Ask The Pilot

[harvyk]

The hurdle that would stop most is actually the very first one. I've been asked this question quite a few times, by cabin crew, over the years. All have the idea that if they can get in touch with someone, then they might have a chance. So, I've simply asked them to select the switch that they will press to call for help. The favourite choice has been the autopilot disconnect.

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As you may know I've been building the sim at home, and before anyone fly's in it I ask which button is the one to press to talk to ATC, every single person has selected the autopilot disconnect button. (Yes, I got the idea from this thread).

I'm not actually aware of any flight sim software which simulates a transmit button in the right place, so even if they are somewhat good with a realistic desktop sim, without having actually sat in an actual sim I really have my doubts that even a desktop simmer would be able to get a plane down.

 

[lastrow]

I want to ask about ice conditions resulting from a very low temperature on the ground. jb, now that your routes are all in warm latitudes I guess the question of ice control is past history. When you operated out of LHR did you ever have to have the airplane de iced? What is the procedure ? At what point would you consider the airplane safe to operate? When cleared for takeoff do any surfaces still have ice on them? Is an airplane weight increase due to residual ice expected and tolerated?
Once de icing is complete I guess you only have a small time window to get going, is everyone already on board? Can waiting in a take off que result in ice re forming?

 

[jb747]

I want to ask about ice conditions resulting from a very low temperature on the ground. jb, now that your routes are all in warm latitudes I guess the question of ice control is past history.

You're right that I'm extremely unlikely to ever operate from an ice and snow affected airport again. I avoided that time of year anyway. I'm not a skier, so I'd rather see snow from miles above it.

When you operated out of LHR did you ever have to have the airplane de iced?

I never had any issues in London. De-iced many times in Frankfurt though. The Germans were typically efficient.

What is the procedure?

Lengthy. There are literally chapters on it in the manuals.

At what point would you consider the airplane safe to operate?

No ice whatsoever is acceptable on the the upper surfaces. A very thin layer, associated with cold fuel, may be accepted on lower surfaces.

When cleared for takeoff do any surfaces still have ice on them?

There should be none. If the deicing effect is wearing off, then you need to go and do it again. Which obviously means that if you don't get away quickly enough, you won't be getting away at all.

Is an airplane weight increase due to residual ice expected and tolerated?

It's not an issue of weight. The ice changes the air flows over the wings, and so reduces lift and increases drag.

Once de icing is complete I guess you only have a small time window to get going, is everyone already on board? Can waiting in a take off que result in ice re forming?

De-icing is done with everyone on board, and all loading complete. In places where it is an ongoing issue (Canada) they might have de-icing bays right near the end of the runway, so you're in a position to take off as soon as the de-ice is complete. Depending upon the conditions, and the type of de-icing fluid used, there will be an allocated 'hold over' time. You must take off within that time....which starts when the de-icing process is started. It's quite possible that the hold over could be exceeded before the de-icing is finished...and again you aren't going anywhere.

 

[RooFlyer]

On de-icing, I asked this previously but I think the answer got overlooked with a bunch of other issues I asked about.

For possible external issues, the SO does an external walk-around beforehand, but for de-icing obviously that can't happen once its done so I imagine a ground person reports status to the flight deck. That seems inconsistent to me, but no practical way around it.

Does that / would that make you a bit nervous? Relying on some guy in high-viz to tell you that she's apples and off you go? Is there any formal 'sign-off' by some-one identifiable as 'senior'?

 

[jb747]

For possible external issues, the SO does an external walk-around beforehand, but for de-icing obviously that can't happen once its done so I imagine a ground person reports status to the flight deck. That seems inconsistent to me, but no practical way around it.

Does that / would that make you a bit nervous? Relying on some guy in high-viz to tell you that she's apples and off you go? Is there any formal 'sign-off' by some-one identifiable as 'senior'?

Not at all. These people are far more experienced in the requirements than we are, and see icing much more often. It's really just the same as the engineers signing off major work. I have to trust that they know their jobs.

 

[Ansett]

Flying from Novosibirsk Siberia (OVB) several times at max minus 40 below we were deiced 1 time and at the runway and only 2 minutes before take off, what would be the maximum time before needing deicing again?

 

[jb747]

Flying from Novosibirsk Siberia (OVB) several times at max minus 40 below we were deiced 1 time and at the runway and only 2 minutes before take off, what would be the maximum time before needing deicing again?

So, you were de-iced at the runway...

Hold over time varies with a whole bunch of factors. The type, and mix of the fluid, the type and rate of precipitation, ambient temperature, humidity, wind.

With light falls, the holdover could be an hour or more. But, with heavy falls, it might be only a couple of minutes.

In the circumstance you mention, with temperatures, of around -40ºC, the charts go red, and state "no holdover guidelines exist".

 

[tgh]

Leads me to ask a really dumb question..
If icing on the deck is such a major problem , how is it manageable in the air ?

 

[jb01]

De-icing is done with everyone on board, and all loading complete. In places where it is an ongoing issue (Canada) they might have de-icing bays right near the end of the runway, so you're in a position to take off as soon as the de-ice is complete.

Not a question (sorry) but just had to add here a de-icing experience I had at JFK. We lined up in the queue for de-icing (approx 1.5 hours). Finally our turn to be de-iced, and once complete heading to join the take off queue. That of course was when some knob decided to get up and use the toilet. FAs knocking on the door to get him to return to his seat or we'd miss our window to takeoff and have to join the back of the deicing queue again.

Luckily we made it though, all flights were cancelled from a blizzard not long after we took off.

