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Could an unpressurised passenger jet ever become competitive?

Posted: Sat Sep 07, 2019 8:54 pm
by tropical
I suspect the answer is no, or it would have been done already. But as technology on composite materials and advanced aerodynamics gets better all the time, could we ever reach a point when an ultralight non-pressurised passenger jet flying low becomes more efficient than the current ones despite the increased drag?

I’d imagine the weight savings could be enormous from structural issues to oxygen supply etc, and maintenance checks and the lifetime cycle limit would also be so much better...

(Mods, feel free to move this to Tech though I fear it might be too dumb a question for that forum)

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sat Sep 07, 2019 8:59 pm
by MIflyer12
Ask yourself why passenger jets don't cruise a 7,000 ft.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sat Sep 07, 2019 9:04 pm
by AirFiero
Passenger JET? No. Jets are only efficient at altitudes that require oxygen and/or pressurization. Props, as in piston engines, yes. Turboprop, generally not so much for the same reasons.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sat Sep 07, 2019 9:09 pm
by enilria
IMHO such a plane could only have benefits in extremely short routes like PHL-LGA or OAK-SFO. That’s a pretty small niche now.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sat Sep 07, 2019 9:09 pm
by tropical
MIflyer12 wrote:
Ask yourself why passenger jets don't cruise a 7,000 ft.

I had thought it was mainly due to drag and perhaps turbulence, but I suspect you might be referring to jet engine efficiency as well?

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sat Sep 07, 2019 9:24 pm
by Karlsands
No, can’t fly below 14k without full oxygen and even at 12,500 you only have 30 mins , come on mate

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sat Sep 07, 2019 9:30 pm
by Noshow
During the times of the Berlin Wall all allied jet aircraft within the Berlin air corridors -like Pan American's 727 or BEA's Tridents- flew at only 10.000 feet because of old customs from propeller aircraft used there after WW2. Everything was intended to keep the status quo going. So nothing got changed.
Flying so low you are flying in and not above the weather and while you don't need to pressurize the cabin the engines use more fuel. Back then many flights climbed over West Germany for the final miles to their destination in order to save some fuel.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sat Sep 07, 2019 11:53 pm
by harleydriver
tropical wrote:
MIflyer12 wrote:
Ask yourself why passenger jets don't cruise a 7,000 ft.

I had thought it was mainly due to drag and perhaps turbulence, but I suspect you might be referring to jet engine efficiency as well?


Turbine aircraft engines are more efficient the higher you go. Just to save weight on oxygen masks wouldn't be a benefit at all and you can expect smoother air at altitude for the most part so passenger comfort would be an issue too. Yes, airframes are limited to the number of times they are pressurized, or a cycle, but the fuel savings at altitude far exceed that limitation as the aircraft will be pretty well aged when it reaches it's cycle limits.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 12:00 am
by dfwjim1
On the opposite end of things will we ever see commercial airliners flying between 45,000 and say 70,000 feet on flights over 4 hours long?

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 12:28 am
by rjsampson
There's often a small exception to the rule...

While not a jet, a Part 121 Carrier called Cape Air placed 100 orders for a brand-new, unpressurized aircraft called the Tecnam P2012:

https://en.wikipedia.org/wiki/Tecnam_P2012_Traveller

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 12:32 am
by UPNYGuy
a prop would make more sense at that point. The human body cannot handle high altitudes where jet a/c operate most efficiently without pressurization.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 12:35 am
by WeatherPilot
That would be like putting a paddle wheel on an aircraft carrier.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 12:39 am
by stl07
rjsampson wrote:
There's often a small exception to the rule...

While not a jet, a Part 121 Carrier called Cape Air placed 100 orders for a brand-new, unpressurized aircraft called the Tecnam P2012:

https://en.wikipedia.org/wiki/Tecnam_P2012_Traveller

was about to post about good old Cape

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 12:41 am
by CanesFan
The lack of pressurization would mean that it couldn't comfortably fly any of the jet climb/descent profiles either .

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 12:44 am
by Aesma
The technological advances you mention also make pressurization less of an issue. That's why plastic planes (A350 and B787) have higher pressurization.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 12:54 am
by ParkFSI
My sinuses couldn’t handle it !

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 1:10 am
by LAXLHR
tropical wrote:
I suspect the answer is no, or it would have been done already. But as technology on composite materials and advanced aerodynamics gets better all the time, could we ever reach a point when an ultralight non-pressurised passenger jet flying low becomes more efficient than the current ones despite the increased drag?

