Ask The Pilot

[jukebox333]

JB - on YouTube after that scrubbed take off (above) is a video of a Qatar plane being escorted in to Manchester.

Other than giving Joe Public a superficial warm and fuzzy feeling our skies are safe, what are your thoughts on what the presence of a fighter jet is going to achieve in the case of a real threat?

FWIW I don't see any pleasant outcomes to the scenario, nor how a military response would change the outcome.

 

[jb747]

JB - on YouTube after that scrubbed take off (above) is a video of a Qatar plane being escorted in to Manchester.

Other than giving Joe Public a superficial warm and fuzzy feeling our skies are safe, what are your thoughts on what the presence of a fighter jet is going to achieve in the case of a real threat?

FWIW I don't see any pleasant outcomes to the scenario, nor how a military response would change the outcome.

When it gets to the point of a military response, it means that the threat has gone well beyond our aircraft, and the authorities are more concerned about what is on the ground below. It is an horrific situation, if played out. The military aim is to ensure that if the aircraft is going to be used as a weapon, that it comes down in as unpopulated an area as they can manage.

The military presence does not change the outcome for the occupants of the aircraft, but it may for whatever the aircraft was targeted at. Hopefully it will remain a precaution and never be used.

 

[flychrisfly]

Hi pilots, If a modern jet aircraft is flying along with autopilot and other automatic systems disabled/turned off, and the aircraft is commanded to bank and does so to a moderate bank angle, say 5 degrees, does the aircraft need to be commanded to bank in the opposite direction to the then regain level flight?
once the bank angle is obtained and he joystick is released, what will happen?
cheers

 

[jb747]

Hi pilots, If a modern jet aircraft is flying along with autopilot and other automatic systems disabled/turned off, and the aircraft is commanded to bank and does so to a moderate bank angle, say 5 degrees, does the aircraft need to be commanded to bank in the opposite direction to the then regain level flight?
once the bank angle is obtained and he joystick is released, what will happen?

Let's start with a cutoff of no non FBW aircraft (so that rules out all 737/747/757/767).

No autopilot. That's easy..turn it off. 5º angle of bank...let go of the stick and it will hold that 5º for ever.

The answer varies with the control law, and the applied amount of bank. A little bit, and it will roll back to zero. Too much, and it will roll back to about 30º. 5º is barely noticeable. Otherwise (in normal laws) they hold whatever they have.

 

[DrA]

So my United flight from Guam to Chuuk just got diverted to Pohnpei in Micronesia, and I'm curious...The pilot said that he'd missed the approach to the airport in Chuuk. Not just overshooting the runway, but he was miles off course and that it was weather related. How?

1. While I concede that the weather wasn't ideal, I've been on flights that have landed in much nastier weather than that. Are there differences in what different airlines will permit as acceptable weather conditions or something?

2. This is just me showing my naivety I suspect, but I thought all planes has computer guided systems for the approach to airports? How could that computer system get the pilot so far off course? He was way off - I saw the runway as we went flying past it when we started to climb again and we were easily 4-5 miles to the west.

I'm now stuck in Pohnpei and kind of bored because they couldn't turn the flight around for another attempt at Chuuk due to flight time rules and fuel load...Figured I'd ask.

 

[jb747]

So my United flight from Guam to Chuuk just got diverted to Pohnpei in Micronesia, and I'm curious...The pilot said that he'd missed the approach to the airport in Chuuk. Not just overshooting the runway, but he was miles off course and that it was weather related. How?

How do you know he was 'miles off course'? I'll bet he wasn't.

1. While I concede that the weather wasn't ideal, I've been on flights that have landed in much nastier weather than that. Are there differences in what different airlines will permit as acceptable weather conditions or something?

All airports, aircraft, and even crews have different operating limits. Because I regularly operate in areas in which fog is common, I'm qualified to CAT IIIB...which is an automatic landing in virtually zero visibility. Most pilots (aircraft and airports as well) do not need this qualification, and so they don't have it. It's expensive in training to get and to keep, and requires equipment in the aircraft and on the ground. The vast majority of runways don't have this equipment..it only comes together in places like London Heathrow.

