Ask The Pilot

[lastrow]

Can an aircraft like the A380 or B747 stay aloft with just one engine operational? What is the minimum engine requirement for level flight and emergency landing?

 

[jb747]

JB, someone shared this on my Facebook page.

https://www.facebook.com/ThePilotsLoungePage/posts/1071290626260613?fref=nf

It's the usual coughpit video of a landing in wet weather and a discussion that followed about whether or not the approach should've continued.

I can't comment, but there are those who, not being pilots, including the author of the article, a journalist, no less, who have their opinions.

What are your thoughts?

It's certainly not ideal, but you need a bit of context. Yes, there's a thunderstorm, but they vary quite a bit around the world. In particular, at Singapore they tended to be large and relatively diffuse. In the Middle East they are very tight, and nasty. So, it's not quite as simplistic as some would make it out.

We don't know why he didn't hold. He may have already done so, and burnt his holding options. Then landing is the only option. You can't necessarily hold and then divert. It's normally one or the other.

The radar being all red means almost nothing, other than the gain is on max. We don't know how they are operating it.


In any event, holding or going elsewhere would have been a better idea. I wonder if he would have continued at night. Wouldn't have been able to see the rain, but the lightning would have been attention getting.

 

[jb747]

JB - with the strong northerly in Melbourne yesterday (Thursday 17/3) both landing and takeoffs were onto / off RWY34. I was on the QF409 SYD-MEL A330-200 service. The PIC said the winds were strong gusting between 30-40kts hence being down to one runway. The approach to RWY34 seems to take you over Essendon to join base for a landing onto RYW34. As we were turning base there were a few significant increases to the power settings that lasted for 3-4 seconds then the power would reduce.

That arrival (I won't call it an approach) has you descending to cross Essendon at 2,500 feet. The aircraft normally have to level off approaching Essendon, so there will be a large power change for that. As you start the descent again, you'll actually be about 500 feet high on the 3º profile, so a large decrease in thrust will be needed. The aircraft should be fully configured as you leave 2,500', otherwise you risk remaining high, and ending up with an unstable approach as you turn onto finals. Short bursts of power are generally used to correct speed excursions.

Assuming the winds at 4,000ft were 50-60kts from the north were these power changes a result of the aircraft automatics trying to maintain a set IAS for the approach as the wind changed from a 50-60kt tail wind at 4,000ft over Essendon to a 50kt head wind on finals to RWY34.

I'm sure you didn't have a 50-60 tail wind at Essendon. A crosswind for sure, but any amount of tailwind on makes that approach unflyable. Overhead Essendon the autopilot would have been disconnected. The automatics CANNOT fly this procedure. I'm told that the A330 auto thrust is fairly stupid, so on gusty days the pilots prefer to manage the thrust themselves, so most likely it was also disconnected leaving Essendon. Power changes from that point would all be to correct any speed deviations.

This doesn't seem to be unique to Melbourne or Airbuses as I've also noticed significant power setting changes coming into airports in windy conditions like Wellington RWY34.

Ah, Wellington. Full power, idle, repeat.

Assuming you are visual would you typically do a manual approach in these sorts of conditions or continue to let the automatics including auto throttle do the work. Does it get to a point where the automatics can't keep up with the conditions and it's more efficient to fly the approach manually?

The automatics do a lovely job in fog. But in the really gusty, nasty conditions, they are often useless. So, on those really horrible days...don't sit there thinking the autopilot is doing the work. The A380 auto thrust does work well, and I've not had to disconnect it for an approach on the line. The Boeings are always manual thrust on finals unless it's an auto land. The smaller ABs may be either.

 

[jb747]

Can an aircraft like the A380 or B747 stay aloft with just one engine operational? What is the minimum engine requirement for level flight and emergency landing?

Well, I guess any number of engines, including zero, can be used for an emergency landing. Not really much choice.

They will generally fly on two engines, and we practice approaches with one and two out. Loss of two engines on take off, or very shortly after, at heavy weights, is likely to have a negative outcome.

We don't practice with three out, and the books include no data...you'll get to write that section yourself. You would need 100% thrust to fly the approach with the gear down, though at lighter weights and clean and low level you may be able to fly level, at around 90+%.

Vmca would be a real problem. If the running engine were an outboard, you'd need to keep a reasonably high speed to ensure that you have sufficient rudder authority. Slow too much and you'd not be able to stop the roll and yaw. My guess would be about 200 knots. You'd literally have to test that (i.e. a control check) with enough altitude to fix the outcome.

Probably the best way to handle it would be to consider all engines out, but with an option to slightly increase the power if going short.

Plus there would be all sorts of hydraulics and control issues.

Anyway, I'll read the book of anyone who manages it.

 

[andmiz]

We don't practice with three out, and the books include no data...you'll get to write that section yourself. You would need 100% thrust to fly the approach with the gear down, though at lighter weights and clean and low level you may be able to fly level, at around 90+%.

I think for some of our 747 three engine ferries when they have occurred in the past, the guys have been trained in one engine handling (or maybe 'exposed' to it), but of course are conducted at min ZFW. I'd presume for certification, some data has been produced.

