[AirbusA340]

Hi there...

For most of the fly by wire variants in the Airbus family, narrow and wide bodies included, the logics are sort of similar but they vary slightly in design. Similarly the design philosophies vary widely for Airbus, Boeing, ATR, McDonell Douglas, etc.,

For e.g. I flew the A320 and the A330 for a while. Even though the basics remain that you start one engine to power one 'engine driven hydraulic pump' to carry out certain functions and so on, the A320 procedures have Engine 2 (right one) to be started first followed by the Engine 1 (left one) whereas the A330 has it the other way around. But rest assured the functions and the logics are similar.

On similar lines, on the A320,...

1. The auto brakes should be selected at one of the three detents, LO (low), MED (medium) & MAX (maximum and only for a rejected takeoff).

2. FULL EXTENSION – REJECTED TAKEOFF PHASE If the ground spoilers are armed and the speed exceeds 72 kt, the ground spoilers will automatically extend as soon as both thrust levers are reset to idle. If the ground spoilers are not armed and the speed exceeds 72 kt, the ground spoilers will automatically extend as soon as reverse is selected on one engine (the other thrust lever remains at idle).

3. FULL EXTENSION - LANDING PHASE If the ground spoilers are armed and all thrust levers are at idle, the ground spoilers will automatically extend as soon as both main landing gears have touched down. If the ground spoilers are not armed and both main landing gears have touched down, the ground spoilers will automatically extend as soon as reverse is selected on one engine (the other thrust lever remains at idle).

4. Now, the auto brakes would operate only after the ground spoiler extension and is based on what auto brake selection was made. E.g. LO would give a time delay of 4 seconds from spoiler extension to auto brake functioning, MED would give a time delay of 2 seconds and MAX for a rejected takeoff would have no time delay and is instantaneous.

5. To make it easy, during landing->touchdown->ground spoilers extend-> Auto brakes function based on time delay appropriate to the selection made by us.

pEaCe

I miss the A330! god put me back on it

[Jeroen]

Originally Posted by AirbusA340

Hi there...

For most of the fly by wire variants in the Airbus family, narrow and wide bodies included, the logics are sort of similar but they vary slightly in design. Similarly the design philosophies vary widely for Airbus, Boeing, ATR, McDonell Douglas, etc.,


On similar lines, on the A320,...

Thanks, that is very good information. And it shows that the auto brake logic does extend beyond merely the wheels touching down.

Am I correct in understanding that on the Airbus there is no separate setting for RTO as there is on the Boeing? (That's how I read you item 1)

On item 3, this is still a bit of my query; what's the condition that gets monitored, is it the wheels spinning up or the gear struts compressing. As per my previous post I have read about the wheels spinning up, but I'm not sure I understand the logic of that. Gear struts compressing would make more sense to me. But maybe I'm overlooking something.

On the Boeing (744) manual braking is actually more powerful than on auto brake. Never quite understood the design philosophy behind that one either, but thats what the AOM says. Is that similar for the Airbus and if so can you explain what's the rationale behind it?

I've seen some post on PPrune that suggest that on the 320 you can not set the auto brake to MAX in flight. Only after landing and compressing of the nose gear olea. I guess its not so difficult to see some rationale behind it, but I was wondering if its true. Could it be a carrier specific option?

Appreciate your thoughts/comments. I'm no commercial pilot, just PPL with a few endorsements and other ratings. But I love to figure out these aviation systems, both from a functional pilot as well as design engineering point of view.

Jeroen

[racingmachine]

Originally Posted by ifly

I am not very sure why they would have done such a thing!! Quite honestly, I am very keenly waiting on the findings myself.

Hello ifly...great thread indeed!!

I was recently watching on Nat Geo the crash video of Turkish Airlines Flight 1951. The boeing aircraft went into Retard flare mode, and caused a crash which looks similar to the Asiana accident. Any thoughts??

On a side note, ive always wondered, when a pilot is piloting the aircraft through a very rough and turbulent sky, is there a chance of plane rotating sideways/somersaulting? Does the autopilot steer the plane through the turbulent weather or pilots have to manually steer the plane?

Thanks.

[airforce1]

Originally Posted by Jeroen

Thanks, that is very good information. And it shows that the auto brake logic does extend beyond merely the wheels touching down.

Well, the meaning is the same!!!, it boils down to the same thing, Autobrake will get activated when the aircraft touches the ground, whether its the Main wheels spun up (Boeing) or the Oleos getting compressed( Airbus)!!