The airport you are talking about has only a few airline movements per week, and so no money is going to be spent on expensive ground installations. All that it has is an NDB (non directional beacon) and DME (distance measuring equipment), both of which are extremely old nav aids. There are a couple of GPS arrivals available, and they will supplant the DME, but without a transponder installation at the airport, they won't get you much lower (if at all) than the older approaches. They are easier to set up and fly though.

Basically though, you need around 3 miles of visibility from the runway. If you don't have that, then you can't continue past the 'missed approach point'. From that point, the aircraft will be flown manually.

2. This is just me showing my naivety I suspect, but I thought all planes has computer guided systems for the approach to airports? How could that computer system get the pilot so far off course? He was way off - I saw the runway as we went flying past it when we started to climb again and we were easily 4-5 miles to the west.

Ah, the computer does everything. They exist to help, but in themselves don't generally allow operations in conditions that couldn't be done manually. They make life easier and more consistent...until they screw up of course.

I'd hazard a guess that he flew an RNAV (GPS) approach to runway 04. The missed approach point is at 1.7 miles from the runway, and involves an immediate climbing left turn. You probably wouldn't get closer than a mile at the minimum, and by the time you could see the runway from the cabin would be well offset.

 

[por930]

So my United flight from Guam to Chuuk just got diverted to Pohnpei in Micronesia, and I'm curious...The pilot said that he'd missed the approach to the airport in Chuuk. Not just overshooting the runway, but he was miles off course and that it was weather related. How?

1. While I concede that the weather wasn't ideal, I've been on flights that have landed in much nastier weather than that. Are there differences in what different airlines will permit as acceptable weather conditions or something?


2. This is just me showing my naivety I suspect, but I thought all planes has computer guided systems for the approach to airports? How could that computer system get the pilot so far off course? He was way off - I saw the runway as we went flying past it when we started to climb again and we were easily 4-5 miles to the west.

I'm now stuck in Pohnpei and kind of bored because they couldn't turn the flight around for another attempt at Chuuk due to flight time rules and fuel load...Figured I'd ask.

Chuuk(PTKK) has the ocean on both sides of the approach, which makes instrument landing systems difficult to set up. As Chuuk appears to have no instrument landing system(ILS) facilities, the aircraft, though possibly capable of an ILS approach, has nothing to 'home' into. Chuuk relies on visible approaches, which in bad weather can be "problematic". JB or other jet guys may have some other magic in their kitbag?

 

[DrA]

How do you know he was 'miles off course'? I'll bet he wasn't.



All airports, aircraft, and even crews have different operating limits. Because I regularly operate in areas in which fog is common, I'm qualified to CAT IIIB...which is an automatic landing in virtually zero visibility. Most pilots (aircraft and airports as well) do not need this qualification, and so they don't have it. It's expensive in training to get and to keep, and requires equipment in the aircraft and on the ground. The vast majority of runways don't have this equipment..it only all comes together in places like London Heathrow.

The airport you are talking about has only a few airline movements per week, and so no money is going to be spent on expensive ground installations. All that it has is an NDB (non directional beacon) and DME (distance measuring equipment), both of which are extremely old nav aids. There are a couple of GPS arrivals available, and they will supplant the DME, but without a transponder installation at the airport, they won't get you much lower (if at all) than the older approaches. They are easier to set up and fly though.

Basically though, you need around 3 miles of visibility from the runway. If you don't have that, then you can't continue past the 'missed approach point'. From that point, the aircraft will be flown manually.



Ah, the computer does everything. They exist to help, but in themselves don't generally allow operations in conditions that couldn't be done manually. They make life easier and more consistent...until they screw up of course.

I'd hazard a guess that he flew an RNAV (GPS) approach to runway 04. The missed approach point is at 1.7 miles from the runway, and involves an immediate climbing left turn. You probably wouldn't get closer than a mile at the minimum, and by the time you could see the runway from the cabin would be well offset.

Thanks for the clarifications. I'm admittedly fairly clueless about these things, and it didn't make sense given what I thought I knew.

