dutchroll

I don't mind LAHSO. I don't know anyone who flies big planes and likes SODPROPS. Fundamentally different reasons for them. LAHSO does increase movement rates. SODPROPS is 100% political. Why else would you have opposite direction arriving and departing traffic on a parallel runway system? The problem is that kicking up a stink about it (whether by paperwork, exercising PIC powers, etc) gets nowhere, except a delay, a hold, complete indifference, etc.

I agree the linked article is ridiculous. My entire point here is that, going by online discussions I've seen recently, there are a swag of small plane pilots who actually believe that a headwind changing to a tailwind has no effect on them. Ever. Articles like the "Flying Magazine" one are not helping to distinguish the different scenarios. This is due to poor quality discussions about the "downwind turn myth". And yeah, I agree in a steady state wind it is a myth. There is no issue turning onto downwind which would be caused by the increasing tailwind. It is not the same as windshear. I agree. I agree. Did I mention that I agree? It is just a demonstrated fact from various message boards that some pilots reckon if they're sitting there on final approach and the headwind turns to a tailwind, the plane will look after it because it doesn't care what its frame of reference is. All that will change is the groundspeed. Best of luck with that.......... Disclaimer for something I wrote earlier: this mythical "instantaneous 180 degree turn" is a different scenario. It's not really the same thing a experiencing a wind change. I shouldn't have even written that because it's irrelevant.

You quoted this: If you're disagreeing with that particular dot point, then you're disagreeing with reality. I can't argue the point any further.

Actually I was specifically referring to some really poor analogies made on the Straight Dope message boards on this topic. For a message board which reckons it gets straight to the truth, they just got more and more confusing as they went on. Even delving into formulas for momentum, etc which really didn't help anyone understand the reality of what was happening when the relative wind changes. Don't be so paranoid Nev! I talked about windshear versus a steady state wind because a number of people online tried to argue that wind changing from headwind to tailwind makes no difference to aircraft performance. True or untrue? Well that depends. If you took a plane with a set power and attitude, and 100 knots headwind, its IAS would be exactly the same if it had 100 knots tailwind. If you took a plane with a set power and attitude, and 100 knots headwind, then very rapidly changed that to 100 knots tailwind, its IAS would drop sharply and it would be in trouble. Turning downwind in a steady state wind isn't really enough to do that (for the purposes of our discussion and in the planes we fly). They had the correct conclusion, but the wrong way of reaching it. A wind change from headwind to tailwind can have dramatic consequences, but again it's that "apple versus oranges" thing. Just as a minor point of curiosity, most people think the big wind changes only happen close to the ground. Not true. It happens more often at altitude during climb or descent. It has the most serious consequences close to the ground. The most dramatic windshear I've ever encountered was in a B767 at 20,000 ft during climbout from Sydney. It caused us to overspeed the aircraft (exceeded VNE of 360 knots IAS) in about 15 seconds, with klaxons and warnings going off everywhere, full speed brake out, still climbing. It's quite a difficult situation because you generate a massive rate of climb to control the speed, but at some point you have to undo that when the wind change stops. On both the B767 and the Airbus A330, you need to continually watch for wind changes on descent from cruise altitude or again you can overspeed the aircraft if you're distracted when it happens. Descending into a reducing tailwind could do it, whereas descending into a reducing headwind would cause the IAS to decrease which is easily fixed with a pitch down and increased rate of descent.

