The great big "ask an airline pilot" thread!

wil · 19-03-2014 11:01PM

ProfessorPlum wrote: »

Cabin crew are required to check the cockpit at regular intervals to check that both crew are still alive, (and more importantly, don't need more coffee:), but take a look at Helios http://en.wikipedia.org/wiki/Helios_Airways_Flight_522

Many airlines changed their procedures after that crash, so that in the event of a depressurisation, if the cabin does not get communication from the cockpit, they are required to go to the cockpit to physically check on the crew to see if they are conscious. While the masks drop down automatically in the cabin, there is no automatic system in the cockpit, so it could happen that there is a loss of pressurisation and the cockpit crew may not be aware.

Does this procedure not have an obvious flaw? The cockpit door is locked.

ProfessorPlum · 20-03-2014 01:17AM

wil wrote: »

Does this procedure not have an obvious flaw? The cockpit door is locked.

No, it doesn't. Can't tell you anymore, or as they say, I'd have to kill you

pclancy · 20-03-2014 02:18AM

Yep, the one thing that we don't want to discuss here is anything security related.

pclancy · 20-03-2014 02:19AM

On the Boeing MCP, can someone explain why and when you would use "Level Change" instead of just selecting a different altitude?

eatmyshorts · 20-03-2014 06:11AM

pclancy wrote: »

On the Boeing MCP, can someone explain why and when you would use "Level Change" instead of just selecting a different altitude?

Selecting a different altitude in the window is simply telling the system what altitude you want it to capture. You then have to select a way to get there.
Level Change is one of the modes that the system can then use to attain the target altitude. Engaging Level Change commands the autopilot/autothrottle to attempt to acquire the target altitude in a time frame of 2 minutes, while maintaining the selected speed in the speed window. If this is not possible, then the autothrottle will command IDLE (or HOLD) for a descent or THR REF (or THR) for a climb.
If the altitude selector knob is pushed while the active pitch mode is in VNAV, then the autopilot/autothrottle will command a VNAV SPD or VNAV PTH climb or descent using THR REF or IDLE.

Neilw · 20-03-2014 08:03AM

I thought I had....

Is there a way for cabin crew to access the flight deck from outside, say for example if the pilot/fo are unconscious?

Suasdaguna1 · 20-03-2014 09:44AM

Neilw wrote: »

I thought I had....

Is there a way for cabin crew to access the flight deck from outside, say for example if the pilot/fo are unconscious?

Classified for public forums

Neilw · 20-03-2014 10:32AM

Suasdaguna1 wrote: »

Classified for public forums

Ok thanks, understandable.

bkehoe · 20-03-2014 10:35AM

eatmyshorts wrote: »

Selecting a different altitude in the window is simply telling the system what altitude you want it to capture. You then have to select a way to get there.
Level Change is one of the modes that the system can then use to attain the target altitude. Engaging Level Change commands the autopilot/autothrottle to attempt to acquire the target altitude in a time frame of 2 minutes, while maintaining the selected speed in the speed window. If this is not possible, then the autothrottle will command IDLE (or HOLD) for a descent or THR REF (or THR) for a climb.
If the altitude selector knob is pushed while the active pitch mode is in VNAV, then the autopilot/autothrottle will command a VNAV SPD or VNAV PTH climb or descent using THR REF or IDLE.

That sounds like the 777 'FL CH' mode. On the 737 (Classic and NG), 'LVL CHG' is much more simple than this...no time logic whatsoever.
Level change simply commands a pitch angle to deliver the selected speed and if in a climb delivers the maximum Climb N1 or in a descent, retards the thrust levers and then puts the auto thrust into the ARM mode (ready for when it hits alt acq and needs thrust again). Because LVL CHG is quite 'crude', we use V/S when approaching the MCP selected altitude (to achieve 1000fpm when 1000ft above of below cleared altitude) to avoid TCAS TA/RAs and it also helps with passenger comfort.

The altitude selector cannot be pushed on the 737 and if in VNAV, selecting the lower cleared altitude on the MCP leaves one with two possibilities - if ATC says descend 'when ready', no further action is needed; once the calculated top of descent point arrives, descent will commence to the MCP selected altitude. Or we can press the Alt Intervent button which will commence a 1000fpm descent until the idle thrust descent profile is intercepted.

eatmyshorts · 20-03-2014 10:40AM

bkehoe wrote: »

That sounds like the 777 'FL CH' mode. On the 737 (Classic and NG), 'LVL CHG' is much more simple than this...no time logic whatsoever.

Yes, to clarify, my description is from the 777.

