The great big "ask an airline pilot" thread!

Jimmy444

How do airliners navigate accurately these days when they are a long way from land? I know that in the 70's/80's for transatlantic flights many used Inertial Navigation Systems, but have these been superseded by GPS now?

smurfjed

The still use inertial navigation systems, but they have improved from the old 3 ring systems to laser systems so they are now called inertial reference systems, a lot use GPS for updating the position. For us the IRS is good enough to navigate for 6 hours without any form of update, so even if the GPS is inoperative we can still cross the atlantic, however with the GPS the updating time limitation goes away.
To cross the atlantic you need two long range independent navigation systems.

smurfjed

Somedays, work is just pure fun:) Rate of climb 9900 fpm :) (I wish:):):))

Jimmy444

smurfjed wrote: »

To cross the atlantic you need two long range independent navigation systems.

By independent do you mean two different technologies such as IRS and GPS, or just two independent IRS units?

smurfjed

Two independent systems even if they are the same technology, for example an aircraft with 2 FMS's but one GPS wouldn't be approved, however same aircraft with 2 GPS's is OK.

Quarks

Could I get a PPL, followed by commercial, even though I am colourblind?

I'm restricted from many jobs as it is, piloting is supposed to be one of them, yet I've heard there are ways and means of getting your license, so long as you literally cannot see in black and white only.

LeftBase

Quarks wrote: »

Could I get a PPL, followed by commercial, even though I am colourblind?

I'm restricted from many jobs as it is piloting is supposed to be one of them, yet I've heard there are ways and means of getting your license, so long as you literally cannot see in black and white only.

There are certain tests that will give somewhat of a false fail and you can have them overturned with a more elaborate test that proves sufficient colour vision for piloting but you still need to not be "colour blind". You need pretty decent colour vision to be a pilot

keith16

No posts in here for a while, so here's one for you.

Do you think there is any merit in linking up the flight computers to SOPs?

It seems to me that there is a bit of a disconnect. Take AF447 for example. The pitot tubes freeze, autopilot disconnects and hands control to the pilots. We all know happens next.

Could or should the flight computer prompt that airspeed indicator is lost, all other systems normal, to maintain airspeed, do x y z?

I know this sounds like a stupid question, but to me, I think airlines are responsible for developing SOPs. Would it not be better served if the likes of Airbus / Boeing were tasked with writing SOPs and programming prompts into the flight computer?

LeftBase

keith16 wrote: »

No posts in here for a while, so here's one for you.

Do you think there is any merit in linking up the flight computers to SOPs?

It seems to me that there is a bit of a disconnect. Take AF447 for example. The pitot tubes freeze, autopilot disconnects and hands control to the pilots. We all know happens next.

Could or should the flight computer prompt that airspeed indicator is lost, all other systems normal, to maintain airspeed, do x y z?

I know this sounds like a stupid question, but to me, I think airlines are responsible for developing SOPs. Would it not be better served if the likes of Airbus / Boeing were tasked with writing SOPs and programming prompts into the flight computer?

The reason you have 2 pilots at the pointy end is largely because a computer cannot think creativity like a human can.

I have heard people suggest similar things before, but my few cents on the matter would be that the FMC would provide alerts or resolution advisories for every little issue then. Pilots would spend a lot of their time cancelling alerts the FMC threw up over every little thing. This IMHO would lead to a culture of "stupid FMC with it's alerts" and thus when an actual serious warning comes about the crew may not react prudently and perhaps with initial apathy given the fact they are dealing with alerts all day long.

Suasdaguna1

Keith , airbus and all manufacturers write their own checklist.....airlines amend them slightly but have to be approved by the regulatory authority.

Re writing SOPs.....airbus / Boeing write a generic ops manual and airlines as above amend to suit their operations,

Your question re computers maintaining airspeed with the loss of info from the pitots is a no....the computers known as ADCs airdata computers rely on the info from the pitot static system and translate this info digitally on the primary flight displays. Loss of this info will disconnect the autopilot. Likewise if ADCs are in disagreement.....the dangerous thing here is two ADCs might be giving duff gen and disregard the sole ADC with correct info......think of the consequences here and the need for humans and a straight head. When you mention we all know what happened next......yeap massive pitch changes and non adherence to memory items.....and the loss of life. If AF held its pitch attitude of 2.5 degrees and maintained 93% N1 power setting......within 30secs they would have got their airspeed back I'm led to believe.

I hope my meandering ramble makes some sense.

keith16

LeftBase wrote: »

The reason you have 2 pilots at the pointy end is largely because a computer cannot think creativity like a human can.

This IMHO would lead to a culture of "stupid FMC with it's alerts" and thus when an actual serious warning comes about the crew may not react prudently and perhaps with initial apathy given the fact they are dealing with alerts all day long.

That is interesting, in fact, you could argue that this culture can develop in reaction, even to serious warnings? Case in point with the Polish Tu crash in Smolensk:

TAWS fired its first audible warning "terrain ahead!" at 10:40:06. This was because the Smolensk airport, as a former military airfield not open to international flights, was not in the system's database and therefore the system did not recognize that the airplane was approaching an airport.

