Ask The Pilot

[JohnM]

Off topic...but I saw someone at my local supermarket the other day, who, after carefully assessing the size of the available space, drove straight into the adjacent car. And that's why I park at the far fringes of any car park. It would be nice if even 5% of the aviation standards were applied to drivers. Sadly, the driving standard is slowing being applied to flying.

This is not a post that I wish to acknowledge with a 'like' .

 

[Captain Halliday]

What are the most common causes of runway excursion? How common is wind in such incidents?

VA1465 MEL-DRW (VH-VUI) left RWY29 on landing in DRW last night.

I don't know what the TAF or observations were at the time, nor whether the runway was wet or dry.

The time of occurrence is broadly consistent with the time a storm passed through the area around 11pm.

 

[knasty]

Off topic...but I saw someone at my local supermarket the other day, who, after carefully assessing the size of the available space, drove straight into the adjacent car. And that's why I park at the far fringes of any car park. It would be nice if even 5% of the aviation standards were applied to drivers. Sadly, the driving standard is slowing being applied to flying.

What an amazing coincidence...

http://mobile.abc.net.au/news/2016-...llision-at-hobart-airport/8099400?pfmredir=sm

 

[Awesom Andy]

Off topic...but I saw someone at my local supermarket the other day, who, after carefully assessing the size of the available space, drove straight into the adjacent car. And that's why I park at the far fringes of any car park. It would be nice if even 5% of the aviation standards were applied to drivers. Sadly, the driving standard is slowing being applied to flying.

Just a week ago, I watched someone in a car park reversed into a pole about a foot wide - twice, into the same pole.

And speaking of driving, I had a rental with a cruise control that had a very large tolerance either side of the set speed (compared to other vehicles), which is a bit of an annoyance on the highway. And my question is, how well does the auto throttle keeps to the desired speed in an aircraft? And in places where there is a speed limit, say, 250 knots IAS, how do you make sure you keep to the limit? For example, you're at 250, and then a gust of wind came and you suddenly find yourself at 270.

 

[AviatorInsight]

And my question is, how well does the auto throttle keeps to the desired speed in an aircraft? And in places where there is a speed limit, say, 250 knots IAS, how do you make sure you keep to the limit? For example, you're at 250, and then a gust of wind came and you suddenly find yourself at 270.

The auto throttle does an amazing job at keeping the desired speed. It is constantly moving during the cruise (even if by 0.1% of N1) to hold speed.

If a gust of wind was to come up, the auto throttle wouldn't just cut all the thrust in one hit. That's called chasing airspeed which can be dangerous. Being a gust, it is temporary, so would be acceptable by ATC to exceed the speed restriction for a moment. The auto throttle system would then counteract the deviation slowly.

 

[eric2011]

If a gust of wind was to come up, the auto throttle wouldn't just cut all the thrust in one hit. That's called chasing airspeed which can be dangerous. Being a gust, it is temporary, so would be acceptable by ATC to exceed the speed restriction for a moment. The auto throttle system would then counteract the deviation slowly.

So lets say you suddenly got hit with a tail wind and increased your speed by 40 knots. To reduce the deviation slowly, how long are you talking, i.e., seconds, a minute or a number of minutes

 

[AviatorInsight]

So lets say you suddenly got hit with a tail wind and increased your speed by 40 knots. To reduce the deviation slowly, how long are you talking, i.e., seconds, a minute or a number of minutes

Yeah it'd be over a matter of seconds. Depending on the severity of the conditions, a gust of wind like that is unlikely to stay like that for more than a couple of seconds anyway. The auto throttle system will then determine the rate at which it needs to compensate for that and adjust the thrust accordingly.

However, should it be a sustained tail wind then the auto throttle will reduce the thrust at a constant rate, any extra help to get it back to the targeted IAS will be accompanied by the use of speed brake.

 

[jb747]

What are the most common causes of runway excursion? How common is wind in such incidents?

VA1465 MEL-DRW (VH-VUI) left RWY29 on landing in DRW last night.

I don't know what the TAF or observations were at the time, nor whether the runway was wet or dry.

The time of occurrence is broadly consistent with the time a storm passed through the area around 11pm.

I haven't seen anything on this, other than the fact that the aircraft departed the runway. In theory a gust could take you off the runway, but it would pretty much have to be both wet, and very strong. I expect that most 'excursions' actually start some time beforehand, perhaps with a landing that's well off the centreline (and downwind puts you closest to the most dangerous edge), or with a touchdown vector that isn't down the runway.

