Ask The Pilot

[cmon0005]

Will the MH incident warrant an ATSB investigation or is it just a technical fault that will be fixed and on their merry way?

 

[harvyk]

Will the MH incident warrant an ATSB investigation or is it just a technical fault that will be fixed and on their merry way?

Investigation: AO-2018-007 - Engine failure or malfunction involving an Airbus A330, 9M-MTM, near Curtin, Western Australia on 18 January 2018

 

[PJ747]

On the return trip of the flight I mentioned earlier, we ended up doing a go around at low altitude (we weren't too far off from touching down when we started to climb again) at Dubai (Capt. advised it was due to wake turbulance from the previous aircraft).
How long in this circumstance (only a few hundred feet off the deck etc) would full power be applied for? Would it just be to get the aircraft (A380 in this case) pointing in the right direction and climbing before reducing thrust to an adequate level or go a bit longer?
Was also my (and my other half's) first go around, which was different!

 

[jb747]

On the return trip of the flight I mentioned earlier, we ended up doing a go around at low altitude (we weren't too far off from touching down when we started to climb again) at Dubai (Capt. advised it was due to wake turbulance from the previous aircraft).

Dubai puts 380s around 4 miles in trail. So, depending upon the wind conditions, that can mean that the wake from the preceding aircraft will be encountered in the last hundred feet or so of the approach. We had a good example of that this morning, where it was very smooth for the vast majority of the approach, only for the aircraft to encounter the rolling portion of the wake, just above the flare. And then you have to earn your keep. Mostly you can keep on top of it, but if you start hitting the control limits, it's time to go around.

How long in this circumstance (only a few hundred feet off the deck etc) would full power be applied for? Would it just be to get the aircraft (A380 in this case) pointing in the right direction and climbing before reducing thrust to an adequate level or go a bit longer?

Boeing and Airbus thrust management is different in the go around. In Boeing, the first press of the TO/GA switches will give you adequate power for a 2,000' per minute climb, and the second push will give TO/GA, if you happen to want it all. So, in most cases, it just stays at that initial level until the actual thrust change to climb at 1,000' or so. When that 1,000' change happens, the limit thrust changes to 'climb', so it's actually possible that the applied thrust could increase. And, if there happens to be a lowish level off, then the limit will go to climb, but the actual power will roll back dramatically.

Airbus, don't have TO/GA switches as such. To engage TO/GA, you need to push the thrust levers all the way forward to the stop. Once the power has increased, if you don't want it all, pulling back one notch, will give 'soft GA', which will target that same 2,000' per minute. Last time I had cause to do a go around, the levers were in the TO/GA position for only a second or two, but it's up to you how long you leave them at that position. The change back to climb will also happen in that 1,000-2,000' area.

Activating TO/GA can do different things depending upon what is engaged. It's actually a thrust lever position or switch, so it always has an effect upon the thrust. If the autopilot is engaged, it will change that to go-around mode too, so it will automatically pitch up. But, if the A/P is not engaged, it only changes the thrust and the flight director mode. It won't change the flight path.

Was also my (and my other half's) first go around, which was different!

They aren't all that common. Back in the 767 days, when sector lengths were much shorter, I averaged about one per year. On the 747 about one in 3 years. And the 380, one in 9 years.

Go around altitudes will vary depending upon the circumstances. At the low side of the scale, I've gone around in both the 767 and 747 after the flare, so below 30'. Most occur at around the 200' mark. It's even possible for some approaches to require a descending go around. In that case they have a low altitude required after the GA, and you have to accommodate the case where in an early GA, you're above that level. LA and London both have this scenario.

 

[Strategic Aviation]

The captain, who was monitoring the flight, twice called for an increase in power and then for a go-around during the final 50 feet of descent, the report said. The first officer responded by increasing power about the same time the plane touched down.

Finding the aircraft under control, the captain cancelled the go-around, took control of the plane and taxied to the gate without further incident.

ATR-72 presumably differs from a heavy, but what's the procedure for cancelling a GA when power has been increased but the wheels have contacted the ground? Such an instance seems ripe for confusion.

 

[jb747]

ATR-72 presumably differs from a heavy, but what's the procedure for cancelling a GA when power has been increased but the wheels have contacted the ground? Such an instance seems ripe for confusion.

Attempting to cancel a go around, once it has started, and airborne, has a fair probability of coming unstuck.

Basically, there's two components to a go around...the power increase, and the pitch change. If you haul the power back, before the pitch has changed more than a degree or two, you'll most likely just make the landing longer, though the fact that you've now destabilised it, increases the odds of it being a poor landing.

But, if you attempt to stop the go around once the attitude has changed to any extent, you'll almost certainly be featuring in the crash comics. So, there's no procedure for this...don't do it.

