Ask The Pilot

[jb747]

has QF72 been replicated in the sim?

There are two types of sim. Systems simulators exist at the makers, and they can be used to see how a system will respond to any given input/failure. They are a way of seeing what the aircraft would do. They aren't so much a simulation of the real system, but rather a subset of the actual thing. Flight simulators on the other hand are simulations. Their responses to any failure are programmed responses. They generally can't be used to experiment on the aircraft's behaviour.

So, you can certainly emulate some level of the behaviour, but it won't necessarily replicate exactly what happened. Control malfunctions do appear in some sim exercises, and ADR issues are commonly seen. Random major control failures would be very difficult to get any worthwhile training value from.

 

[Quickstatus]

Speculating... What would have happened if the pilots did not input any flight commands during the pitch downs

 

[eastwest101]

There are two types of sim. Systems simulators exist at the makers, and they can be used to see how a system will respond to any given input/failure. They are a way of seeing what the aircraft would do. They aren't so much a simulation of the real system, but rather a subset of the actual thing. Flight simulators on the other hand are simulations. Their responses to any failure are programmed responses. They generally can't be used to experiment on the aircraft's behaviour.

So, you can certainly emulate some level of the behaviour, but it won't necessarily replicate exactly what happened. Control malfunctions do appear in some sim exercises, and ADR issues are commonly seen. Random major control failures would be very difficult to get any worthwhile training value from.

Oh OK - should have been clearer in my question, I understand that the SIM is not actually the aircraft and they can't replicate whatever software error brought about QF72, so can't use it as a software diagnosis tool, I was approaching it more from a seeing what the human responses are to that situation, i.e. simulators are good for seeing human behaviour and designing future training and learning.

Good to know that airlines are simulating complex system control failures so that pilots have a chance and get training in how to deal with that, I think Airbus will have to relent eventually and provide the big obvious off/reset switch for FBW control law software if there are future events like this with worse outcomes

 

[AviatorInsight]

Autopilot and auto thrust are not part of this discussion...like the Boeings, they can be eliminated at any time. I assume the 777/787 also have some form of protections built in. There is no point in allowing such an aircraft to be stalled, so I'd be interest to hear just what the Boeing laws do. The Asiana SFO accident would have been difficult to emulate in an AB.

Without going too much into the auto thrust system, the laws of the stall are quite basic. At the top of the amber band (min manoeuvre), trimming is unable to occur and the PLI's show. About half way through the amber band, an Airspeed Low EICAS Message shows with associated Master Caution lights. By now you're basically deliberately pulling the aircraft into the stall and if you're in the correct mode (which the Asiana B777 weren't), the thrust levers will 'wake up' and apply maximum thrust. Failing that the stick shaker and pusher are next to break the high nose attitude.

So before the stall has even occurred, there are numerous indications that a stall is impending. As I said above, for it to even get to the stall, you would need to have a considerable amount of force 'holding' the aircraft up.

We replicated the Asiana accident in the sim (a bit of negative training in my opinion), but a new directive (from Boeing?), placed the rule to not use FLCH below 1000ft.

 

[jb747]

Without going too much into the auto thrust system, the laws of the stall are quite basic. At the top of the amber band (min manoeuvre), trimming is unable to occur and the PLI's show. About half way through the amber band, an Airspeed Low EICAS Message shows with associated Master Caution lights. By now you're basically deliberately pulling the aircraft into the stall and if you're in the correct mode (which the Asiana B777 weren't), the thrust levers will 'wake up' and apply maximum thrust. Failing that the stick shaker and pusher are next to break the high nose attitude.

So before the stall has even occurred, there are numerous indications that a stall is impending. As I said above, for it to even get to the stall, you would need to have a considerable amount of force 'holding' the aircraft up.

That's interesting. The thrust lever wake up is part of the alpha protection in the AB, but the overall behaviour that you describe is more like alternate law than normal law.