Six seconds later, someone (most likely the captain or navigator) pressed a button on the captain's FMS panel commanding standard barometric pressure be set on the captain's main electronic altimeter.

This had the effect of increasing the altimeter's reading by 170 meters; as the TAWS takes readings from this particular altimeter, this had the additional effect of silencing the warning

I'm no expert, but it seems that everything needs to be working perfectly (ILS not present at Smolensk, or turned off at SFO) or it doesn't and the pilots earn their money or don't.

I guess my question is more around diagnostics. An A330 will tell you you've lost an airspeed indicator, but not necessarily that the plane is still functioning, and other indicators are working fine, such as the stall warning - which went of 58 times on AF447 with no reaction?

It's almost as if the pilots were trying to second guess / doubted the validity of additional indicators just because one temporarily failed?

keith16

Suasdaguna1 wrote: »

......yeap massive pitch changes and non adherence to memory items....

I hope my meandering ramble makes some sense.

Definitely makes sense. Interesting insight. Why do you think there was non adherence to those memory items?

As I said above, could it be down to interpretation of what loss of airspeed indication actually means?

Lets say if a fuel indicator fails. Chances are, the pilots will know how much fuel they have anyway and continue on to their destination.

With airspeed, it could be interpreted differently? No different to fuel, before the indicator fails, you know what speed / fuel you have. But if unreliable readings are provided, there is room for misinterpretation. Is that my speed now? Is it working now?

IRLConor

keith16 wrote: »

Do you think there is any merit in linking up the flight computers to SOPs?

Just another point on this, in addition to the ones made above.

Software is expensive to write. Custom software to add in the tweaks for a particular airline's preferences/customs is even more expensive. To top it all, software for a safety-critical system is typically several times more expensive than conventional software.

It's a big pile of money for a very small net reduction in risk. You could probably get a better reduction in risk from a smaller amount of money by investing it elsewhere.

Rabbitt

Can any pilots here tell me the following :
What is the max (in MPH) head winds and cross winds that a plane can take off in?

Also re wind why is it safer to abort a landing in cross winds even though the plane is say 10 feet from ground( seem some footage on Sky News last week)?

Finally, if on takeoff you hit V1 then loose an engine can you still takeoff?

Growler!!!

Rabbitt wrote: »

Can any pilots here tell me the following :
What is the max (in MPH) head winds and cross winds that a plane can take off in?

Also re wind why is it safer to abort a landing in cross winds even though the plane is say 10 feet from ground( seem some footage on Sky News last week)?

Finally, if on takeoff you hit V1 then loose an engine can you still takeoff?

1. Depends on the aircraft type. On my own type the max take off x wind is 35 kts dry (approx 70km), 30kts wet. There is no listed max headwind but if the wind speed goes over 52kts then an engineer must inspect for damage to controls.

2. You're referring to the go arounds in BHX last week. The aircraft doesn't "know" it's close to the ground. The aircraft must be stabilized on the approach for the pilots to land. If it becomes destabilised then most operators procedures is to carry out a "missed approach".
This is always the safest option as the aircraft may be uncontrollable on the ground.

3. If you lose an engine at V1 then you have no option but to take the aircraft into the air. V1 is your stop/go decision speed. Lose an engine before it and you have enough runway to safely stop. Public transport type aircraft are certified to be able to climb away on one engine.

LeftBase

Rabbitt wrote: »

Can any pilots here tell me the following :
What is the max (in MPH) head winds and cross winds that a plane can take off in?

Well headwinds are measured around here in knots(nautical miles per hour). If you had a headwind down the barrel of the runway there would be no limit as such to how strong it could be (within reason...if it was 140kts that may cause a few issues) pilots would be happy to have it as it would shorten take off distance. As far as crosswind goes.....many light aircraft have a "demonstrated crosswind velocity" which is an amount of crosswind that the aircraft was operated in during take off or landed in the test phase of it's design...they are saying "we got it down in say 15kts so we know it can be done...but above that we cannot guarantee anything but you can try". Most(all?) airliners have a crosswind LIMIT which is the limit amount of crosswind they can take off and land in...for an a320 it is 29kts(max gusts 38kts) on take off. Landing crosswind is 33kts...but there are other limits too depending on the type of landing.

Also re wind why is it safer to abort a landing in cross winds even though the plane is say 10 feet from ground( seem some footage on Sky News last week)?

The aircraft has a natural tendency to cock in to wind. Landing in a heavy crosswind you will see an aircraft approach with it's nose off centre of the runway until virtually the roundout or flare when the pilot uses the rudder to straighten the nose up and drops the windward wing to prevent the wind picking that wing up on touch down. People often mistake one side of the main gear touching down before the other as a "bad landing" but it's just a crosswind landing.
The reason pilots go around from low altitude if it doesn't look good is because you can make the proverbial cock and balls of this maneuver if it is executed badly or you are not set up right.

