Coved-19 and Recirculation Fans

[TyroPicard]

Question for you current airline pilots... Are you still operating with Recirculation Fans ON? Or is your company accepting a higher fuel burn to protect the travelling public from that nasty Coronavirus?

[Riskybis]

Question for you current airline pilots... Are you still operating with Recirculation Fans ON? Or is your company accepting a higher fuel burn to protect the travelling public from that nasty Coronavirus?


yep still doing that , more likely to catch it from using the toilet door handle or in the airport etc....

[tdracer]

Most aircraft put the recirc fan air through a HEPA filter. The Coronavirus is relatively large and would easily be trapped by a HEPA filter.

I'd be more worried about the person sitting next to you...

[wiggy]

Most aircraft put the recirc fan air through a HEPA filter. The Coronavirus is relatively large and would easily be trapped by a HEPA filter.

I'd be more worried about the person sitting next to you...

yep, that’s the advice we are getting...

[golfyankeesierra]

What I am told is that when recircs are off, any virus could travel through a larger part of the cabin before it is vented out the outflow valves.
And with the recircs on, the cabin air is extracted more locally and while being recirculated back into the cabin, any virus would have been caught in the HEPA filters.
So it is better contained by keeping the recircs on.

[sky9]

So what happens to the virus in the HEPA filter; and how often is it changed and by who?

[BIGBAD]

Air recirculation systems on Airbus and Boeing aircraft have HEPA (High Efficiency Particulate Air) Filters which remove dust, allergens, bacteria, viruses and other irritating particles from the air in pressurised cabins and cockpits.

All of the air in the cabin is on average completely changed every 3 minutes.

HEPA filters are very effective at removing viruses (testing shows a virus removal efficiency of 99.999%). This means that the virus will be retained in the filter.

[marchino61]

So what happens to the virus in the HEPA filter; and how often is it changed and by who?

All the information you need is on the website of Pall, a world leader in filtration:
https://shop.pall.com/us/en/aerospace/military-vehicles/cabin-air-filtration/bacterial-and-virus-removal-efficiency-of-pall-hepa-cabin-air-filters-zidgzyl8yrb

Specifically:
Is there a danger to maintenance personnel by removing used cabin air filters?
There is no more risk involved in replacing a cabin air filter than carrying out general maintenance on
any aircraft part that has been in service for a number of years. Maintenance staff should wear the
same personal protective equipment as for other aircraft maintenance tasks which require protection
against dust, and per the local regulations.
The used HEPA filter should be placed and sealed in a plastic bag. A specific biohazard bag is not
required for disposal of the HEPA filter in most juristictions.

[OldnGrounded]

Most aircraft put the recirc fan air through a HEPA filter. The Coronavirus is relatively large and would easily be trapped by a HEPA filter.

I'd be more worried about the person sitting next to you...

Yup. Lots of good reasons to be concerned about inflight exposure. The recirc systems just don't make it to the list of credible risks.

[Check Airman]

No way (that I know of) to turn off the recirculation fans on an A320 anyway.

[compressor stall]

The bigger risk is the immigration queue, the baggage pickup, the quarantine and of course the aerobridge. No ventilation there.

[Sallyann1234]

The official advice seems to be to keep one metre apart from others to avoid direct transfer by infected particles in the breath. That rules out most aircraft passenger seating.

[dcoded]

The official advice seems to be to keep one metre apart from others to avoid direct transfer by infected particles in the breath. That rules out most aircraft passenger seating.

Or any other form of public transport, like the bus or the train.
Why is it that the public avoid air travel like the plague, when the same threat of contagion exist on the local bus or train?
i just don’t get it.

[Sallyann1234]

Or any other form of public transport, like the bus or the train.
Why is it that the public avoid air travel like the plague, when the same threat of contagion exist on the local bus or train?
i just don’t get it.
Possibly because air travel takes them further from home, and to countries with a perceived greater risk of infection.

[DaveReidUK]

The official advice seems to be to keep one metre apart from others to avoid direct transfer by infected particles in the breath. That rules out most aircraft passenger seating.

Strictly speaking, the WHO and NHS UK advice is to avoid close contact with people suffering from a fever and cough. While staying a meter away from every other human being would satisfy that requirement, it's both impractical and unnecessary.

[triploss]

Most aircraft put the recirc fan air through a HEPA filter. The Coronavirus is relatively large and would easily be trapped by a HEPA filter.

I'd be more worried about the person sitting next to you...
Most of the reports I've seen claim that HEPA filters will NOT stop (or catch) the Coronavirus.

