Page 2 of 2

Re: Why do aviation safety agencies overlook obvious safety deficiencies ?

Posted: Tue May 12, 2020 1:50 pm
by abcgogo
Thanks for the replies :)

I admit my knowledge is not upto the level because I am not a hardcore avgeek or industry insider. That said, I have been a longtime lurker on this forum & other websites learning as much as possible because I like aviation a lot. Seeing some situations, incidents/accidents, quirks, possibilities, etc. is what made me ask these questions. I'm not trying to troll or mock the aviation community in any way, just very curious.

The problem is that I searched for the topics (whose questions I asked) and did not find satisfactory answers on the internet (& even old threads of the airliners-net-forums), hence I started this thread & updated it with more questions. The answers by many members made me understand why things I mentioned are not done in aviation-industry.

Thanks again for the replies. :)

Re: Why do aviation safety agencies overlook obvious safety deficiencies ?

Posted: Sat May 16, 2020 6:56 am
by tommy1808
VSMUT wrote:
abcgogo wrote:
1) Why don't aircraft cockpits have a big-size "Level-Checking-Vial" like the one used in level-measurement-tools ? Those bottles with green color liquid that move based on gravity (& hence indiciate whether surface is level or not) is a good idea for aircraft in case instruments have failed or are having errors because it gives the pilot the most basic idea of whether their aircraft is levelled or not . This is especially useful at cloudy & night operations too where it is difficult/impossible to tell which way the aircraft is rolling/pitching due to spatial-disorientation. This seems to be a a quick, error-free (depends on gravity), maintenance-free, system-independent tool.


No, these are completely useless because of centrifugal forces. I could literally make a bubble level indicate straight and level while banking 90 degrees.


Wouldnt you need more than 90° bank angle to make it level?

Best regards
Thomas

Re: Why do aviation safety agencies overlook obvious safety deficiencies ?

Posted: Sat May 16, 2020 7:14 am
by VSMUT
tommy1808 wrote:
VSMUT wrote:
abcgogo wrote:
1) Why don't aircraft cockpits have a big-size "Level-Checking-Vial" like the one used in level-measurement-tools ? Those bottles with green color liquid that move based on gravity (& hence indiciate whether surface is level or not) is a good idea for aircraft in case instruments have failed or are having errors because it gives the pilot the most basic idea of whether their aircraft is levelled or not . This is especially useful at cloudy & night operations too where it is difficult/impossible to tell which way the aircraft is rolling/pitching due to spatial-disorientation. This seems to be a a quick, error-free (depends on gravity), maintenance-free, system-independent tool.


No, these are completely useless because of centrifugal forces. I could literally make a bubble level indicate straight and level while banking 90 degrees.


Wouldnt you need more than 90° bank angle to make it level?

Best regards
Thomas


A coordinated turn is all you need. At 90 degrees it is just a matter of pulling some g.

Re: Why do aviation safety agencies overlook obvious safety deficiencies ?

Posted: Sat May 16, 2020 7:47 am
by tommy1808
VSMUT wrote:
tommy1808 wrote:
VSMUT wrote:

No, these are completely useless because of centrifugal forces. I could literally make a bubble level indiciate straight and level while banking 90 degrees.


Wouldnt you need more than 90° bank angle to make it level?

Best regards
Thomas


A coordinated turn is all you need. At 90 degrees it is just a matter of pulling some g.


Even if you pull 9g, the 1g vector down doesn't disappear and has to be compensated for.

Best regards
Thomas

Re: Why do aviation safety agencies overlook obvious safety deficiencies ?

Posted: Sat May 16, 2020 2:17 pm
by GalaxyFlyer
Yes, 90* requires infinite G, 6G at 81* of bank.

Re: Why do aviation safety agencies overlook obvious safety deficiencies ?

Posted: Sat May 16, 2020 9:20 pm
by TSS
WayexTDI wrote:
abcgogo wrote:
6) Why aren't all airliners equipped with inbuilt airstairs (like on Ryanair-aircraft and ACJ/BBJ) so that they do not have to depend on airport airstairs ? Such a mandatory feature would increase the versatility of airliners usage where in an urgent situation (not emergency), the passengers & crew can quickly embark/disembark instead of damaging the aircraft by using the emergency slides. An example of this is the evacuation of civillians in Yemen done by Air-India (at behest of the Govt-of-India) which sent two A321 aircraft. Luckily for AI, there were stairs available at the war-stricken airport, had it been damaged/destroyed, then there would have been no way for Air-India to be able to board it's aircraft and the civillians would have been left stranded in Yemen. Check out this picture, if they had inbuilt airstairs, then that would have been an additional peace-of-mind factor for them. We have seen many such evacuations where by sheer luck or good planning, there have always been airstairs available, but what if one day the luck/planning runs out and there are no airstairs ? How are civillians going to be evacuated then ?
https://1ep6sa1jro642bl0n01shxzi-wpengi ... EN-FLT.jpg
https://www.airliners.net/photo/Ryanair ... /1277441/L


The 737 built-in airstair is a heavy (from memory, 300 lbs or so), expensive ($1/4 million) and maintenance intensive (as it wasn't meant to be used 10 times or so per day) piece of equipment.
Furthermore, they are slow to deploy and require electrical power (AC or DC, DC is even slower).

