Hi,

I wonder if I could request some technical help from anyone here please?

I was on TUI flight TOM375 from Sanford Orlando to Bristol UK on 21st May this year, which had to make an emergency landing due to "2 crew members being taken ill shortly after take off."

The explanation given by Thomson was that just after take off the plane flew through a brush fire. Due to the design of the cabin air intake on the Dreamliner, a large concentration of CO2 was taken into the cabin, concentrated at the rear where the 2 crew members were sat, causing them to pass out. 27 other passengers were also taken ill feeling nauseous.
When we landed paramedics and firemen came on board, who after monitoring the air, found no abnormal readings. I contacted the Sanford Airport Authority who were extremely helpful in providing me both with a contact at the fire department who (also very helpfully) supplied a copy of their report and also a copy of the ARFF report. Both of these reports state that no abnormalities were found, however, "at the rear of the plane a strong odour was detected (it doesn't state what of) so the SHOT team assessed the air quality. E35 arrived and di the air quality assessment on the aircraft, inside the cargo holds and necessary ports as determined by the aircraft mechanic. It was determined that the air-quality was within normal range and that the cause could have possibly been a nearby brush fires smoke that entered the cabin."

Now, I'm an Engineer, but not in aviation, and I don't buy it. I did a quick search about the 787's air system and found this:
"The cabin air-conditioning system improves air quality by removing ozone from outside air, and besides standard HEPA filters which remove airborne particles, uses a gaseous filtration system to remove odors, irritants, and gaseous contaminants as well as particulates like viruses, bacteria and allergens. The bleedless engine cabin air system also allows the 787 air to avoid oil fumes and toxins which are dangerous to the health of passengers and crew and are found in all other aircraft bleed air systems."

This says to me that out of any plane that should survive flying briefly through a brush fire without filling the cabin with CO2, it is the Dreamliner. Even if it was the case, I don't see that the air supply should be so localized as to only affect the extreme rear of the plane - surely it should be equal throughout?

Obviously, Thomson are sticking with this as it then alleviates them from a compensation claim (the total delay was 25 hours) as it would be an "extreme circumstance." The other issue with this claim is that speaking to a rep at the hotel, brush fires are very common in the surrounding area of the airport, so surely the Airport Authority would be aware of this and advise the flight plans to avoid these if they can cause situations such as these?

My personal interpretation of what happened based on my (limited) knowledge, accounts of other passengers and my suspicious mind is this:
One air steward released herself before the captain had finished levelling off (indeed, all this occurred whilst still climbing) to prepare for service. She unclipped a box which came crashing down on her. During the fall, the box or some other cooling equipment was damaged causing propylene glycol to be spilled. The other steward rushed to assist and slipped (this slip is confirmed by the airline but it not explained) thus injuring herself too. The fumes of the propylene glycol overwhelm the 2 crew and cause respiratory complaints in those nearby. The other cabin crew who went to assist, clean up the spill, thereby removing any source of the fumes and it gets explained off by a convenient brush fire, when in actuality it was gross negligence.
I could be completely wrong, but that's the way I'm seeing it.

I would really appreciate any advice on the possibility of any of this - both the brush fire causing the crew to pass out and my theory.
I've contacted Boeing to see what their view is on Thomson's claims but I have yet to hear back.

I again, appreciate any comments.

Kind regards,
Jon

I don't know about the effect of brush fires, but CO2 isn't toxic per se, and wouldn't be filtered. It is a normal component of the air. Also we breathe out CO2 just like other animals.

CO2 only becomes a problem if the concentration increases over around 1% of the air, at which point it starts inducing various effects like drowsiness.

CO2 colourless and odorless, so would be pretty hard to see. It is also heavier than other gases, so could concentrate in a certain area.

The only wildfire I can find around that day was in Avon Park, well south of Orlando. Would a flight departing to the UK go that far south before heading north/east? Could winds carry enough CO2 north towards Orlando for it to be such a debilitating problem on your flight? It's not like this was a massive wildfire, only ~6 square miles, about half of which had been contained by the 19th of May.
Was there another wildfire closer to Orlando that I can't find?
http://www.orlandoweekly.com/Blogs/arch ... orce-range

First, I have a question for you, Jonboy. Did you detect any fumes during the flight? I did not see any indication in your post. Also I am curious if you or your traveling companion felt ill. Thank you.

The galley chillers and avionics cooling system does circulate a liquid, water-based coolant from a central pump, however the plumbing is not exposed inside the galley cabinets, and ducting and fan shrouds would have to first be broken or removed in order to reach the lines. The Norwegian Zodiac supplied cabinets are designed to be rugged enough to prevent damage to coolant plumbing such as may have been suggested here.