Do you have sources claiming otherwise?

[Busbert]

Most of the reports I've seen claim that HEPA filters will NOT stop (or catch) the Coronavirus.

Do you have sources claiming otherwise?

Every test report I’ve seen from Pall, Donaldson and independent test houses has shown that the HEPA filters used on Boeing and Airbus aircraft are extremely effective at removing viral particles in the size range of Covid-19. So I’d suggest your sources are rather questionable.

[Chu Chu]

One of the theories as to why seasonal flu is seasonal has to do with indoor humidity. In the summer, indoor humidity is normally high. Expelled droplets settle to the floor or other surfaces. People touch surfaces, but luckily they don't breathe them.

In the winter, indoor humidity is generally low. Droplets tend to dry out before they reach the floor, leaving the virus itself to float in the air for a prolonged period.

Of course, it's always winter at 38,000 feet. That may make recirc fans and HEPA filtration even more important. On the other hand, increasing the frequency of air changes could lower the humidity even further, and perhaps make things worse.

[OldnGrounded]

Quote:
Originally Posted by dcoded View Post (https://www.pprune.org/rumours-news/630300-coved-19-recirculation-fans.html#post10706856)
Or any other form of public transport, like the bus or the train.
Why is it that the public avoid air travel like the plague, when the same threat of contagion exist on the local bus or train?
i just don’t get it.

Possibly because air travel takes them further from home, and to countries with a perceived greater risk of infection.

It also tends to take them to places where they may not have access to the same healthcare choices they have at home. And to places where the risk of being caught in quarantine are perceived as higher. Or the chances of facing quarantine upon return.

[compressor stall]

Most of the reports I've seen claim that HEPA filters will NOT stop (or catch) the Coronavirus.

Do you have sources claiming otherwise?

Has it crossed your mind why they are used in hospitals? The HEPA performance graphs are available with respect to viruses etc.

stop reading the National Enquirer.

[Centaurus]

In a passenger evacuation which is more important - keeping at least one metre apart to minimize catching a virus? Or getting the hell out of there?

[The AvgasDinosaur]

In a passenger evacuation which is more important - keeping at least one metre apart to minimize catching a virus? Or getting the hell out of there?
That rule only applies if you’ve been sat minimum 1 meter apart pre and post boarding,
and while transiting to or from the ‘facilities’.
David

[Airbubba]

Delta mentions HEPA filters and fresh air in their obligatory coronavirus web page below:

Aircraft in Delta’s fleet feature either a state-of-the-art air circulation system with HEPA filtration or a system that pulls fresh air in from the outside to replace cabin air. HEPA air filters extract more than 99.999% of even the tiniest viruses, including coronaviruses.

HEPA filter technology came from the U.S. nuclear bomb project in World War II.

While efforts to contain COVID-19 continue to evolve, Delta has taken proactive and voluntary steps to help customers have a healthy flying experience.

Cleaning, cleaning, and more cleaning


Disinfecting surfaces is one key way to minimize the spread of viruses, according to the CDC and WHO. From airports to aircraft, here are some ways Delta is working to ensure a healthy flying experience using EPA- and OSHA-approved virus-killing products:

Aircraft – Delta has doubled down on its regular cleaning program while adding a fogging process – often used by the food industry– to disinfect trans-oceanic aircraft interiors. As trans-oceanic flights come in, fogging takes place after an initial cleaning, this time with tray tables lowered and overhead bins and lavatory doors open. Seatback entertainment touch-screens are given an extra cleanse using disinfectant wipes. Check out more details about Delta’s aircraft cleaning and sanitizing procedures here (https://news.delta.com/updated-deltas-aircraft-cleaning-and-sanitizing-procedures).
Check-in kiosks – While touch screens are convenient, they require customers to touch the same surface that others have. That’s why we’re disinfecting airport kiosks multiple times daily. Customers can always download the Fly Delta app so you can check-in from your phone instead. Simply sign in as a “guest” or create a Delta SkyMiles account for free with no obligations.


Gate areas – In addition to the ticket counter and airport lobby area, Delta has increased the cleaning schedule of gates areas, making supplies readily available to our customer service agents for spot or more frequent cleaning and more seat cleaning in the process.


Giving customers a hand (sanitizer, and more)

Simple personal hygiene including frequent hand washing and not touching one’s eyes, nose or mouth is essential to minimizing the spread of the COVID-19 and other viruses. While we know many customers are following this guidance, here are some other ways Delta is arming customers with ways to stay clean:

Hand sanitizers -- Delta is putting hand sanitizers on all ticket counters, boarding gates, Need Help Centers, Baggage Service Offices and Sky Clubs starting with our hub airports where we serve the highest volume of customers – something employees and customers alike can take advantage of before boarding the aircraft.
Amenity kits – These kits for customers on long-haul international flights include hand sanitizer or cleansing towelettes.