On the other hand, if the aircraft is actually on the ground when you decide to stop the G/A, you can't have a heavy landing...you've most likely already had it. If the aircraft is under control at that point, all you need to do is close the thrust levers.

Looking at the article you've referenced...the FO has reduced the thrust to idle (bad call near the ground) to control the speed. If he's been holding the slot at a higher than target speed, he would need to increase the pitch coincident with the speed reduction. If you don't change the pitch, the speed will decrease, but the sink rate will increase...which is apparently what happened.

 

[mjt57]

If he's been holding the slot at a higher than target speed, he would need to increase the pitch coincident with the speed reduction. If you don't change the pitch, the speed will decrease, but the sink rate will increase...which is apparently what happened.

By changing the pitch do you mean nose up? If so, wouldn't that also slow the aircraft?

 

[moa999]

From Twitter - presumably some screens that are pretty familiar jb747

Spot the difference that a wet runway makes to our takeoff speeds. (I forced the computation to use the same flap setting for dry as the optimum one for wet so the wet runway was the only change). #A380 @British_Airways BA55 LHR-JNB Captain Dave on Twitter




Captain Dave on Twitter

 

[jb747]

By changing the pitch do you mean nose up? If so, wouldn't that also slow the aircraft?

Yes...eventually. Actually that leads us to something I've never understood. When pilots are learning to fly in the GA world (in say, a Cherokee), speed control on finals will be done by small pitch changes, and aim point by power changes. Jump to the military (CT4), and it's the other way around. You aim the aircraft where you want it to go, and use the power to control speed. To me that has always been the logical link and I've never understood why it would be looked at the other way around.

The two are, of course, inextricably linked. No matter which one you change first, it the other will have to change.

Airliners are flown the military way.

 

[jb747]

From Twitter - presumably some screens that are pretty familiar jb747

Spot the difference that a wet runway makes to our takeoff speeds. (I forced the computation to use the same flap setting for dry as the optimum one for wet so the wet runway was the only change). #A380 @British_Airways BA55 LHR-JNB Captain Dave on Twitter

V1 is slightly slower in the wet runway case. In the 'go' case, where you continue after an engine failure, you're normally looking at a regulatory requirement of 50' at the end of the available tarmac. In the wet case that is reduced to 35', and can be achieved from the slightly slower V1.

Whilst V1 is normally described as the maximum speed from which you can abort the takeoff, that's not necessarily the case. It's really the first speed from which you can continue the take off after the loss of an engine, and achieve that 50' target. As it's almost always safer to go flying than it is to carry out a high speed abort, we remove our hands from the thrust levers at V1...signifying that the stop option is no longer considered.

The MEL items entry at the bottom left is interesting. Many MELs have an effect on the performance of the aircraft, and for that reason they are entered into the 'basket' which propagates them across the performance applications. In this case, we can't read it all, but at least 2 brakes on one of the body gear bogies are unlocked.

I don't have the actual performance application on my laptop, but we do have iPad apps. They don't necessarily give identical answers (to the laptops), but they are close enough to perform an error check. In this instance, they don't give a different V1 for the wet or dry case, in all cases giving a much lower V1 value of 131 knots. I also get a different value for the engine out clean up. I expected that our performance data would be similar, if not identical, but they are appreciably different.

 

[Flying Fox]

I was just reading an article about AU Super Hornets coming back from the middle east. This raised a few questions -

1. I'm assuming that the F18s are flown back and not transported in a C17 or similar?
2. Do the F18s land for fuel or mid-air refuel to get back to AUS?
3. Do F18s have auto pilot?
4. How are bathroom visits handled?

Thanks in advance!

 

[docjames]

I was just reading an article about AU Super Hornets coming back from the middle east. This raised a few questions -

1. I'm assuming that the F18s are flown back and not transported in a C17 or similar?
2. Do the F18s land for fuel or mid-air refuel to get back to AUS?
3. Do F18s have auto pilot?
4. How are bathroom visits handled?

Thanks in advance!

5. I assume they have a "max cruise range" speed - presumably sub-sonic or will higher speeds to be used to reduce flight time / overall time?

 

[moa999]

I also get a different value for the engine out clean up.

Is that the 1580ft?
What's the significance of this number

I expected that our performance data would be similar, if not identical, but they are appreciably different.

Interesting indeed. Are these Airbus programs/apps?
Possibly another MEL that can't be seen.

How often do you have a MEL on brakes?

 

[AviatorInsight]

Boeing and Airbus thrust management is different in the go around. In Boeing, the first press of the TO/GA switches will give you adequate power for a 2,000' per minute climb, and the second push will give TO/GA, if you happen to want it all. So, in most cases, it just stays at that initial level until the actual thrust change to climb at 1,000' or so. When that 1,000' change happens, the limit thrust changes to 'climb', so it's actually possible that the applied thrust could increase. And, if there happens to be a lowish level off, then the limit will go to climb, but the actual power will roll back dramatically.