 

[day-heg]

Last year, I wrote a bit about my training as a low-hour pilot and what it involved. I passed the CPL test a couple of months ago, came back to the UK, and had an instrument rating test last weekend… Obviously, I'm at the other end of the experience scale from JB & Boris, but I thought a quick rundown might interest some of you.

[Mods - please spin this off into another thread if you think appropriate]

The brief for the flight is that I’m to get to Exeter airport using conventional nav-aids, then make an RNAV (GPS) approach, missed approach and back to Bournemouth. On the way back, well do some general handling, and then we’ll enter the hold back at Bournemouth, followed by the ILS procedural approach.


Depart Bournemouth airport and at 200ft AGL the screens go up, and I can’t see outside. Set course for a point 40 miles along the 275 radial from the VOR beacon at nearby Southampton airport, using the Bournemouth NDB to track outbound. Climb to FL060. Shortly after departure we enter uncontrolled airspace and receive a traffic service form Bristol radar. Arrive at the turning point bang on time, and left turn onto the 275 radial and head west towards ‘MULIT’ - a GPS waypoint but for the purpose of this exercise it’s defined by a radial and distance from the Berry Head VOR/DME on the south coast. MULIT is in controlled airspace (CAS), so I tell Bristol my ETA and negotiate with them and Cardiff radar services and to enter CAS east of MULIT. I’m cleared to enter and to climb to FL070, which is an appropriate level for the airspace and direction I'll be going.


Left turn at MULIT and head south towards ATWEL, another waypoint which marks the point I can swap onto GPS. RW26 is in use at Exeter and between ATWEL and the IAF for the RNAV approach is a very active parachuting area. I’m about to negotiate to track to the airfield and onwards to a different, more southerly IAF, when ATC tell me that the runway has changed to 08, and I’m recleared for the RNAV approach for 08 via the SISRI IAF. Into the descent as I’ve got about 5000ft to lose and about 25 track miles to go to the final approach fix (FAF), followed by a quick reprogram of the GPS system and I’m on the way. Exeter airfield is also in uncontrolled airspace, so we leave CAS during the descent, and get a traffic service. Lots of reports of gliders and microlights, but they are well clear of us, and we’re in and out of cloud so the examiner can’t see too much.


At the FAF, and I’m about 100ft above profile, so edge the nose down a touch to increase the rate of descent, and regain the profile about 4 miles out. At the minimum decision altitude (MDA) of 560ft (460ft AGL) we simulate not-visual - the screens are still up, so I cant see anything outside, but the examiner can - and we go around. At about 800 feet, he covers the throttles and closes one of them rapidly to simulate a failed engine. Lower the nose so the airspeed doesn’t decay too quickly, run through the drills, simulate closing down the engine and he sets zero-thrust load as if the engine has been shut down and the prop feathered. Aim for ‘blue-line speed’ - the speed at which we’ll achieve the best rate of climb on one engine. Make sure I’m still on heading, and trim for pitch and yaw. Simulate a PAN PAN call and the secondary engine shut down drills.


After a few minutes, he gives me back the ‘failed’ engine and we head back up to FL050. For the general handling, he covers up the PFD and I move to using the back up instruments - compass, artificial horizon, altimeter and airspeed indicator. Climbs & descents whilst maintaining heading and airspeed, compass turns remembering the vagaries of compass indications in the turn, some stall recovery exercises in different airframe configurations, and two unusual attitudes recoveries where I close my eyes and put my head down, he throws the plane around for 30 seconds to disorientate me and then hands me back control for me to recover to straight & level flight and stable speed.


That all done, I talk to Bournemouth radar and it’s pretty busy - the fella is under the pump and is asking people to remain clear of the control zone. However, here the advantage of having an 'Exam’ call sign for the trip pays dividends and I get cleared straight in and into the NDB hold at 4000ft. One lap of the hold (during which the examiner takes away the left engine again - we’re asymmetric from here until we land) and we’re cleared for the RW08 ILS procedure. A bit of a northerly wind at 4000ft but it drops as we descend. Approach works out pretty well, but part of the test is an asymmetric go-around, so we do that at 200ft AGL and climb to 700ft on one engine, with a simulated cloud base of 800ft and visibility at 2500m. Complete an asymmetric low-level circuit to land, and I’m very sweaty but happy it’s done! Another step closer...