Breathing easy in flight

Aircraft in Delta’s fleet feature either a state-of-the-art air circulation system with HEPA filtration or a system that pulls fresh air in from the outside to replace cabin air. HEPA air filters extract more than 99.999% of even the tiniest viruses, including coronaviruses.

Arming employees with facts and supplies

Delta employees are the foundation of our success – their health, safety and knowledge are paramount. Here are some ways we’re supporting employees so they can better support customers:

Supplies – Providing hand sanitizer, gloves and other protective equipment, particularly for those who engage directly with customers, and masks for use by ill customers, their caretakers or flight attendants or pilots who are in close contact with ill customers.
Information – Delta has launched a cross-divisional COVID-19 command center with key leaders and subject matter experts so we can nimbly respond and communicate with employees about evolving CDC and WHO guidance. General updates and role-specific guidance are being provided to employees regularly.
This week Delta welcomed CDC doctors working on the COVID-19 outbreak to a town hall in Atlanta, where frontline employees were able to ask questions and hear from experts. For employees not able to attend, Delta leaders are sharing what was learned and key takeaways were distributed to every Delta employee worldwide.


Staying in lockstep with the experts

Delta’s Air Crew and Passenger Health Services team has a close relationship with the CDC and WHO, and they’ve increased their contact as guidance evolves to ensure we are taking all necessary precautions for healthy flying. As such, all of Delta’s health and safety processes meet the high standards of these organizations, and many exceed them.

Remembering what we’ve learned from other global outbreaks

COVID-19 isn’t the first epidemic we’ve faced, and what we’ve learned from H1N1 and Ebola has helped prepare us to take care of customers today. While every health event has unique elements, the adjustments Delta has made in the past continue to pay dividends for managing COVID-19. These include equipping aircraft with Universal Precaution Kits, hand and surface sanitizers and other items, in accordance with CDC recommendations, so flight attendants can maintain their own health and the health of those onboard should a customer show signs of infection.


https://news.delta.com/6-ways-delta-supporting-healthy-flying-JP

[triploss]

Not that I don't believe you, but even research by the air-force is less confident than most people on this thread:
https://www.researchgate.net/publication/235048517_Viral_Penetration_of_High_Efficiency_Particulate_A ir_HEPA_Filters_PREPRINT?fbclid=IwAR1JJm4HIrKffbPQqnbNpubsMX iEeRHSTIG31KWZFRrHknbEKamj-k0C_A0&mod=article_inline

While Covid-19 may be "large", it fits exactly into the size range discussed in the above paper.

[oliver2002]

Or any other form of public transport, like the bus or the train.
Why is it that the public avoid air travel like the plague, when the same threat of contagion exist on the local bus or train?
i just don’t get it.

People are scared of flying in general because the loss of control. While crossing a street or driving, which is far more dangerous, you are always in control...

[Longtimer]

A message from Canadian WestJet:I am writing you today to provide information regarding the coronavirus (COVID-19) outbreak and what we at WestJet are doing in response.

As a valued WestJet guest, your safety has always been, and remains, our number one priority. We train comprehensively for these scenarios as part of our overall emergency response and stood up a COVID-19 direct response team immediately as the situation began to unfold.

From the onset of the coronavirus, we have been in contact with the Public Health Agency of Canada (PHAC), Transport Canada and other agencies around the world to ensure we are aware of, and aligned with, guidance regarding air travel.

There are hundreds of WestJetters across Canada involved in the planning and implementation of our coronavirus response. In addition to the standard aircraft cleaning that has been part of our daily maintenance schedule, we have introduced additional measures to increase the sanitization of our aircraft.

We already disinfect and sanitize our aircraft using industry-approved products and have also introduced hospital-grade Clorox Wipes and Spray to our cleaning processes. These new products are used to clean the galleys, lavatories, tray tables, seat armrests and headrests, seatbelt buckles, the power supply unit panel, overhead bin door latches and lavatory door handles.

In the air, our aircraft are equipped with state-of-the-art HEPA filters which are similar to those used in hospitals. These filters achieve a viral and bacterial removal efficiency of greater than 99.99 per cent. These aircraft also introduce fresh air into the cabin every two to three minutes.

To help you continue to book with confidence, we had already instituted a flexible change policy giving those guests who booked between March 3, 2020 and March 31, 2020 the ability to change their flight without the applicable change fees.

