Dear a.netters,

I am reading with great pleasure and interest the technical topics that are discussed in particular in this sub-forum and it appears that we've got a number of contributors who seem to know even the tiniest details about specific aircraft systems, parts, procedures etc. Many of them are or have been pilots of these aircraft. I am regularly impressed and amazed...

But - is this type of in-depth knowledge typical for a professional airline pilot?
Of course, a certain knowledge is required to obtain the license & type rating, but would this required knowledge include these highly specialized topics? Or are the contributors in here just tech nuts like me who have a passion to go far beyond the required minimum knowledge?

Many thanks & regards,
Hendric

As with anything technical, it’s not what you know but how to find out what you need to know

As planes have become more software-oriented, systems knowledge has become less useful. Yes, there is a hydraulic pump, but how much control over it may be dependent on a computer. The C-5 was very mechanical, pilots or engineers could physically apply a wrench to a valve and adjust air flows or push button and direct hydraulic pressure to retract/extend a landing gear bypassing all the controls. The engineers got tested on “schematics”; they knew every relay, solenoid and valve, what it did and how misuse would create problems. The B727 FE oral included drawing out the systems, where does the air come from, what does the standby hydraulic pump power, what happened it the pump failed. This detail is mostly gone because the crew just can not exercise that level of control.

That a reliability has improved, such that detailed mechanical knowledge isn’t needed or frequently applied. When you, as a crew member, are running an abnormal or emergency checklist every few months, you acquire lots of skill and knowledge by necessity. The C-5 , when I first flew it, didn’t have an MEL, what you flew with inop was up to the captain and crew, systems knowledge kept one safe and on schedule, if it was possible.

I have about 2,500 hours on Globals and had about one “break”; no in-flight problems and while I knew how the systems interacted during normal or emergency ops, nearly zero knowledge on the details of the software interfaces. I wrote a problem with pneumatics, IIRC, once, asked what the fix was, “we replaced the fuel measuring computer—software told us that a input there was in error.”

Taking hydraulics as an example, I know which pumps exist and how to turn them on and off from the cockpit. I couldn't tell you exactly where they are located in the airframe.

I know in general terms what each hydraulic system drives, at least when it comes to systems where it might be operationally important for me to know. For example, I know the green system drives normal braking and nose wheel steering. So if the green system conks out I won't have those.

Ask me which hydraulic system drives spoiler 4, and I'd have to look it up in the QRH. (Turns out it is the yellow system.) It isn't like that sort of information will be time-critical in an emergency. And if the yellow system conks out, ECAM will tell me that spoiler 4 is inop anyway.

As Lpbri says, knowing where to look stuff up is important.

hitower3 wrote:

But - is this type of in-depth knowledge typical for a professional airline pilot?
Of course, a certain knowledge is required to obtain the license & type rating, but would this required knowledge include these highly specialized topics? Or are the contributors in here just tech nuts like me who have a passion to go far beyond the required minimum knowledge?

Answering this more specifically, for the initial type rating course you are required to study, and be tested on, quite a range of technical stuff. But I wouldn't say the topics are really that specialised. Compared to the engineers, I don't really know the systems that deeply. I know what I need to operate proficiently and safely.

The focus is always on "what does it mean to the operation?" as opposed to rote learning things like the layout of the entire electrical system. Being able to draw the electrical system from memory is a fun party trick, but the important thing is knowing how the various possible failure modes affect the operation. "If I lose both engines, what electrics do I have left, and what does it mean to the operation?" is more important than knowing the names of the bus ties that might have been disconnected at that moment. E.g. I should know that with a dual engine flameout the electrics go into EMER ELEC CONFIG and only the captain side instruments will work, but I don't need to know precisely how the electrical bus layout that has led to this configuration. Knowing that instruments are captain's side only is important. What exactly the systems did behind the scenes to get there has no material impact on my actions in the scenario.

In a wider perspective, once you've been on the plane for a while, and you've done a number of proficiency checks, line checks, and recurrent trainings, a lot of the knowledge just seems to stick. You've now seen how a number of non-normal sim scenarios are affected by systems design and failure modes.

Starlionblue wrote:

I couldn't tell you exactly where they are located in the airframe.

They are not in the airframe, they are attached to the engine.

zeke wrote:

Starlionblue wrote:

I couldn't tell you exactly where they are located in the airframe.

They are not in the airframe, they are attached to the engine.

I walked right into that one.

I suppose I did know that about the engine-driven pumps, but what about the electric pumps?

I find that the maintenance manuals have a little bit more in-depth info about the aircraft systems than the system descriptions in the flight crew operations manual.

It’s like having to learn a whole new language,

Using the hydraulic pump example, a maintenance manual might say, to access the hydraulic pump you need to access this specific panel. Access panels have a specific numbering system, So there is a separate section about the numbering system that you have to read in order to understand the maintenance procedure to access the hydraulic panel.

Anytime the mechanics are poking around the avionics bay, or the landing gear bay, I like heading down onto the ramp to see if i could poke my head into the avionicss bay just to see a part of the aircraft i normally dont get to see. Or have the engine cowls open, I’m down there playing where’s Waldo on the engine.


