2 Silicon chip Australia’s electronics magazine siliconchip.com.au
“Crippleware” possibly to blame
for two airliner crashesNicholas Vinen
Editor Emeritus
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Editorial Viewpoint
No doubt you have heard about the two Boeing 737 Max
8 airliners which crashed in the last six months: Lion Air
flight JT610, which crashed on 29 October 2018, killing
189; and Ethiopian Airlines flight 302, which crashed on
March 10, killing 157.
You may have also heard that there is a suspicion that a
fault in the angle-of-attack (AOA) sensor, which controls the MCAS anti-stall sys-
tem, led to both crashes. This system can move the nose of the aircraft up or down
if it thinks the aircraft is in danger of stalling. But faulty sensor data could lead it
to ‘fight’ the pilots during normal flight.
(A report on the flight 302 crash, unofficially released as I am writing this, claims
that there was no indication of damage to the AOA sensor. But it still seems that
MCAS was a factor in both crashes.)
In a truly bizarre engineering decision, although these aircraft have two AOA
sensors, only one was used as an input to the MCAS system. I can’t understand
that; if you have redundant sensors, why not use them? And how could they have
thought that MCAS did not need redundancy, when it affects how the plane flies?
At the very least, if the two sensors were giving different data, MCAS could be
disabled on the basis that it’s better to do nothing than act on suspect data.
But even more damning to me is the fact that the aircraft were fitted with a
warning system which tells pilots when the two sensors are giving conflicting
data (which would be required even if MCAS paid attention to both sensors). But
on both doomed aircraft, it had not been enabled because that feature cost extra!
I’m sorry, but these sensors were inputs into a system which affects how the air-
craft flies. Charging extra for a safety system which is just activating a pre-existing
warning light is wrong on so many levels. I understand that this system will now
be enabled on all 737 Max 8 aircraft via a software update.
I think that’s called closing the stable door after the horse has bolted.
I’m not the kind of person to get worked up about little things, but it annoys me
when manufacturers sell me an expensive product which has extra hardware fea-
tures, but they won’t enable them unless I pay more.
This practice is known as “crippleware”, which is when “vital features [of soft-
ware or hardware] ... are disabled until the user purchases a registration key”.
While I don’t necessarily mind paying a little bit extra to enable more features,
it isn’t unheard of for the cost of these extra features to add up to way more than
what you pay for the item in the first place! That makes me very annoyed.
And it isn’t just aircraft where safety features have become crippleware. Every
night I see people driving around without their headlights on. That’s dangerous.
There have been times where I have come close to having a collision with such a
vehicle, as I could not see it until the last second.
In modern vehicles, this can be easily solved by the addition of a ten cent LDR
to detect the ambient light level, a few lines of code to switch on the headlights
when it’s dark and maybe an extra transistor or relay to do the switching.
We’re hardly talking sheep stations to implement this basic safety feature.
In some cases, automatic headlights can be enabled by plugging a laptop into the
car and twiddling a bit in the ECU. And yet, many manufacturers charge several
thousand dollars for the “options” package which includes this feature.
I think this should be made mandatory on all new vehicles. It’s a fundamental
safety feature which costs almost nothing to implement.
And I’d hate to have been involved in designing the 737 Max 8, especially the
MCAS or related systems. They’re going to have some very awkward questions
to answer.