Small Regional Jets Usually Lack The Most Important Covid Protection, But American Airlines Is Adding It

HEPA air filtration seems to be one of the reasons that Covid-19 doesn’t appear to spread very much on planes. Big commercial aircraft refresh air inside the cabin with outside air frequently, perhaps 20 times an hour, and when air recirculates most of the virus gets caught in filters.

Many smaller planes, including 50 seat regional jets, do not usually have HEPA air filtration. That’s one reason why I’ve suggested staying away from small planes during the pandemic.

American Airlines Is Adding HEPA Filters To Small Regional Jets

Just as there’s been a huge move towards frequent cleaning of aircraft, there’s also been a push to improve air filtration, too. That’s important not just now but in the future too because HEPA filters can help reduce the spread of most airborne illnesses.

This month American Airlines’ wholly-owned regional carrier Piedmont took a big step, getting FAA approval to install HEPA air filtration in their 50 seat Embraer regional jet aircraft. The Supplemental Type Certificate, or ‘STC’, was approved October 6th and doesn’t even appear to be listed yet on the FAA website yet.

I spoke with Bill Arndt, Piedmont’s Vice President of Aircraft Maintenance and Engineering, about the project. He said that the thinking used to be that the ERJ-145 was designed “with so much fresh air coming in that they didn’t think needed filtration,” that they certainly viewed the aircraft as safe currently, but that they had already begun work on a project to do greater filtration prior to the pandemic so it made sense to fast track it now.

Piedmont ERJ-145

One major challenge is that HEPA filters are potentially flammable in the cabin. However they have the filters designed to be installed under the floor, out of the passenger cabin.

While they’re still in contract negotiations with local machine shops and welding facilities, most of the work to retrofit the planes with HEPA filters will be done in-house. They expect to have all of their 59 ERJ-145 aircraft upgraded by the end of the year. That’s faster than they anticipated being able to accomplish it – Arndt was amazed by how quickly the FAA moved on the certification.

Envoy Air, also fully owned by American Airlines Group and which used to be called American Eagle, has 80 ERJ-140 and -145 aircraft. Piedmont has given them the design and details on the project. American expects these planes will all be retrofitted with HEPA filters by March 2021. A spokesman for American tells me “so once the E140s and E145s are retrofitted with the new HEPA solution, our entire mainline and regional fleets will include HEPA filtration.”

I’ve written about the Covid projects undertaken by airlines that have seemed to be ahead of American (Delta especially). Given the relative importance of HEPA filters, compared to surface cleaning, this project has the potential to trump a lot of what other carriers have done so far.

How HEPA Filters Work

HEPA filters are essentially sheets of fiberglass fibers, with diameters between half a micrometer and 2 micrometers, randomly arranged. A fan pushes air through the filter, and particles get trapped inside. The very smallest of particles collide with molecules of gas, which slows them from passing through the filter and increases the chance of their becoming trapped.

HEPA filters aren’t really a kind of filter, though, the name speaks more to their standard of effectiveness – capturing at least 99.97% of airborne particles that are larger than 0.3 micrometers (or 0.00001 of an inch). Bacteria are easily trapped by HEPA filters. Viruses are smaller than a HEPA filter’s pores, but they often travel in clusters, on mucus, or respiratory droplets.

This level of air filtration was developed in the 1940s. The Manhattan Project used HEPA air filtration to limit the spread of radioactive material. They ‘spread’ into commercial use in the 1950s to catch viruses, pollen, bacteria, and other particles in the air.

Large commercial aircraft have these filters, and increasingly we’ll be seeing smaller ones have them too. That’s great news not just for travel now but also for those of us who are fearful of getting sick from our fellow passengers even during normal times.

About Gary Leff

Gary Leff is one of the foremost experts in the field of miles, points, and frequent business travel - a topic he has covered since 2002. Co-founder of frequent flyer community, emcee of the Freddie Awards, and named one of the "World's Top Travel Experts" by Conde' Nast Traveler (2010-Present) Gary has been a guest on most major news media, profiled in several top print publications, and published broadly on the topic of consumer loyalty. More About Gary »

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  1. Great piece, this is worthy of mainstream journalistic outlets like Reuters, AP. Very informative…and good news.

  2. Your self-referential assertion that somehow HEPA works in absence of masks (hint: people eat and drink on planes and God knows what happens in the bathroom) is exactly why western civilization is going to keep catching this stuff until we reach herd immunity status.