Activating TO/GA can do different things depending upon what is engaged. It's actually a thrust lever position or switch, so it always has an effect upon the thrust. If the autopilot is engaged, it will change that to go-around mode too, so it will automatically pitch up. But, if the A/P is not engaged, it only changes the thrust and the flight director mode. It won't change the flight path.

Unless you’re in a 737...firstly, it’ll stay in TO/GA until you change the mode yourself or you get altitude capture so the thrust won’t actually change unless you tell it to. Secondly, and I can never understand this point, but in a GA the A/P will automatically disengage. So you’ll have A/T but you’ll need to hand fly until you’ve got it under control in which case you can’t throw the aircraft at the A/P. It needs to be in trim and no force on the controls for it to engage. The ONLY time the A/P will remain engaged is when doing a dual channel approach.

ATR-72 presumably differs from a heavy, but what's the procedure for cancelling a GA when power has been increased but the wheels have contacted the ground? Such an instance seems ripe for confusion.

To be changing your mind that much in quick succession is guaranteed to force errors. A GA can still be conducted even after the wheels touchdown, but once you crack the reversers it’s all over and you’re committed to the landing.

 

[jb747]

I was just reading an article about AU Super Hornets coming back from the middle east. This raised a few questions -

1. I'm assuming that the F18s are flown back and not transported in a C17 or similar?
2. Do the F18s land for fuel or mid-air refuel to get back to AUS?
3. Do F18s have auto pilot?
4. How are bathroom visits handled?

They will be flown back. It's quite an exercise, as you'll probably need multiple tankers for each leg (just in case one is unable to transfer fuel), plus some sort of SAR provision.

They'd probably be configured with 3 or 4 drop tanks, which they'll keep as full as possible for most of the trip.

The aircraft has a autopilot, though I have no idea of its capabilities.

Bathroom. Well, you can't leave the seat....so that leaves few possibilities.

 

[jb747]

5. I assume they have a "max cruise range" speed - presumably sub-sonic or will higher speeds to be used to reduce flight time / overall time?

Subsonic. Very subsonic. I'd expect it to be around .75 mach. Perhaps a little faster.

 

[Quickstatus]

What’s inflight refuelling airspeed range?

Are raaf pilots trained to operate to/from Aircraft carriers?

 

[jb747]

Is that the 1580ft?
What's the significance of this number

It's a number that varies for each and every runway. It's the level that we'll stop the climb and accelerate and clean up after an engine failure. It is chosen to ensure obstacle clearance close in, but also to ensure that the aircraft is clean within the TO/GA time limit (10 minutes engine out).

Interesting indeed. Are these Airbus programs/apps?

Yes, part of the performance suite. But, individual airlines will tailor them to their needs. They also vary to cover all of the variants (engines, and allowed thrust levels).

Possibly another MEL that can't be seen.

I'll have a look again when I get a chance in the aircraft. I don't expect it to differ much from the iPad app, but the V1 speed difference was larger than I expected, given that there's little difference between our aircraft and BA's. We have slightly more power, but it's not relevant to that take off.

How often do you have a MEL on brakes?

Not often. If you are watching aircraft at that airport, you can generally pick an aircraft with such an MEL, as the gear will be left down for a couple of minutes after take off.

 

[jb747]

What’s inflight refuelling airspeed range?

I'll see if I can get the exact answer for the Hornet, but I expect that it will be around the 250-270 kias area. Doesn't matter how fast the fighters can fly, they have to fit in with the tanker.

Are RAAF pilots trained to operate to/from Aircraft carriers?

No. The RAAF I knew were mostly scared of the water, though I expect that has changed. Individuals who've been on exchange with the USN or Marines would have had to qualify, but that's only a few people. Our Chief of Defence Force, Air Marshall Binskin was qualified...but that's because he started his career as an RAN A4G pilot.

 

[jb747]

Unless you’re in a 737...firstly, it’ll stay in TO/GA until you change the mode yourself or you get altitude capture so the thrust won’t actually change unless you tell it to.

The 767 had similar behaviour...or at least the -200 did. In that we’d have the non flying pilot select CLB at the clean up altitude. At least some of the -300s were capable of doing it automatically, but because it wasn’t the entire fleet, we didn’t use it.

Secondly, and I can never understand this point, but in a GA the A/P will automatically disengage. So you’ll have A/T but you’ll need to hand fly until you’ve got it under control in which case you can’t throw the aircraft at the A/P. It needs to be in trim and no force on the controls for it to engage. The ONLY time the A/P will remain engaged is when doing a dual channel approach.

I’m pretty certain that the 767 did not behave this way, with whatever autopilots were engaged remaining engaged. I’ve still got the manual, so I’ll look it up.