NewSigGuy · 20-03-2014 03:26PM

bkehoe wrote: »

That sounds like the 777 'FL CH' mode. On the 737 (Classic and NG), 'LVL CHG' is much more simple than this...no time logic whatsoever.
Level change simply commands a pitch angle to deliver the selected speed and if in a climb delivers the maximum Climb N1 or in a descent, retards the thrust levers and then puts the auto thrust into the ARM mode (ready for when it hits alt acq and needs thrust again). Because LVL CHG is quite 'crude', we use V/S when approaching the MCP selected altitude (to achieve 1000fpm when 1000ft above of below cleared altitude) to avoid TCAS TA/RAs and it also helps with passenger comfort.

The altitude selector cannot be pushed on the 737 and if in VNAV, selecting the lower cleared altitude on the MCP leaves one with two possibilities - if ATC says descend 'when ready', no further action is needed; once the calculated top of descent point arrives, descent will commence to the MCP selected altitude. Or we can press the Alt Intervent button which will commence a 1000fpm descent until the idle thrust descent profile is intercepted.

Wow the "Boeing Way" sure sounds complicated, you guys need to try Airbus.. Push/Pull its absolutely intuitive.

eatmyshorts · 20-03-2014 04:17PM

NewSigGuy wrote: »

Wow the "Boeing Way" sure sounds complicated, you guys need to try Airbus.. Push/Pull its absolutely intuitive.

I've flown both Airbus and Boeing. To be honest, it's pretty much the same system just different names for the modes.

robbieVan · 20-03-2014 04:22PM

eatmyshorts wrote: »

I've flown both Airbus and Boeing. To be honest, it's pretty much the same system just different names for the modes.

Did you fly the 330 for aer lingus and then head for the desert to fly the 777?

Is this being way too nosey? lol

pclancy · 21-03-2014 01:27AM

Cheers. So the norm would be to let the autothrottle just chop power when it approaches TOD and the aircraft starts to descend, rather then a slow gentle manual retardation of thrust to reduce speed before descending?

I remember watching an old 737 Classic documentary (think it was an airline called Go Fly at the time) and the Irish captain spoke of the "Good Airmanship" of manually retarding the throttles before TOD to reduce engine wear due to the massive changes in heat in the engines.

Which method would be more gentle on the passengers? I guess you want to avoid negative G sensation when you hit TOD.

wil · 21-03-2014 01:29AM

pclancy wrote: »

Yep, the one thing that we don't want to discuss here is anything security related.

I can well understand, and almost goes without saying, absolutely sensible.

However, with a touch of devils advocate, I might ask, under mod advisement, and in light of all recent news (sorry) are you more aware or concerned about your social security.
Of course I don't mean PRSI payments, I am referring to your online presence, social networking etc that could be trawled through or abused.
I would have thought there would be guidelines, either company or professional organisation issued. This may be a broad assumption considering one of the persons involved posted both his employer, aircraft class, face and location on at least one publicly accessible networking site, along with various political views and links to other family members.
I would have thought that unwise, for a multitude of reasons.

Now that may appear bordering on paranoia, but different countries have different degrees of concern and if I was a bank manager in Ireland, I wouldn't be publishing my name, address, place of work and family members etc for probably obvious sensible reasons.

basill · 21-03-2014 10:19AM

Cheers. So the norm would be to let the autothrottle just chop power when it approaches TOD and the aircraft starts to descend, rather then a slow gentle manual retardation of thrust to reduce speed before descending?

I remember watching an old 737 Classic documentary (think it was an airline called Go Fly at the time) and the Irish captain spoke of the "Good Airmanship" of manually retarding the throttles before TOD to reduce engine wear due to the massive changes in heat in the engines.

Which method would be more gentle on the passengers? I guess you want to avoid negative G sensation when you hit TOD.

Descent planning is a bit of an artform. Firstly the aircraft will compute its on TOD point but as with most computers its very much a case of garbage in, garbage out. It will only be as accurate as what is in the fmc/fmgs. Secondly, the fadec takes care of the engines and wont allow them to under/over temp. There isn't really a chopping of power anymore. In fact even when at IDLE the N1 on the modern day CFMs and GEs is actually around 20-30%. Finally, the airline might specify in their OPS manuals how they want their aircraft flown and have an SOP to cater for this.