I’d imagine the weight savings could be enormous from structural issues to oxygen supply etc, and maintenance checks and the lifetime cycle limit would also be so much better...

(Mods, feel free to move this to Tech though I fear it might be too dumb a question for that forum)


I think its a fine question.

There is technology coming that will turn the industry on its head.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 1:27 am
by Aesma
But the technology is rather people not taking short flights on turboprop or jets, instead using a flying car.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 1:28 am
by klm617
One of the biggest problems would be noise no one wants a jet flying over their house at such a low altitude.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 2:06 am
by atcsundevil
dfwjim1 wrote:
On the opposite end of things will we ever see commercial airliners flying between 45,000 and say 70,000 feet on flights over 4 hours long?

They certainly wouldn't be operating above FL600. Controlled airspace only extends to FL600 (in the US, anyway). That said, I don't think that flying that high is terribly practical until there's a radical redesign in how aircraft are powered. Bizjets regularly cruise at FL430/450, but even the fanciest of Gulfstreams can only manage FL510 at the highest (at least that's the highest I've personally seen, and according to a Gulftest pilot, that's their max). At least for the foreseeable future, I think that FL410 will probably be as high as commercial aircraft will go. FL420 isn't a usable altitude, so FL430 is just beyond what most commercial aircraft can manage with current tech.

tropical wrote:
I suspect the answer is no, or it would have been done already. But as technology on composite materials and advanced aerodynamics gets better all the time, could we ever reach a point when an ultralight non-pressurised passenger jet flying low becomes more efficient than the current ones despite the increased drag?

I’d imagine the weight savings could be enormous from structural issues to oxygen supply etc, and maintenance checks and the lifetime cycle limit would also be so much better...

(Mods, feel free to move this to Tech though I fear it might be too dumb a question for that forum)

I just don't think there's any practical reason for it. Having an aircraft pressurized isn't a significant additional expense. Operationally, it would be extremely limiting, and rather unpopular in any sort of commercial application. Flying below 10,000ft means 250kts max, so even if they could manage higher speeds, they'd be limited unless they could climb higher than 10K. It also limits their ability to climb above weather, so precip and icing would have a significant impact. Operating at higher altitudes means they could simply climb above. Those limitations alone would be far more costly in the long term than carrying the additional weight and paying for additional maintenance to have the aircraft pressurized.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 5:39 am
by Super80Fan
Yeah sure, just got to upgrade a humans' lungs/oxygen consumption!

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 5:59 am
by spacecadet
dfwjim1 wrote:
On the opposite end of things will we ever see commercial airliners flying between 45,000 and say 70,000 feet on flights over 4 hours long?


Probably not as you generally get an inversion of the efficiency curve before that point. Not enough lift combined with not enough oxygen for the engines. So you can do any combination of three things: a) make a higher lift, higher drag wing, b) make engines that burn more fuel, and/or c) lighten the load. Any and all of those things are poor profit drivers.

We're pretty well stuck with the types of airliners we've got for a while, at least. And I don't really see any new technology on the horizon that's going to change that. It's *possible* to fly higher, or faster, or whatever. The issue is whether an airline can actually make more money doing that, either with existing tech or anything currently in development, and the answer so far is always a resounding "no".

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 6:37 am
by Silver1SWA
It seems a lot of people missed the part when the OP was asking about jets traveling low enough to not need pressurization.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 7:27 am
by bluejuice
WeatherPilot wrote:
That would be like putting a paddle wheel on an aircraft carrier.


The USS Sable and USS Wolverine would like a word with you outside. :)

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 7:55 am
by RJMAZ
We will definitely see unpressurized airliners in a decade or two.

Electric propulsion will be the reason why. On a multiple hour flight it is worth the effort to climb up to 30,000ft. On a very short flight the benefit of flying high is not as great. As electric aircraft will be limited to ultra short haul they may as well save weight and fly low.

The noise issue of flying low will not be a problem for electric aircraft.

Also generating cabin pressure and cabin heat in an all electric aircraft might be an issue as there is no bleed air from a gas turbine.

I expect small general aviation airports close to city centres that have strict noise curfews to open up with electric aircraft. We can then have small point to point flights between tiny airports capturing a new market often served by cars and trains. These electric aircraft can also feed into large hubs to take conventional fueled aircraft for long flights.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 7:56 am
by Nomadd
No.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 8:59 am
by umichman
rjsampson wrote:
There's often a small exception to the rule...