HEPA filters will not prevent the passing of CO or CO2. While the 787's unique pressurization arrangement also includes a carbon-based airborne chemical trapping filter layer, supplied by Donaldson Aerospace and known as APS, it too, will not prevent the passage of smaller molecules like CO or CO2, although the filter is designed to limit the production and release of ozone through a chemical process.

While carriers are loathe to admit it, there is some truth in the rear passenger cabin being a collection area for airborne fumes and contaminants. Airflow to return and exhaust ducts is most effective forward and mid-cabin, while the flight deck on nearly all commercial aircraft enjoys the best quality air (least recirculated) from the packs due to the pressure difference in the feed plenum.

Right after take off the acceleration together with the aircraft pitch could easily make the heavier CO2 from a forest fire accumulate in the back.
I'm not an engineer, but I use dry-Ice often at work in and we have some very strict rules regarding transportation, and room usage and ventilation.
Is there any air vent at the very end of the 787?

rbretas wrote:

Is there any air vent at the very end of the 787?

Like all commercial transport aircraft, there are return grilles at the intersection of the sidewall and the floor. The L4 and R4 doors on the 787 however do limit airflow from the cabin to the cargo holds, recirculation ducts, and outflow valves despite the galleys and hanging lockers being positioned next to the aft pressure dome, which also have their own return vents. Smoke tests have shown that the aft area of any modern commercial aircraft tends to collect smoke and fumes.

jonboy wrote:

This says to me that out of any plane that should survive flying briefly through a brush fire without filling the cabin with CO2, it is the Dreamliner.

Actually no, it doesn't. The "bleedless" part only means that instead of being sucked in via the engine compressors, the air is sucked in via a dedicated compressor. Which has the advantage of putting more distance between the air path and the engine combustion areas and oily parts. But there are many other potential sources of cabin air pollution, contrary to common belief.
If the outside air is contaminated, then the inside air may be as well. It depends more on the filtering, not on how it is sucked in. As for the filtering part, CO2 doesn't react so easily so the gaseous filtering would probably not do much, if indeed it is a CO2 contamination.

Another possibility is cleaning agents. If improperly used they could generate nocive gases. A reaction could possibly be triggered by a coffee machine or an oven being turned on, or any other heat source.

It could be a contamination directly in the air system following maintenance. Or any of dozens of possibilities.

The trouble with these air contamination/smells/irritation issues is that they are usually transient. This makes it difficult to figure out the exact source of contamination. An exterior contamination will disappear as soon as the aircraft moves away. A chemical contamination will disappear as soon as the contaminant has reacted and transformed away, unless there is sustained leak. But such a leak should trigger some warning somewhere.

Honestly I will not judge the proposed explanation either way, but if many people were indeed feeling ill, that would justify a medical issue regardless of the actual cause. And that should justify the "exceptional issue" clause regarding European compensation claims.
Legally enforcing automatic compensations for delays following a medical diversion is a very slippery slope.

jonboy wrote:

surely it should be equal throughout?

Only at the very beginning, and even then it is not perfectly equal but depending on the way the air is split for distribution.
However the cabin air then moves through the cabin, and then is recirculated. This creates new dynamics which will depend on cabin layout, number of passengers, galley and lavatory positions, usage & ventilation, position of the outflow valves, etc...so over time there may well be a local accumulation in a given area. This adds to the complexity of contamination investigation.

jonboy wrote:

my theory

I'm not a specialist in liquid cooling systems, especially on the 787, but
- as mentioned, if the galleys are liquid cooled (and not air cooled) then the pipes would be located in some place where they are not too exposed to incidental damage
- AFAIK PGW does not have much effect on humans. It would have to be vaporised, and then would only cause irritations.
- If it is used in proximity to food/drinks or areas accessible by humans, it would be dyed (pink I think ?). A leak would likely be noted by the ARFF in the report
- the report should be able to differentiate between the F/A falling and hurting himself/herself, and an object falling on him/her

thank you very much for all your comments they are most helpful.

Out of interest - I've been reading up on TCP coming from engine air feed into cabins. I realise this isn't supposed to be possible with Dreamliners, but is there some other way they can get in? Particularly at low altitude before the cabins become pressurized?

jonboy wrote:

I've been reading up on TCP coming from engine air feed into cabins. I realise this isn't supposed to be possible with Dreamliners, but is there some other way they can get in? Particularly at low altitude before the cabins become pressurized?

On the ground, engine and APU exhaust from itself or other aircraft can be inducted into the 787 cabin compressor inlets, located in the forward section of the wing root faring, but no bleed air can find its way into a 787 cabin. Cowl damage could leak engine anti-ice (EAI) bleed, but this would be carried away by the slipstream (outside) or the engine intake stream (inside). This is the only source of engine bleed air on this aircraft.