Reading through this thread both made my head spin, and led me to the same topic on the "Straight Dope" message boards, which made it spin even faster to the point it was lucky not to fall clean off and whiz across the room. One problem is using poor analogies, and another is getting excessively bogged down in physics. (I'm truly surprised no one has invoked Einsteins Theory of General Relativity.....oh wait, I think they did!) Simply: I can't imagine a normal, correctly executed turn onto downwind, would lead to a stall in constant wind conditions. Unless you're flying out at perilously close to the power-on stall speed - and that's not the wind's fault. So what therefore, do we think of windshear? Is this not a sudden change of headwind into tailwind or vice-versa which can cause tragedy? - I see the heads nodding furiously. Well, yes it certainly is. But equating the way the aircraft responds to a wind change during windshear (especially a severe one) to the wind change on a downwind turn is a case of "apples versus oranges". A windshear event where headwind very quickly turns into a tailwind causes a transient loss of lift. This is because the inertia of the aircraft prevents it adjusting to that wind change instantaneously. Normally your power and attitude would give you a set performance (and thus IAS). This is true in whatever static headwind/tailwind conditions you like. But a rapidly changing wind results in the aircraft briefly needing to play "catchup" in the absence of power and/or attitude changes to force it. Mild windshears are not too much trouble. Severe ones are different, and need accompanying severe action. A constant wind velocity during a normal downwind turn simply doesn't result in an adverse lift change that quickly, at least not one which can't easily be controlled by a modest adjustment in attitude. Some people on message boards have said "yeah well what if you did a 180 degree turn instantaneously in a 60 knot headwind?" WTF? Ok yeah sure, you're probably "simulating" the equivalent of a severe windshear then, and yeah theoretically you could be in trouble if you want to maintain level flight (if you haven't already g-stalled it). However this discussion doesn't involve advanced aerobatics. We're talking "normal" flight. It's all about how a wind change affects your lift and how you respond to that. What could cause you to stall turning onto downwind is poor flying technique (eg, inattention etc), much like stalling on base, and that's another discussion, and also not the wind's fault.

Sort of amusing, and sort of dumb and generally untrue at the same time......

Yours truly, getting ready to go for a bit of a hoon. "Bloody hell.....I know I put the Maintenance Release in here somewhere!" Big prop. For scale purposes, I'm 6'1 (185cm).

.......and crazy Drifter pilots. Aside from that, the normal people are inside with the A/C on enjoying an ice cold beer.

No one comes out on those days. Except slightly batty glider pilots.

This scenario is not at all uncommon but unfortunately the combination of an ATC trainee using confusing terminology and a LAHSO sequence which was a bit tight resulted in 2 almost simultaneous go-rounds. It doesn't appear that any aircraft got a TCAS RA, so there was no imminent threat of collision or any requirement to take avoiding action by the pilots of the two 737s. They may have got a TCAS Advisory ("Traffic, Traffic") but this is just a monitoring situation. It looks untidy and it was a bit, but the two aircraft would've been well aware of each other's presence and also well aware of their respective tracks. I'd love to post video of simultaneous visual arrivals on 34 at Sydney for you if you want a real eye opener (being turned onto final while being head on with traffic turning onto final for the other runway, then paralleling them so close that you feel you can reach out and touch them), or SODPROPS (simultaneous opposite direction parallel runway ops, one aircraft departing opposite to you while you're on final)). Unfortunately I'm not allowed to do that! So yeah.....although it was a bit untidy and ATC need to get their LAHSO spacing sorted out a bit better, this is being made out to be a lot dicier than it actually was.

The United 811 door loss which was pictured was actually traced to an electrical fault (short circuit) in the door locking system which drove the latches towards unlocked after the aircraft departed. The eventual recovery of the door from the ocean bed several years later allowed them to determine this. Also a couple of years after this accident there was an incident on the tarmac with another United B747 where engineers were trying to trace an electrical fault in the cargo door and it spontaneously opened. Boeing had to redesign all B747 cargo door locking mechanisms after this accident.

Strong floor beams & longerons!

Yes that was a prime example - probably still to this day - of the "unzipping" of a fuselage skin structure already weakened by undetected corrosion and cracking. With the new maintenance regimes around the world put in place as a direct consequence of that accident, a similar major structural failure should never happen again.

Actually the Airbus sneaks in a couple of mechanical links too, but let's not complicate things....

Traditionally under the floor or through the ceiling cavity. But with fly by wire aircraft, there are no big cables as such with control commands travelling on a databus. There is quite extensive segregation built into the FBW system on an Airbus with the primary and secondary flight control computers all being in different locations, as well as having different databus routes through the plane.