While not a jet, a Part 121 Carrier called Cape Air placed 100 orders for a brand-new, unpressurized aircraft called the Tecnam P2012:

https://en.wikipedia.org/wiki/Tecnam_P2012_Traveller


Not really an exception as it's piston-engined prop aircraft (OP specifically said jet).

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 9:09 am
by JayinKitsap
rjsampson wrote:
There's often a small exception to the rule...

While not a jet, a Part 121 Carrier called Cape Air placed 100 orders for a brand-new, unpressurized aircraft called the Tecnam P2012:

https://en.wikipedia.org/wiki/Tecnam_P2012_Traveller


Cessna SkyCourier seems to have a similar approach as the P2012 but in the 19 seat size. Anyone know when 1st flight is expected for the SkyCourier?


https://cessna.txtav.com/en/turboprop/skycourier

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 9:10 am
by VSMUT
RJMAZ wrote:
We will definitely see unpressurized airliners in a decade or two.

Electric propulsion will be the reason why. On a multiple hour flight it is worth the effort to climb up to 30,000ft. On a very short flight the benefit of flying high is not as great. As electric aircraft will be limited to ultra short haul they may as well save weight and fly low.


This. Flying the ATR on really short island hopper routes, I've found it much faster to fly at around 6000 to 8000 ft. You waste a lot of time climbing, it is much faster to just level off and rush off towards the destination at Vmo. On a short 80 mile flight, I could do it in half the time it took the competitors' CRJs. I saved a lot of fuel too.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 9:24 am
by tomcat
In today's world, the main benefit I'd see in flying unpressurized aircraft is that the security requirements for checked-in items might be relaxed. Shower gels and bottles of water might be allowed again on board. For short distance trips, we'd be back to a travel experience closer to the train experience, ie a more "hop-on, hop-off" kind of experience. It's not that unpressurized aircraft are not explosion-proof but they are more tolerant to limited energy explosions.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 9:49 am
by leghorn
If emissions taxes are introduced in Europe then low flying un-pressurised electric powered aircraft will become feasible or even highly desirable on short routes.
London for example is less than 300NM from loads of major cities.

The aircraft cabin will stop being a pressurised tube and will be more like a Gondola hanging beneath the Wings with the main landing gear slung below the Wings like on a Dash8 Q400.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 9:49 am
by Lufthansa
Short answer No.
Firstly, there's the issue of engine efficiency. As to the question about flying above 45000 ft we did it already for
decades with the Concorde and for this very reason.
Building on this, the claim of electric engines is hogwash. With all this investment into the geared turbofan and new
exotic materials, they'll be moving to biofuels or hydrogen based engines in the future. Most likely biofuels as
a lot of aircraft are designed for a 30 year service life, and liquid, or liquified gases provide a far faster turn around
than any battery will ever.

Next passenger comfort. Flying at pressurised altitudes means you can also avoid most of the weather.
Now even with a fully flat bed, its hard to sleep in bad turbulence. If an airline deliberately chose to
do this, they'd quickly lose out to the competitors for premium traffic who chose to stick with the
old technology. In short.... the idea is a step backwards.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 9:51 am
by BAeRJ100
tomcat wrote:
Shower gels and bottles of water might be allowed again on board.


That would create further complications on the security/airport side of things. You'd either need an airport/terminal to be dedicated solely to those aircraft types, or find another way to segregate those catching pressurised/unpressurised flights. Otherwise it becomes way too easy for people with nefarious intentions to get things into the cabins of those pressurised flights.

leghorn wrote:
If emissions taxes are introduced in Europe then low flying un-pressurised electric powered aircraft will become feasible or even highly desirable on short routes.
London for example is less than 300NM from loads of major cities.


It would certainly need to be limited in its range, anything of significant distance would run into a little problem called the Alps.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 9:59 am
by leghorn
For the exact same reason that the Q400 is preferred to the ATR in some other regions but if the business case is compelling and allows an ATR72 then that is what the airlines choose. An operator in the west of Europe will deploy planes with lesser abilities on those routes that suit them.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 10:09 am
by OA940
I'm surprised so few people have mentioned the natural limitations. The weather is one, and that would make diversions and deviations much more frequent. There is also terrain. There are a lot of hilly areas above 10k feet. Plus, at that altitude the plane would have to fly at 250 knots max which would bring a slew of problems. I suspect the only unpressurised aircraft we'll ever see will be turboprops on short flights.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 10:14 am
by trijetsonly
The only thing that I can think of in this topic would be a revival of the ground effect vehicles

https://en.wikipedia.org/wiki/Boeing_Pelican

https://en.wikipedia.org/wiki/Spasatel

https://www.theregister.co.uk/2006/09/22/caspian_sea_monster/


Or maybe there will be a time again where Zeppelins rule the sky? But those won't be jets me thinks.