In addition, we are temporarily removing the normal change and cancel restrictions for guests who had previously booked a Basic fare for travel beginning on or before March 31, 2020. More information can be found on the WestJet travel advisory page (http://t.em.westjet.com/r/?id=h126fea3e,46290d8,462f3c4&j_cid=email%3ATeal%3ACoronavirus%3ACoronavirusEmail%3A202003 09). If you have any questions regarding your reservations, there are a number of ways to contact us that you can find here (http://t.em.westjet.com/r/?id=h126fea3e,46290d8,462f3c5&j_cid=email%3ATeal%3ACoronavirus%3ACoronavirusEmail%3A202003 09). If you booked with a travel agent, please contact them directly.

PHAC has assessed the public health risk associated with coronavirus as low for Canada. To date, there are no known cases where this virus has been transmitted from one person to another on an aircraft. We recognize that this is an evolving story and my commitment is to provide you with up-to-date information as it becomes available. We will continue to post to the WestJet blog (http://t.em.westjet.com/r/?id=h126fea3e,46290d8,462f3c6&j_cid=email%3ATeal%3ACoronavirus%3ACoronavirusEmail%3A202003 09) which remains the best place to find the most current information.

I hope this gives you confidence in the actions we are taking on your behalf. We remain committed to providing you a safe travel environment and I look forward to welcoming you on board in the near future.









Sincerely,

http://content.westjet.com/2020/images/signatures/Ed_Signature_01.jpg

Ed Sims
President & CEO
WestJet Airlines

[threep]

Whilst I applaud the steps taken by airlines and manufacturers to reduce the risks of Covid-19 transmission, they only have partial control of this.

In the link below a couple who became infected sat 2 rows behind a person who was suffering from Covid-19 (though apparently was presenting no symptoms at the time of the flight). The flight was Vietnamese Airlines VN54, which is serviced by a B787, i.e. its a modern aircraft with presumably the best filtration systems. Vietnam did very well at containing the initial Covid-19 outbreak, so my assumption is that VA would also have been very switched to the steps needed to clean/disinfect aircraft between flights. Yet they still got infected. What was the mechanism for transmission? We don't know and probably never will, but it is how we as individuals behave which will determine the extent to which Covid-19 infects and kills people.

US researchers suggest people only start to show symptoms on day 5 after infection. As this thing spreads, it will become increasingly likely that we will share cabins with infected, but symptom-less people. We need to adopt the right behaviours. That means catch-kill-bin, self isolating if there any any signs of infection, social distancing and regular, thorough washing of hands with soap to an almost fanatical extent. We all have responsibility to our fellow citizens.

https://www.theguardian.com/world/2020/mar/09/british-couple-contract-virus-on-flight-from-heathrow-to-vietnam

[Pearly White]

HEPA Filter specifications: https://shop.pall.com/us/en/aerospace/military-vehicles/cabin-air-filtration/bacterial-and-virus-removal-efficiency-of-pall-hepa-cabin-air-filters-zidgzyl8yrb?tracking=searchterm:familypage

[Webby737]

The HEPA filters are all well and good however what about when the aircraft is on the ground (boarding and disembarking) with the packs off ?

[Check Airman]

The HEPA filters are all well and good however what about when the aircraft is on the ground (boarding and disembarking) with the packs off ?

Turn them on prior to boarding...

[cats_five]

We already disinfect and sanitize our aircraft using industry-approved products and have also introduced hospital-grade Clorox Wipes and Spray to our cleaning processes. These new products are used to clean the galleys, lavatories, tray tables, seat armrests and headrests, seatbelt buckles, the power supply unit panel, overhead bin door latches and lavatory door handles.

Between each flight?

[Beausoleil]

Or any other form of public transport, like the bus or the train.
Why is it that the public avoid air travel like the plague, when the same threat of contagion exist on the local bus or train?
i just don’t get it.

Buses and trains are crowded in the rush hour when people are going to work. Most of the people on a crowded train or bus can't not travel without losing their jobs.

Lots of people on crowded flights are holidaymakers or visiting family, or maybe going to an unusual work event that is not core to their job.

If I decide not to make "discretionary" trips my use of the train will drop by a few percent and my use of air travel will be down by 50+ %

[wiggy]

Re packs etc.....Turn them on prior to boarding...

Yep, some operators have introduced guidance along the lines of if at all possible having APU and packs running at all times passengers are on board, i.e. from prior to first pax boarding to after last pax disembarks.

Local airport restrictions regarding APU use to be disrgarded.