 

[QF WP]

I think that is perfect for this thread, day-heg and note you already have a like from jb747. Just like a sim, but the real thing. Well done on passing and onto the next part of your training. We'll note your "ability" to answer questions from the floor...

 

[mikenz]

In making a turn do you forfeit aerodynamics? would it be more efficient to turn in the cruise rather than during the climb?

 

[day-heg]

In making a turn do you forfeit aerodynamics? would it be more efficient to turn in the cruise rather than during the climb?

In straight & level flight, lift and weight are equal and opposite vertical forces. In a turn, the weight continues to act vertically towards the earth, but with the aircraft banking the lift is split into vertical and horizontal components. To maintain a given altitude in a turn, the overall lift required increases so the vertical component of the lift matches the weight. An increase in lift causes an increase in induced drag, which increases fuel consumption. In practical terms, it means applying a small amount of back pressure on the stick in a turn, otherwise the nose would drop and you'd descend. Unless you have an autopilot which would fix all that for you.
In terms of efficiency, out of any flight, time spent in a turn is a fraction, so not likely a consideration. If you're turning, it's likely to point to where you want to go, or ATC have pointed you somewhere for a reason... in either case, you need to turn...

 

[aussiel]

Leaving PVG last night, we sat just back from the gate with the engines running above idle and the brakes applied (plane was "wobbling" a bit, like when they run up the props to do an engine test). The FO announced over the PA that the re-fueller had put too much fuel in and they had to burn some to get under MTOW. I seem to recall reading somewhere in this thread that fueling is controlled from the coughpit. Was the FO just 'simplifying' things with his explanation? Would the likely problem sit with the load calculations, entry into the computer, or the rig putting the fuel in?

 

[jb747]

Leaving PVG last night, we sat just back from the gate with the engines running above idle and the brakes applied (plane was "wobbling" a bit, like when they run up the props to do an engine test). The FO announced over the PA that the re-fueller had put too much fuel in and they had to burn some to get under MTOW. I seem to recall reading somewhere in this thread that fueling is controlled from the coughpit. Was the FO just 'simplifying' things with his explanation? Would the likely problem sit with the load calculations, entry into the computer, or the rig putting the fuel in?

If it's wobbling, then I'd guess the power was substantially above idle, and near the gate is a silly place to run anything much above idle. Anyway, if you want to burn it down, you'll need a reasonable handful of power.

Refuelling is controlled externally. There is a panel on most aircraft on which the desired load is set, and it normally cuts of pretty well on the load you want. But, you can end up a couple of hundred over on a big fuel order. You can't stop the loading from the coughpit. If, for whatever reason, it ends up manually controlled, then there's quite a bit error potential.

There are some other reasons that could give you too much fuel. For instance, a weather change (wind or temperature) or runway change, could reduce your performance limited weight to less than you'd planned for. In LA, we almost always want to take off on the 94 right on max brakes release, but there is a difference of about 1,000 kgs in the fuel used for taxi for the two most likely runways. So, if you plan 25 but end up on 24, you may be heavy, whereas planning 24 but ending up on 25 may put you light on fuel before you even take off.

 

[eric2011]

but there is a difference of about 1,000 kgs in the fuel used for taxi for the two most likely runways. So, if you plan 25 but end up on 24, you may be heavy, whereas planning 24 but ending up on 25 may put you light on fuel before you even take off.

JB, to me, 1000kg doesn't seem a lot, 1 tonne, approx 1000 ltrs, but what is 1000kg to you in terms of distance you could fly on it etc etc

 

[Kangol]

I saw the show "Britain's Busiest Airports - Heathrow" which had a segment about the QF A380.
In the same episode, they talked about the problem with birds - if it flies into an engine and causes enough damage, it could potentially bring a plane down, so they say.
Now I realise there is a lot to be said for a reality TV show, but what is your take on it? Can one bird cause a plane to crash? Have you any experiences with stray birds?