Re: Could an unpressurised passenger jet ever become competiti

Posted: Sun Sep 08, 2019 12:53 pm
by asdf
atcsundevil wrote:
dfwjim1 wrote:
On the opposite end of things will we ever see commercial airliners flying between 45,000 and say 70,000 feet on flights over 4 hours long?

They certainly wouldn't be operating above FL600. Controlled airspace only extends to FL600 (in the US, anyway). That said, I don't think that flying that high is terribly practical until there's a radical redesign in how aircraft are powered. Bizjets regularly cruise at FL430/450, but even the fanciest of Gulfstreams can only manage FL510 at the highest (at least that's the highest I've personally seen, and according to a Gulftest pilot, that's their max). .


You are right

Gulfstream 650
Service ceiling FL510

But they dont use it often
Only works if they are light, at the last part of the journey

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 12:56 pm
by VV
Is it competitive?
Against submarines the answer is affirmative.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 1:25 pm
by Palumboism
JayinKitsap wrote:
rjsampson wrote:
There's often a small exception to the rule...

While not a jet, a Part 121 Carrier called Cape Air placed 100 orders for a brand-new, unpressurized aircraft called the Tecnam P2012:

https://en.wikipedia.org/wiki/Tecnam_P2012_Traveller


Cessna SkyCourier seems to have a similar approach as the P2012 but in the 19 seat size. Anyone know when 1st flight is expected for the SkyCourier?


https://cessna.txtav.com/en/turboprop/skycourier


There will be pressurized and non-pressurized versions of the SkyCourier with the non-pressurized version coming first.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 2:42 pm
by AirFiero
RJMAZ wrote:
We will definitely see unpressurized airliners in a decade or two.

Electric propulsion will be the reason why. On a multiple hour flight it is worth the effort to climb up to 30,000ft. On a very short flight the benefit of flying high is not as great. As electric aircraft will be limited to ultra short haul they may as well save weight and fly low.

The noise issue of flying low will not be a problem for electric aircraft.

Also generating cabin pressure and cabin heat in an all electric aircraft might be an issue as there is no bleed air from a gas turbine.

I expect small general aviation airports close to city centres that have strict noise curfews to open up with electric aircraft. We can then have small point to point flights between tiny airports capturing a new market often served by cars and trains. These electric aircraft can also feed into large hubs to take conventional fueled aircraft for long flights.


Have you *heard* an electric aircraft? Google is testing their electric whatever at my local airport. It has something like 10 electric props. It is anything but quiet. Maybe a design with larger and fewer engines *might* end up noticeably quieter, but don’t assume it. Most electric “flying car” designs have multiple engines like drones.

Edit, add link to article: https://sanbenito.com/2018/03/14/driver ... hollister/

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 2:43 pm
by jeffrey0032j
The Boeing 929 would had been the closest to it.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 2:50 pm
by AirFiero
VSMUT wrote:
RJMAZ wrote:
We will definitely see unpressurized airliners in a decade or two.

Electric propulsion will be the reason why. On a multiple hour flight it is worth the effort to climb up to 30,000ft. On a very short flight the benefit of flying high is not as great. As electric aircraft will be limited to ultra short haul they may as well save weight and fly low.


This. Flying the ATR on really short island hopper routes, I've found it much faster to fly at around 6000 to 8000 ft. You waste a lot of time climbing, it is much faster to just level off and rush off towards the destination at Vmo. On a short 80 mile flight, I could do it in half the time it took the competitors' CRJs. I saved a lot of fuel too.


I’d like to see the cost of these flights versus longer routes flown at typical altitudes. I’d bet it’s higher (also meaning higher fares).

One thing that doesn’t seem to be taken into account in this discussion is that the physics of flight and air density doesn’t change with an electric aircraft. The engine efficiency might not matter, but the denser air at lower altitudes is still an issue. Even my single engine airplane gets much higher true airspeed in the mid-teens. And less air resistance means better fuel consumption. An electric motor still needs to use more power to overcome the denser air, which is still inefficient. Those short flights will eat up a lot more battery power.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 3:02 pm
by WN732
Karlsands wrote:
No, can’t fly below 14k without full oxygen and even at 12,500 you only have 30 mins , come on mate


Pilots need oxygen at 12.5 and everyone needs it at 14 and above.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 3:11 pm
by bigb
JayinKitsap wrote:
rjsampson wrote:
There's often a small exception to the rule...