Alternatively, we can make an attempt to get it back on topic. But first, just something I have to deal with...... What utter rubbish. Gathering facts has never been your strong point has it? Aside from seeing it in several major newspapers here, I also saw it on national TV news. A quick google search also shows it prominently reported on CNN, NBC news, CBS news, Reuters, The Guardian, The Daily Mail, The Independent, The Seattle Times, BBC, Sky News, New York Post, New York Times, Japan Times, New Zealand Herald, Times of Israel, The Mirror, The Sun, Los Angeles Times, French TV, China Daily, India News........and I'm sick of scrolling through the news links already. Now, only one person having died, the plane landing successfully, and being anything to do with Africa, it makes for a short lived news story and very limited shock and horror in any case. Now where was I? Ah yes, that's right. An interesting facet of this is the structural integrity of the aircraft. A lot of people think bomb + hole = plane disintegrates, but you can clearly see that providing it doesn't explode into any vital systems, it actually hasn't caused anywhere near a mortal wound. Same goes for the myth of gunshots fired from inside the plane. A gunshot won't blow a massive hole in the side. Just a small hole with a small pressure leak would be the result. Modern well maintained aircraft structures are quite self limiting in terms of damage. As far as the bombing itself goes, it was clumsily inept. It was nowhere near powerful enough to bring down an airliner by an explosion inside the cabin.

Yeah that's technically correct Nev, but we already know pilots are imperfect creatures, and bad stall characteristics coupled with a pretty tight flight envelope in a homebuilt aircraft, well........someone needs to make it clear that has consequences. It's not a plane for beginners. Yet beginners with a lot of money like to buy them. The IV has been criticised for its flight envelope characteristics by some very experienced pilots. One former U2 pilot was shocked by its stall characteristics, another likened it to flying a P-40 Warhawk, and Doug Rozendaal of the Commemorative Air Force said after flying it that he wouldn't recommend it to anyone! The company has made substantial improvements to the later variants however.

High performance, fast, slippery single engine homebuilt aeroplane often bought and flown by people who should be aiming at something a bit less demanding........a common cause of high accident rates in these types. The Lancair 4 in particular is a bit of a handful at the edges of its flight envelope. "Challenging" stall characteristics, etc. Also if you attempt a turn back following EFATO in a Lancair 4 as in the Appleton accident, you will die. ** I believe the stall characteristics of the later models are vastly improved

Ah....I must've been off flying somewhere!

A little disappointing you didn't get a shot of the beautiful orange & blue beast next to it.......

Off topic threads are where people either seek to let off steam, or observe how the other half live, or sometimes just muse over various alternate realities. It also allows a degree of "robust" discussion of the above. I think you'd find (at least it's my experience) that visits to the off topic thread often occur after a browse of the flying threads turns up nothing of particular interest to that individual, ie, people don't specifically come to the site just to go to the off topic thread. At least I hope not. Having said that I'm perfectly happy if Admin wants to go the way of VAF forums. Although with VAF forums being US-centric, allowing off topic threads would start World War 3, so I can understand why they don't do it there. Not so much the case here in comparison.

Perhaps I should have written (and the witness should have stated): The plane was seen flying at very low altitude. A short while later it impacted the water. But I think we all knew the intended meaning..........

We use "RAISE" to manage upwards to the PIC. Enquiry stage: R - Relay information (We're at 500ft and it looks pretty bad ahead) A - Ask if they are aware (Are you seeing that weather ahead?) Concern stage: I - indicate concern (I'm a bit worried about that weather ahead and our altitude.) S - offer a solution (How about we turn around and go back?) Emergency stage: E - use emergency language (WE MUST TURN AROUND NOW OR WE'LL BE IMC AT 500 FEET!) I know this sounds long-winded, but you can skip any stage as appropriate (eg you might end up going straight to the "emergency" stage). Also you'd be surprised how often just the "enquiry" stage is enough to prompt action from a pilot. Then you don't have to go any further into it.

The ATSB, like almost every Government organisations except the Border Force, is very under-funded. With multiple concurrent investigations running and a limited numbers of investigators and resources, unfortunately the long wait for final reports is a consequence.

Yes. That's correct.