    That’s why Singapore wants to keep us out. Can’t say I fault them.

  3. @Aland – those already have HEPA filters

    @Andrew – I don’t see the problem with referencing a prior discussion. By the way Singapore Airlines uses HEPA filters, too.

  4. For sure, this is welcome news & an important upgrade that eliminates a significant disparity in air quality between AA’s mainline aircraft/larger regional jets & the 139 smaller Embraer 140/145 RJs operated by Piedmont & Envoy Air.

    Obviously, other airlines with regional affiliates that still operate RJs that lack HEPA rated filtration capabilities would be wise to similarly upgrade their fleets.

    However, while this is a significant improvement that will better harmonize the inflight air quality for a more consistent passenger experience across mainline aircraft/larger RJs & the smallest jets across American Airlines’ fleets, the fact still remains that for many airlines, this exceptional onboard air quality provided by powerful ventilation equipment featuring uniquely robust refresh rates (e.g., “top/down” diffusing & venting) using HEPA-rated filtration (comparable to or even exceeding “hospital surgery rooms” as the industry likes to cite!) is available ONLY while inflight…

    …but *NOT* when aircraft are at the gate during boarding, pre-departure dwelling & deplaning (which is when passengers, often toting carryon bags & searching for available overhead bin space to stow their hand baggage or placing them beneath the seat in front of them, etc., are clogging aisles & moving about the cabin that most experts believe is the period when risk of Covid19 transmission is highest) & ventilation is provided by entirely separate (& significantly less capable/robust) equipment called “Pre-Conditioned Air (or PCA) Units”, that do NOT:

    – refresh in-cabin air nearly as rapidly using the same intense top/down diffusing & venting as that during inflight

    – or even HEPA-rated filters (typically, they’re G4, except for airlines such as United & Delta, both of which already announced changes of varying degrees to better narrow the disparity between the exceptional air quality available inflight & that provided during boarding, pre-departure dwelling & deplaning using less hearty, lower filter rated PCA’s) as also used inflight

    For the non-hard core avgeeks (or those less familiar with Ground Support Equipment, or GSE) among us, “Pre-Conditioned Air Units”, or “PCA” for short, resemble, but are NOT quite identical (to allow for different environments deployed) to, conventional commercial grade HVAC units commonly used at office/commercial buildings whose refresh rates & filtration, typically “G4”-rated, are *NOT* nearly as robust & precise as the onboard ventilation equipment & HEPA-rated filters touted by the International Air Transport (IATA), industry leaders & widely cited/quoted in media reports that are powered up shortly before doors are closed & aircraft push back from the gate for taxiing out to takeoff.

    [PCA units are typically mounted below jetbridges/jetways & can be spotted wherever a pair of large/wide, school bus yellow colored hoses are seen]

    This is a critical disparity I began pointing out as a series of reader reply comments here on “View From The Wing” (VFTW) on July 5th, & repeatedly since then in other online media, perhaps most often on LinkedIn, which is where most of my online industry focused comments & analysis are now found.

    To its credit, five (5) days after the initial series of reader comments I began posting here on VFTW (on July 5th) plus several additional detailed critiques & analysis I posted in the reader comments section for posts, including very slick/polished video presentations/advertisements, made by the International Air Transport Association (IATA) on LinkedIn (& Twitter), as well as others on my LI homepage, on July 10th IATA *CONFIRMED* that its messaging, including that provided in its (“informational”) videos/advertisements touting exceptional onboard ventilation equipment featuring robust refresh rates, “top/down” diffusing & ventilation, & HEPA-rated filtration applied while inflight only, & therefore NOT when aircraft are at the gate during boarding, pre-departure dwelling & deplaning/disembarkation periods when PCA units are used.

    [Links for the original VFTW reader reply posts & selected others referenced above will be posted separately later today as available & pending approval by the moderator(s)]

    Additionally, & again to its credit, on August 17th IATA (supported by International Civil Aviation Organization, or ICAO) updated its official Covid19 recommended safety protocols [links to be included in separate post discussed immediately above & subject to same conditions of availability & moderator approval(s)] in its “Health Safety Standards Checklist – Edition 1 August 2020” to incorporate new remedies to mitigate disparities between the exceptional air quality touted in its (& others’ messaging) available only inflight with that during boarding & deplaning/disembarkation that uses less capable PCA units & appreciably lower rated, “G4” filtration when aircraft are at the gate, per Sections 1.4 & 1.6.

