Posts by SkippyBing

Re: Like AF447?

According to the report the pitot heaters were definitely on, the belief is that there was a build up of moisture in the pitot system that led to a blockage, leading to unreliable airspeed and AoA measurement.

Re: Dry, hot and dusty

Update having skimmed the report, it appears due to occasional issues with water ingress to the pitot system the aircraft are always operated with the pitot heaters on, including in this case. Plus they purge the system as part of the maintenance. What they didn't do was activate the wing de-icing but examination of the air frame with the camera pod didn't show any icing.

Two different designs of pitot are used, but the conclusion seems to be that moisture accumulated in both during the flight leading to errors in speed as altitude changes. It could also affect Angle of Attack and Angle of Slip measurement as they're done via the pitot system on Watchkeeper, rather than a rotating vane as on most airliners, including the 737.

This one really isn't the Army's fault, it was the manufacturer flying it to test something that they'd done. So totally on Thales.

Re: Dry, hot and dusty

Not true, Watchkeeper is supposed to be an all-weather version of the Hermes 450. Hence pitot heaters, a redesigned icing resistant wing etc. In this case as far as I could make out, although the aircraft was obviously in icing conditions the operators didn't select the heating on as there was no indication from the aircraft, despite all the warning signs being there.

Incidentally it was being flown by Thales, the manufacturer rather than the Army, so I'd blame them for this one.

Re: Birds

In the first crash the sensor appears to have been faulty before take-off so it may just have been faulty, certainly the work was done on it post the previous flight indicates there were issues. In the second crash the sensor became faulty after take-off, which makes it most likely it hit a bird. If you google pictures of bird strikes they don't have to be direct to cause damage that would cause a false reading.

Re: Birds

AirAsia Flight 8501 was caused by the pilot trying to do something only an engineer should do while the aircraft is on the ground.

I can't figure out what the 'Fairfax incident in Canada' is as there's no obvious link to an Airbus crash.

I think the air show incident you're referring to was actually at Mulhouse–Habsheim and was due to the flight control system preventing the pilot stalling the aircraft, mainly because it thought that if you configure the aircraft to land that's what you want to do. Especially if you make your flypast at 30' not the 100' that had been briefed.

None of these are directly attributable to negligence on the part of Airbus, not that I'm denying that there may have been, or could be accidents due to negligence on their part. It's just your examples don't demonstrate that.

It's perfectly acceptable to have someone with less than 300 hours as the co-pilot on the 737. Ultimately if they've got 1000 hours experience on a Cessna and 150 on a 737 they're unlikely to be any better at handling the situation.

What could be construed as negligence is designing a flight critical piece of software that only uses one sensor and doesn't do a sanity check on the input. It appears in this instance the AoA sensor was reporting ~70 degrees nose up, if you've managed that at 250+ knots in an airliner stalling is the least of your problems.

Re: Fun Fact

Also of ex-USN WWII vintage were the submarine we sunk and the patrol boat that was subject to the Gotcha headline.

Re: Add them to the power grid

I think they looked at that in the '60s or '70s to cope with strikes leading to power cuts. It was more trouble than it was worth in that case, and the retired ones probably need re-fueling.

Re: Plymouth?

'Having decaying ships & subs so near to where people live isn't a good thing, they leak all the time.'

Decaying is a misnomer, they're still maintained and have a skeleton crew to prevent that happening.

Re: the most expensive weapon system in history?

'On the other hand, an F-15K actually costs about the same as an F-35, but the F-15 costs far less to keep it running.'

It's actually not that much less. F-35A is ~$29,500 an hour, F-15C is ~$24,000 an hour. Not sure about the K but it's not going to be that much less, and the F-35 is still in the developing stage where the F-15 is in the mature stage where they've used experience to lower the costs.

https://www.businessinsider.com/price-military-aircraft-per-flight-hour-2016-8?r=US&IR=T#f-15c-6

I've seen other lists that include the V-22 and that's more like $80,000 an hour vs $7,000 for a C-130.

Re: A sporting chance

'The lessons learned in WWI and WWII about aircraft and mission types has been forgotten.'

On the flip side since then there have been many successful aircraft that combined the fighter and bomber roles. E.g. F-4, F/A-18, F-14 (once they remembered the software was in there), F-16 etc.

Plus there were several aircraft in WW2 that performed fighter and bomber roles, e.g. the F4U and F6F, hell even the Seafire could dabble in bombing and reconnaissance.