 

[jb747]

JB, to me, 1000kg doesn't seem a lot, 1 tonne, approx 1000 ltrs, but what is 1000kg to you in terms of distance you could fly on it etc etc

I couldn't get very far on it airborne; about 45 miles. But, on the ground, it will keep us going for about 15 minutes. But, if I need every kg of fuel that I can get for a sector, then even a fraction of that thousand may make the difference between getting to Melbourne, or diverting. When we do the fuel calculations (in flight) they are black and white. If we work out that we need to arrive at our decision point with (say) 20 tonnes, and we look like having 19.9...then we don't have enough.

The LA issue is that to take off at maximum brakes release weight (569 tonnes), we need to juggle the fuel burnt in taxi to get to the runway. Max taxi weight is 571 tonnes, and in most cases we'll allow 1,000 kgs for the taxi. But, LA 24 needs about 500 and LA 25 about 1,500. We try to lock the runway choice in as early as possible, but it doesn't always work out.

 

[jb747]

I saw the show "Britain's Busiest Airports - Heathrow" which had a segment about the QF A380.
In the same episode, they talked about the problem with birds - if it flies into an engine and causes enough damage, it could potentially bring a plane down, so they say.
Now I realise there is a lot to be said for a reality TV show, but what is your take on it? Can one bird cause a plane to crash? Have you any experiences with stray birds?

Bird strikes happen all the time. Mostly they leave a smear on the paintwork, and very occasionally a dent. (Actually one dented the aluminium bonnet of my Land Rover, does that count)?

Most birds are small, and the engine simply eats them. But, as they get bigger, and if they hit the hot section and not the cold, then they can cause engine damage. Again, in most cases, the engine keeps on running, but if big enough, or in sufficient numbers, then they can kill the engine. The A320 in NYC showed the end result. Engines aren't the only places to be hit too...the RAAF lost an F-111 after a pelican strike on the canopy.

I've hit many a bird, but only once has it been an issue. On that occasion we were departing Perth for Singapore in a 767, when we ran into a flock of birds. The event recorder got it at 1,212 feet. I saw them go down the right hand side, and literally as I said 'birds', the engine note changed. Looking inside, both engines were running, but the right had reasonably high vibration. We pulled it back to about half power, cleaned up, and climbed to about 5,000 feet. Had a think about the state of the world, and came back and landed. We left the engine running, but at minimum power (just in case the right had some hits too). On the ground the engineers counted 12 hits. One of the flap fairings was missing entirely (obviously hit on the front, and then ripped off by air loads). The engine had lost two fan stator blades, and had four fan blades bent. Plus there was a hole in the engine casing. As it turned out, nothing had gone through the hot section of the engine, and it took the guys just 4 hours to fix it and have it run, ready for departure again.

 

[docjames]

I couldn't get very far on it airborne; about 45 miles. But, on the ground, it will keep us going for about 15 minutes. But, if I need every kg of fuel that I can get for a sector, then even a fraction of that thousand may make the difference between getting to Melbourne, or diverting. When we do the fuel calculations (in flight) they are black and white. If we work out that we need to arrive at our decision point with (say) 20 tonnes, and we look like having 19.9...then we don't have enough.

The LA issue is that to take off at maximum brakes release weight (569 tonnes), we need to juggle the fuel burnt in taxi to get to the runway. Max taxi weight is 571 tonnes, and in most cases we'll allow 1,000 kgs for the taxi. But, LA 24 needs about 500 and LA 25 about 1,500. We try to lock the runway choice in as early as possible, but it doesn't always work out.

If you've allowed for 25 and you end up with 24, do you have to remove fuel before taxi, or sit around burning it off?

 

[Major]

Just looking at this clip of a 787-9 and was staggered at the climb angle. It almost looks vertical but I assume it's the camera position. Just what would be the climb rate ?

https://www.youtube.com/watch?v=KYbM-3E11Qo&feature=youtu.be