    Regarding specific airlines (in addition to American’s upgrade to HEPA rated filtration for its Embraer 140/145 fleet discussed in Gary’s post above):

    – On July 21st United announced it was upgrading onboard air quality for all mainline aircraft at the gate during boarding & disembarkation to match the exceptional ventilation featuring HEPA-rated filters beginning July 27th, thereby eliminating a disparity between inflight & when aircraft are at the gate;

    – On September 10th, Delta announced it was upgrading the filters used by the PCA units to MERV-14 rated, which it says are 40% more effective than filters previously used, for more than 600 gates at its largest 31 airports, with unspecified other airports/gates to follow in the coming months;

    – To date, while larger regional jets such as Mitsubishi (née Bombardier) CRJ 700/900 models (including the “550” dual class 50 seater at United) as well as Embraer 170/175 (& mainline 190/195) also use HEPA-rated filters inflight only, the “quick & dirty” research done for this reader comment post does NOT indicate if any upgrades for ventilation of aircraft at the gate during boarding & deplaning is included with the above referenced efforts by United & Delta;

    – other airlines (US domestic or foreign based) may have similarly acted to remedy/mitigate the disparity between onboard air quality available inflight & that during boarding & deplaning/disembarkation while aircraft are at the gate, as this reader comment is NOT intended to offer, nor should it be construed as providing a detailed, worldwide industry review.

    For additional information, please refer to additional links posted later today (assuming moderator approval).

    I will also endeavor to post additional information as warranted; others who may already be aware of announcements or additional actions undertaken to address the disparity of in cabin air quality be it among fleet types and/or for aircraft at the gate during the critical boarding, pre-departure dwell time & deplaning/disembarkation not referenced in my reader comments above are encouraged to fill in any omissions/gaps, or errors, as appropriate!

    Finally, onboard aircraft air quality & ventilation equipment/filtration is but one, of many considerations when evaluation risks of air travel.

    Other factors include, but are not limited to:

    – ground transportation to/from airports &/or at destinations while away from one’s home;

    – navigating airports during check in, pre-departure periods in lounges, restaurants, bars, other airport retail & hold rooms, plus any delays/queues/crowding awaiting delivery of checked baggage at carousels or at customs/immigrations halls for international travel;

    – any required/mandated time for quarantining (domestic or foreign);

    – variability of “Community Spread” rates that may result unexpected delays &/or sudden imposition of quarantining;

    – availability of venues, especially indoors, for larger gatherings;

    – availability of accommodations at destinations, with stays at family/friends’ homes outside of existing “bubbles” especially of concern for their widely documented higher rates of Covid19 infections & therefore NOT recommended per Dr. Anthony Fauci;

    – availability of other activities such as food & beverage, entertainment/recreation, etc., at reduced/limited capacity venues at destinations;

    – availability & quality of medical facilities & doctors at destinations in the event of sudden onset of Covid19 presenting symptoms, especially if severe, while traveling

    – for better or for worse, the habits & attitudes of others while traveling since some yet still seem to be unconvinced about the severity of the Covid19 pandemic, or that even if they are at the peak of health & remain asymptomatic even if exposed to the novel coronavirus, that others could become seriously ill, or even die, from exposures such that mitigation of risk is only as good as the commitment by everyone to wear masks, remain properly socially distanced on the ground, while waiting to board at the gate, in jetways or in the aisles of aircraft at all times, or of course, most importantly wear face masks PROPERLY (snugly covering their mouth & nose) throughout their flight (with as few & short duration removals for food & drink as possible) – which, sadly, is never really assured even after many of those that were openly hostile & dismissive of the utility of face masks became very sick recently.


    See sections 1.4 & 1.6 in IATA’s “Health Standard Checklist for Airline Operators – Edition 1 August 2020” at link above ⬆️

    Selected comments on LinkedIn:

    The link above ⬆️ includes a screenshot of IATA’s July 10th confirmation that the exceptional air quality featuring robust refresh rates & HEPA rated filters is available inflight only in reply to my series of critiques & analysis regarding the use of Pre-Conditioned Air Units for aircraft at the gate during boarding, pre-departure dwelling & deplaning/disembarkation

    For a wider discussion of commentaries & analysis regarding in cabin air quality, ventilation equipment, PCA’s & air filters to reduce transmission of Covid19, please feel free to scroll down using the “Posts” tab at on my
    LinkedIn page.

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