Or try describing a location of a dent on the wing, or fuselage. The entire aircraft has a reference system.. The wings, horizontal stabilizer and vertical stabilizer have a separate reference system. It’s all “interesting” stuff in the maintenance manual.

I find that a lot of things just make sense because that’s that way it “works.”

For example the fuel pumps. I do have fuel pump switches in the cockpit, i can turn them “auto” or “off”. I cant turn the pump on specifically, but I can allow the computer to control whether the pump turns on or off. The pilot training says these are the “fuel pumps”. I think of these pumps in my mind using the terms i understand as the “low pressure fuel pumps”

But there is another set of fuel pumps that i have no direct control over. (I guess you can argue that I dont have direct control over the ones in the wing either) These fuel pumps are controlled by the FADEC and are located within the engine cowling. If these fuel pumps (which I think of as the “high pressure fuel pump”) break, the engine isnt going to run, even though the fuel pumps in the wing - the low pressure fuel pumps in my mind - are working and providing fuel to the engine.

But i think of the fuel pumps that way because I came from a steam plant operator background. When i need to send water back to the boiler, i had two sets of feed pumps, The main feed pumps (the “high pressure fuel pump”) and the main feed booster pumps (the “low pressure fuel pump”). I could still keep the boiler running if i didn’t have the main feed booster pumps, but if the main feed pump failed, there was no more water going into the boiler and the boiler was going to be shut down one way or the other without the feed pump.

One of the things they made you do when you were in training for the steam plant was “you are a drop of water, describe the path of the water drop thru the steam cycle”. So you had to describe all of the parts the water drop went thru, temperatures, pressure, etc.

For the airplane, when they start asking you temperatures and pressure, you used to have to know the numbers and what the limits are, but today, all i have to know specifically when asked what is the maximum/minimum pressure/temperature, etc is “red line”. And have no idea what the number that is attached to the answer “red line.” Well i have a general idea of the ballpark pressure / temp / etc but not the exact number

Starlionblue wrote:

I suppose I did know that about the engine-driven pumps, but what about the electric pumps?

Sounds like I need to add some more questions to the OTE database for you. The two EMPs are on the keel beam in the MLG, the yellow in the front and green in the rear. Technically there is an additional one on the yellow servicing panel where mechanics to connect a battery powered drill to power another pump to open the cargo doors or use the manual handle.

If you then really want to go into more detail look at the control surfaces with their own self contained power packs, they have electric hydraulic pumps.

zeke wrote:

Starlionblue wrote:

I suppose I did know that about the engine-driven pumps, but what about the electric pumps?

Sounds like I need to add some more questions to the OTE database for you. The two EMPs are on the keel beam in the MLG, the yellow in the front and green in the rear. Technically there is an additional one on the yellow servicing panel where mechanics to connect a battery powered drill to power another pump to open the cargo doors or use the manual handle.

If you then really want to go into more detail look at the control surfaces with their own self contained power packs, they have electric hydraulic pumps.

Well, I've now learned exactly where the electric pumps are located. For the record, though, I did look in the FCOM, and I could not find the information there.

For the self-contained power packs, the FCOM uses the verbiage "locally generate their own hydraulic pressure" so the location is clear.

My first commercial aircraft that I checked out in the left seat was a 727. The oral part of my type rating lasted 5 hours. I had the typical questions of tracing a molecule of air through the pneumatic system with all the protection in the bleed system include anything bleed air was used for. As the 5 hours went by, the questions became and more trivial.

My next aircraft was the 757 and that was a completely different experience. Very little, in terms of memory items, lots of general discussion of how certain things work. Discussion about abnormal procedure which have traps in them. A complete 180 from my 727 checkout.

I would say the entire philosophy changed with the introduction of first generation aircraft. In the steam gauge era, pilots were encouraged to troubleshoot problems. With the glass introduction, that philosophy disappeared. Simply put, if you can’t fix it in the cockpit, you don’t have to know how to take it apart. As has been pointed out already, it was more important to know how and where to get the information. I have to say, I prefer the change.

For most 121 operations in the US with AQP training, the answer is "enough to satisfy the local Certificate Management Office."

Honestly, having trained under the "I'm a molecule of air...tell me what I see as I travel through the engine/bleed system" and the newer "system logic" training systems, I see advantages to both. Ultimately, legally speaking in the US, we are system operators/integrators, and not junior mechanics or maintenance controllers, assistant dispatchers or attorneys.

So, our manuals are written for technical and legal compliance, we assume professional competence from fellow professionals.

Luckily, the just culture model is driving the industry to compliance and data-gathering for incremental improvement, versus the old compliance at the point uncaring and unfeeling regulatory pain.

VMCA787 wrote:

I would say the entire philosophy changed with the introduction of first generation aircraft. In the steam gauge era, pilots were encouraged to troubleshoot problems. With the glass introduction, that philosophy disappeared. Simply put, if you can’t fix it in the cockpit, you don’t have to know how to take it apart. As has been pointed out already, it was more important to know how and where to get the information. I have to say, I prefer the change.