 

[Captain Halliday]

View attachment 66856.

Do the sterile coughpit rules vary between operators?

What do these rules typically cover?

In the video you've commented on above the FO appears to be using a hand held camera. Even if technically allowed, it seems foolish to me at just a few thousand feet in poor weather.

 

[jb747]

Do the sterile coughpit rules vary between operators?

Everything varies between operators.

What do these rules typically cover?

Mostly talking about things that aren't relevant. Cameras were very rarely seen, and now tend to be of the GoPro variety, which can be fixed, or, I guess, worn.

In the video you've commented on above the FO appears to be using a hand held camera. Even if technically allowed, it seems foolish to me at just a few thousand feet in poor weather.

Perhaps he's shooting the video for the accident investigators.

 

[andmiz]

Hi Pilots

I was on a delayed flight recently and was curious to understand when the seat belt signs might be switched on/off. The delay was before takeoff and it was only 20 mins at first and then another 20 mins but then the captain came on and said we'd be delayed a further 50 mins due to cargo loading issues. Understand that 20 mins isn't enough time to let a 747 full of pax run around inside the plane but when the delay is known to be a further 40+ minutes I couldn't understand why we needed to remain seated and not use the loos, for example.

I think this question got skipped. While you're still at the gate and the door is still opened, I wouldn't hesitate to use the loos unless it seemed unreasonable, even though the seatbelt sign is turned on. There's procedures in place which restrict cabin crews duties while the aircraft is refuelling; once the seatbelt sign is turned on its their signal that they can commence their other duties.

Kudos for obeying the sign...it's obvious that it typically isn't obeyed especially arriving at the gate. The engines being shut down isn't necessarily an indication that the aircraft isn't going to keep moving.

 

[jb747]

We don't practice with three out, and the books include no data...you'll get to write that section yourself. You would need 100% thrust to fly the approach with the gear down, though at lighter weights and clean and low level you may be able to fly level, at around 90+%.

I had a look at a couple of power requirements yesterday. Clean, level, 7000'. 24% on each of four engines. The A380 actually gives a thrust % as well as the normal rotation numbers...so on one engine, you might think you'd need 96%. But, once you apply the rudder that will be needed, the figure will be well over 100%. So, basically on one engine, you'd be descending, but fairly slowly.

 

[aussiel]

I had a look at a couple of power requirements yesterday. Clean, level, 7000'. 24% on each of four engines. The A380 actually gives a thrust % as well as the normal rotation numbers...so on one engine, you might think you'd need 96%. But, once you apply the rudder that will be needed, the figure will be well over 100%. So, basically on one engine, you'd be descending, but fairly slowly.

Hi JB,

This interests me greatly. I remember watching Air Crash Investigation showing the BA 777 Crash at LHR (BA38), which praised the captain's actions of retracting the flaps, allowing the plane to fly further and clear the runway obstacles. The reasoning in the episode was that flaps increased drag, thus allowed the aircraft to fly further. But surely, given the imminent landing, having the flaps extended would give the aircraft greater lift to fly over the obstacles and land at a slower speed?

 

[jb747]

This interests me greatly. I remember watching Air Crash Investigation showing the BA 777 Crash at LHR (BA38), which praised the captain's actions of retracting the flaps, allowing the plane to fly further and clear the runway obstacles. The reasoning in the episode was that flaps increased drag, thus allowed the aircraft to fly further. But surely, given the imminent landing, having the flaps extended would give the aircraft greater lift to fly over the obstacles and land at a slower speed?

Retracting the flaps a stage or so in the BA accident, moved the touchdown point by about 50 metres. Not much, but as it turned out, enough to clear the obstructions on the approach. It probably didn't make a huge difference, but you never know.

Flaps increase the drag. The early stages of flap extension are largely area increasing, so there's more lift and slightly more drag. The later stages (Boeing 25 & 30, AB 3 & 4) give far more drag than lift.

More drag means a steeper approach, and less distance covered. An aircraft in a glide has a certain amount of energy. You can't add to that, so anything that increases the expenditure of that energy will reduce your ability to fly over obstacles.

I was in London the day it happened. It was quite surreal departing that night, and taxying past the triple. We'd flown over from HK the day before, and encountered extremely low temperatures, and ultimately had to descend to maintain the fuel temperature.

 

[alieninperth]

This is probably more of an ATC question but how long would it take to clean up and re-open the runway after an incident like the BA 777 at LHR or the BA 77 that caught fire in Vegas or for that matter QF32?

 

[jb747]

This is probably more of an ATC question but how long would it take to clean up and re-open the runway after an incident like the BA 777 at LHR or the BA 77 that caught fire in Vegas or for that matter QF32?

It's going to vary dramatically each time. But where the aircraft is intact, and can be towed (after a couple of wheel changes), then it won't take long at all.

The triple was next to the runway for some days, and really couldn't be moved until the accident investigators were finished with it. If I recall correctly they halted most of the short haul ops for the remainder of the day. According to google, it was moved 3 days later.

For operations to airports with single runways, it's something that you should consider. If an aircraft ahead of you closes the runway, what options do you have?