Emergency Evacuation Slides take just a few seconds to deploy, can (must) work in case of power failure and in extreme cold. During deployment, you do not damage the aircraft or the slide; slides are tested regularly and repacked on a calendar basis. Repacking is rather cheap (less than $10K per slide).
Lastly, slides are much quicker at evacuating passengers, are able to evacuate physically disabled passengers (they just slide down and don't have to walk down the stairs) and can double as rafts in case of water landing.


I genuinely did not know the optional 737 airstair was powered. Having only seen photos of one already deployed/in use, since 737s are quite low to the ground I simply assumed it was a manual thing and that someone on the ground opened the door, slid it out, articulated it into place, then popped it back in it's hole when they closed up the aircraft for takeoff or to overnight.

Re: Why do aviation safety agencies overlook obvious safety deficiencies ?

Posted: Sun May 17, 2020 12:53 am
by strfyr51
Is it possible to land safely with 99% or even 80% fuel load (even if it may lead to requiring lots of intensive maintenance after landing) ? I was under the impression that the maximum safest landing can be done only when the aircraft is just above Maximum-Landing-Weight (MLW), say 20% above MLW....otherwise, it would lead to a crash landing where the landing gear would collapse (unable to handle the weight) and the heavily loaded full tanks in the wings would burst open causing a fireball explosion that could severely-injure/kill everybody on board.....something like the DC-10 crash at Sioux-City.

you are mistaken. An aircraft can land with all the fuel it took off with in a pinch, However? the Maintenance that might need to be performed after such a landing?
could be Extensive if the landing is performed badly...
Overweight/Hard landing inspection is very similar in that the accelerometers are both downloaded and recorded. and the inspection starts with a simple walkaround and possible defueling. Once the problem that caused the return to field is fixed? the airplane may be re-crewed and re-dispatched. While at United ive had airplanes that returned after 7Hrs of flying for a 45 Minute repair. I almost got fired for not dispatching an airplane (747-422) with a no go message I couldn't fix in time for the crew to run out of time. I didn't get fired as I was in the right, So I never let my guard down. sometimes? It's the luck of the Draw.

Re: Why do aviation safety agencies overlook obvious safety deficiencies ?

Posted: Sun May 17, 2020 1:04 am
by GalaxyFlyer
Part 25 certification requires the OEM to demonstrate 10 feet per second (FPS) touchdown at MLW and 6 FPS at MTOGW minus 15 minutes fuel burn to account for take-off and return without damage. Landing gear are pretty tough. Landings above MLW may have Hard Landing Inspections done.

Re: Why do aviation safety agencies overlook obvious safety deficiencies ?

Posted: Tue May 19, 2020 9:40 pm
by Moose135
GalaxyFlyer wrote:
Landing gear are pretty tough.

I can attest to that...
:rotfl:

Re: Why do aviation safety agencies overlook obvious safety deficiencies ?

Posted: Wed May 20, 2020 2:34 pm
by WayexTDI
TSS wrote:
WayexTDI wrote:
abcgogo wrote:
6) Why aren't all airliners equipped with inbuilt airstairs (like on Ryanair-aircraft and ACJ/BBJ) so that they do not have to depend on airport airstairs ? Such a mandatory feature would increase the versatility of airliners usage where in an urgent situation (not emergency), the passengers & crew can quickly embark/disembark instead of damaging the aircraft by using the emergency slides. An example of this is the evacuation of civillians in Yemen done by Air-India (at behest of the Govt-of-India) which sent two A321 aircraft. Luckily for AI, there were stairs available at the war-stricken airport, had it been damaged/destroyed, then there would have been no way for Air-India to be able to board it's aircraft and the civillians would have been left stranded in Yemen. Check out this picture, if they had inbuilt airstairs, then that would have been an additional peace-of-mind factor for them. We have seen many such evacuations where by sheer luck or good planning, there have always been airstairs available, but what if one day the luck/planning runs out and there are no airstairs ? How are civillians going to be evacuated then ?
https://1ep6sa1jro642bl0n01shxzi-wpengi ... EN-FLT.jpg
https://www.airliners.net/photo/Ryanair ... /1277441/L


The 737 built-in airstair is a heavy (from memory, 300 lbs or so), expensive ($1/4 million) and maintenance intensive (as it wasn't meant to be used 10 times or so per day) piece of equipment.
Furthermore, they are slow to deploy and require electrical power (AC or DC, DC is even slower).

Emergency Evacuation Slides take just a few seconds to deploy, can (must) work in case of power failure and in extreme cold. During deployment, you do not damage the aircraft or the slide; slides are tested regularly and repacked on a calendar basis. Repacking is rather cheap (less than $10K per slide).
Lastly, slides are much quicker at evacuating passengers, are able to evacuate physically disabled passengers (they just slide down and don't have to walk down the stairs) and can double as rafts in case of water landing.


I genuinely did not know the optional 737 airstair was powered. Having only seen photos of one already deployed/in use, since 737s are quite low to the ground I simply assumed it was a manual thing and that someone on the ground opened the door, slid it out, articulated it into place, then popped it back in it's hole when they closed up the aircraft for takeoff or to overnight.

Check out this video. It's very complex, and slow.

Re: Why do aviation safety agencies overlook obvious safety deficiencies ?

Posted: Sat May 23, 2020 6:58 am
by rlwynn
Starlionblue wrote:
2. Thrust reversers on smaller jets. The majority of braking comes from the brakes. Reversers are a bonus and not even included in performance calculations except on contaminated runways. You could have larger airliners without reversers but you start running into brake temperature issues on short turns.



That was a big issue with the BAE-146 and SNA.