 

[jb747]

Speculating... What would have happened if the pilots did not input any flight commands during the pitch downs

Probably nothing much. The aircraft would have been nose down, and accelerating. Depending upon exactly what law it was in, it would have either stayed in the one attitude, or gently pitched back up. Aircraft generally don't do anything suddenly if you put them somewhere and then let go of the controls.

 

[Quickstatus]

Are flying foxes a nuisance for airports?
I've not heard of bat strikes

J1506/17 NOTAMR J1429/17
Q) YBBB/QFAHX/IV/NBO/A/000/999/2723S15307E
A) YBBN
B) 1705122144 C) 1705200930 EST
D) DAILY 0800/0930
E) INCREASED FLYING FOX ACTIVITY (SPECIES BLACK AND GREY
CREATED: 12 May 2017 21:46:00
SOURCE: YBBBZEZX

 

[jb747]

Are flying foxes a nuisance for airports?
I've not heard of bat strikes

J1506/17 NOTAMR J1429/17
Q) YBBB/QFAHX/IV/NBO/A/000/999/2723S15307E
A) YBBN
B) 1705122144 C) 1705200930 EST
D) DAILY 0800/0930
E) INCREASED FLYING FOX ACTIVITY (SPECIES BLACK AND GREY
CREATED: 12 May 2017 21:46:00
SOURCE: YBBBZEZX

Anything that flies, that we can run into, is a problem. They weigh a kilo or so, and if you hit them at 300-400 kph can do real damage. Just the same as any birdstrike.

 

[Quickstatus]

Do bird strikes occur after dark.

Bat strikes? I think they come out after dark?

 

[AviatorInsight]

Do bird strikes occur after dark.

Bat strikes? I think they come out after dark?

I haven't had a bird strike after dark, but have had a bat strike on approach into Bathurst one night. Have had more near misses (strikes?) than actual hits. It definitely catches you by surprise seeing something appear in the beam of the landing lights then a second later disappear on you and you wait to hear/feel a thud.

 

[straitman]

whats the practical difference between a PAN and a MAYDAY call? Obviously Mayday is more serious / catastrophic, but does ATC treat the 2 any different,y in terms of the priority you get? In the US, isn't it just an emergency ?

When to Call Mayday Versus Pan-Pan

A Mayday radio call should be reserved for life threatening situations. These may include, but are not limited to:

• Loss, or imminent loss of aircraft control for any number of different reasons

1. aircraft upset by turbulence;
   
2. pilot incapacitation;
   
3. spatial disorientation;
   
4. control surface or structural failure;
   
5. engine failure that will lead to a forced landing/ditching/ejection/bailout;
   

• Or, an onboard fire.

​

Pan-Pan-Pan

A Pan-Pan call should be used for urgent situations that are not immediately life threatening, but require assistance from someone on the ground. These include, but are not limited to:

• Becoming lost;
• A serious aircraft system failure, that requires an immediate route or altitude change;
• Other emergencies that require immediate attention and assistance from the ground.

​

This is what the Aeronautical Information Manual has to say about using Mayday and Pan-Pan on the radio.

6-3-1c. The initial communication, and if considered necessary, any subsequent transmissions by an aircraft in distress should begin with the signal MAYDAY, preferably repeated three times. The signal PAN-PAN should be used in the same manner for an urgency condition.
d. Distress communications have absolute priority over all other communications, and the word MAYDAY commands radio silence on the frequency in use. Urgency communications have priority over all other communications except distress, and the word PAN-PAN warns other stations not to interfere with urgency transmissions.

​

Bottom Line

If you feel your life is in jeopardy, call Mayday. If you need immediate assistance to deal with a serious situation that is not life threatening, call Pan-Pan.

 

[coriander]

Anything that flies, that we can run into, is a problem. They weigh a kilo or so, and if you hit them at 300-400 kph can do real damage. Just the same as any birdstrike.

... but only if they're frozen.....:shock:

 

[Boris spatsky]

Do bird strikes occur after dark.

Bat strikes? I think they come out after dark?