 

[AviatorInsight]

Leads me to ask a really dumb question..
If icing on the deck is such a major problem , how is it manageable in the air ?

Not a dumb question at all. As an aircraft flies through the air, the aircraft surfaces (Nose, windscreen, pitot tubes, wing, engine and tail surfaces) all come in contact with these supercooled water droplets which are suspended in the air. These droplets are still liquid below 0ºc but as they strike the wing or tail they flow over it and freeze forming a 'streak' of glazed ice (clear ice). As the temperature gets cooler (around the -20ºc mark) these droplets freeze immediately on impact creating a 'chunk' of ice (rime ice).

In a jet aircraft the critical surfaces (as noted above) use bleed air to heat and the probes are electrically heated to melt away the ice. Engine Anti Ice is used before entering flight in icing conditions. The wing anti ice (is basically a de-ice) is only used once ice is actually accrued on the wings. In a turboprop you may have seen a black rubber on the wings and tail, these are pneumatic boots which inflate to crack the ice away.

 

[RooFlyer]

Are the surfaces warmed all the time, or only when ice conditions are expected? I recall one of those TV shows where i think the cause of a crash was that the warmers weren't put on.

I guess if a plane did fly into a band of wet, cold air and ice began to form, the speed of the craft and aerodynamics (smoothing the ice surface) would mitigate against a stall, at least until descent?

 

[AviatorInsight]

Are the surfaces warmed all the time, or only when ice conditions are expected? I recall one of those TV shows where i think the cause of a crash was that the warmers weren't put on.

I guess if a plane did fly into a band of wet, cold air and ice began to form, the speed of the craft and aerodynamics (smoothing the ice surface) would mitigate against a stall, at least until descent?

The components heated all the time are the probes and windscreen (electrically). The engine anti ice is only used when visible moisture is present below a certain temperature. Regardless if ice is present or not. For the B737 it's 10ºc.

Ice is just bad all round. It can clog probes, change the shape of the wing (destroying lift), add weight to the aircraft so more thrust is required and thus all increasing the likelihood of a stall.

 

[tgh]

leads to.. how do you evaluate an icing threat in the air ; that innocent looking cunim that you decided to run through is suddenly exploding.
How long does it take for the anti icing to reach maximum value and how long does it take for manageable icing to become a serious issue and /or an emergency.
Have there been any losses or near misses in passenger aircraft due to icing ?

 

[jb747]

leads to.. how do you evaluate an icing threat in the air ; that innocent looking cunim that you decided to run through is suddenly exploding.

There is no such thing as an innocent looking cunimb.

Ice accretion in flight isn't a real problem, in the large aircraft anyway. Engine anti icing is used when the temperature is between +10ºC and -40ºC. Warmer or colder, and you don't get ice formation on the aircraft. On the 767/747, leading edges could be heated via bleed air, but in about 18,000 hours on those aircraft, I can only recall it being turned on a couple of times. On the A380, only one very small section of the leading edge is heated at all. This system is only used for ice removal, not icing prevention.

How long does it take for the anti icing to reach maximum value and how long does it take for manageable icing to become a serious issue and /or an emergency.

As the bigger aircraft use bleed air, it's very hot, instantly.

Have there been any losses or near misses in passenger aircraft due to icing ?

Yes, quite a few, but I think you'll find that it's icing of probes that is the major problem. This is probably the best known...
Air Florida Flight 90 - Wikipedia

 

[AviatorInsight]

The big focus in airline cyclic sims at the moment is ice crystal icing (ICI) in where under certain conditions allow solid ice particles to cool internal engine components and results in ice build up which then breaks off and can lead to engine failure. So in the cunim example with the convective cloud presence can bring ICI.

 

[jb747]

A small display of St Elmo's.....

 

[Himeno]

Yes, quite a few, but I think you'll find that it's icing of probes that is the major problem. This is probably the best known...
Air Florida Flight 90 - Wikipedia

I knew about that one, but I had forgotten it until you mentioned it. I instantly thought of AA4184 when the topic came up American Eagle Flight 4184 - Wikipedia

 

[jb747]

I knew about that one, but I had forgotten it until you mentioned it. I instantly thought of AA4184 when the topic came up American Eagle Flight 4184 - Wikipedia

An interesting read, particularly as some of the nastier characteristics were known by the maker, and had been tested at Boscombe Down (Empire Test Pilots).

 

[Quickstatus]

Confusion on flight deck and ATC facilitates that confusion?

Should runways be named differently?
02/20 = 02/19?
31/13 = 30/13?

Are there other ones?

 

[AviatorInsight]

Confusion on flight deck and ATC facilitates that confusion?

Should runways be named differently?
02/20 = 02/19?
31/13 = 30/13?

Are there other ones?

Seems to me like the pilots lost situational awareness. At the very start of the video they were already on a straight in approach to 02. They got cleared to land on 02, then decided to break off and join downwind to 20. Then it gets messy.

I don't believe ATC facilitated that confusion at all. They were definitely trying to help 211 by giving them clearance for whatever they wanted to land "cleared to land either runway 02/20", basically, just put the plane on the black stuff. They then ask if they had the runway in sight and reported "negative". This worries me because they're now flying low level doing what is only supposed to be a visual manoeuvre but then all of a sudden they have the runway in sight.

I'm not sure of the weather conditions, in particular the cloud height. The tailwind component shouldn't have been an issue seeing as it's a 1.2% up slope on 02.

Should the runways be named differently? I don't believe so. The idea behind the naming of the runways is coincided with the magnetic heading, in this case 02 is 022º and 20 is 202º. You could also dial up navaids (ILS/VOR, etc) and the associated course bars to aid with situational awareness.