Re: [SystemSafety] MH370

From: Peter Bernard Ladkin < >
Date: Mon, 10 Mar 2014 21:25:28 +0100

> On 10 Mar 2014, at 18:45, Gergely Buday <gbuday_at_xxxxxx >
> Any expert opinion on that?


Some of this is tropes that arose 5 years ago with AF 447 and were then definitively answered. It is disappointing that a journalist for a major newspaper is repeating them without taking into account the engineering answers that were available, and aired, then.

There is a question how far we have come since then, and the article does mention some development work by Boeing, which I found intriguing but know nothing further about, despite having asked.

The answer to "my iPhone can do this-and-this; why can't this hi-tech airplane?" is that your iPhone doesn't have the reliability requirements that critical data transfer from an airplane has or will have. Quite apart from the engineering requirements, consider that when a large commercial transport airplane is lost, there is some €200m-€1bn in play in terms of compensation. Get the data a bit wrong and somebody is paying out huge amounts of money that they shouldn't have to pay out, and somebody else is getting away scot free who should be paying.

The answer to "we send movies over WiFi, why can't we do DFDR data?" is that (i) we obviously can, but (ii) it has to travel by satellite for over-ocean flight; (iii) there are lots and lots of airplanes out there flying - at any one time, two-thirds of the entire fleet is in the air, so that's lots of data over a comparatively narrow channel; (iv) most of that data is useless, since the aircraft arrive safely, but it would cost the airlines oodles of money to send all that useless data, each flight.

The answer to the subsequent question: "why don't we fix all that?" is: using current protocols, including appropriate error detection, we'd have to put up more satellites - and of course the industry will pay; that is, it comes on your ticket, whereas the current setup is free courtesy of the US military (and, more recently, the EU to whom populations of member states want to give less money). And for what?

I could check, but off the top of my head we've only had two accidents over water in the last twenty years in which finding the FDR was difficult: Adam Air; AF 447 (maybe three, if Malaysia turns out to be difficult, but I would bet on finding it within a week. An ELT transmits up to 30 days by requirement, and often longer by happenstance). This is a small, but I grant not negligible, proportion of over-water losses. TWA 800, SW 111, the last China Air passenger Boeing 747 were all found relatively easily. Air India took a lot of work. But *all* were eventually found, including Adam Air and AF447. So it's purely a question of effort, that is, cost.

So it's worth doing a cost-benefit analysis. Who's done it? No journalist I know.

But, of course, we don't stand still. The article suggests that Boeing has been trying to figure out ways of transmitting useful data routinely and cost-effectively. More power to them, and to those other engineers trying to make it easier to get useful data from lost airplanes with lost DFDRs.

But, finally, would we be better off, if we got sparse data transmitted by satellite from a lost airplane at lower cost and then we give up at that point, rather than actually spending all those resources to find and retrieve the DFDR with all its data, along with most of the airplane? As an engineer, I'd say: I don't think so. As an engineer, I want to know What Went On in all its detail, not just some summary chosen as "enough" by beancounters. I am very glad the effort was put in in all these cases to find the wreckage and, along with it, the DFDR. I don't want that not to be done in future.

PBL Prof. Peter Bernard Ladkin, University of Bielefeld and Causalis Limited

The System Safety Mailing List
systemsafety_at_xxxxxx Received on Mon Mar 10 2014 - 21:25:41 CET

This archive was generated by hypermail 2.3.0 : Tue Jun 04 2019 - 21:17:06 CEST