Am I correct in understanding that on the Airbus there is no separate setting for RTO as there is on the Boeing? (That's how I read you item 1)

RTO is the setting on the Boeing, Vis-a-Vis, MAX is the same setting on the Airbus. Both are used for Rejected Take Off Maneuver in their respective Aircrafts.

On item 3, this is still a bit of my query; what's the condition that gets monitored, is it the wheels spinning up or the gear struts compressing. As per my previous post I have read about the wheels spinning up, but I'm not sure I understand the logic of that. Gear struts compressing would make more sense to me. But maybe I'm overlooking something.

Both of them mean the same thing, I.e., aircraft is on ground.

On the Boeing (744) manual braking is actually more powerful than on auto brake. Never quite understood the design philosophy behind that one either, but thats what the AOM says. Is that similar for the Airbus and if so can you explain what's the rationale behind it?

This is true for all the Aeroplanes and not just The Jumbo. Manual Braking will always give you the Shortest Landing Distance.


I've seen some post on PPrune that suggest that on the 320 you can not set the auto brake to MAX in flight. Only after landing and compressing of the nose gear olea. I guess its not so difficult to see some rationale behind it, but I was wondering if its true. Could it be a carrier specific option?

Appreciate your thoughts/comments. I'm no commercial pilot, just PPL with a few endorsements and other ratings. But I love to figure out these aviation systems, both from a functional pilot as well as design engineering point of view.


Hope that this helps some of your queries :-)

[norhog]

Hi ifly
Like all here please hear out my query's and please try n reply even if they are silly.
Here goes
1).Do aircrafts fly at crusing altitude with nose slightly up (trim by aft as in marine industry)?Why?
2).How do fighter planes fly upside down, the wings generating lift would bring the plane down to earth in this upside down position?
3). Heard rumors Qatar Airways funding research for airplanes to run on LNG. (Qatar has worlds biggest gas fields and biggest producers and exporter of LNG) How true is that? If yes how soon will we get it?
Thanks

[norhog]

Also I will be flying on Indigo flight 6E-325 from Mumbai to Kolkata on 09 Aug 2013. Dep Mum 19:55hrs and arrival Kol 22:30 hrs. Any chance you will be flying that aircraft.

[AirbusA340]

Originally Posted by Jeroen

Am I correct in understanding that on the Airbus there is no separate setting for RTO as there is on the Boeing? (That's how I read you item 1)

On item 3, this is still a bit of my query; what's the condition that gets monitored, is it the wheels spinning up or the gear struts compressing. As per my previous post I have read about the wheels spinning up, but I'm not sure I understand the logic of that. Gear struts compressing would make more sense to me. But maybe I'm overlooking something.

On the Boeing (744) manual braking is actually more powerful than on auto brake. Never quite understood the design philosophy behind that one either, but thats what the AOM says. Is that similar for the Airbus and if so can you explain what's the rationale behind it?

I've seen some post on PPrune that suggest that on the 320 you can not set the auto brake to MAX in flight. Only after landing and compressing of the nose gear olea. I guess its not so difficult to see some rationale behind it, but I was wondering if its true. Could it be a carrier specific option?
Jeroen

Hi there...

The A320 is quite an old design. The RTO setting has never turned up. Maybe it will come up in the future A320 Neo! But the A340/A380 have an RTO setting. Weird but even the A330 didn't have it.

It's the shocks compressing which is called WOW(Weight On Wheels).

It's more in the physics than the design that determines manual braking being more effective than auto braking. In line experience we have experienced manual braking to be so damn effective that you have to rewrite your logics in the brain of what the aircraft is capable of. Well, that is assuming that you apply full manual brakes and maintain the brake pressure constant. Even the braking distances for manual braking in the onboard documentation are less than that with the auto brakes on. All said and done, we have to understand that it's helpful only in specific situations wherein manual braking would be helpful and you don't run the risks of a locked wheel,etc., When it pours outside, we are seriously advised to use the auto brakes for the obvious reason to have the best balance between braking enough and stopping enough without having a locked wheel. For the same reason, if we are still not happy then MED is selected. This setting gives best braking on wet and short runways. That's how the thinking goes.