I've hit two lots of bats. One in western NSW in a Herc - it went down the engine inlet and made the aircraft smell like KFC (or KFB ) and the others in 2015 on final into Brisbane when we flew through a flock of them. Very surprising as we only heard the thuds of them hitting the airframe, but never saw them.

 

[Skyring]

Anything that flies, that we can run into, is a problem. They weigh a kilo or so, and if you hit them at 300-400 kph can do real damage. Just the same as any birdstrike.

A drone with a good camera aboard would mass about a kilo, and be more concentrated than flesh or feathers. I don't know how tough airliner windscreens are, but there must be limits. Are there any real-life examples of dronestrike incidents?

 

[Boca68]

Noticed QF72 being mentioned recently in this thread.

Not sure if the resident pilots have seen this from the Perth Now website a couple of days ago. But worth a read.

'The plane went psycho': captain | Perth Now

 

[Quickstatus]

All been discussed starting at post #11036 12May by JB747

 

[jb747]

A drone with a good camera aboard would mass about a kilo, and be more concentrated than flesh or feathers. I don't know how tough airliner windscreens are, but there must be limits. Are there any real-life examples of dronestrike incidents?

Not that I know of. The airliner would win.

Re Mayday or Pan....If I need new undies, it's a mayday.

 

[jb747]

Speculating... What would have happened if the pilots did not input any flight commands during the pitch downs

Whilst not exactly related to your question, I suggest you have a look at "pilot induced oscillations". Some interesting video too. I expect Sully was ensuring he avoided it.

I hadn't heard of this accident, but it's PIO and autopilot related. http://skybrary.aero/bookshelf/books/681.pdf In this instance the effects of not having the seat belt on at all times was fatal for 50% of the passengers. And yet the aircraft survived to fly again.

 

[Quickstatus]

Yes I was thinking that Sully (of QF72) might have been trying to prevent the overcorrection of a potential phugoid? when he let go - which otherwise may have led to a PIO??

But then I was reminded of the other Sully who said the water landing could have been less energetic but for the anti-phugoid software embedded in the A320 preventing him obtaining a longer flare just before the water landing????.
https://m.youtube.com/watch?v=cKuw49KBywA
An example of the software having unintended consequences and inability of the pilots to override in situations where the software is inappropriate?

 

[jb747]

Yes I was thinking that Sully (of QF72) might have been trying to prevent the overcorrection of a potential phugoid? when he let go - which otherwise may have led to a PIO??

Probably not so much the PIO, but if the aircraft suddenly decided to give you (your requested) full aft stick, the wings might not like it.

But then I was reminded of the other Sully who said the water landing could have been less energetic but for the anti-phugoid software embedded in the A320 preventing him obtaining a longer flare just before the water landing????.
https://m.youtube.com/watch?v=cKuw49KBywA
An example of the software having unintended consequences and inability of the pilots to override in situations where the software is inappropriate?

Below 100', the pitch law is direct, with a little extra damping. You really couldn't fly a flare in normal law. Whether his aircraft knew that it was about to land would be an entirely different question.

The accident report (https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1003.pdf ) is very interesting reading.

It discusses the certified ditching characteristics (sink rate) on page 78. Discussion of laws and AoA limiting is on page 96. Basically from about 150 feet, the aircraft was in alpha protection mode. The aircraft was not going to allow any more pitch because it was already at max alpha. If you could actually get more AoA at that point, it would result in an increased sink rate, as the, now stalled, wing would produce less lift. The nose would also drop, which is also very bad at that point.

The only way around that situation would have been to fly the entire event at a higher speed, so that you'd have more energy available for the flare. This was discussed as having been done by one of the test pilots, who was the only person to achieve the Airbus design impact rate in the testing. His technique was not something you'd consider viable for the real world.

Selection of flap during the flare, may have momentarily reduced the sink rate (as the speed bled), but get it wrong by even an instant, and not only would you have a higher sink rate, but perhaps pitch issues as well.

Sullenberger's effort was pretty damn good!