Here is an example of such a balls: http://www.youtube.com/watch?v=k50ddM1J1MA

Finally, if on takeoff you hit V1 then loose an engine can you still takeoff?

V1 is the speed you are committed to take off if you lose an engine so not only can you take off, you must take off.

Rabbitt

Thanks folks for the replies

Tenger

Rabbitt wrote: »

...
Also re wind why is it safer to abort a landing in cross winds even though the plane is say 10 feet from ground( seem some footage on Sky News last week)?....

One of my most memorable approaches as about 6 years ago. I was a pax near the back of an A320. We touched down on a windy runway at DUB.....wheels on runway for approx 2-3 seconds, during this time I could feel the aircraft veering to the left.....engines powered up and back up we went. Got talking to the F/O (who was flying that leg) after we got back in approx 30 minutes later. She confirmed that the crosswinds were in danger of pushing the aircraft off the verge of the runway so TOGO was called.

It was a pretty cool experience at the time for me....looking out and feeling the inertia pushing me into my seat as we climbing back up.

eatmyshorts

40kts for Takeoff and 45kts for landing are the limits on my type.
Also, zero crab landings are prohibited above 30 kts due to nacelle clearance issues. Did a gusty 40 knot crosswind touchdown last week and just left all the crab in until touchdown. Wasn't pretty but it did the job!

smurfjed

Found this link in the weather forum, pretty neat

Originally Posted by youreadthat View Post
http://earth.nullschool.net/#current....04,47.96,1087

Live zoomable wind map of earth.

pclancy

Question for 737NG Drivers, do you drain the wing tanks first then switch to the centre or drain them all at once or whats the norm?

faceman

I was reading recently an article about the world's most dangerous jobs and pilots & cabin crew were in the top 5 because of the radiation exposure. I know its no secret to anyone working in the industry but I'm wondering does it effect your health or life insurance and is it something your employer briefs you on?

Bonus question. Was on the B744 again today. While it's not as a comfortable experience for an economy passenger as say the A380, I still believe the B747 is the Marilyn Monroe of the airline world. It's just sexy! Which plane does it for you and why?

Cessna_Pilot

pclancy wrote: »

Question for 737NG Drivers, do you drain the wing tanks first then switch to the centre or drain them all at once or whats the norm?

Centre first then wings

LeftBase

faceman wrote: »

I was reading recently an article about the world's most dangerous jobs and pilots & cabin crew were in the top 5 because of the radiation exposure. I know its no secret to anyone working in the industry but I'm wondering does it effect your health or life insurance and is it something your employer briefs you on?

As a general rule of thumb you wont pick up any sort of serious exposure below FL400, however employers have to keep a record of the amount of possible exposure crew have for up to a year after you leave their employ for future medical purposes

smurfjed

It's just sexy! Which plane does it for you and why?

Have to agree with the B747, my love affair started when i got to listen to ASI/ASJ/BED flying over my home on their way back from the USA Then there was the fun of camping in Shannon watching in total awe as Pan Am, TWA, Northwest Orient, Flying Tigers etc landed and took off. Later i got to ride as the only passenger in the upper deck of a -100, 14 sofa, couch style seats all to myself, plus 2 double beds, and that was it, total love affair. I love the -400 with the bedroom and toilet inside the cockpit, like your own little apartment, and I have had the pleasure of touring around 5 B747 BBJ's and flown in one of them, totally amazing.

Even if the A380 VIP aircraft ever gets delivered, i don't think that it will have the same je ne sais quoi as the B747.

amen

During night time flight when do you have the cockpit lights on/off ?

View Profile

Off for takeoff and landing so you can see outside better. Other than that it's whenever you like.

beer enigma

When taking off in an A320 it often feels as though there are two stages to full throttle. When lined up on the runway ready for takeoff you feel the thrust applied then almost immediately after you feel the full power applied.

Is it a two stage process or is that just an illusion.

basill

Power is set to 50% N1 initially to stabilise the engines and ensure that the thrust comes up equally to avoid yaw before take off thrust is set. Same procedure on the 330. There is also a variation of the theme for takeoff in strong cross winds and/or tailwinds.

pclancy

Same in any jet, they spool them up to 30-40%, watch the Ns, temps and pressures stabilise and then go for takeoff power when they're happy both engines are behaving as they should. Sometimes you'll feel them hold at that lower power for a bit longer then normal, I expect that's because often there's some variation between the response from both engines. Recently in Japan I noticed we sat there for 30 seconds at that lower power setting before they released the brakes and off we went, not sure why but I guess the above.

You'll do a similar thing but on a much smaller scale if you go for flying lessons in a prop aircraft, you taxi somewhere away from other people and point the nose into the wind then do a "run up" by taking the power to 1700rpm and making sure the engine is running well and all the guages look normal. You test both magnetos are working before dropping back to idle rpm and beginning your preparations for takeoff.