No. It is not carrier specific. Airbus has restricted the selection of the MAX setting in flight which suggests that you cannot use it for landing. To be more specific, the MAX setting when activated during a rejected takeoff is designed to brake at a deceleration equivalent to '3g'. One of my friends from Hyderabad had a rejected takeoff after bird injestion in Delhi a few years ago and he still swears by the deceleration he felt that day and that it has to be felt to believe in. Optimally, that sort of braking which puts extreme stress on the mechanicals is required only for a rejected takeoff condition because of the urgency of the situation and to attain best deceleration rate possible over every inch of the runway. The reason it's not even selectable in flight is purely decided by Airbus and I personally feel that they wanted to avoid any pilot error in selection at some point in the future. Just my 2 cents.

pEaCe

[girishglg]

What a thread captain! The info in this thread is something that most of us will never know unless one is inside the cockpit. Just glued to the thread and a very well deserved 5 star!

A recent observation from a passenger perspective, had a return trip to Del from Blr last week and flew JetConnect - Boeing 737-900 and returned in Indigo A320.

Sat in similar rows both times 11, 13 so nearly same distance from the jet engines and wings.

Noticed that the sound levels seeping into the cabin in a 737 was much higher than the A320. Not sure if this is the real case but this is just my observation as a passenger.

Over to you for your expert comments

[plimsollmark]

Originally Posted by ifly

Thanks for sharing

PS: If I have not replied to any of the queries, please pardon thy limited attention span.

You are welcome. Thanks for all the detailed answers to everyone's queries.

One of the reasons I followed the air France crash investigation was that I had flown on the same sector a few weeks prior to the crash (probably on the same plane !) Spooked me.

[kaushal21fb]

Thanks for starting this awesome thread iFly. Nice to see so many aviation buffs on TBHP. I always wanted to be a pilot, but fate had some other plans. I'm always the last one to get out of the plane after landing, because that's when the pilots open the cabin door and you have a good chance to do peek a boo inside.

Last year finally got a chance to enter the A320 cockpit, courtesy my father in law and some super friendly cabin crew. Posting some pictures for your view. It'll help if any of the pilot(s) can explain the controls.

[Jeroen]

Originally Posted by airforce1

RTO is the setting on the Boeing, Vis-a-Vis, MAX is the same setting on the Airbus. Both are used for Rejected Take Off Maneuver in their respective Aircrafts.


This is true for all the Aeroplanes and not just The Jumbo. Manual Braking will always give you the Shortest Landing Distance.
Hope that this helps some of your queries :-)

Originally Posted by AirbusA340

Hi there...

The A320 is quite an old design. The RTO setting has never turned up. Maybe it will come up in the future A320 Neo! But the A340/A380 have an RTO setting. Weird but even the A330 didn't have it.

To be more specific, the MAX setting when activated during a rejected takeoff is designed to brake at a deceleration equivalent to '3g'. One of my friends from Hyderabad had a rejected takeoff after bird injestion in Delhi a few years ago and he still swears by the deceleration he felt that day and that it has to be felt to believe in.
pEaCe

Hi Airforce1, Aribus340,
Thanks for taking the time and patience for these eleborate answers.

Once, I was in my little Cessna Cardinal I was told by the tower to line up and hold. A Boeing 737 had taken off just in front of me. Whilst I taxied onto the runway they executed a RTO. Couldn't tell how fast they were going when they did it, but it must have been close to V1. They came to full stop on the runway and, smoking tires/wheels. And somehow the brakes got stuck as they couldn't move. Shouldn't have happened. You should be able to execute an RTO and just taxi off and cool down brakes etc.

I also executed a RTO on the CargoLux Full motion Simulator in Luxembourg. The instructor told me it was one of the few manoevres that are simply not realistic from a motion feeling point of view. The simulator dips to give you the deceleration feeling but can't do that long enough and or aggressively enough. Real life deceleration should be much more aggressive. Still, it was impressive.

Over the last 36 hours I've managed to get hold of various FCOM and other technical documentation on the Airbus 320. And as I suspected, the total interlocking logic is pretty complex. In order for the system to ARM, at least four different conditions must be met.

On SYSTEM ACTIVATION it reads:

Automatic braking is activated:
- At the command for ground spoiler extension for LO and MED mode
- at the command for ground spoilers extension and the aircraft speed is above 40kt, for MAX mode

So here it clearly states ground spoiler. When I look at the various diagram and logic sequence, I think in essence that is the same as Weight on Wheels, i.e. struts compressing. I can't tell if it is one or the same sensor, or two indepent circuit but the effect is the same

I've also found that on older 320 you could set the autobrake to MAX whilst in flight, although you were not supposed to do so. On the more recent versions it appears as if you can't anymore. Which suggest another interlock. Not sure what condition would release it, haven't seen evidence to show its the nose gear, but something must unlock it again, and it should only happen when the plane is firmly on the ground. Suppose having the nose wheel on the runway before hitting MAX might be advisable.