From a practical perspective I personally like to start a gentle descent at something around the 1000fpm mark and get slightly below the profile. This avoids large pitch/power changes for the pax and also keeps the speed under control and stop it racing towards the barbers pole. Then I gradually increase the rate to 1500-2000fpm before picking up the ideal profile when lower. There will be by now a much greater margin on the barbers pole which means I can wind up the speed if needed without the worry of overspeeding.

guyjohn · 21-03-2014 11:28AM

sopretty wrote: »

Howdy.

Is it even remotely possible that an aircraft could have a fire onboard which would incapacitate certain navigational systems and also pilots and then continue on flying for 5 hours? :rolleyes:

http://www.wired.com/autopia/2014/03/mh370-electrical-fire/ check this out.

I did see a pilot on CNN say that if the aircraft was trimmed properly its possible to fly manual for 5 hours .
My own response is that the weather conditions would have a factor.

sopretty · 21-03-2014 12:53PM

guyjohn wrote: »

http://www.wired.com/autopia/2014/03/mh370-electrical-fire/ check this out.

If I see that article being quoted to me one more time, I will spontaneously combust myself!!!

guyjohn · 21-03-2014 12:56PM

sopretty wrote: »

If I see that article being quoted to me one more time, I will spontaneously combust myself!!!

You are not the only poster here ?

sopretty · 21-03-2014 12:59PM

guyjohn wrote: »

You are not the only poster here ?

You quoted my post - I replied to you. The reason I actually asked my question here (directed at pilots) was as a result of reading that article!

PapaQuebec · 21-03-2014 01:31PM

pclancy wrote: »

Cheers. So the norm would be to let the autothrottle just chop power when it approaches TOD and the aircraft starts to descend, rather then a slow gentle manual retardation of thrust to reduce speed before descending?

I remember watching an old 737 Classic documentary (think it was an airline called Go Fly at the time) and the Irish captain spoke of the "Good Airmanship" of manually retarding the throttles before TOD to reduce engine wear due to the massive changes in heat in the engines.

Which method would be more gentle on the passengers? I guess you want to avoid negative G sensation when you hit TOD.

Capt John Mahon

crazygeryy · 22-03-2014 02:08PM

In today's paper in reference to MH370 it says and i quote " shutting down the ACARS deliberately is a complicated process and beyond the training of most pilots" .

Is that true? Any of the pilots in here able to do it?

View Profile · 22-03-2014 03:47PM

Thought it might be as easy as pulling the breaker but maybe not?!

Aphex · 23-03-2014 09:40PM

pclancy wrote: »

Cheers. So the norm would be to let the autothrottle just chop power when it approaches TOD and the aircraft starts to descend, rather then a slow gentle manual retardation of thrust to reduce speed before descending?

I remember watching an old 737 Classic documentary (think it was an airline called Go Fly at the time) and the Irish captain spoke of the "Good Airmanship" of manually retarding the throttles before TOD to reduce engine wear due to the massive changes in heat in the engines.

Which method would be more gentle on the passengers? I guess you want to avoid negative G sensation when you hit TOD.

John Mahon for ITVV? I have learned a lot from them great programmes. He was speaking on the Air France A330 episode of Air Crash Investigation. I believe he is in that line of work now.

Sorry for the off topic post. This was just a brief heads up, which I think you will find interesting. There won't be any further chat from me, I promise

pclancy · 24-03-2014 01:12AM

Yeah I've seen him pop up on a few different programs, nice to put a name to the face, cheers. I wonder does he frequent Boards.ie.

Aphex · 24-03-2014 01:56AM

Hopefully. It would be nice to have him on here.

Question: How sturdy is a plane? How can something that is attached together in many sections be so "solid"?

lambayire · 24-03-2014 02:35PM

This is probably a really stupid question.

I live in Baldoyle. I guess the planes pass by about a mile or so from the house.

Yesterday the planes were leaving from runway 10. It seemed to me that the planes were quieter at night than during the day as the flew over us.

Does this make any sense?

faceman · 25-03-2014 11:22AM

Do airlines have differing policies on turbulence and turning on the seat belt sign?

I find that BA dont often turn on the light unless its gets really bumpy but I find EI will flick the light on sooner. Is it in my head?

bkehoe · 25-03-2014 08:08PM

faceman wrote: »

Do airlines have differing policies on turbulence and turning on the seat belt sign?

I find that BA dont often turn on the light unless its gets really bumpy but I find EI will flick the light on sooner. Is it in my head?

Usually the individual crews discretion.

Dr.Rieux · 30-03-2014 10:22PM

With all the sandy rain in Dublin last night what extra prep work would be needed before first flights this morning? I am assuming some cleaning of the wing surfaces would need to take place, and if so, how would it be done?

The great big "ask an airline pilot" thread!

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