F4U also had the slight issue that the pilot was so far from the nose you couldn't see the carrier on finals. The RN actually took it to sea before the USN as a) they were desperate for modern fighters and b) they'd already mastered the curved final approach with the Seafire as that had the same problem.

The USAF did also use the originally designed for the USN A-7 Corsair, although the USMC didn't going for the Harrier instead. In the UK the RN and RAF both used the Buccaneer, Harrier, Phantom, and Venom.

Re: Easy to hack ...................

'By the time the F-35 enters UK service'

So 10 Jan this year then?

Currently it has full nose down trim authority, which means you have to be pulling something like 50kg back force on the control column to keep it in level flight. I'm assuming they did this rather than limit it to avoid potential problems with the limit, after all there's no situation where it'd actually need to wind it all the way forwards right?...

Re: Avionics experts and the court of public opinion....

The grounding is because they're not sure why a second 737 Max has ploughed in in only six months, for a type that's only been in service since May 17 that's a terrible record. If you don't know why an aircraft has crashed it's often considered a good idea to stop flying them until you know why. For a similar example look at the Comet, until they know for certain why these things are crashing it's not worth the risk. Although if you think it is you can probably get a used example quite cheaply now.

Re: Seafire conversion of Spitfires in the 1940s

The fix was slightly more than a spring. Basically the problem was the pilot could apply more back stick than the aircraft could handle in certain situation leading to the nose pitching up too far/rapidly and the aircraft breaking up, due to the aft centre of gravity. It was so far aft they packed lead into the engine bearer and it was still on the limits of what would be acceptable for the land based variant.

To counter this a weight was hung off the front of the control column, this meant as the g-forces increased the pilot would have to apply increasing back pressure. Consequently pulling out of a dive the stick would actually be moving forwards despite the pilot maintaining a constant pressure.

The spring came into it to keep the control column in the neutral position. Unfortunately Supermarine mounted the weight horizontally off the front of the control column, so in a vertical dive it was hanging straight down and the pilot could still apply too much aft pressure before the g would act on the weight in the required direction. Leading to a loss of wings and the aircraft. The Fairey Firefly had a similar issue but the mount for the weight was at a 45 degree angle. And they didn't faff around with springs.

More on this, and other aspects of flying the most inappropriate naval aircraft of WW2, in the excellent 'They Gave Me a Seafire' by Mike Crosley.

Re: A programming error?

'the software seem to always assume that the sensors are correct and the pilots are not'

Actually the software realised it wasn't sure what was going on and handed over to the pilots. It turns out suddenly handing a difficult situation to a pilot who is mentally relaxed doesn't work well...

Re: Background

'As I understand it, it does warn about what it is doing.'

My understanding is that the pilots were unaware it even existed prior to the Lion Air incident, and therefore there's no indication that it's doing anything.

Re: According to the BBC...

This would probably be classed as LOC-I, Loss of Control Inflight, which is also an option under the ICAO Air Accident Taxonomy.

Re: Background

'You can describe MCAS like that'

Which is why I did, mainly because I found it too depressing copying and pasting the full explanation of the certification issue I made four months ago.

https://forums.theregister.co.uk/forum/all/2018/11/27/boeing_737_max_mcas_lion_air/#c_3665169

Re: Background

Strictly it's not a new stall warning system, it's an anti-stall feature that trims the aircraft nose down to prevent it stalling. If it gets erroneous data it can continue to trim nose down when there's no need to. The trim moves the whole tailplane, whereas the pilot's controls only affect the elevator, consequently it's almost physically impossible to pull out of a fully trimmed dive.

It doesn't work in the opposite sense, so it shouldn't trim the aircraft into a stall, although the normal trim could do that, although I'm not sure it has full trim authority*.

*i.e. the automatic system may not be able to trim to the limits.

It also looks like SWA ticked the AoA display option on their 737 Max aircraft which means they also get a warning if the two sensors disagree. So if it is the same problem Lion Air had SWA pilots have a bit more information to work with.

Only 35 of SWA 737s are this variant at the moment, although they've got over 200 on order...

Worth noting Ethiopian can't be that bad as they're allowed to fly into European airports. There's a disturbingly long list of airlines from the developing world that aren't due to maintenance and training concerns.

Incidentally you can cover static ports (the ones that are flush with the skin) you basically get a little plug that sticks in the hole. Clever designers make sure the tube part has a hollow core so if it gets broken on removal the static port still works.

Re: Just to big to win

To be fair far more of Rolls-Royce's A380 engines stayed on the aircraft...