There's a bunch of other sensors/parameters than come into play as well, Aircraft Longitudinal acceleration and aircraft speed/wheel speed at impact. Trying to figure out the inner working and logic of the BSCU.

One thing I have noticed, very similar to my knowledge and experience with Boeing documentation; The FCOM, AOM of the manufacturer and the various carrier variants show different information. At first this came as a surprise to me, but it does show how different parties might have different thoughts on how they want to present the information to pilots and what they find relevant.

On the 747-400 I have just about every official Boeing manual, and then I have sets of similar manuals from 6 or 7 different carriers. Very different in sequence, text, graphics and sometimes even in actual technical detail. If you want to understand where the technical differences come from you usually have to dig much beyond the documentation that is available in the cockpit and or pilot training. I love flying, but I'm also an engineer, so it's an interesting journey figuring this all out.

Thanks again for your help.

Kaushall, nice pictures; For those who wondered what the tiller for steering the airplane looks like we discussed earlier, look at photographs of the First Officer seat, just right of his/her joystick you will see the tiller.

Jeroen

[bsdbsd]

Originally Posted by ifly

• Speed.
• Normally about 1500 to 2500 feet per min but not limited to that

It's brilliant that you used the word human factors. Also, if I may this was not a "pilot error" but rather, a human error.

I am not very sure why they would have done such a thing!! Quite honestly, I am very keenly waiting on the findings myself.

If this subject matter interests you, i suggest the following read:

http://www.flipkart.com/naked-pilot-...mdymfgtsqbzuh9

Whenever it is in stock

Thanks much. I am thrilled to have received a compliment from you! To me, it looked like a cultural issue than anything else. Lets wait for the report.

Apologies for misspelling your t-bhp handle. This is what Apple has done to us. Its funny to see many of us have made the same mistake.

I immensely respect the pilots because of the sheer responsibilities they deal with on a daily basis. They are super-humans. ATCs, Pilots and Doctors - in that order.

I will be ordering the book soon (on Amazon.in).

Can you please make a video of one of your entire flight and post it in YouTube? Not sure if your company or airline regulations allow to do it. Its rather amusing to see our "no camera" allowed policy in our airports.

Couple more questions:

You mentioned speed. Which speed? Aircraft or Vertical?
What should be the cruise altitude for a 100NM, 200NM and 300NM+ flight?
Have you ever landed in Bangalore? Whats your take on our new airport?

Once again, thanks for your willingness to share your time with us.

[desertfox]

In Indian conditions what is the fuel consumption of an Airbus 320 with Pratt & Whitney VR2500 engines, that Indigo 320s have must be close to about 3050 Kg - 3300 KGg/ hr i guess.

What were the engines on the Kingfisher 320s ? CFM 56 seroes or PW 2500 ? There were two sets of Kingfisher Aircrafts, their own and those taken over from Deccan Airlines.

Originally Posted by saket77

That is really surprising ifly! I followed the mid air collision of charkhi dadri which irked me thinking us of using obsolete radars & signalling technology as compared to other parts of world. Surely, a lot must have changed since then and you being the 'insider' to the industry, would be able to elaborate much better. Hence, would like to ask you that is there anything worth notable that makes the Indian airspace more safer than even the US?

During this incident, the incoming Tu 154 pilot made an error, he was more than 1000 ft lower than the height where he should have been, but additional equipment has been installed at IGIA in Delhi now which identifies the code from the aircraft on the screen.

[saket77]

Originally Posted by desertfox

During this incident, the incoming Tu 154 pilot made an error, he was more than 1000 ft lower than the height where he should have been, but additional equipment has been installed at IGIA in Delhi now which identifies the code from the aircraft on the screen.

Yes, that is what actually happened. That was a Kazak plane; the Russian IL-76.

[desertfox]

Yes the whole incedent is 18 years old now, in many of the Russian aircraft cockpits I have seen, also flown some, the altimeter was caliberated in Meters while the general aviation industry norm is ft.

At 31,100 ft I would say on the radio I am at 31.1, or level 31.1 in the USA or 31.1 K, English language is another problem with Russian aviators and standards.

In Kazakistan itself old russian origin aircraft that have done 30,000 to 40,000 cycles ( take offs and landings ) are used, configration between passenger seats and cargo hold is frequently changed on the upper deck and the aircraft is never weighed for balance. This goes on at Sharjah airport as well but the civil aviation authorities are better there.

As for C check and D check and structural inspections of these old Russian aircraft, now largely under private ownership, only god can help.