While not a jet, a Part 121 Carrier called Cape Air placed 100 orders for a brand-new, unpressurized aircraft called the Tecnam P2012:

https://en.wikipedia.org/wiki/Tecnam_P2012_Traveller


Cessna SkyCourier seems to have a similar approach as the P2012 but in the 19 seat size. Anyone know when 1st flight is expected for the SkyCourier?


https://cessna.txtav.com/en/turboprop/skycourier

Not really a similar approach, the Cessna will be a turboprop unlike the Tecnam which will be a Twin-piston engine.


Sent from my iPhone using Tapatalk

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 3:23 pm
by monomojo
BAeRJ100 wrote:
That would create further complications on the security/airport side of things. You'd either need an airport/terminal to be dedicated solely to those aircraft types, or find another way to segregate those catching pressurised/unpressurised flights. Otherwise it becomes way too easy for people with nefarious intentions to get things into the cabins of those pressurised flights.


That's not a significant hurdle. If unpressurized electric aircraft are only used for commuter hops, it'd be desirable to segregate their facilities, if for no other reason to be able to move passengers faster by not mixing them in with long haul passengers. The faster and more convenient it is for passengers to utilize those aircraft, the more likely they are to want to use them, and the better the business case for them becomes. I could see it becoming not much different than a bus station: catch the shuttle from the parking area or hop off your transportation at ticketing, take a seat in the waiting area, and then walk straight out to your aircraft when it arrives.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 3:48 pm
by 2175301
Overall, I think the answer to the OP question is no for a pure jet engine with current or near current technology. Clearly possible for a turboprop (and turbo props have some advantages over piston prop engines, which is part of the reason why a number of DHC-2 Beavers have been converted from piston prop to turbo prop).

Along with the other modern options mentioned above; the Twin Otter is a 19 seat unpressurized turbo prop, with the 400 model currently in production. It's also a rugged STOL aircraft and designed to operate in arctic conditions (although a number of them are used for tropical island hopping passenger service - with or without floats). I've never heard of anyone complaining about its fuel consumption. Perhaps only because of where it is most commonly used.

Have a great day,

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 3:51 pm
by RetiredNWA
Noshow wrote:
During the times of the Berlin Wall all allied jet aircraft within the Berlin air corridors -like Pan American's 727 or BEA's Tridents- flew at only 10.000 feet because of old customs from propeller aircraft used there after WW2. Everything was intended to keep the status quo going. So nothing got changed.
Flying so low you are flying in and not above the weather and while you don't need to pressurize the cabin the engines use more fuel. Back then many flights climbed over West Germany for the final miles to their destination in order to save some fuel.


That is not entirely correct. Air corridor altitudes changed in the late 70’s with the IGS operations.

Additionally, this topic is off the rails.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 3:59 pm
by johns624
bluejuice wrote:
WeatherPilot wrote:
That would be like putting a paddle wheel on an aircraft carrier.


The USS Sable and USS Wolverine would like a word with you outside. :)
You beat me to it!

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 6:36 pm
by SoCalPilot
atcsundevil wrote:
They certainly wouldn't be operating above FL600. Controlled airspace only extends to FL600 (in the US, anyway).

Not correct. The airspace above FL600 is Class E airspace which is controlled airspace.

rjsampson wrote:
There's often a small exception to the rule...

While not a jet, a Part 121 Carrier called Cape Air placed 100 orders for a brand-new, unpressurized aircraft called the Tecnam P2012:

https://en.wikipedia.org/wiki/Tecnam_P2012_Traveller

While Cape Air does have a some operations under Part 121, these aircraft will be operating under part 135.

Re: Could an unpressurised passenger jet ever become competitive?

Posted: Sun Sep 08, 2019 6:38 pm
by rbavfan
rjsampson wrote:
There's often a small exception to the rule...

While not a jet, a Part 121 Carrier called Cape Air placed 100 orders for a brand-new, unpressurized aircraft called the Tecnam P2012:

https://en.wikipedia.org/wiki/Tecnam_P2012_Traveller



Yes and that is for a short hop to smaller airports. Not really meant for mainline ops at some of the airports. Not the same market needs, irrelevant to the situation.