Not only an aircraft mindset, but also very old-school. Can't speak for the US military, but from some posters it seems to have been similar to our (South African and British background military) mindset - we had to memorize a lot of useless info. Absolutely useless for flying the aircraft safely, and you would be quizzed to death about it, exactly like the molecule of water in the boiler system.
Our -1's had the limitations of the overheat detection vs fire detection systems: on what temperature does it trigger etc. It really makes no difference knowing the temp; light on, switch off etc.
But it keeps you busy on long flights. We had some engineers who'd get creative with their questions with new F/E's, and you'd better know which parts on the C-130 was made of wood. Same engineers did not like it as much if you'd ask them technical stuff about the FMS or navigation

SAAFNAV wrote:

But it keeps you busy on long flights. We had some engineers who'd get creative with their questions with new F/E's, and you'd better know which parts on the C-130 was made of wood.

LOL, let me guess: the friction pads that slow down the nose wheel after gear retraction are made of wood?

This topic makes me think of a discussion here on a.net from maybe 10/15 years ago when, I think it was AA, updated the flap mechanism of their MD-80s to decrease drag. I was surprised that the pilots of the fleet were not aware of the change nor seemed to even noticed it happened.

kearnet wrote:

This topic makes me think of a discussion here on a.net from maybe 10/15 years ago when, I think it was AA, updated the flap mechanism of their MD-80s to decrease drag. I was surprised that the pilots of the fleet were not aware of the change nor seemed to even noticed it happened.

It's like the updated sharklets on the A350. It has no material effect on how we operate the aircraft, so it isn't really an important piece of knowledge.

Starlionblue wrote:

It's like the updated sharklets on the A350. It has no material effect on how we operate the aircraft, so it isn't really an important piece of knowledge.

I never knew that Airbus updated the Sharklets on the A350. How do the new Sharklets differ from the first A350 to enter service? Do they appreciably look different?

(Or were you referring to the A330 NEO)?

rjsampson wrote:

Starlionblue wrote:

It's like the updated sharklets on the A350. It has no material effect on how we operate the aircraft, so it isn't really an important piece of knowledge.

I never knew that Airbus updated the Sharklets on the A350. How do the new Sharklets differ from the first A350 to enter service? Do they appreciably look different?

(Or were you referring to the A330 NEO)?

The new sharklets were introduced at some point in 2017 if memory serves. They confer a range boost.

They do look somewhat different, especially from the side.

kearnet wrote:

This topic makes me think of a discussion here on a.net from maybe 10/15 years ago when, I think it was AA, updated the flap mechanism of their MD-80s to decrease drag. I was surprised that the pilots of the fleet were not aware of the change nor seemed to even noticed it happened.

It’s just something we don’t need to know. It doesn’t effect how the aircraft flies, and, unless it’s missing, most of us won’t even notice that it’s different.
When it comes to systems, we are there to tell the time, not learn how to make the watch.

Procedure proficiency is much more important these days than trivial systems knowledge. With that being said we know a lot about our planes. We know the general system schematic but our focus is on limitations and warning lights. I can tell you the logic on my planes emergency electrical system or the brakes and their subsequent backups. I probably can’t tell you the tire pressure of my landing gear or where there’s some special alloy only found in the brakes of the outer mains. The longer you’re on the plane the more you pick up on things like that but it boils down to what’s nice to know and what’s necessary to know. I remember when I flew caravans taking a recurrent ground school exam that was 18 pages long. One of the questions asked how many AC fans are in the airplane. I really wanted to write down “who cares.”

One of the more important things I’ve learned flying my airplane is if you have a caution or status message that is not supposed to be there. The first thing you do before calling the maintenance is to reference the QRH for the computer reset procedure. Basically Ctrl-Alt-Del the appropriate computer. And if that doesn’t work then call maintenance

Or for any of the NAV faults. Put 109.90 in the RAD NAV ILS frequency with the front course of 060.

That solves 99% of my problems

The only odd ball one for me was when I got a FUEL FILTER IMPENDING BYPASS caution

The only way to clear that one was to change the ATSU flight ID from my actual flight number to MX001. When I did that. The ECAM caution cleared. As soon as I put the correct flight number in the ECAM caution returned and would not clear until the flight number was changed back to MX001.

SAAFNAV wrote:

But it keeps you busy on long flights. We had some engineers who'd get creative with their questions with new F/E's, and you'd better know which parts on the C-130 was made of wood. Same engineers did not like it as much if you'd ask them technical stuff about the FMS or navigation

Let's not forget the pencils for the FEs...

DarkSnowyNight wrote:

SAAFNAV wrote:

But it keeps you busy on long flights. We had some engineers who'd get creative with their questions with new F/E's, and you'd better know which parts on the C-130 was made of wood. Same engineers did not like it as much if you'd ask them technical stuff about the FMS or navigation

Let's not forget the pencils for the FEs...

Some checkers used to ask how many knots are on the escape rope on the A330... Sometimes in the form, "how fast does the escape rope go?"

Nine knots, if you were wondering...