At this point though, there's too little in the public domain to really say.

 

[jb747]

So lets say you suddenly got hit with a tail wind and increased your speed by 40 knots. To reduce the deviation slowly, how long are you talking, i.e., seconds, a minute or a number of minutes

The Airbus uses a different programme mode when in the cruise, to reduce the amount of thrust chasing (which is itself not efficient). So, in the cruise a variation of a few knots will be adjusted for, but not in any particular hurry. Probably around a minute or so. The system will become more aggressive as the deviation increases, and manoeuvring around weather at altitude it's not that unusual to see maximum power.

The sort of wind change you're taking about is normally seen in climbs or descents, and the response will generally be a pitch change, or manual selection of the speed brakes if that can't catch it. In climb/descent, the auto thrust isn't attempting to control the speed.

An instantaneous 40 knot tailwind at altitude would almost certainly drop your speed below Vmin drag, and you'd be unlikely to have enough power to accelerate again without trading off height. Thankfully not a normal scenario.

In level flight, a gust that puts you into the 'bricks', will initially be countered by thrust reduction (to idle if necessary), but if it stays above the max for more than a few seconds or about 4 (variable) knots the flight control system will cause a pitch up.

It's normally never an issue unless you're operating at the very fast end of the speed scale, and about .03 mach above the normal numbers.

On approach the systems are aggressive, and chase any speed change instantly.

 

[TomVexille]

I know while go-arounds are normal I experienced my first one as a passenger (done a couple in a 172) on Sunday morning. The explanation once we got back up was that we had lost communications with the tower, didn't yet have landing clearance and we didn't get the green light. So I guess the question in there is, how often do you lose comms and not get the green light?

 

[Boris spatsky]

I know while go-arounds are normal I experienced my first one as a passenger (done a couple in a 172) on Sunday morning. The explanation once we got back up was that we had lost communications with the tower, didn't yet have landing clearance and we didn't get the green light. So I guess the question in there is, how often do you lose comms and not get the green light?

Never seen it in civil flying - we have so many radios and a satphone so unlikely to lose all of them unless there is a total electrical failure.

 

[TomVexille]

Never seen it in civil flying - we have so many radios and a satphone so unlikely to lose all of them unless there is a total electrical failure.

It did sound like it was a very temporary issue as they had reestablished comms by the time they explained the reason for going around
to the cabin

 

[jb747]

I've never seen an airliner lose all comms, but I have seen it in the other direction, in which the tower loses everything. Twice, both times at Singapore Changi.

The first time, thankfully, I was on the ground, listening. It was extremely messy, and went on for over an hour. Not only was the tower gone, but also the entire area control.

The second time, I was on approach, and was impressed to see a green light. We probably would have landed anyway, because having seen the previous debacle, I wasn't about to launch back into some very crowded, uncontrolled airspace.

 

[jb747]

The sort of stuff that leaves you unable to decide whether to laugh or to cry.
Incident: Go2Sky B738 at Kristiansand on Nov 4th 2016, "racing start"

 

[TomVexille]

The sort of stuff that leaves you unable to decide whether to laugh or to cry.
Incident: Go2Sky B738 at Kristiansand on Nov 4th 2016, "racing start"

Isn't that why there are checklists??

 

[QF WP]

I think I'll advise my brother (who is over there at present), not to fly them...what a clusterduck . Some re-training needed

 

[petercr]

Sounds like Go2Sky = flying with wings and a halo...

 

[Boca68]

The sort of stuff that leaves you unable to decide whether to laugh or to cry.
Incident: Go2Sky B738 at Kristiansand on Nov 4th 2016, "racing start"

Laugh from this distance, probably cry if I was on the flight.

 

[docjames]

The sort of stuff that leaves you unable to decide whether to laugh or to cry.
Incident: Go2Sky B738 at Kristiansand on Nov 4th 2016, "racing start"

Just appalling.

 

[joey1695]

Afternoon JB, Boris and AviatorInsight!
Let me preface by saying I know that JB has both Airbus and Boeing experience however Im not sure about both Boris and AviatorInsight.
My question to all three of you is, if you could design an aircraft out of a combination of Airbus and Boeing technology, which of each manufacturers components would you choose for their specific jobs and why?
Im thinking along the lines of the coughpit and the interfaces within (fmc), PFD, ND, EICAS/ECAM etc etc. Also any specific structural designs you feel may be of interest (door types, wing shapes) etc. Bit of a broad question I know, but I'd be very interested in reading the various responses.
All the best,
Joe.