Robert Heinlein:
What are the facts? Again and again and again — what are the facts? Shun wishful thinking, ignore divine revelation, forget what “the stars foretell,” avoid opinion, care not what the neighbors think, never mind the unguessable “verdict of history”
What are the facts, and to how many decimal places?
You pilot always into an unknown future; facts are your single clue. Get the facts!
IFALPA says “Stop speculating about MH370“
IFALPA says “Stop speculating about MH370“