[Webby737]

Re packs etc.....

Yep, some operators have introduced guidance along the lines of if at all possible having APU and packs running at all times passengers are on board, i.e. from prior to first pax boarding to after last pax disembarks.

Local airport restrictions regarding APU use to be disrgarded.
Sounds like a sensible (if somewhat expensive) solution.
It wasn't the case this morning with my flight out of BRU.

[tdracer]

Threep, if they were sitting within a couple meters of the source, it was likely direct transmission - person sneezes/coughs, the droplets move about before they eventually get sucked away via recirc fans or overboard.
Short story, HEPA filters are an order of magnitude better than the surgical style face masks people use - the major risk is the people in close proximity, not something that has gone through a filter...

[threep]

Threep, if they were sitting within a couple meters of the source, it was likely direct transmission - person sneezes/coughs, the droplets move about before they eventually get sucked away via recirc fans or overboard.
Short story, HEPA filters are an order of magnitude better than the surgical style face masks people use - the major risk is the people in close proximity, not something that has gone through a filter...

I guess that's what I was trying to say. If one is vulnerable to direct transmission with anyone within say 2 rows forward and back, it doesn't matter how perfect the HEPA filters are at removing droplets, you may catch something. Now add in the risks that an infected person contaminates the toilet door latch, or asymptomatic cabin crew infect 10-20% of the food trays during a flight.

I'm not trying to scaremonger, just pointing out that there are risks that are not mitigated by tech. Frequent hand washing, social distancing and not taking that trip if you show any signs of infection, that's what will keep flights operating.

[golfyankeesierra]

As mentioned before, the whole point of recirculation is reducing and containing airflow, NOT filtering air. With the recirculation on, you will have a lower risk on catching something from a person 5 rows away. It will not change a thing when you are sitting next to him(her).
Air filtration is not the objective of recirculation. The filters only mitigate the risk of recirculating contaminated air (and apparently the HEPA filters are well suited for this).

[compressor stall]

So two people two rows back apparently caught it. What of the people the row back? In front?
It was just probably transmitted in the aerobridge boarding or more likely during the “as soon as the belts sign is off, let’s all stand crowded in the aisle as wait 5 mins until the jam of pax starts moving towards the front exit” period.

I’m not saying the risk is nil. It’s that the likelihood is lower than other aspects of the flight that people ignore.

[Loose rivets]

I've made my feeling clear, but today I saw evidence of bewildering pig-ignorance of supposedly intelligent people. A minister? stepping out of a car. Press leaving a tight passage to the target door. A woman screeches a question into his face.


I've calmed down now. This Scientific American article may be of interest. It ties in well with Sir Fred Hoyle's Intelligent Universe.

https://www.scientificamerican.com/article/are-viruses-alive-2004/

[Aithiopika]

Or any other form of public transport, like the bus or the train.
Why is it that the public avoid air travel like the plague, when the same threat of contagion exist on the local bus or train?
i just don’t get it.

US passenger here, I might be able to give an answer for myself at least. On Monday, before the latest round of travel bans, we canceled a long (three passengers times five flight legs total) international trip, the first flight of which was to leave on Tuesday. Fear of actual infection on the plane wasn't really a big concern for us or a reason for the decision. We all figured we were just as likely to get sick staying in the US, or probably even more likely.

There were two big things that tipped us to cancel:

Risk of being quarantined because someone twenty rows back got sick. And even if we do cross paths with someone sick here at home, two weeks self isolation is a much smaller burden at home than it is in a foreign country.
Risk of flights getting canceled or someone with an itchy Twitter finger deciding that he needs to look tough and decisive and Protect the Borders from the Foreign Virus Problem, so that the return home falls through. Three weeks (when we were due to return) seemed long in Pandemic Time and it just isn't very clear what the political reaction will have gotten to in one week, let alone three.

We thought these risks were a lot higher than the risk of actually getting infected on the plane.

Does that help you understand the thought process?

[Tom Sawyer]

The HEPA filters are all well and good however what about when the aircraft is on the ground (boarding and disembarking) with the packs off ?

The recirc fans (cabin fans ) run independently of the packs, i.e., they run all the time the aircraft is powered unless turned off by us Engineers usually or crew abnormal ops. If you go and stand next to an outflow valve, which is normally the exhaust point for the old recirc air, you will feel a positive airflow being exhausted even with the packs off. That is the case on the aircraft I work on anyway.

I've changed the recirc filters numerous times. They are pretty dusty and we would normally wear a mask and paper all-over suit......certainly would at present if I had to change one.