On a slightly different note, I thought the treatment of the crew by BA was appalling. The day after the crash a very shaken looking group of pilots was standing behind Willie Walsh during a press conferference. That was so insensitive as to defy belief.

 

[alieninperth]

Thanks JB,

Hopefully this isn't too personal, but what was it like taxying past the 777? I would have thought that it would have been an eye opening/awareness experience rather than apprehensive, or were you happy that the industry has training and standards set so high that everyone walked away. (I accept that not all companies have the same approach to standards as QF/BA etc.)

 

[jb747]

Hopefully this isn't too personal, but what was it like taxying past the 777? I would have thought that it would have been an eye opening/awareness experience rather than apprehensive, or were you happy that the industry has training and standards set so high that everyone walked away. (I accept that not all companies have the same approach to standards as QF/BA etc.)

Any time that you see something like that, it's always somewhat surreal. We knew that nobody had been killed, so that lightened it a bit.

Over the years I've seen the results of many accidents. The one that made the biggest impression was a Porter at Pt Cook back around 1984. I heard it from my office, and it had just caught fire as we rushed out of the 1FTS building.

I was walking over to flight planning at Nowra back in 1976, when I saw an A4 make an arrested landing, and the nose gear collapsed. I thought that made for an exciting day...but when I went into the ATC office I found out that the aircraft I'd seen was the survivor, and another had crashed at the range.

In the civilian world I was at LA the day the 737 landed on top of another aircraft. The wreckage ended up not far from our taxi route. Sobering.

And who can forget the 747 in HK harbour....

 

[por930]

This accident with the FlyDubai 737 at Rostov, Southern Russia is very tragic. From the pics I have seen of the accident site, it is like the plane broke into so many small pieces and disappeared. Several posts back on this forum comments were made how different a/c react to pilot inputs. Seems looking on the pprune site, many pilots say a light 737 in bad weather at night can be quite a handful if the TOGA button is pressed and they are not ready for the sudden nose up. Many many discussions and theories how the TOGA system works. Some of the pilots were saying their companies do not foster manual throttle, and where possible to use TOGA and leave the automatics on where possible.

Jb, Borris etc, when you perform a go around, do you prefer to apply manual throttles so you can better control the amount of grunt you are about to receive and does your company leave it to your discretion as to TOGA or manual?

 

[Awesom Andy]

And who can forget the 747 in HK harbour....

I lived in HKG when that happened. Winds were gusting but it wasn't impossible to land (although a BA pilot deemed the risks to be too great only minutes earlier). Most locals put it down to the poor standard of pilots/safety (given the airline's origin country). I believe the crash investigations findings blamed the pilots.

 

[jb747]

This accident with the FlyDubai 737 at Rostov, Southern Russia is very tragic. From the pics I have seen of the accident site, it is like the plane broke into so many small pieces and disappeared. Several posts back on this forum comments were made how different a/c react to pilot inputs. Seems looking on the pprune site, many pilots say a light 737 in bad weather at night can be quite a handful if the TOGA button is pressed and they are not ready for the sudden nose up. Many many discussions and theories how the TOGA system works. Some of the pilots were saying their companies do not foster manual throttle, and where possible to use TOGA and leave the automatics on where possible.

Jb, Borris etc, when you perform a go around, do you prefer to apply manual throttles so you can better control the amount of grunt you are about to receive and does your company leave it to your discretion as to TOGA or manual?

The Boeing system doesn't actually give you TO/GA when you push the go around switches. It modulates the power to give approximately a 2,000 fpm rate of climb. If you push the switch a second time, you'll get the full hit.

If you are manually controlling the power, the auto throttle will re-engage when you push the TO/GA button. If you don't push the button, the flight guidance won't go into the correct mode. Just pushing the throttles up yourself will give full go around power. You don't manually adjust for less, until you reach the altitude for selection of climb power.

All of the non FBW aircraft have a very strong nose up pitch couple, i.e. the power increase pushes the nose up, you don't need to do much pulling. In fact, you'll have to quite strongly push and then trim to hold the target go around attitude. It's just their normal behaviour, it shouldn't be a big deal.

In the big Airbus, we initially select full TO/GA, but if we want, we can pull the levers back to MCT to enable 'GA SOFT', which also targets about 2,000 fpm. Chances are that I'd just leave it until the CLB power point.

Using the automatics in poor conditions is the desirable course. Flying manually is something that should be kept for the nice weather.

I don't understand the mechanism of this accident. The conditions weren't nice, but they weren't that bad either. The crew had already had one 'practice' go around, so they obviously knew how to do it. The radio call for the go around is pretty relaxed too. The aircraft is less identifiable than the A320 in Egypt, and that came down from height. A very high energy event.

 

[jb747]

When the seat belt is on, this is why you don't decide to stand up.... Magenta is where the radar expects severe turbulence.

I

It never rains in the desert...Dubai is in this picture somewhere.

 

[knasty]

What degree of roll upon landing would cause contact with the ground? Would it be the wingtip, engine or fully-extended flap which would be the first object to contact? Do you need to use opposite inputs from rudder and ailerons to keep it level in a crosswind? Thanks.